Reliable chronology is crucial for reconstructing the sedimentary history and sea level fluctuations. However, the lack of robust ages for late Quaternary deposits on the North Yellow Sea (NYS) shelf hampered our understanding of its sedimentary processes. In this study, quartz optically stimulated luminescence (OSL) and feldspar post-infrared infrared stimulated luminescence (post-IR IRSL) dating protocol were utilized to establish a detailed chronostratigraphy for the upmost 30 m of core DLC70-2 from the central NYS. Based on lithology features and dating results, three transgressive layers (hereafter referred as T1, T2 and T3, respectively from top to bottom) were identified. The consistency between two OSL dates (10.3-6.7 ka) and six radiocarbon (14C) dates (10.4-4.9 cal ka BP) indicates that the T1 layer deposited during MIS 1. Five quartz samples yielded saturation ages of >53 ka, combined with one feldspar pIRIR290 age of 76±7 ka from the top of the T2, suggested that the T2 layer should have formed no later than MIS 5. For T3 layer, two saturated quartz ages of >71 ka and a feldspar corrected age (191±17 ka) revealed that the T3 layer has formed at least during MIS 7.
Based on the renewed chronostratigraphy of core DLC70-2, we reconstruct a comprehensive late Quaternary stratigraphy using ten previously published cores from the Bohai Sea and Yellow Sea. The occurrence of cold-water species Buccella frigida and Protelphidium tuberculatum during MIS 5 indicates there existed a cold-water mass (cyclonic eddy) similar to present-day marine circulation. Additionally, the late Quaternary stratigraphic correlation is supported by the previously chronostratigraphic reconstruction of coastal loess. These findings will enhance our comprehending on the sedimentary processes and their paleo-environment changes on the eastern Chinese shelves during late Quaternary.
Key words: luminescence dating; North Yellow Sea; late Quaternary; stratigraphic construction; transgressive deposits; core DLC70-2
How to cite: Tang, N., Wang, Z., Lin, P., Liu, Y., Wu, Z., Tian, H., Mei, X., Sun, J., Qi, J., Li, R., Wu, S., Chu, H., and Lai, Z.: Luminescence dating of core DLC70-2 from the North Yellow Sea in China and its implication for late Quaternary transgressions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15355, https://doi.org/10.5194/egusphere-egu25-15355, 2025.
East Asian summer monsoon (EASM) played key role in controlling the hydroclimate of East Asia continent regions. However, the Late Holocene changes of EASM in its northern margins are still unclear, which urgently needs to be revealed in the field of climate research. Here we systematically analyze the grain size of peat ash from core ZB-7 in the Zhibian peatland and core DFHN-2 in the Dongfanghongnan peatland to address this issue. Results show that the silt fraction occupies the most component of peat ash in cores ZB-7 and DFHN-2. The grain size distribution curves of peat ash of two cores display single peak pattern. The probability cumulative curves of two cores exhibit as two-sections mode. Three end-members (EMs) displaying single peak are identified in cores ZB-7 and DFHN-2. The EM2 of core ZB-7 and EM1 of core DFHN-2 represent the contributions of surface runoff. The EM2 of core ZB-7 demonstrates a series of periodicities, such as 1000a, 500a, 210a, 110a, 88a and 66a during the Late Holocene. The correlation relationship analyses indicate that the EM2 of core ZB-7 and total solar insolation (TSI) show opposite phase with El Niño-Southern Oscillation (ENSO) activities. Furthermore, five evolutionary stages of the EASM in northern margins were identified. Less ENSO activities and declined TSI regulated the decreased precipitation during stage 1 (4338-3479 cal. yr BP). The frequent ENSO activities and declined TSI induced low precipitation in stage 2 (3479-2297 cal. yr BP). In stage 3 (2297-949 cal. yr BP), the continuously decreasing ENSO activities resulted in high precipitation. Frequent ENSO activities and low TSI induced low precipitation during stage 4 (949-231 cal. yr BP). While the increase in TSI and decrease in ENSO activities regulated increased precipitation during stage 5 (231 cal. yr BP-Present). This study would expand our predictions on the future hydroclimate changes in monsoon northern margins.
How to cite: Zhang, M.: Late Holocene variations and driving mechanisms of the East Asian summer monsoon in northern margins: Evidence from peat ash grain size, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2109, https://doi.org/10.5194/egusphere-egu25-2109, 2025.
High-resolution (millennial-scale) chronology is becoming more and more important in sedimentary process reconstruction, which could uncover unexpected events, in particular hiatus. It is assumed that sediments in endorheic basin should be continuous. However, Our large luminescence chronology data revealed that, since late Quaternary, hiatus were common in the cores of the endorheic Qaidam Basin in the Tibetan Plateau, especially in the Last Glaciation Maximum (LGM) during which the endorheic lakes dried up and then the wind erosion was dominant.
Our large dataset of luminescence dating in deltas/fluvial-plains also displayed similar discontinuous pattern in core sediments, demonstrating unexpected hiatus which was omitted by previous studies, as well as the impacts of human activities revealed by changes of sedimentation rate.
It is strongly recommended the wider application of high-resolution chronostratigraphic methods in sedimentary research, and dense sampling for optically stimulated luminescence (OSL) dating. The combination of Single Aliquot Regeneration (SAR) protocol (Murray and Wintle, 2003) and Standardized Growth Curve (SGC) protocol (Roberts and Duller, 2004; Lai, 2006), SAR-SGC (Lai and Ou, 2013), routine used in our laboratory, will be of great help in this regard, which could save machine measurement time for at least 70%.
Key words: Luminescence chronology; high resolution; hiatus; sedimentary process.
References
Lai, Z.P., 2006, Testing the use of an OSL standardized growth curve (SGC) for determination on quartz from the Chinese Loess Plateau: Radiation Measurements, 41, 9–16, doi:10.1016/j.radmeas.2005.06.031.
Lai, Z.P, Ou, X.J., 2013. Basic procedures of optically stimulated luminescence (OSL) dating. Progress in Geograpgy, 32, 683-693 (in Chinese with English abstract).
Murray, A.S., and Wintle, A.G., 2003, The single aliquot regenerative dose protocol: potential for improvements in reliability: Radiation Measurements, 37, 377–381, doi:10.1016/S1350-4487(03)00053-2.
Roberts, H.M., and Duller, G.A.T., 2004, Standardised growth curves for optical dating of sediment using multiple-grain aliquots: Radiation Measurements, 38, 241–252, doi:10.1016/j.radmeas.2003.10.001.
How to cite: Lai, Z.: Chronological data is the best proxy in sedimentary process reconstruction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15450, https://doi.org/10.5194/egusphere-egu25-15450, 2025.
Paleohydrology studies are an emerging field of research linked to paleoclimatology and hazard estimation studies. Understanding the patterns of extreme events in the context of global change is of great importance, especially for regions where extreme events are an integral part of the hydrological regime, due to their social (e.g., vulnerability) and political (resilience and adaptation) implications. For many regions of the world where the instrumental record is very short and there are no historical records of hydrological events. These instrumental records can be extended by hundreds to thousands of years by reconstructing especially paleoflood events using fluvial archives.
We present the first detailed paleohydrology study in Anatolia. Our research focuses on the lower reaches of the Sakarya River at Adapazarı Basin, NW Anatolia, Türkiye. Here, the due unique tectonic setting controlled by the North Anatolian Fault, deposition of a 4.5-meter-thick fine-grained floodplain sediment since CE 1350 was possible. This timing constraint corresponds to the reign of the Ottoman Empire as well as to the Little Ice Age (LIA), an intermitted period(s) of cold and dry climate defined for the northern Europe. The characterization of past flow regimes of the river and the detailed identification of paleohydrology events within the studied section have been facilitated through a multidisciplinary and multi-proxy approach (grain size, mineralogy, geochemistry). All identified events have been precisely dated using age-depth model based on dendrochronology, radiocarbon, luminescence, and event-based dating techniques.
The focus sedimentary record revealed that the Sakarya River experienced distinct long-duration regular flow and drought episodes with intermittent flooding events for the last 600 years. Within this time frame, with intervals of uncertainty, three dry and three regular hydrological regimes have been identified from the year CE 1350 to 1950. Within these hydrological regimes, 9 periods of extreme drought and 10 flood events have been identified. These episodes are closely comparable with the published local and regional paleo-climatic record.
How to cite: Okur, H., Erturaç, M. K., Çelen, M., Şahiner, E., Ön, Z. B., Akçer Ön, S., Köse, N., Güner, H. T., Karlıoğlu Kılıç, N., and Öncel, M. S.: Multiproxy evaluation of the Paleohydrology of the Sakarya River during the Last Milennium, NW Anatolia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1067, https://doi.org/10.5194/egusphere-egu25-1067, 2025.
X-ray fluorescence (XRF) and other advanced analytical techniques provide detailed information on geochemical composition in chronologically dated sedimentary sequences. These methods yield high-resolution data on elemental concentrations and ratios, enabling the reconstruction of past environmental conditions. In this contribution, we introduce a novel approach that uses multivariate analysis of all available biogeochemical and geochemical data (elementome) to characterize the trajectories of elemental composition over time and link them to drivers of environmental change. Our analysis of records from Atlantic islands, characterizing the magnitude, graduality and direction of biogeochemical shifts in paleoecological records from several archipelagos, shed light to a potential modern-time shift towards organic-dominated elementomes; and on the effect of human arrival and climate changes on the stability of ecosystem elementomes. Moving ahead, elementome trajectories hold promise as descriptive tools for paleoecology, but also in the interpretation of biogeochemical shifts at any timescale.
How to cite: de la Casa Sánchez, J., Peñuelas, J., de Cáceres, M., Sardans, J., Pla-Rabés, S., Benavente, M., Giralt, S., Hernández, A., Raposeiro, P., Castilla-Beltrán, Á., de Nascimento, L., and Nogué, S.: Elementome trajectories: a framework for studying ecosystem biogeochemical shifts in paleoenvironmental records., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9273, https://doi.org/10.5194/egusphere-egu25-9273, 2025.
The relationship between depositional environments and transportation processes associated with the general properties of formed siliciclastic sediments has greatly interested researchers. The grain shape properties of the sediments reflect the transport mechanisms of different geomorphological and sedimentary environments. The spread of new, high-resolution analytical methods has made it possible to quickly examine the grain shape properties of a large number of individual mineral grains. We investigated three sediment types from different environments (aeolian, fluvial, glacial, [n=27]) using automated image analysis (Malvern Morphologi G3-ID). During the analysis and data processing (e.g. Kruskal-Wallis, MANOVA, PCA) we examined four variables related to grain shape, which were the following: HS circularity (form, roundness), convexity (surface texture), solidity (roundness) and elongation (form). Our vital aim was to determine the key variables that can help to distinguish certain geomorphological environments and define the possible limits and boundaries of each granulometric feature of the medium sand fraction (250-500 µm). Five groups were distinguished according to the three types of environment (p<0.001; α=0.05). The grains from the aeolian and glacial sediments each formed a separate group, while the grains from the fluvial environments were classified into three groups. HS circularity was the most effective attribute, and the elongation variable proved to be the least influential parameter in differentiating sedimentary environments. However, the high values (mean: 0.24-0.3) of the elongation variable indicate a very fresh state of grains from glacial and certain fluvial samples. The HS circularity value changes slowly over time, and a large amount of energy is needed to increase the roundness value, but relatively less time and presumably shorter distance are required to decrease the surface roughness. We tried to interpret the results by comparing the granulometric properties of recent sediment grains with paleo sediments (aeolian and fluvial, n=15). One additional group was formed containing the highest granulometric values of the investigated samples, and the other sediments were classified into the recent fluvial and aeolian groups. Although according to their stratigraphic position, they should have been classified into the opposite sediment groups, indicating that the paleo-aeolian sediments bear the transport features of the fluvial medium and vice versa. By increasing the number of samples and documentation of grains in various geomorphological environments makes it possible to delineate preliminary grain shape boundaries (e.g. for solidity glacial-fluvial: 0.95; fluvial-aeolian: 0.97). However, this may also have a hindering effect, as the grouping methods hide the differences in some parameters within the classified sediments. Presumably, for example, the aeolian environments may be as diverse as the fluvial ones and need to be studied separately. It is important to note that the presented granulometric fingerprinting method can only provide comprehensive and detailed insights into the depositional environment of the mineral particles when applied together with other proxies.
Support of the National Research, Development and Innovation Office (Hungary) under contract NKFIH FK138692 is gratefully acknowledged.
How to cite: Gresina, F., Farkas, B., Magyar, G., Szalai, Z., and Varga, G.: Comparison of recent sediments from different geomorphological environments using automated static image analysis with insight into its applicability to paleo archives, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12819, https://doi.org/10.5194/egusphere-egu25-12819, 2025.
To unveil the relationship between reconstructed paleoclimatic and paleoceanographic changes based on geochemical proxies, we analyzed the marine sediment Core RC10-265PC retrieved from the Gulf of Mexico (GoM). The core spans the interval from Marine Isotope Stage (MIS)-6 to MIS-1 at a glacial to interglacial scale resolution. We studied the relationship between changes in biogenic constituents as proxies of primary productivity and those in continental terrigenous contributions as a source of micronutrients. The core constituents were identified and described by determining carbon content, the elemental concentration by X-ray fluorescence (XRF), and the mineral phases by X-ray diffraction (XRD). The biological constituents include total organic carbon (TOC) and calcium carbonate (CaCO3), whereas terrigenous constituents mainly include the major elements Si, Fe, K, Al, and Ti. In the core, we observed four ash deposits with high Si, K, and Zr concentrations but low in Al, Fe and Ca. Although they were a few cm thick, they did not contribute to increasing primary production. The XRD analysis in the bulk sediments shows that the most abundant mineral phases are calcite, phyllosilicates, quartz, feldspar, and pyroxene. Overall, increases in terrigenous components occurred during the early MIS-6, from MIS-5e to MIS-2, and during MIS-1. In parallel, a decrease in CaCO3 occurred, sometimes coincident with TOC increases. The former suggests a dilution of calcareous by terrigenous components that possibly arrived at the basin by riverine inputs. Such an input increase is not in tune with the latitudinal displacement of the Intertropical Convergence Zone nor with orbital periodicities. However, neighbouring evidence suggests moisture and runoff increase at the regional level, revealing that the oligotrophic oceanographic conditions in the GoM have remained for approximately 180 ka. Such findings expose several ecological implications if eutrophic conditions emerge under modern climate change.
How to cite: Arellano-Torres, E., Villafuerte-Bazaldua, S. M., Roy, P., and Kasper-Zubillaga, J. J.: Continental input and its relationship with biological sedimentary constituents over the MIS 6 to MIS 1 in the SW Gulf of Mexico, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7363, https://doi.org/10.5194/egusphere-egu25-7363, 2025.
Temporal variations in the Na/Cl, Mg/Cl, Br/Cl, Br/Mg ratios of deep brines that filled the Dead Sea Basin during the past ~100 kyr were retrieved from soluble salts within the lake’s sediments. The soluble salts were extracted from cores drilled in the Dead Sea floor and sediments of the last glacial from the high margins of the Dead Sea. The variations in these elemental ratios (e.g., declining/rising Na/Cl ratios) reflect processes of halite precipitation/dissolution during arid/wet periods in the drainage basin, respectively, and exchanges between the epilimnion and hypolimnion brine. Ions of Na+ and Cl- were mainly supplied to the brines by the dissolution of the Mount Sedom salt diapir and halite deposits at the lake’s margins (e.g., halite which precipitated during arid periods of the last interglacial). The main observations are: (1) Between ~100-30 ka the deep lake’s hypolimnion evolved through a steady “enrichment” by Na+ and Cl- ions, due to continuous dissolution of marginal halite and/or from the Mt. Sedom salt diapir. Towards the end of this period, between ~43-30 ka, the Amiaz plain, a marginal basin, that comprised a semi-isolated water body, witnessed frequent episodes of halite precipitation/dissolution with temporal patterns that resemble millennial temperature (δ18O) variations in the Greenland ice core; (2) Between ~30-18 ka (MIS 2), when Lake Lisan reached its highest stands and maximum spatial expansion, the soluble salts indicate on frequent changes in the composition of the hypolimnion, reflecting centennial dissolution cycles of the Mt. Sedom salt diapir; (3) Between ~18-9 ka, when the lake declined to low levels, the variations in the elemental ratios reveal several episodes of enhanced supply of freshwater to the shrinking lake, causing massive halite dissolution and supply of Na+ and Cl- to the hypolimnion. The long-term (~100 kyr) pattern in the elemental ratios of the hypolimnion resembles global CO2 concentrations and sea temperature trends, while the short-term fluctuations in these ratios are correlated with short warm/cold cycles in the Greenland ice core δ18O data, indicating a strong impact of the global climate engines on the regional hydro-climate in long and short time scales.
How to cite: Stein, M., Khalifa, O., Schimmer, P., Katz, A., and Lazar, B.: Interstitial soluble salts in Dead Sea lakes sediments as monitors of the East Mediterranean-Levant hydroclimate during the past ~ 100 kyr, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9213, https://doi.org/10.5194/egusphere-egu25-9213, 2025.
Bedding-parallel fibrous calcite veins (BPCVs) are prevalent in sedimentary basins and typically formed in petroleum source rock. This study examines the development of BPCVs in the Permian carbonate of the Khao Khwang Formation in central Thailand using petrographic, geochemical, and isotopic investigations, as well as total organic carbon (TOC) evaluation. Five rock specimens, comprising ten veins and five host rocks, were examined. The findings indicate that BPCVs display cone-in-cone and beef structures, categorizing them as unitaxial veins. The geochemical analyses and stable isotope compositions indicate that local fluid sources derived from inorganic carbonates and diagenetic formation fluids in the microbial methanogenic zone. Oxygen isotope analysis indicates that vein development occurred at late diagenetic stage. In situ U-Pb dating reveals that fibrous calcite veins originated from the Early to Middle Permian. The development of BPCVs linked to petroleum source rock provides critical insights into the history of fluids and petroleum generation within sedimentary basins.
How to cite: Kanta, T. and Chenrai, P.: Bedding-parallel fibrous calcite veins in Permian carbonate, central Thailand, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2703, https://doi.org/10.5194/egusphere-egu25-2703, 2025.
An analysis of allogenic forcing on shallow-marine strata of the Miocene–Pliocene Kueichulin Formation in the Taiwan Western Foreland Basin shows that changes in the sedimentary record were predominantly driven by: 1) orogenesis and basin subsidence, 2) precession-driven changes in hydroclimate, and 3) obliquity-driven changes in atmospheric and ocean circulation.
The transition from a wave-dominated open shelf to a tide-dominated shallow-marine deltaic environment was influenced by a combination of basin subsidence and the denudation of Taiwan. The rapid deepening of the Western Foreland Basin near 5400 Ka and low sedimentation rates resulted in the formation of lower offshore to distal delta front environments, characterized by limited fluvial and storm influences. Shallow-marine deltaic environments formed as sediment from Taiwan filled the Western Foreland Basin, as a result of accelerated uplift after 4920 Ka, and rapid erosion of the orogen by tropical cyclone precipitation intensified. Tidal currents also intensified as the paleo-Taiwan Strait became shallower and narrower with continued uplift and southwest migration of Taiwan. The sedimentary record also shows a strong link between sedimentation and hydroclimate, driven by eccentricity-modulated precession. Tropical cyclone deposition corresponds to precession maxima, with amalgamated beds that form during periods of sea-level minima. Periods of high obliquity and associated changes in atmospheric and ocean circulation also resulted in a strengthening of tidal currents, recorded as a prevalence of tidal beds in the stratal record.
The findings of this study demonstrate the effectiveness of shallow-marine strata as a paleoenvironmental archive with the potential to resolve the influence of competing allogenic controls on sedimentary systems, which is crucial for understanding how depositional systems responded to climate change, tectonic activity, and sea-level fluctuations throughout Earth’s history.
How to cite: Hsieh, A. I., Vaucher, R., MacEachern, J. A., Zeeden, C., Huang, C., Lin, A. T., Löwemark, L., and Dashtgard, S. E.: Relative influence of allogenic forcings on shallow-marine sedimentary archives, Taiwan Western Foreland Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8426, https://doi.org/10.5194/egusphere-egu25-8426, 2025.
Sedimentary provenance studies have long played a crucial role in elucidating source-to-sink processes across various tectonic settings throughout geological time. Foreland basins, in particular, record the erosional and exhumation history of their source areas, offering valuable insights into the chronology of deformation and the evolution of drainage areas. However, detrital signatures do not always fairly represent the composition of their drainage areas. Therefore, efforts are needed to better understand the factors controlling signal propagation from primary sources to ultimate sinks. The Jaca-Pamplona basin in the southern Pyrenees provides an excellent opportunity to explore the propagation and distribution of provenance signals in a setting with multiple source areas. We present combined data from detrital zircon U-Pb dating, sandstone petrography, and pebble point counting which allow us to infer the source area composition, its evolution, and the controls on provenance signal propagation. Our results indicate that alluvial fans had a source area composed of the North Pyrenean Zone and earlier, deep-marine synorogenic deposits, as evidenced by the overwhelming presence of recycled turbidite clasts. However, detrital zircon U-Pb age data from these alluvial fan deposits show a dominant Cadomian signature, while the turbidites exhibit a dominant Variscan signature, highlighting the complexity introduced by sediment recycling. We propose that the areal distribution of source rocks in the drainage area, transport distance, and differential weathering processes can explain this compositional effect. This is further supported by the clear grain-size dependence of the petrographic detrital modes, which show a positive correlation between grain size and the amount of recycled grains. Therefore, this study underscores the importance of integrating various provenance techniques to improve provenance reconstructions and to identify the intrinsic factors controlling the propagation and representativity of sediment sources.
How to cite: Roigé, M., Gómez-Gras, D., Coll, X., Stockli, D., Teixell, A., Boya, S., and Poyatos-Moré, M.: Sediment recycling in the South Pyrenean Foreland Basin: impact of grain size and source rock distribution on compositional signatures, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9382, https://doi.org/10.5194/egusphere-egu25-9382, 2025.
The Asian continental margin is located at the convergence and collision boundary of the Eurasian, Pacific and Indo-Australian plates, and is subjected to the strongest land-sea interactions and the most frequent exchanges of material and energy. The rivers in the Asian continental margin contributes about two-thirds of the global sediments from rivers to the ocean, which has a great impact on the sedimentation, biogeochemical processes and marine ecology of the marginal seas and the global oceans. Through international cooperation, we have studied the sediment source to sink system and paleoenvironment in the Asian continental margin from the East Siberian shelf in the north to the Bay of Bengal in the south. We compiled a serial of sediment type map with different scales of the Asian continental margin, and elaborated the distribution pattern of the sediments; We established a set of effective provenance tracing index system to elucidate the properties of fluvial sediments, identified the sediments provenance in Bay of Bengal, east China seas, Sea of Japan, and East Siberian Sea, described the transport and deposition processes of the fluvial sediment in the sea, and established the sedimentation model for the key areas; The source, input mode and burial of organic carbon on the shelf at different latitudes and their response to natural processes and human activities have been quantitatively evaluated; The controlling mechanism of sediment source-sink process impacted by the Asian monsoon, sea level change, uplift of Tibetan Plateau, sea current and sea ice variations has been revealed.
How to cite: Shi, X., Qiao, S., Liu, S., Zou, J., Liu, Y., Yao, Z., Wang, K., Hu, L., and Li, J.: Sediment source to sink process and controlling mechanism from the Bengal Bay to the East Siberian Sea of Asian continental margin , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7649, https://doi.org/10.5194/egusphere-egu25-7649, 2025.
The Dangerous Grounds, located along the southern margin of the South China Sea, has undergone substantial tectonic and paleogeographic changes during the Cenozoic, spanning three distinct evolutionary stages: continental rifting, breakup from South China and southward drift, and collision with Borneo. This study utilized a robust dataset comprising 67 seismic reflection profiles, complemented by drilling and dredging data, to quantitatively reconstruct the sedimentary filling history of the Dangerous Grounds. By correlating sediment budget outcomes with the spatial distribution characteristics of sediment thickness, we have gained valuable insights into the region’ s geological evolution.
Our findings reveal a progressive increase in sediment budgets across the three tectonic stages, despite relatively stable sediment budgets during the southward drift stage associated with seafloor spreading. Spatial analysis of sediment distribution, as revealed by sediment isopath maps, shows a continued decrease in the north and expansion in the south and west, suggesting the influence of regional tectonic transitions and variations in paleogeographic environment. By integrating the temporal and spatial distribution of depocenters with drilling results and sediment provenance geochemical analyses, we provides a comprehensive regional perspective on the factors controlling sediment budget trends, including regional tectonic transitions, variations in paleogeographic environment (such as climate, sea level, and sedimentary facies, and the evolution of local river systems).
The sedimentary inputs to the Dangerous Grounds have shifted over time, with Paleocene-Eocene sediments primarily originating from the north. From the Oligocene to the Early Miocene, northern sediment supply progressively declined, while inputs from the southwest, transported through river systems originating in the Indochina and Malay Peninsulas, gradually increased. Since the Mid-Miocene, the collision with Borneo has led to enhanced sediment supply from the south, with sediments predominantly accumulating along slope edges, channel outlets, and within the Nansha Trough.
How to cite: Wang, F. and Ding, W.: Impacts of Tectonic-Paleogeographic Transitions on Cenozoic Sedimentary Distribution in the Dangerous Grounds, South China Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5567, https://doi.org/10.5194/egusphere-egu25-5567, 2025.
The Eocene-Oligocene Transition (‘EOT’) marks a global deterioration in climate associated with the establishment of the Antarctic polar ice cap, but is poorly constrained in continental areas. In Europe, a marked seasonality and a major replacement of European flora and fauna by Asian species (the ‘Grande Coupure’ described by Stehlin, 1909) were recorded during this period. Deposits at the ocean-continent interface are recorded in the Paris Basin at the EOT, from the lagoon-marine to the lacustrine domains. Lithology and facies distribution are therefore controlled by mechanisms on a global and local scale (tectono and glacio-eustatism, climate, tectonic), which need to be differentiated and highlighted. We present a mineralogical, elemental and isotopic geochemistry record of three Upper Priabonian to Upper Rupelian sections located in the northern Paris basin (Cormeilles-en-Parisis, Le Pin-Villeparisis and Saint-Soupplets), near the Bray anticline. Cormeilles-en-Parisis, the westernmost, is located in the Saint-Denis synclinal and shows the most complete sedimentary sequence, more clayey and carbonaceous. It is fossiliferous but not very diverse. The Saint-Soupplets section, located on the eastern flank of the perianticlinal end of the Bray, shows the same sequence of formations as the Cormeilles-en-Parisis section, but is characterised by sandier deposits with current and erosive figures. The Le Pin-Villeparisis section, located on the western flank of the Bray anticline and between the two other sections, is truncated in its upper part and relatively condensed. It is essentially clayey and mostly barren of fossils.
In the Upper Priabonian, the sedimentary record shows a tectonic pulse at the origin of terrigenous inputs and the creation of positive topography, then the Late Eocene regression and the decrease of the tectonic activity inducing the progradation of continental deposits. In the Lower Rupelian, the long-term increase in detrital terrigenous deposits and the environmental changes suggested by floral and faunal data are probably due to the combination of tectonics and eustatism. To the west (Cormeilles-en-Parisis section), a few evaporitic levels show a lagoonal environment that is almost always submerged. To the east, the sections are incomplete (erosive levels and missing formations), influenced by the structure of the anticline, which forms a topographic barrier and a positive relief. The absence of certain formations and the presence of a clearly lacustrine formation at the top of the Le Pin-Villeparisis section show the proximity of the coastline, which is more prone to emersion when subjected to tectonic uplift.
Reference:
Stehlin, H., 1909. Remarque sur les faunules de mammifères des couches éocènes et oligocènes du Bassin de Paris. Bull. Société Géologique Fr. 19, 488–520.
How to cite: Beernaert, M., Le Callonnec, L., Minoletti, F., Bauer, H., Merle, D., Baut, J.-P., and Génault, B.: Controls on sedimentary deposits in the coastal environments of the Paris Basin at the Eocene-Oligocene transition., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8616, https://doi.org/10.5194/egusphere-egu25-8616, 2025.
The Ayeyarwady-Thanlwin rank among the world’s top three river systems in terms of sediment load, and discharge into the energetic shelf environment of the Northern Andaman Sea. The fate of this material has been investigated through a range of interdisciplinary studies since a 2017 field campaign to the present, and here we synthesize the resulting findings based on a combination of sedimentological, geochemical and oceanographic insights. With no dams along the mainstems, this system has remained in a relatively steady-state condition during the past century, despite increasing human pressure, primarily from land-use changes and river sand mining. Tectonic setting plays a first-order control on the fate of the rivers’ sediment, with the formation of a mid-shelf pull-apart basin, the Martaban Depression, that serves as the major depocenter for this system. Oceanographic conditions conspire to feed the rivers’ sediment into the Depression through the action of tides, waves and monsoon-driven circulation. Extreme tides up to 7 m in amplitude keep sediment in suspension in an extensive shallow embayment, the Gulf of Martaban, before this material is released to the offshore Depression, likely because of some combination of spring-neap excursions, near-bed turbidity flows, or rapid offshore transport during cyclones. Monsoon winds drive circulation toward the east during the SW Monsoon, coincident with the period of highest river discharge, further focusing sediment discharged from the numerous western Ayeyarwady distributaries into the Gulf. Modeling results suggest surface and bottom net transport toward the Gulf may occur throughout the year.
Seabed geochemistry contributes much toward our understanding of shelf circulation and sediment dispersal patterns, and the preservation of the immense sediment-associated terrestrial organic carbon discharged by the rivers. Core-scanning XRF elemental ratios show pronounced east-west trends that are attributed to three distinct sources: the Ayeyarwady, Thanlwin, and small rivers draining the Indo-Burman Range (IBR). Distinct geochemical signatures on the shelf fronting the IBR suggest that sediment dispersal from the Ayeyarwady-Thanlwin is largely constrained to the Andaman Sea shelf. Downcore profiles of stable carbon isotopes from the Northern Andaman Sea show remarkably uniform values during the past century, suggesting that land-use changes evident in the catchment, especially during the past 50 years, are not preserved in the offshore record. We suggest that extensive tidal reworking in the Gulf efficiently mutes such signals in the downcore record. Organic carbon studies further suggest that very little remineralization of terrestrial organic matter occurs during transport from the Gulf to the Depression, despite reworking and consequent oxidation in the Gulf. Based on geochemical budgets of particle-reactive radionuclides scavenged from seawater, we estimate that significant onshore flow of open ocean water must occur, along with the substantial input of marine organic matter. The absence of an observed “sediment priming” effect reflets the recalcitrant nature of this carbon pool. The Ayeyarwady-Thanlwin system represents an end member within the family of such systems, and underscores the role of tectonic and oceanographic conditions in determining sediment dispersal and accumulation patterns in the marine environment.
How to cite: Kuehl, S., Flynn, E., Wa Aung, D., Yi Hla, K., and Harris, C.: Ayeyarwady-Thanlwin Rivers Shelf Sediment Dispersal: A High-Discharge Tidally-Dominated Monsoon-Influenced Tectonically-Active Setting, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6880, https://doi.org/10.5194/egusphere-egu25-6880, 2025.
Tidal environments are highly dynamic systems whose evolution is shaped by a complex interplay of natural and anthropogenic factors. These systems respond to intricate hydrodynamic processes such as tidal asymmetry, sedimentation, and channel morphodynamics. These environments are characterised by the presence of tidal channels, which are critical for ecosystem functioning as they facilitate the exchange of water, sediments, and nutrients. Despite their importance, the spatial and temporal evolution of tidal channels remains insufficiently studied, particularly in terms of their morphological and sedimentological characteristics. Information on their evolution is particularly relevant in densely populated areas, where natural processes are closely connected with anthropogenic pressures.
This study aims to explore the tidal channel seafloor characteristics and spatiotemporal evolution focussing on a case study from the northern Venice Lagoon.
With this aim, high-resolution MultiBeam Echo-Sounder (MBES) bathymetry and backscatter data were acquired over an eight-year period, in 2013 and 2021. Ground truth sediment samples and seabed video footage were collected to characterize the substrate and validate the maps produced from the MBES acoustic data. Morphological features were analyzed in a GIS environment using bathymetric data. The analysis identified both erosional and depositional features, finding depositional features dominating the study area. A seafloor sediment map was generated by classifying backscatter data using the unsupervised Jenks Natural Breaks algorithm. To assess changes over time, data from 2013 were compared to those gathered in 2021. Our findings suggest that deposition processes were predominant, with an overall net sediment accumulation of 542.7 · 10³ m³, strongly influenced by anthropogenic activity, related to the recent operation of mobile barriers at the lagoon inlets and salt marsh restauration efforts in the area.
In the context of rising mean sea levels and associated adaptation measures, this work not only enhances understanding of highly valuable and vulnerable transitional environments but also helps to assess the long-term impact of anthropogenic interventions.
Aknowledgements
This work was partially carried out within the Research Program Venezia 2021, with the contribution of the Provveditorato for the Public Works of Veneto, Trentino Alto Adige and Friuli Venezia Giulia, provided through the concessionary of State Consorzio Venezia Nuova and coordinated by CORILA. The authors acknowledge the facilities of the International Centre for Advanced Studies on River-Sea Systems DANUBIUS-RI (https://www.danubius-ri.eu/ ) in undertaking this research.
How to cite: Lahami, T., Guarneri, I., Galvez, D., Petrizzo, A., Prampolini, M., Grande, V., Castellan, G., Rizzetto, F., Foglini, F., and Madricardo, F.: Spatial and temporal evolution of tidal channels' submarine geomorphology in the northern Venice Lagoon, Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11902, https://doi.org/10.5194/egusphere-egu25-11902, 2025.
The morphodynamics of coastal tidal wetlands and salt marshes are closely tied to the tidal channel networks that link these ecosystems to the sea. Tidal channels, shaped by strong currents and dynamic bathymetry, are vital for sediment transport and key ecological functions in coastal environments. They act as pathways for sediment, nutrients, and organic matter, supporting the health and resilience of tidal wetlands. These networks provide essential ecosystem services, including erosion control and habitats for fish and shellfish, which are crucial for biodiversity and fisheries.
However, tidal wetlands face growing threats from human activities. Dredging disrupts sediment transport and alters flow patterns, leading to habitat loss. Increased navigation accelerates bank erosion and raises water turbidity, degrading habitat quality. Coastal infrastructure, such as seawalls and dikes, further fragments these ecosystems, disrupting natural hydrological processes. Climate change exacerbates these pressures through rising sea levels and more frequent storms, accelerating wetland degradation.
Understanding the geomorphology and sediment dynamics of tidal channels is critical for managing these ecosystems, to mitigate natural and human-induced changes, enhance biodiversity, and promote sustainable management. Geomorphological studies often rely on satellite imagery and aerial surveys to analyze channel morphology and path changes. Seismic surveys and laboratory experiments contribute to understanding large-scale and fine-scale geomorphic processes. However, few studies employ high-resolution multibeam echosounder systems to document the detailed underwater morphology of tidal channels, with limited work on their three-dimensional structures.
This study aims to deliver a detailed 3D mapping of the seafloor morphology and sediment distribution in the tidal channels of the northern Venice Lagoon (Italy), one of the most studied coastal lagoons globally. While many studies have explored the migration and evolution of Venetian tidal channels, fewer have focused on high-resolution 3D mapping of their underwater features. We conducted morphometric analyses and classified channel substrates by means of high-resolution multibeam echosounder data validated with grab samples and video footage. The approach integrated bathymetric derivatives, expert geomorphic interpretation, and supervised classification of acoustic backscatter to produce a comprehensive understanding of tidal channel features.
The findings reveal fine-scale details of tidal channel seafloor geomorphology, providing new insights into their structure and functioning. This research enhances our understanding of tidal channel dynamics and offers valuable information for preserving and managing these critical ecosystems effectively.
How to cite: Prampolini, M., Lahami, T., Castellan, G., Galvez, D., Petrizzo, A., Grande, V., Ferrarin, C., Foglini, F., Rizzetto, F., and Madricardo, F.: Submarine geomorphology of tidal channels in the northern Venice Lagoon, Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15862, https://doi.org/10.5194/egusphere-egu25-15862, 2025.
The Ayeyarwady and Thanlwin Rivers deliver ~485 Mt of sediment/year to the northern Andaman Sea. The Ayeyarwady river mouths empty via the Ayeyarwady Delta, while the Thanlwin empties into the Gulf of Martaban located east of the delta. The Gulf of Martaban is a macrotidal, shallow embayment, and the abundant sediment supply and tidal energy make it one the world’s largest perennially turbid zones. Seasonal monsoons bring high precipitation during summer when winds are energetic and from the southwest (SW), and dry during winter when winds are moderate and from the northeast (NE). Surface circulation implies that sediment would be trapped in the northern Andaman Sea during SW monsoon and exported to the Bay of Bengal during the NE monsoon. A clinoform depocenter has been found seaward of the Gulf, and a second depocenter on the northwest side of the delta in the Bay of Bengal. The phasing and timing of sediment delivery to these depocenters has relevance for sediment budget, event preservation, and carbon cycling, however, the sediment delivery mechanisms to these depocenters remain a question.
To address this, a coupled hydrodynamic and sediment transport numerical model was used to quantify suspended sediment dispersal offshore of the Ayeyarwady delta and within the Gulf of Martaban. Based on the Regional Ocean Modeling System (ROMS), it accounted for suspended sediment fluxes and used SWAN (Shallow Waves Nearshore) for waves. Open boundary and atmospheric conditions were derived from available global model products to account for larger scale ocean conditions and winds. The model has been run using different versions of initial sediment bed grain size distributions, based on either simple assumptions or historical and recent grain size observations. The magnitude of suspended sediment flux shows sensitivity to the initial grain size distribution, but the overall seasonal and tidal trends are less sensitive.
Model applications to date have focused on quantifying the variability of suspended sediment flux over tidal and seasonal timescales. The model has been run for two one-month cases: one each representative of the winter and the summer monsoon. Results indicated that offshore of the delta, surface currents flowed eastward during the summer monsoon and westward during the winter monsoon. The bottom currents offshore of the delta, however, showed less dependence on seasonal signals and were westward on average for both the summer and winter model runs. Within the macrotidal Gulf of Martaban, turbidity was maintained by asymmetric tidal trapping. Sediment export from the Gulf primarily directed toward the Martaban Depression Clinoform, with very little sediment delivered westward to the Bay of Bengal. Sediment export was larger during the summer than the winter monsoon, and especially high during spring tides that extended the turbid area to the vicinity of the clinoform.
How to cite: Harris, C. and Du, Z.: Seasonal and tidal variability in suspended sediment dispersal offshore of the Ayeyarwady delta, Myanmar: results from a numerical model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7518, https://doi.org/10.5194/egusphere-egu25-7518, 2025.
Sedimentary records of event deposits are crucial for regional natural disaster risk assessments and hazard history reconstructions. This study aims to identify deep-sea typhoon deposits through immediate post-event sampling following super typhoon Haiyan (2013) and typhoon Morakot (2009). After super typhoon Haiyan passed through the South China Sea in 2013, five gravity cores were collected along the typhoon path in the southern South China Sea Basin (>3800 mbsl). The results showed that Super Typhoon Haiyan deposits with clear graded bedding are preserved at the top of all cores. The thickness of the typhoon layers ranges from 20 to 240 cm and is related to changes in typhoon intensity. The lack of river-connected submarine canyon systems limited the transportation of terrestrial sediments from land to sea. Super Typhoon Haiyan-induced large surface waves played an important role in carrying suspended sediment from the Philippines. A distinctive feature is that Mn-rich layers were found at the bottom of the typhoon layers, potentially linked to the soil and rock composition of the Palawan region, which experienced tsunami-like storm surges caused by super typhoon Haiyan. Similar Mn-rich layer characteristics were also observed in the typhoon Morakot (2009) layer in the sediment cores from the lower reach of Gaoping submarine canyon. These Mn-rich layers may serve as a proxy for sediment export from large-scale extreme terrigenous events. This study provides the first sedimentary record of extreme typhoon events in the deep basin of South China Sea, which may shed light on reconstructing regional hazard history.
How to cite: Chen, Y.-H., Su, C.-C., Yu, P.-S., Hsu, T.-W., Hsu, S.-T., Juan, H.-C., and Chang, Y.-P.: Sedimentary Signatures of Typhoon: Insight from Core Record in the South China Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8410, https://doi.org/10.5194/egusphere-egu25-8410, 2025.
Grain-size of clastic sediment is generally considered to be the result mainly of physical processes active during transport and deposition (e.g. grain-size sorting by dimension/density, sediment by-pass); less importance is generally given to other factors, such as the parent rock lithology. In this work, we investigate the control exerted by the parent rock lithology on the grain-size of daughter sediments. Our approach combines fieldwork-based sediment characterization (in-situ grain-size measurements and petrographic analysis of pebbles > 2 cm), laboratory analyses (sieving, measurement and petrographic point counting at the microscope on grains < 2 cm) and geospatial statistics of the source area.
To do so, we selected as study site a sandy-gravelly bar of the Avisio River, located in Valle di Fassa (Dolomites, Italy) which is sourced by a relatively small catchment area made by very different parent rocks. This allows us to disregard the effect of sediment transport from the source to the sampled depositional site, i.e. to consider the analysed samples representative of the sediment produced at the source by the studied catchment. The lithologies exposed in the catchment area are mainly represented by (i) dolostones, (ii) mafic to intermediate volcanics and (iii) limestones and sandstones, which all outcrop in similar proportions. From the fluvial bar, we collected sand and gravel samples analysing their dimensional (pebble measurements and grain-sizes sieving) and compositional properties (rock identification and sedimentary petrography). We analysed both the overall grain-size and composition of the collected samples and the composition of each grain-size fraction between 16 cm and 0.075 mm contained in each sample. Moreover, we performed a GIS-based geospatial analysis of the sediments source area to quantify the rock type distribution and have the true geology of the source region to be compared with its image provided by its daughter sediments.
Our results show a significant relationship between grain-size and sediment composition: gravels are mainly made by dolostone pebbles, while sands are mainly composed of volcanic grains. This trend persists across the separated grain-size portions: sediment fractions > 1 mm are richer in dolostone grains, while sediments fractions < 1 mm are richer in volcanic grains, and proves that dolostone and volcanic rocks feed at the source daughter sediments with dramatically different grain-size curves. Moreover, none of the samples shows the same proportion of the compositional distribution derived from the GIS-based geospatial analysis (i.e., similar proportion between the three lithologies considered).
These findings indicate that since their origin, sediment grain-size is strongly controlled by different weathering effects on the diverse parent rocks and therefore distinct grain-sizes provide very different geologic scenarios for the same source rock geology. This, while often overlooked, significantly impact provenance studies aimed to paleo-geologic reconstructions and must be also carefully considered in facies tract models, challenging the assumption that grain-size variations along depositional systems are solely due to physical processes acting on sediments having at the origin a simple grain-size distribution.
How to cite: Pezzoli, S., Menegoni, N., and Di Giulio, A.: Parent rocks control on grain-size of daughter sediments and implications for provenance studies: insights from the Avisio River (Dolomites, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6440, https://doi.org/10.5194/egusphere-egu25-6440, 2025.
Lake sediments in mountain areas worldwide have been analysed to reconstruct erosion dynamics on local to regional scales. In the tropical Andes, an area of globally-relevant biodiversity hotspots and carbon sinks, long-term erosion patterns in response to climate and land use change are poorly known. In this study we examine the local erosion history as archived in a high-elevation (<3,700m asl) caldera lake north of Ecuador’s capital Quito. A multi-proxy approach was conducted on a 72 cm-long lake sediment core retrieved from Caricocha in the Mojanda Lake Region, including visual core description, X-ray fluorescence (XRF) core-scanning, magnetic susceptibility (MS), C/N and grain-size analyses. Two radiocarbon dates were combined with tephra-stratigraphy to derive a viable timeframe for sediment accumulation. Data obtained from XRF, MS, C/N and grain-size analyses were evaluated using multivariate statistical methods. Results from cluster and principal component analysis revealed at least 3 stratigraphic units alternating with at least 8 tephra layers. We will discuss a multi-proxy approach to identify different sedimentary environments, sources of material and underlying patterns in this volcanically active region. Including log-transformed element ratios of the XRF data we report on the challenges to disentangle proxies for past erosion dynamics from further palaeoenvironmental conditions, of relevance for future land use under climate change.
How to cite: Heyer, B., Feist, L., Karius, V., Halaś, A., Słowiński, M., Pérez, L., Mothes, P., Velarde-Cruz, E., Valdés-Uribe, A., Mariscal Chávez, A., and Dietze, E.: A multi-proxy reconstruction of past erosion dynamics based on lake sediments from the northern Ecuadorian Andes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9822, https://doi.org/10.5194/egusphere-egu25-9822, 2025.
We present a compilation of provenance data derived from the lower reaches of the Mississippi river showing how the source of sediment supplied to the lower reaches has changed through time in the recent geologic past. We integrate data from a late Holocene point bar, its associated oxbow lake (False River) and the channel plug that infilled since ~500 y BP, as well as another oxbow located upstream at Lake St John. Another finer grained sediment record was derived from coring close to the Mississippi south of New Orleans. The sediments were analysed for an array of major elements, Sr and Nd isotopes, as well as detrital zircon U-Pb geochronology. Grain size is a critical factor in controlling the provenance because suspended sediment is transported rapidly through the river compared to coarse-grained material which travels more slowly as bedload. The radiogenic isotope signature of the fine-grained sediment shows a long-term shift since 4.5 ka towards more radiogenic signatures indicative of more erosion from ancient continental crust, likely the Appalachians and Mid Continent rather than the Rocky Mountain foreland, although this remains the dominant source of material supplied to the Gulf of Mexico. While some of this shift may be anthropogenic, the trend suggests long-term drying of the continental interior and reduced erosion of the foreland. Nonetheless, sand-silt sized zircon U-Pb ages indicate that between 1600 and ~1920 CE flood sediments were dominated by supply from the Missouri River, which is largely sourced from the Rocky Mountain foreland. From 500 BCE until 1600 CE supply was more skewed to the Upper Mississippi and Red River, and with some input from the Arkansas River, also derived from the west. Coarse grained sediments deposited in the lower reaches during the last 10 years show a high degree of variability which we interpret to reflect reduced sediment buffering driven by the inability of the lower reaches to meander and recycle flood sediments in the way expected prior to the installation of levees. The modern tributaries all carry sediment that is much more altered than was true in the recent geological past and reflects heightened soil erosion driven by agriculture. The modern Mississippi is a poor analogue for the natural state of the river when compared to ancient geological deposits.
How to cite: Clift, P., Wycoff, B., Carter, A., Mũnoz, S., and Rittenouer, T.: Climatic versus Anthropogenic Influences on Sediment Delivery to the Gulf of Mexico Marginal Sea since 5000 y BP, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1438, https://doi.org/10.5194/egusphere-egu25-1438, 2025.
Alum Shale is a finely laminated organic-rich sedimentary rock which has recorded an anoxic-euxinic period which lasted for more than 20 My during tthe Cambrian and early Ordovician in the current-day Scandinavian region. A younger section (Tremadocian) of Alum Shale formation is located in Estonia, eastern part of the Baltic Paleobasin.
A 10-meter section of Alum Shale (black shale) and associated sediments (glauconitic sandstone, grey shale, sandstone) were scanned in core PED-403 with a Geotek XRF analyser, attached to automated Geotek-MSCL workstation. The concentrations of Mo, U, Ti, Al, S, and Si were analysed and corrected by measuring in-house reference samples.
Mo and U mostly co-vary in the sediments, but certain sections indicate a preferential uptake of Mo instead of U, indicating periods where particulate shuttle was active during slightly more oxic periods. Fine laminae also contain very low Mo and U enrichments, pointing to short-lived oxygenated conditions instead of prevailing perennial oxygen minium zone conditions on the shelf. Suble redox changes do not correlate with sedimentary textures described in the core. Systematic cyclicity was detected in the case of Ti, Al and Si. Sørensen et. Al. (2020) have demonstrated that astronomically forced climate cycles have been recorded in Cambrian-age Scandinavian Alum Shale cores. With follow-up analyses we wish to reveal whether cycles detected in the Estonian core have similar forcings.
This study was supported by EGT-TWINN project (GA no 101079459).
How to cite: Vind, J., Plado, J., and Põldsaar, K.: Millimeter-scale scanning of redox-sensitive elements in Tremadocian Alum Shale for revealing subtle redox variations and cyclicity, northwestern Estonia, Baltic Palaeobasin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13006, https://doi.org/10.5194/egusphere-egu25-13006, 2025.
Taiwan is located in the western Pacific typhoon corridor and the Pacific Ring of Fire, where typhoons and earthquakes frequently happen, making submarine geohazards prone to occur. As the second longest river in Taiwan, the annual sediment load of the Gaoping River averages approximately 35.61 million tons, making it the dominant contributor of terrestrial sediments offshore southwestern Taiwan. Su et al. (2018) pointed out that the sedimentation rate in most areas offshore southwestern Taiwan is less than 0.5 cm/year, and the upper continental slope in the northern part is relatively more stable compared to the southern part. Natural disasters significantly influence sediment distribution and sedimentation processes off the southwestern Taiwan. In 2005, Typhoon Haitang caused heavy rainfall, leading to the rapid transport of large amounts of suspended materials from the Gaoping River to the offshore area of southwestern Taiwan. Based on the radionuclides data published by Huh et al. (2009), a distinct Typhoon Haitang event layer can be observed, and the high-activity layer associated with the 1963 global fallout can also be identified. In this study, we intend to integrate the findings of Huh et al. (2009) regarding the application of radionuclides with 13 box core samples collected in 2023 from the same locations (the shelf and slope areas on the northern and southern sides of the Gaoping Canyon). We aim to utilize the multi-tracer approach and grain size distribution to assess modern sedimentary event records, sediment transport pathways, and potential disaster risks offshore southwestern Taiwan. Additionally, we plan to analyze the correlation of sedimentary sequences across different coring sites, as well as their temporal variations in sedimentary records at the same site. The current results indicate a positive correlation between sediment porosity and water depth. Grain size analysis shows that the median grain size and sorting decrease as water depth increases. The higher sand content observed on the northern shelf is due to northward coastal currents and overflow effects at the canyon head. Future research will focus on investigating hydrodynamic differences across various layers to better understand sedimentary dynamics over the past two decades. This study will further examine how bioturbation affects radioactive dating results, which will help to establish a more accurate chronological model for sedimentary records.
References
Chih-An Huh, Hui-Ling Lin, Saulwood Lin, Ya-Wen Huang, Modern accumulation rates and a budget of sediment off the Gaoping (Kaoping) River, SW Taiwan: A tidal and flood dominated depositional environment around a submarine canyon, Journal of Marine Systems, Volume 76, Issue 4, 2009, Pages 405-416, ISSN 0924-7963, https://doi.org/10.1016/j.jmarsys.2007.07.009
Su, C.-C., S.-T. Hsu, H.-H. Hsu, J.-Y. Lin, and J.-J. Dong, 2018: Sedimentological characteristics and seafloor failure offshore SW Taiwan. Terr. Atmos. Ocean. Sci., 29, 65-76, doi: 10.3319/TAO.2017.06.21.01
How to cite: Wang, B.-H. and Su, C.-C.: Modern Sedimentary Mechanisms and Evolution of Extreme Event Layers Offshore Southwestern Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4791, https://doi.org/10.5194/egusphere-egu25-4791, 2025.
Tephrochronology provides a stratigraphic approach to correlating geologic and paleoenvironmental events using volcanic ash layers. Stratigraphic correlation, especially over local and regional scales, plays a vital role in tracing the evolutionary trajectory of our hominin relatives across space and time in eastern Africa. The goal of this study is to employ tephrochronology to distinguish tephra layers within the Chemeron Formation at the site of Sinibo, Kenya. The Chemeron Formation is a sequence of Plio-Pleistocene sediments spanning the 5.3 to 1.6 Ma interval in the eastern foothills of the Tugen Hills — a fault block in the Baringo Basin of the Kenyan Rift Valley. This formation is an ideal site for the application of tephrochronology, as it comprises multiple tuff units interbedded with fluvial and lacustrine deposits that yield mammalian fossils, including hominins. In this project tephra layers from the Sinibo section are differentiated by analysing the geochemistry of volcanic glass shards from the tephra and establishing potential isochronous volcanic events in the stratigraphic record. Tephra samples analysed in this study were collected in the field and analysed for major element geochemistry using an Electron Microprobe. Distinct tephras were reconfirmed, including the Lokochot and Tulu Bor tuffs that are found broadly across eastern Africa. Ultimately, the tephra sequence from the relatively continuous section at Sinibo will be used to constrain the chronostratigraphy of fossil sites in structurally disrupted sequences in the Chemeron Formation. This work builds upon previous analyses (Namwamba, 1993) and is integrated with existing stratigraphy.
How to cite: Batlay, A., Beck, C., Kingston, J., Mbua, E., Skinner, M. M., Kivell, T., and Chirchir, H.: Tephrochronological analysis of the Plio-Pleistocene Chemeron Formation, Baringo Basin, Kenya: Refining stratigraphy and constraining chronology of vertebrate fossil sites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11989, https://doi.org/10.5194/egusphere-egu25-11989, 2025.
The Gunsan Basin is located between the eastern Chinese coast and the Korean Peninsula. The basin originated during the Cretaceous due to tectonic activity. After several rifting events, the final rift occurred during the Oligocene. Since the Miocene, the postrift phase has been ongoing to the present day. This study focuses on the interval of the final rifting event of the Cenozoic. The Gunsan Basin remains a frontier basin for hydrocarbon exploration, with only five wells drilled between 1975 and 1991. The study area is located in the eastern sag, known as the East Subbasin, approximately 26 km from the nearest well. Typically, more than 10 wells are needed near a reservoir to predict sand bodies effectively. In this study, we employed geostatistics to generate facies models. The Sequential Indicator Simulation (SIS), one of the stochastic methods, is particularly effective for modeling facies in areas with sparse well data. The pixel-based SIS approach is using trend maps, especially when lateral information is unavailable. These trend maps, derived from the RMS (Root Mean Square) attribute, are based on amplitude and help delineate facies. During the Miocene, the paleoenvironments in the depocenter and margin were lacustrine and littoral, respectively, and the lithology was interpreted as mudstone and sandstone. The transition from littoral to lacustrine environments is attributed to thermal subsidence. Through attribute analysis, we indirectly infer the rift system and the associated facies changes.
How to cite: Lee, C. and Park, S. Y.: Facies modeling of Cenozoic successions in the Gunsan Basin using statistical methods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11785, https://doi.org/10.5194/egusphere-egu25-11785, 2025.
In recent years, with the development of computer vision analysis and the free release of satellite images, it has become possible to observe and evaluate coastal and shoreline changes through satellite images. However, the shorelines obtained by satellite detection are instantaneous at the time of satellite capture, and some correction processes are required to validate them with actual monitoring data and ensure their reliability.
In this study, Landsat and Sentinel-2 satellite images, along with a Python toolkit, were used to analyze shoreline data over a 40-year period on the east coast of Korea. Validation was performed using national research monitoring data collected bi-quarterly over approximately 10 years for 9 sites. Data containing changes greater than the standard deviation and errors in the data itself were removed from the shoreline results. The accuracy of the shoreline data was corrected by comparing it with monitoring data and reflecting the conditions of offshore external forces.
All of the shoreline changes over the past 40 years have shown a relatively stable change of less than 3m per year. However, there has been rapid continuous change over the past 10 years. This is likely due to recent coastal development, including direct and indirect impacts from artificial structures, nourishment effects, and natural erosion.
Continuous collection and analysis of shoreline change data are necessary to ensure the stability and management of coastal buffer zones, including coastal hinterlands and sandy beaches, long-term equilibrium, and continuous shoreline changes caused by extreme typhoons, human impacts, and changes in artificial structures. Ensuring coastal resilience and stability through satellite data and analysis methods is crucial. We plan to detect continuous shoreline changes on both the east and west coasts of Korea. Furthermore, research will be needed on digital twin-based data display to ensure convenience for stakeholders and respond effectively to coastal erosion.
How to cite: Yoo, H.-J., Kang, T.-S., Hur, D.-S., and Yoon, S.-S.: Study on the long-term shoreline extraction and analysis method on the east coast of Korea using Python toolkit, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5284, https://doi.org/10.5194/egusphere-egu25-5284, 2025.
On continental shelf seas, the spatial and temporal interaction between hydrodynamic processes and seabed substrate impacts seabed evolution and sediment distribution. For instance, when the magnitude of bed shear stress, induced by waves and/or currents, is greater than the threshold of movement, sediment is mobilised, giving rise to a range of dynamic bedforms and intricate local and regional sediment transport systems. These processes have direct implications for a wide range of offshore economic exploits (e.g., siting renewable energy and telecommunication infrastructure).
This area of research is currently at the forefront of policy and society due to the ongoing climate crisis. For instance, the Renewable Energy Directive (Directive (EU) 2023/2413) sets the European Union renewable energy target to at least 42.5 % by 2030. With offshore renewables playing a key role in reaching this objective (111 GW by 2030), the demand on the seabed is increasing. A common challenge in exploiting such offshore resources is characterising and monitoring Europe’s variable and dynamic seabed which poses significant risks to the siting and installation of engineering structures. The fiscal implications of poor background knowledge of geological and geotechnical risk before construction onset are well demonstrated by previous projects in Europe. To promote the growth of this sector in a sustainable and economically efficient manner, alongside other existing and prospective industries, the development of integrated geo-spatial tools that facilitate the interrogation of key oceanographic and geological datasets to generate standardised indicators are paramount.
To date, the characterisation and description of sediment mobilisation and seabed disturbance has been carried out using a labour and expertise intensive process. This Project will develop a ‘Sediment mobility and seabed disturbance geo-spatial toolbox (Sed-mob-bed Tool)’, a time-saving, reliable and repeatable means of qualifying and quantifying sediment mobility for a range of sediment types. This novel Sed-mob-bed Tool will facilitate the interrogation of spatial oceanographic and sedimentological datasets to produce a set of standardised sediment mobility and seabed disturbance indices (e.g., Mobilisation Frequency Index (MFI), Seabed Disturbance Index (SDI) and Sediment Mobility Index (SMI)) applicable to international end-users. Several research questions will be addressed, including:
- What are the key physical processes, sedimentological characteristics and parameters critical to sediment mobility?
- What are the most effective geospatial tools to garner this information?
- Can this be applied in a way that is geostatisically robust?
- How well do these approaches perform (i) in differing seabed morphological settings, and (ii) at scale?
The developed tool will be tested under several different environmental and seabed conditions. This includes an application to Irish Waters as a case study, leveraging the wealth of existing national and European level datasets (e.g., INFOMAR, EPA, EMODnet, GSI, Marine Institute). The results of which will be of particular interest to a cross-disciplinary group of practitioners including marine archaeologists, oceanographers, marine geoscientists, and engineers. The methodology and results from this work will ultimately provide a scientific knowledge base for the sustainable growth of the marine economy.
How to cite: Creane, S., Totska, A., and Coughlan, M.: A new sediment mobility and seabed disturbance geo-spatial toolbox (Sed-mob-bed Tool), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18440, https://doi.org/10.5194/egusphere-egu25-18440, 2025.
The principles of stratigraphy, rooted in the foundational works of Nicolaus Steno, William Smith, and Johannes Walther, assert that sedimentary layers are deposited sequentially and preserve a temporal and environmental record. While these principles have guided stratigraphic interpretation for centuries, carbonate successions challenge their straightforward application due to the impact of diagenetic processes. This was clear to earlier work on diagenetic bedding by e.g. Robin Bathurst or Werner Ricken, who discussed the implications for their models. More recent work on early diagenetic transformations, including dissolution, cementation, and differential compaction, can modify or completely obscure primary depositional features, resulting as well in a specific type of secondary “diagenetic bedding,” introducing intra-stratal lithological patterns that mimic primary bedding but are unrelated to depositional events.
Here we compare the mechanisms behind a variety of types of diagenetic bedding, with a focus on their implications for stratigraphy, paleoenvironmental reconstruction, and geochronology. We demonstrate how secondary features can disrupt traditional stratigraphic assumptions, obscure temporal resolution by combining distinct depositional layers into single beds or splitting original layers into multiple diagenetic units, and explore how differential preservation of aragonitic and calcitic components introduces spatial and temporal variability in fossil records, potentially disrupting correlations across stratigraphic sections. We summarise for the individual diagenetic models the key features to identify diagenetic bedding and the potential implications for stratigraphic applications.
How to cite: Nohl, T., Munnecke, A., and Wright, V. P.: Superposition and Intra-Stratal Bedding: Comparing the effects of different diagenetic models on stratigraphy., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11379, https://doi.org/10.5194/egusphere-egu25-11379, 2025.
Halimeda, calcareous green algae, bioherms are among the largest inter-reef biogenic structures in the Great Barrier Reef, spanning over >6000 km2 of the continental shelf – an area exceeding the adjacent coral reefs at equivalent latitudes1. Previous studies have shown the peculiar circular to reticulate shapes, the internal structure and volume of these accumulations, underscoring their significant contribution to the global neritic carbonate factory throughout the Holocene2,3. However, a comprehensive understanding of the formation and development of these uniquely shaped bioherms has been hindered by the absence of densely spaced core samples that target bioherm morphologies.
This study presents new data from the 2022 RV Investigator voyage IN2022_V07 “Halimeda bioherms: Origins, function and fate in the northern Great Barrier Reef (HALO)”. Forty-two densely spaced vibrocores were collected (up to 6 m length) over 3 inter-reef sites between lat 15⁰ 48’ 45” S and lat 13⁰ 21’ 11” S. Core locations to target bioherm morphotypes were collected with the aid of 50 cm resolution multibeam bathymetry data, and closely spaced sub-bottom profiles collected during the voyage. A total of almost 200 m of cores have been scanned with high-resolution CT, 50 m of core have been split, logged, scanned with multi-sensor core logger (magnetic susceptibility, spectrophotometer, X-ray fluorescence) and subsampled for grain size, composition and microfossil analysis to show a variety of facies ranging from estuarine to coral-rich deposits. Selected cores have been sub-sampled for radiocarbon dating of Halimeda grains, benthic foraminifers, and organic rich mud (23 samples), spanning from 12 ka to present, aligning with previous findings3. Initial observations revealed further facies complexity than previously thought in morphotypes, including Halimeda floatstone-rudstone and Foraminiferal wackestone-packstone facies in the south, while having facies minor mud matrix and richer in coral, mollusc, rhodolith and lithified clumps abundance towards north. This new dataset significantly advances our understanding of Halimeda bioherm morphology, development, and regional influences, providing new insights into their formation processes and ecological significance.
References:
- McNeil, M. A., Webster, J. M., Beaman, R. J., and Graham, T. L., 2016, New constraints on the spatial distribution and morphology of the Halimeda bioherms of the Great Barrier Reef, Australia: Coral Reefs, v. 35, no. 4, p. 1343-1355. doi: 10.1007/s00338-016-1492-2
- McNeil, M., Nothdurft, L. D., Dyriw, N. J., Webster, J. M., and Beaman, R. J., 2021, Morphotype differentiation in the Great Barrier Reef Halimeda bioherm carbonate factory: Internal architecture and surface geomorphometrics: The Depositional Record, v. 7, p. 176– 199. doi: https://doi.org/10.1002/dep2.122
- McNeil, M., Nothdurft, L. D., Hua, Q., Webster, J. M., and Moss, P., 2022, Evolution of the inter-reef Halimeda carbonate factory in response to Holocene sea-level and environmental change in the Great Barrier Reef: Quaternary Science Reviews, v. 277. doi: 10.1016/j.quascirev.2021.107347
How to cite: Szilagyi, Z., Nothdurft, L., Webster, J., McNeil, M., Braga, J. C., Graham, T., Behrens, B. C., Yokoyama, Y., Beamen, R., Paumard, V., Shragge, J., Goh, S., Reeves, J., Picton, L., and Bostock, H.: Subsurface dissection of Holocene inter-reef Halimeda bioherms: morphology, facies and latitudinal variations in the northern Great Barrier Reef, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14906, https://doi.org/10.5194/egusphere-egu25-14906, 2025.
Lacustrine and palustrine carbonates form in lakes and swamps of various shapes and sizes. They can accumulate through chemical or biological processes and are constantly under the influence of external alteration sources such as meteoric waters, vegetation or fauna. Thus, there are the result of a complex primary fabric later modified by early and late diagenesis processes which makes them highly heterogeneous.
Their study is mainly motivated by their ability to act as a reservoir for underground water or for Carbon Capture & Storage (CCS), which both require a precise understanding of their structure and variability of permeable bodies.
The 3D architecture and the scale of heterogeneity of such carbonates remains a question as depositional and alteration processes can occur on centimetre scales or less (e.g., roots), to metre and kilometre scale (e.g., subaerial exposure). This variability cannot be assessed without any large, pluri-directional outcrop or without a high density of cored boreholes.
The O-ZNS platform (“Observatoire des transferts dans la Zone Non-Saturée”) located near Orleans, France, is an observatory of the vadose zone of the Beauce aquifer. The host rocks are aquitanian lacustrine and palustrine limestones (the Beauce Limestones formation).
The observatory offers an exceptional 20 m deep and 6 m diameter well surrounded by eight cored boreholes (20-25 m deep) within a radius of 30 m, which were described at a centimetric scale (1:6).
Our study focuses on the control of the 3D architecture of the sedimentary facies by understanding the chronology of the successive depositional environments. Also, it aims to consider the diagenetic overprint of the Beauce Limestones to decipher what is the impact of the primary fabric on secondary processes that finally lead to the heterogeneities we observe today.
This contribution will present: (1) How the 16 sedimentary facies distributed in 4 depositional environments (lake, lake margins, external palustrine, internal palustrine) vary at a decametric scale, (2) the paleo-environmental evolution of the site, located at the transition between lacustrine and palustrine settings, built thanks to the correlation of 8 transgressive-regressive cycles, and (3) the link between sedimentary facies, diagenesis and petrophysical properties (porosity, permeability).
How to cite: Jamey, T., Andrieu, S., Mallet, C., Laurent, G., Husson, E., and Azaroual, M.: Sedimentary and diagenetic processes at the origin of the 3D architecture of heterogeneous lacustrine and palustrine limestones., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1688, https://doi.org/10.5194/egusphere-egu25-1688, 2025.
International Ocean Discovery Program (IODP) Site U1417, located in the Surveyor Fan (Gulf of Alaska), preserves hemi-pelagic sediments influenced by glacial and fluvial depositional processes from the Cordilleran Ice Sheet in the Chugach–St. Elias Mountains and Coastal Mountains. A total of 441 samples from the late Miocene to early Pleistocene were used to measure the biogenic opal content and calculate its flux to trace the degree of diatom productivity in surface water and depositional history. In general, the biogenic opal content confirms the division of the lithostratigraphic units and subunits: diatom-bearing clay-rich intervals versus clast-rich terrigenous intervals. Despite large fluctuations from the late Miocene to early Pleistocene, the variation of biogenic opal content and deposition of biogenic opal flux might have been controlled by global climate change, such as the high levels during the Late Miocene Biogenic Bloom (LMBB) and mid-Pliocene Warmth (MPW) and its abrupt decline at the Northern Hemisphere Glaciation (NHG). These variations of surface water productivity may be attributed to the basin-to-basin redistribution of nutrients by global thermohaline circulation and the related Pacific Ocean ventilation in response to global climate change.
How to cite: Khim, B.-K., Kim, S., and Asahi, H.: Biogenic opal deposition in the Surveyor Fan (IODP Site U1417) of the North Pacific during the late Miocene to early Pleistocene, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1739, https://doi.org/10.5194/egusphere-egu25-1739, 2025.
Posters virtual: Mon, 28 Apr, 14:00–15:45 | vPoster spot 2
EGU25-3094 | Posters virtual | VPS25
Flow transformation processes recorded in the Eocene early syn-rift deep-lacustrine fine grained sedimentary rock in the Qibei Sub-sag, Bohai Bay Basin, ChinaMon, 28 Apr, 14:00–15:45 (CEST) | vP2.1
Gravity flow is a key sedimentary process in deep-lacustrine environments, with transitional flow deposits commonly occurring in both distal and proximal zones of the turbidite systems. These deposits are crucial to understanding the sedimentary dynamics of fine-grained deep-water sediments. The transitional deposits between turbidity currents and mud-rich debris flows are particularly important for advancing our understanding of fine-grained sedimentation processes and have significant implications for unconventional oil and gas exploration.
The aim of this study is to describe transitional-flow facies, interpret their flow evolution and depositional processes, and assess their impact on the differential accumulation of organic matter in a fresh-water syn-rift deep-lacustrine system. Data were collected from the 111.39-m-thick Eocene lacustrine oil-prone source rock succession, penetrated by the two wells in the Qibei Sub-sag, Bohai Bay Basin, China. Nine sedimentary facies were identified in the studied fine-grained succession, with various internal sedimentary structures (e.g., ripple cross lamination, low-angle cross lamination, wave lamination, parallel lamination, graded structure, deformed structure, and homogeneous structure) reflecting the dynamics of sedimentary processes in a deep-lacustrine depositional lobe distal environment. Millimeter-scale logging defined 5 bed types based on 2383 measured and recorded beds, with inferred transitional flow deposits exhibiting distinctive stacking patterns, from coarser grained turbidites to fine-grained debrites. A wide range of transitional-flow facies are recognized and can be assigned to turbulence-enhanced transitional flow, lower transitional plug flow, upper transitional plug flow and quasi-laminar plug flow. Despite the predominance of finning upward grain size trends, sedimentary structures in these heterolithic deposits may stack in varying orders, reflecting different flow dynamics.
The vertical facies trends of transitional flow deposit provide insights into the longitudinal flow evolution of flows, which were initially turbulent, but became increasingly laminar through deceleration and fine-grain entrainment. The assimilation of the lake-bottom mud into the density flows likely played a key role in modulating flow turbulence, helping to explain the common occurrence of transitional-flow facies indicated by sedimentological features such as sheared flame structures and deformed mud intrusions, which suggest interaction between the flow and the muddy lake floor.
Lacustrine organic matter was delivered to the lake floor by continuous settling, whereas terrestrial organic matter was transported via sediment density flows. The deep-lacustrine background mudstone is dominated by Type II1 kerogen, whereas the quasi-laminar plug flow mudstone is dominated by Type II1 and II2 kerogen, turbulence-enhanced transitional flow and lower transitional plug flow mudstones are dominated by Type II2 and III kerogen. These observations challenge the view that mud accumulates only from suspension fallout in distal basin-floor environments. This study suggests that composition, texture, and organic matter types of mud-dominated deep-lacustrine mudstones vary predictably in response to changes in depositional processes. The results have broader applicability to other deep-lacustrine sedimentary systems, highlighting the dynamic nature of transitional flows. Detailed microtextural and compositional analysis, combined with rigorous geochemical parameters, is essential for the understanding of the source-rock potential of basinal mudstones and fine-grained organic-rich sediments more general.
How to cite: Wang, J., Zhao, J., You, Z., Pu, X., Liu, K., Zhang, W., Shi, Z., Han, W., and Wang, Z.: Flow transformation processes recorded in the Eocene early syn-rift deep-lacustrine fine grained sedimentary rock in the Qibei Sub-sag, Bohai Bay Basin, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3094, https://doi.org/10.5194/egusphere-egu25-3094, 2025.
EGU25-7676 | Posters virtual | VPS25
The Study of Stratigraphic Integrity of Marine (Lake) to Terrestrial Transitional Clastic Rocks Based on 2D Flume ExperimentsMon, 28 Apr, 14:00–15:45 (CEST) | vP2.2
This study aims to simulate the sedimentary processes of marine (lake) to terrestrial transitional clastic rocks and quantitatively analyze the impact of geological control factors on stratigraphic integrity. Most sedimentary strata exhibit discontinuities of different scales, represented by both temporal and spatial incompleteness. Defining and quantitatively characterizing "stratigraphic integrity" is of great importance for accurate stratigraphic correlation, reconstructing the depositional history of geological periods, and guiding oil and gas exploration.
2D physical water tank experiments can realistically simulate geological processes such as erosion, transport, deposition, and reworking of clastic materials. These experiments allow for the calculation of stratigraphic integrity at any given location. In this study, a narrow 3D water tank was used to approximate the 2D sedimentary processes, simulating the entire sedimentary sequence of marine (lake) to terrestrial transitional clastic rocks and calculating stratigraphic integrity.
A transparent glass water tank (1.5m×0.5m×0.05m) was chosen as the experimental setup. Based on a thorough review of relevant literature, multiple sedimentary bottom shapes were designed to replicate different real-world geological depositional environments. Specific time steps were set to quantitatively introduce different types of quartz sand, achieving visualization of the experimental results. A water level control curve was designed to change the water level over time, allowing for precise control of water height in the tank and effectively simulating the evolution of stratigraphic sequences. Finally, based on the experimental data, stratigraphic integrity was calculated for various depositional environments, enabling further analysis of the experimental results.
The experimental results clearly reveal the evolution of stratigraphy and depositional sequence features, which closely match actual geological conditions. This indicates that the experiment can realistically simulate the sedimentary processes of marine (lake) to terrestrial transitional clastic rocks. From an overall perspective, erosion near the sediment source is more pronounced and frequent, while at the distal end, the strata remain more complete due to prolonged subaqueous conditions, and erosion is less noticeable. The depositional sequence shows a typical progradation pattern, with thin oblique and wavy bedding structures. Stratigraphic integrity studies show that the integrity increases from the proximal to distal end. A comparison of integrity at the same location shows that horizontal surface fluctuations have a much stronger impact on stratigraphic integrity than changes in the bottom shape, with frequency variations in the water level control curve having a greater effect than changes in amplitude.
This study uses 2D physical water tank experiments to simulate and reconstruct the sedimentary processes of marine (lake) to terrestrial transitional clastic rocks. It also quantifies the influence of geological control factors on stratigraphic integrity. The results demonstrate that both the sedimentary bottom shape and water level change curves affect stratigraphic integrity, with water level changes having a more significant impact. This research is the first to combine 2D water tank simulations with stratigraphic integrity control factors, providing innovative experimental methods and technical tools for sedimentary physical modeling and stratigraphic integrity assessment.
How to cite: Fu, S. and Liu, J.: The Study of Stratigraphic Integrity of Marine (Lake) to Terrestrial Transitional Clastic Rocks Based on 2D Flume Experiments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7676, https://doi.org/10.5194/egusphere-egu25-7676, 2025.
