Orals: Wed, 30 Apr | Room D3
We studied the feasibility of using laser ablation inductively coupled plasma mass spectrometry (LA–ICPMS) for U–Pb dating of fossils (vertebrate-invertebrate) and pedogenic calcite. U–Pb dating of hydrogenic and fossil material can be challenging because samples often contain low U levels and variable amounts of non-radiogenic Pb. Our improved processing methods (UtilChron) give accurate U–Pb ages for low U samples. Line scans using LA–ICPMS provide the widest range of ratios available for defining the radiogenic to common Pb mixing line, hence the best age estimate for calcite and fossil material. For example, the first accurate U–Pb age on fossilized soft tissue, yielded an age of 3.16 ± 0.08 Ma consistent with its late Pliocene stratigraphy while coexisting shark teeth are variably reset by late-diagenesis. U–Pb dating on a paleosol sample from the Katberg Formation, Karoo Basin, South Africa yielded an age of 252 ± 3 Ma, which overlaps with a previous high-precision U–Pb zircon date from a volcanic ash deposit 2 meters above the paleosol demonstrating, for the first time, the reliability of using LA–ICPMS dating on terrestrial pedogenic calcite. Processing LA–ICPMS data at the single cycle level allows more precise absolute dating of fossils and carbonates. In some cases, separate regression of totally reset and partially reset domains can resolve ages of early and late diagenesis. Apatite fossils such as teeth or bones contain high U content, but they are more susceptible to late diagenetic alteration whereas calcitic invertebrate fossils like belemnites or rugose corals seem to be more stable but usually show low U content. Our research has demonstrated that pedogenic carbonate nodules and fossils can potentially be dated with meaningful precision, providing another mechanism to constrain the age of sedimentary sequences and study events associated with fossil extinctions.
How to cite: Rochin-Banaga, H., Davis, D. W., and Kamo, S.: U-Pb Dating of Fossils and Calcite: dating the Sedimentary and Paleontological record, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20743, https://doi.org/10.5194/egusphere-egu25-20743, 2025.
The WaverideR R package was initially developed to use the Continuous Wavelet Transform (CWT) to conduct cyclostratigraphic analyses. In the initial release of the R package, the functions mainly focussed on plotting wavelet scalograms, extracting astronomical cycles from the CWT and to create simple age-models. Over time the WaverideR R package has seen some major updates in capabilities regarding both functionality and visualisation of cyclostratigraphic results. Enhanced visualisation options now allow users to customise wavelet scalograms, with flexible plotting directions and an array colour palettes to create personalised outputs. Existing functions have also been updated, resulting in the elimination of bugs and enhanced computational efficiency. New functionalities have also been added, including Monte-Carlo modelling functions that allow the use of multi-proxy datasets to create an astrochronology including uncertainty, calculate the duration of a hiatus and anchor an astrochronology to a single absolute age date. In conclusion the updated WaverideR package contains many new functionalities that are complementary to existing cyclostratigraphy R codes/packages.
How to cite: Arts, M. and Da-Silva, A.-C.: The WaverideR Package: a tool for cyclostratigraphy, the updated version, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17106, https://doi.org/10.5194/egusphere-egu25-17106, 2025.
Variations in Earth's orbit and axial tilt induce climatic changes on its surface, which are recorded in sedimentary deposits. These cyclical variations are driven by the main secular frequencies of the solar system. Analyzing these cycles in sedimentary records can help establish an astronomical time scale for the geological record by correlating geological proxies with computed variations in insolation on the Earth's surface, in accordance with the laws of celestial mechanics. A critical aspect of this analysis is the estimation of the sedimentary deposition rate, which determines the time-depth transfer function, relating geological depth to relative or absolute time.
We propose a novel approach for constructing astronomical time scales for geological stratigraphic records. The AstroGeoFit method establishes a time-depth transfer function throughout the record, accommodating variable sedimentation rates, and extracts the primary astronomical signal from the geological sequence. This is achieved using a genetic algorithm that adapts to a wide range of sedimentation rate variations. This statistical analysis enables the reconstruction of an astronomical signal (e.g., eccentricity and/or precession) purely from the stratigraphic sequence with minimal personal bias. When this template is correlated with an astronomical solution, an absolute time scale is obtained for the entire record. In addition, we show that quantitative uncertainties can be estimated at each stage of the AstroGeoFit process with the Bayesian approach.
The publication of the AstroGeoFit approach will be associated to an open source python package that fully implement the AstroGeoFit algorithm.
Ref: J. Laskar, N. Hoang, N. Hara, Y. Wu, A.Sultanov, M. Sinnesael, T. Westerhold, P. Bujons, AstroGeoFit. A Genetic Algorithm and Bayesian approach for the Astronomical Calibration of the Geological Timescale, 2025, in revision.
How to cite: Laskar, J., Hoang, N., Hara, N., Wu, Y., Sultanov, A., Sinnesael, M., Westerhold, T., and Bujons, P.: AstroGeoFit. A Genetic Algorithm and Bayesian approach for the Astronomical Calibration of the Geological Timescale, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13546, https://doi.org/10.5194/egusphere-egu25-13546, 2025.
Astronomical cycles in the Earth’s orbit and axis orientation have been widely recognized to drive climatic changes that result in cyclic sediment deposition. The developing discipline of astrochronology uses these cycles to progressively refine the geological time scale. Astronomy therefore informs geology. Conversely, can the geological record provide astronomical information?
We present here the results of applying a Bayesian inversion method to estimate the Earth’s axial precession frequency in 34 high-quality cyclostratigraphic records spanning the past 650 million years. Sediment cycles record the Earth’s axial precession frequency (via climatic precession and obliquity), which is a function of the lunar distance and of the Earth’s spin rate. Through time, tidal energy dissipation progressively slows down the Earth’s rotation, transferring angular momentum to the Moon’s orbit and increasing lunar distance. Our analysis reveals that the axial precession frequency has decreased markedly in geologic time (by about 30% between 650 Ma and the present). From the estimated variation in the axial precession frequency and angular momentum conservation in the Earth-Moon-Sun system, we calculate the corresponding evolution of the length of day and lunar distance. The results indicate an interval of high tidal energy dissipation between ~300 to 200 Ma and are in general agreement with independently calculated tidal evolution models. Moreover, our analysis provides an improved determination of the past frequencies of obliquity and climatic precession for astrochronology applications.
How to cite: Malinverno, A., Wu, Y., Meyers, S., and Hinnov, L.: Cyclostratigraphic constraints on the evolution of the Earth-Moon system over the last 650 million years, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7309, https://doi.org/10.5194/egusphere-egu25-7309, 2025.
The middle Cambrian was a critical period of Earth’s history, marked by explosive diversification of metazoans and several profound changes in Earth’s surface environments and global climate. A valid temporal framework for the middle Cambrian period and across the major bio-events is yet poorly constrained, and millennial-scale climate variability (MCV) are not fully addressed. Here, high-resolution spectral gamma-ray logs, of Potassium, Uranium, Thorium and magnetic susceptibility records are utilized to conduct a cyclostratigraphic analysis of the global stratotype section for the Wuliuan Stage in South China. A ∼1.1 Myr-long high-resolution astronomical time scale across the Wuliuan-Stage 4 is developed by astronomical tuning of gamma-ray logs to the ~100-kyr short-eccentricity cycles. We report semi-precession cycles of 11.7–7.9 kyr, which were probably associated with the twice-annual passage of the intertropical convergence zone across the intertropical zone, consistent with the paleogeographical location of South China near the equator during the middle Cambrian. Furthermore, our results suggest that MCV (with periods of 4-7 kyr) is modulated by eccentricity, obliquity, and precession cycles and can be directly generated by the harmonization between fundamental orbital cycles (e.g., obliquity and precession cycles). These results describe one of the oldest known geological candidates for solar-influenced climate change modulated by Milankovitch forcing.
How to cite: Zhang, Y., Fang, Q., Shi, M., Gai, C., Zhang, S., Yang, T., Li, H., and Wu, H.: Millennial-scale climate cycles detected in the middle Cambrian GSSP (ca. 509 Ma) of the basal Wuliuan Stage, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-351, https://doi.org/10.5194/egusphere-egu25-351, 2025.
In the central portion of the Orobic Basin (Trabuchello-Cabianca anticline), on the Valtellina side of the Orobic Alps, the Val D’Ambria (Sondrio, Italy) represents a site of exceptional paleontological richness, both for the high quality and quantity of data.
This sedimentary basin is renowned for its geological complexity and the preservation of a thick stratigraphic sequence dating back to the early Permian. The fossils found at the site belong to the Kungurian Pizzo del Diavolo Formation and are characterized by remarkable diversity, consisting primarily of tetrapod footprints, invertebrate traces, and sparse macroflora remains. The vertebrate footprints represent a diverse ichnofauna, with at least eight different ichnogenera identified, including Amphisauropus, Batrachichnus, Dimetropus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, and Varanopus. Among these, Dromopus and Erpetopus are the most common, whereas footprints assigned to Dimetropus are the rarest and, therefore, of particular interest. These fossil tracks suggest that the area was frequented by a community of terrestrial animals, including reptiles, amphibians and rare synapsids.
In addition to the tetrapod footprints, the discovery of invertebrate traces and macroflora remains provides crucial data for interpreting the depositional environments, as well as the climatic and ecological conditions of the early Permian in the Southern Alps. The combination of these paleontological data, stratigraphic logs, and detailed descriptions of sedimentary facies will allow for a more precise reconstruction of the paleoenvironmental and palaeoecological evolution of the Orobic Basin during the time interval in which these biotas thrived.
Preliminary analyses suggest that the Orobic Basin, located in the paleoequatorial domain, may have hosted diverse depositional settings, under alternating semi-humid and dry seasonal conditions. These frequent changes are characteristic of specific present-day fluvial-lacustrine landscapes, which feature extensive alluvial sand-to-mud flats, playa and ephemeral lakes, situated not far from the basin margins. Further analyses of palynological data and other methodologies, such as C and O stable isotopic analyses as paleoenvironmental indicators on clay deposits and geochemical analyses on volcanic deposits, are expected to provide a better understanding of the climate change during this time interval in the studied area.
Since the late Pennsylvanian, the Palaeozoic was interested by global warming and progressive depletion of the Southern Pole glaciers, which culminated in the Artinskian Warming Event and the subsequent establishment of greenhouse-like-conditions that lasted for the rest of the Permian. Thanks to the different data gathered in the Val D’Ambria locality, its rich fossil record can highlight the consequence of the increased aridity and seasonality on the low-latitude biota during the Kungurian, and potentially provide information regarding the purported Olson’s Extinction (or Olson’s Gap).
The ongoing field research at this site will provide increasingly detailed insights into the biodiversity of this region during the early Permian, enriching our understanding of the dynamics of life and climate change at the end of the Paleozoic Era.
How to cite: Scarani, R., Marchetti, L., Dal Sasso, C., Cattaneo, M., Della Ferrera, E., Bonizzoni, S., Rossi, S., Merati, M., and Ronchi, A.: A new exceptionally preserved ichnofauna from the lower Permian of the Southern Alps: insights into the continental ecosystems after the Artinskian warming event, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7496, https://doi.org/10.5194/egusphere-egu25-7496, 2025.
Accurately estimating the duration of the Induan Stage (Early Triassic) is crucial for understanding biotic recovery and environmental upheavals following the Permian–Triassic Mass Extinction. However, considerable uncertainties remain due to discrepancies between astrochronological and radiometric dating methods. In this study, we present an integrated stratigraphic framework for the Induan Stage by combining cyclostratigraphy, magnetostratigraphy, radiometric dating, biostratigraphy, and chemostratigraphy. By analyzing gamma ray series from marine deposits at the Xiejiacao, Chaohu, and Daxiakou sections in South China, and correlating them with biostratigraphic, magnetostratigraphic, geochemical, and radiometric data, we establish a composite 405-kyr eccentricity cycle-calibrated time scale. Our results estimate the Induan duration at 1.55 ± 0.2 Myr. Anchoring this time scale to the Permian–Triassic boundary at 251.902 ± 0.024 Ma, we propose an estimated age of 250.35 ± 0.2 Ma for the Induan–Olenekian boundary. By reconciling discrepancies between astrochronology and radiometric dating, our results provide a robust temporal framework for stratigraphic correlations, carbon cycle perturbations, and biotic and environmental changes in the aftermath of the mass extinction.
How to cite: Zhang, H., Ji, K., Chen, Y., Ogg, J., Sun, Z., Wignall, P., Wang, M., Zhang, H., Zhang, X., Zhang, Y., Huang, K., and Li, M.: Astronomically calibrated integrated stratigraphy of the Induan Stage in the aftermath of the Permian–Triassic mass extinction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6527, https://doi.org/10.5194/egusphere-egu25-6527, 2025.
Paleotropical lacustrine strata of eastern North America are only known place where vertebrate and floral records of the end-Triassic extinction (ETE) (1) are directly interbedded with U-Pb zircon CA-TIMS-dated lavas of the CAMP (2) and a high-resolution, orbitally paced, lacustrine cyclostratigraphy (3, 4). New, continuous XRF elemental scans of Newark and Hartford rift basin cores (5) confirm previous work in showing expected climatic-precession-dominance modulated by eccentricity for most of the section (6, 7), but an emerging major surprise is that the 500 kyr interval around the Triassic-Jurassic transition is very strongly obliquity-dominated. Tied by sub-Milankovitch magnetic polarity stratigraphy [chron E23r (3)] to rich outcrop-based biostratigraphy, this new Mn/Fe, K/Al, Zr/Rb, S and Na chemostratigraphy requires a revision of environmental interpretations of the proximal cause of the continental ETE. We argue that despite the clear record of pulsed massive pCO2 increases tied to CAMP emplacement, CAMP eruptions produced extreme, sulfur-driven, mega-volcanic winters that were proximal drivers of extinction on land (8) — not the giant hyperthermal itself. We hypothesize that these extreme cold events, superimposed on a background of polar latest Triassic-earliest Jurassic cooling (9) and wintertime freezing (10, 11), enhanced polar ice-albedo feedback and possibly glaciation (12). This amplified Earth System sensitivity to obliquity forcing, perhaps not unlike the initiation of the “40 kyr” world of the Late Neogene [e.g. (13)]. Onset of this Triassic-Jurassic obliquity pacing modality marked the continental phase of the ETE, but in light of these competing radiative balance forcings, interpretations of end-Triassic sea-level drop (12) and marine extinctions require reevaluation as well, considering factors beyond global warming alone (14).
1, Olsen+ 2002 Science 296:1305. 2, Blackburn+ 2013 Science 340:941–945. 3, Kent & Olsen 1999 JGR 104:12831-12841. 4, Olsen & Kent 1996 PPP 122:1-26. 5, Kinney+ 2002 Abstract PP25D-0899, AGU Fall Meeting. 6, Van Houten 1962 AJS 260:561. 7, Olsen 1986 Science 234:842. 8, Kent+ 2024 PNAS 121:e2415486121. 9, Judd+ 2024 Science 385:eadk3705. 10, Olsen+ 2022 Science Adv. 8:eabo6342. 11, Chang+ 2024 GSL Spec Pap. 538:114. 12, Schoene+ 2010 Geology 38:387. 13, Westerhold+ 2020 Science 369:1383-1387. 14, Funded by NSF & the Heising-Simons Foundation.
How to cite: Olsen, P., Kinney, S., Tibbits, D., Fang, Y., Chang, C., Schaller, M., Slibeck, B., Whiteside, J., and Kent, D.: Obliquity pacing of tropical lacustrine cyclostratigraphy of the great end-Triassic hyperthermal and mass extinction: competing radiative balance forcings induced by the Central Atlantic Magmatic Province (CAMP) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10277, https://doi.org/10.5194/egusphere-egu25-10277, 2025.
The end-Triassic mass extinction (ETME) and global climatic perturbation coincide with the onset of Central Atlantic Magmatic Province (CAMP) emplacement. The associated perturbation to the global carbon cycle is reflected by a ~ 3 – 6 ‰ negative carbon isotope excursion (CIE) coinciding with the ETME. The magnitude and duration of the negative CIE are however poorly constrained. Furthermore, the Early Jurassic Hettangian stage, marking the initial recovery phase following the end-Triassic mass extinction, has been the subject of significant debate over its precise timing and duration. Estimated Hettangian stage durations derived from cyclostratigraphic and U-Pb geochronological analyses vary between a ‘short Hettangian’ of 1.8 – 2.5 Myr, and a ‘long Hettangian’ of 3.9 – 4.4 Myr. Poor time constraints for the Triassic–Jurassic interval impact understanding of the timing and rate of biogeochemical cycling, environmental and biological recovery after the end-Triassic mass extinction, and global climatic perturbation.
We here conducted carbon isotopic and cyclostratigraphic analysis of the well-preserved, biostratigraphically complete, and expanded Hettangian succession in the Carnduff-2 core of the Larne Basin (Northern Ireland), nearby the Waterloo Bay outcrop. The studied sedimentary succession (~120 m in core) stratigraphically spans the upper Rhaetian (upper Triassic), including the end-Triassic mass extinction, Hettangian, and lower Sinemurian (lower Jurassic), and consists of predominantly mudstone, with varying degrees of limestone and silt throughout the succession. Cyclostratigraphic analyses of elemental and carbonate concentration data show a hierarchy of dominant frequencies, interpreted to reflect long and short eccentricity, obliquity, and precession. These observations suggest a total duration of ~2.2 Myr for the Hettangian Stage with a sedimentation rate of ~ 4.1 cm/kyr, confirming the ‘short-Hettangian’ hypothesis. The negative carbon isotope excursion (CIE) duration, which coincides with the ETME, is estimated at ~290 kyr. The first occurrence of the Jurassic ammonite Psiloceras tillmanni, marking the onset of Hettangian biotic recovery after the ETME across the British Isles, ~320 kyr after the end-Triassic negative CIE, suggesting a prolonged period of biotic demise in response to CAMP induced climatic and environmental upheaval at this time.
Key Words: end-Triassic mass extinction, Early Jurassic, Hettangian stage, Milankovitch cycles
How to cite: Perera, A., Ruhl, M., Xu, W., Silva, R. L., Raine, R., and Goodhue, R.: “Short” or “Long” Hettangian? Astronomical chronometry on the duration of lower Jurassic Hettangian stage and the recovery dynamics following the end – Triassic mass extinction. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13954, https://doi.org/10.5194/egusphere-egu25-13954, 2025.
Global perturbations to the Jurassic environment have been extensively documented over the last decades, notably those that were associated with major events such as mass extinctions, global environmental crisis and hyperthermal events that often mark stage boundaries. However, much less attention has been given to background times and to lesser palaeoenvironmental and palaeoclimatic events. As such, the long-term secular evolution in the Jurassic carbon cycle and palaeoenvironmental response, that provide the broader context, is very poorly understood. One such understudied time interval is the Bathonian-Callovian transition (Middle Jurassic). Although at first it may appear as a relatively stable time, there is evidence for biotic turnover, climate warming, dramatic sea-level rise, and carbon cycle disturbance. A positive excursion in the carbon isotope ratio (CIE) has been documented in Europe and Greenland, but the current state of records does not yet allow determination of the exact causes and nature of the isotope shift and the environmental changes across the Bathonian-Callovian boundary. As for other Mesozoic positive CIEs, it has been proposed that increased burial of organic matter due to elevated primary productivity might have generated the positive shift. The lack of continuous well-dated records with robust stable carbon isotope chemostratigraphy and environmental context complicate the attribution of a Global Boundary Stratotype Section and Point for the Bathonian-Callovian.
This study aims to tackle this lack of empirical data by providing a multi-proxy dataset combining sedimentological observations, nannofossil biostratigraphy, mineralogical and geochemical analyses. The Ravin des Vas section in SE France has been selected because it encompasses the Bathonian-Callovian boundary and comprises an extended 100 m-thick homogeneous succession of dark marls, with little lithological change, which is an advantage for geochemical analysis. Organic carbon isotope analysis reveals a pronounced positive excursion at the base of the Callovian, associated with an increase in organic carbon content. This excursion can be correlated to other coeval sites, confirming the likely global nature of this carbon cycle perturbation. Whole-rock and clay mineralogy will be used to determine the climatic and weathering conditions, and phosphorus content will inform on the nutrient availability. Altogether, the new dataset from France will give new insights into our understanding of the palaeoclimatic and palaeoenvironmental conditions across the Bathonian-Callovian boundary, and hence provide a reference framework for further studies on this yet poorly known time interval.
How to cite: Fantasia, A., Gavillet, L., Bodin, S., Hesselbo, S. P., Mattioli, E., and Adatte, T.: Unravelling the base Bathonian-Callovian boundary event: New insights from the SE France Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15198, https://doi.org/10.5194/egusphere-egu25-15198, 2025.
The early Aptian OAE 1a is one of the most prominent hyperthermal events in Earth’s history. This event is associated with global environmental and biotic perturbations, including global rise in temperatures, ocean oxygen depletion, and widespread deposition of organic-rich marine sediments.
The onset of OAE 1a coincided with a major disturbance of the global carbon cycle, recorded with a marked negative spike in the C-isotope record. A complex response of the environmental and biotic system occurred, ultimately triggered by volcanism of the Ontong-Java Plateau.
In this study, we present two expanded records of OAE 1a from the Southern Iberian Palaeomargin (SIP, Western Tethys): the Carbonero and Cau sections, which comprise high-resolution C-isotope records that have served as the basis for a precise stratigraphic correlation.
The Carbonero section is composed of black shales, radiolarites and marls, deposited on a fault-bounded, highly subsiding sector of the pelagic basin of the SIP. The Cau section (also studied in a core), consists of an alternance of hemipelagic marls and marly limestones deposited in the distal platform settings of the SIP. Previous studies have provided with multiproxy evidence, including stratigraphy and sedimentology, biostratigraphy (ammonites, planktonic foraminifera, calcareous nannofossils and radiolaria), C-O and Re-Os isotope stratigraphy, elemental composition and biomarker distributions. The time model has been based on a combination of biostratigraphy and cyclostratigraphy. Atmospheric CO2 concentrations records across OAE 1a have been derived from bulk and compound-specific C-isotope data from the Cau section. The high-resolution C-isotope stratigraphy from the Cau core has been used to refine the previously defined C-isotope segments of the Aptian, and to correlate the succession with other records worldwide.
The onset of the OAE 1a has been studied at ultrahigh-resolution scale (0.2–0.5 kyr spacing) revealing a succession of sharp C-isotope negative spikes, interpreted as a record of pulses of volcanism and methane emissions. The largest spike was rapid (<10 kyr) and marks the base of OAE 1a, which occurs within a longer-term falling C-isotope trend. The C-isotope profile across OAE 1a records the negative (C3/Ap3), positive (C4/Ap4), steady (C5/Ap5), and positive (C6/Ap6) segments that were defined from Cismon (Italy) and subsequently recognized worldwide.
Our results illustrate a complex evolution of environmental and biotic changes throughout the OAE 1a event, with an estimated duration of ca. 1.47 Ma. Moreover, the unprecedented resolution of the study of the onset of the event reveals rapid environmental and biotic changes at the scale of the thousands of years, providing valuable insights on the mechanisms acting at shorter time intervals and enabling comparisons with more recent hyperthermal events.
How to cite: Castro, J. M., de Gea, G. A., Quijano, M. L., Sequero, C., Ruiz-Ortiz, P. A., O'Dogherty, L., Froehner, S., Martinez-Rodriguez, R., Batenburg, S., Naafs, D., and Pancost, R.: Records of the early Aptian OAE 1a (Southern Iberian Paleomargin, Western Tethys): multiproxy evidence from expanded successions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20508, https://doi.org/10.5194/egusphere-egu25-20508, 2025.
Late Maastrichtian to Early Eocene sediments from Wadi Nukhul, Egypt (67–55.5 Ma) were deposited during the eruptions of the Deccan Traps and the North Atlantic Igneous Province (NAIP). Using tellurium (Te) and mercury (Hg) as proxies for volcanic activity, we investigate the timing of flood basalt volcanism relative to environmental changes and extinction events. Te enrichments are observed during the latest Maastrichtian, earliest Danian, and Late Paleocene to Early Eocene, indicating increased volcanic inputs. In the Late Maastrichtian, a Te peak aligns with the Maastrichtian Warming Event, while a larger Te peak begins 120–80 kyr before the Cretaceous/Paleogene boundary (KPB), continuing into the Danian. The highest Te values (70–30 kyr before the KPB) suggest association with eruptions of the Deccan Wai Subgroup, independent of the Chicxulub impact. This suggests that Deccan volcanism caused climate instability, amplifying the environmental effects of the impact. A 6 Myr period of low Te during the Paleocene is followed by a sharp increase beginning at 57.5 Ma, peaking at the Paleocene-Eocene boundary (PEB, 56 Ma), coinciding with NAIP’s highest eruptive rates. In contrast, Hg variations during this period are less consistent. Our findings highlight Te as a robust proxy, complementing Hg, for tracking large volcanic events in Earth’s history.
How to cite: Adatte, T., Baumann, N., Regelous, M., Khozyem, H., Regelous, A., and Haase, K.: Tracing Volcanic Activity in the Deccan and North Atlantic Igneous Provinces Using Tellurium and Mercury Proxies (Late Cretaceous–Early Eocene), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10073, https://doi.org/10.5194/egusphere-egu25-10073, 2025.
Extreme climate warmth (hyperthermal) events occur throughout the geologic record. In particular, several transient events are well documented for the early Eocene with the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) standing as the major star. Yet, earlier short-lived (104–105 years) warming events, correlated with abrupt negative carbon isotope excursions (CIEs), also struck in the Paleocene producing noticeable environmental disturbances (e.g., DAN-C2 event in the Danian, ~65.2 Ma and the ELPE event in the early late Paleocene, ~59 Ma). The Early Late Paleocene Hyperthermal Event (ELPE), also known as the mid-Paleocene biotic event (MPBE), was first discovered during ODP Leg 178 Shatsky Rise in the northern Atlantic as a prominent clay-rich ooze close to the first occurrence (FO) of the nannofossil Heliolithus kleinpellii, a marker for the base of nannofossil Zone CNP8 (=NP6), and the base of chron C26n. It was interpreted as an abrupt warming that possibly caused a brief switch in the source of deep waters at Shatsky Rise.The base of C26n marks the Selandian/Thanetian stage boundary as defined in the Selandian GSSP in the hemipelagic relatively expanded section at Zumaia that provides an astronomical template including the first documented ELPE event from a land section.
Here, a conspicuous ~40 cm clay-rich layer occurring at Hole U1556A (located ~1250 km west of the Mid-Atlantic Ridge at a 5002 m water depth) in interval 390-U1556A-29X-5, 70-110 cm (270.7 to 271.1 m CSF-B) (also occurring in Holes U1556C and U1557B) is investigated at high resolution. Paleomagnetic directional data is presented from four U-channel samples from sections 390-U1556A-29X3 to 390-U1556A-29X6 that confirm the presence of chron C26n, also in agreement with the FO of H. kleinpellii. Rockmagnetic and bulk rock stable isotope (d13C and d18O) measurements (155 samples) along with calcareous nannofossil determinations (80 samples) and XRD bulk mineral analysis (51 samples) were achieved spanning cores 390-U1556A-29X and 390-U1556A-30X at variable resolution (average 9 cm but 1.5–3 cm along critical intervals, shipboard age model indicating 0.49 cm/ky).
Quantitative analyses on calcareous nannofossils are carried out following the random settling technique to obtain the relative (%) and absolute abundance (coccoliths*gr-1) data. The relative nannofossil fragmentation was also determined. Calcareous nannofossil assemblages are well to moderate preserved and diversified, and allowed determination of key biostratigraphic datums, and the main calcareous nannofossil dissolution events. During the ELPE, the total clay content reached up to 70 wt.%. Additionally, increased quartz and feldspar contents during this period suggests wind-driven sediment transport. Orbital chronology and paleoclimatic/paleoceanographic proxy data encompassing the ELPE event will be examined.
How to cite: Dinarès-Turell, J., Bonomo, S., Kim, S., and Yang, K.: Decoding the ELPE hyperthermal: a new biotic and paleoclimate record from South Atlantic IODP Sites U1556/U1557, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4546, https://doi.org/10.5194/egusphere-egu25-4546, 2025.
Due to their environmental sensitivity, planktic foraminifera are important proxies for reconstructing past climatic and oceanographic shifts, offering critical insights into marine ecosystem responses during intervals of rapid warming. Early Eocene hyperthermal (~50-200kyrs) episodes provide a unique opportunity to explore the effects of extreme heat on planktic foraminifera, a group of marine calcifiers highly sensitive to temperature, pH, and nutrient levels changes that may induce evolutionary modifications and variations in abundance and test size. Here we disentangle the global-scale impacts of Eocene Climatic Optimum (EECO,~53-49 Ma) hyperthermals on planktic foraminiferal communities, offering insights into their adaptability or loss of resilience under climatically related environmental stress.
We reveal significant modifications in PF assemblages during two major hyperthermals of the EECO, the J event (53.26 Ma), which marks the beginning of the EECO, and the K/X event (52.86 Ma). Following the J event, the symbiont-bearing genus Morozovella experienced a permanent decline in abundance and diversity at low-latitude locations while Acarinina thrived globally. At the same time, size in another symbiont bearing taxon Acarinina exhibits a reduction at tropical Pacific sites while Morozovella is becoming larger. Our stable isotope analyses reveal that Acarinina displays lower δ13C values than Morozovella, a feature likely linked to a reduction in photosymbiotic activity or change in symbiont and habitat deepening. This ecological strategy probably enabled Acarinina to succeed under the EECO environmental conditions.
Approximately 400kyr later, during the K/X event, a switch in Morozovella coiling direction – a dominance clockwise (dextral) or counterclockwise (sinistral) morphotypes- from dextral to sinistral was observed in the Atlantic, Pacific and Indian Oceans. This coiling shift represents a valuable biostratigraphic tool. It is linked to an evolutionary turnover in Morozovella species, with M. crater and M. aragonensis becoming dominant. These two morphotypes may represent cryptic species, akin to living taxa, and their change can be interpreted as a further evolutionary change in the taxon. The K/X event is characterized by the disappearance of the Oxygen Deficient Zone (ODZ)-dwelling genus Chiloguembelina, indicating ODZ contraction during the EECO, as also supported by published Foraminifera-bound nitrogen isotope data from the Atlantic and tropical Pacific.
The J and K/X events appear to represent turning points for foraminiferal assemblages. δ13C records distinct long-term decrease (J) and increase (K/X), consistent with respectively enhanced and lowered fluxes in carbon inputs
Across the studied hyperthermals PF communities shifted to a new configuration that was never fully recovered, reflecting loss of resilience.
The environmental impacts of these relatively slow, compared to modern warming events underscore the potential for more severe and rapid ecosystem consequences in the modern context. Our findings provide critical insights into the mechanisms and limits of marine ecosystem resilience.
How to cite: Luciani, V., Filippi, G., Sigismondi, S., and Schmidt, D.: Impact of EECO Hyperthermals on Planktic Foraminiferal Communities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19492, https://doi.org/10.5194/egusphere-egu25-19492, 2025.
Over geological time, climatic fluctuations and hyperthermal events profoundly influenced carbonate systems and the related marine ecosystems. During the Eocene, approximately 40.1 Ma, a significant warming phase, the Middle Eocene Climatic Optimum (MECO), occurred persisting for around 500,000 years. Within this context, the composition and calcification rates of marine organisms, such as corals and larger benthic foraminifera (LBF), were shaped by variations in global CO2 levels and oceanographic conditions, exerting a profound influence on photic-zone carbonate factories.
The Middle Eocene Monte Saraceno sequence (Gargano Promontory) and the San Domino Formation (Tremiti Islands), cropping out along the eastern margin of the Apulia Carbonate Platform (southern Italy), represent case studies to explore the carbonate factory responses to climatic variations as the MECO event. In this areas, Middle Eocene deposits are mainly characterized by two distinct intervals with different modes of carbonate production. In particular, a well-exposed section belonged to the Monte Saraceno sequence reveals a lower interval with clinostratified, thick beds of rudstone to floatstone, predominantly formed by LBF belonging to the genus Nummulites, indicating an early Bartonian age (Shallow Benthic Zone 17). The upper interval, separated from the lower by a sharp boundary, is characterized by branching coral floatstone to rudstone with a packstone matrix associated with bivalve, gastropods, and rare, small LBF. Here, the Heterostegina sp. and Glomalveolina ungaroi occurrences define a late Bartonian age (Shallow Benthic Zone 18). Likewise, in the Tremiti Islands, the San Domino Fm is characterized by abundant LBF in the lower intervals covered by coral-rich facies exhibiting a great diversity in coral species and morphologies.
Integration of biostratigraphy, stable-isotope, and sedimentological evidences of the Monte Saraceno sequence indicates that the lower clinostratified interval, featuring abundant Nummulites and an absence of corals, corresponds to the MECO event. Conversely, the abrupt transition in the late Bartonian to a coral-dominated carbonate factory, accompanied by a marked decline in LBF abundance and size, is likely attributable to a temperature drop that fostered conditions more favorable for coral growth. Analogously, the coral factory flourishing, occurred within upper interval of the San Domino Fm, is associated to colder environments probably reaching the late Bartonian-Priabonian ages.
Therefore, this study provides compelling evidence of how the environmental changes can impact on marine carbonate production, highlighting how these studies can be a powerful tool in understanding the relationship between climate dynamics and carbonate systems across geological timescales, including the past, present, and future.
How to cite: Morabito, C. and Morsilli, M.: Impact of the MECO (Middle Eocene Climatic Optimum) on shallow-water carbonate systems: a case study from the Apulia Carbonate Platform (Gargano Promontory and Tremiti Islands, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21136, https://doi.org/10.5194/egusphere-egu25-21136, 2025.
Conventional neo-Darwinian theory views organisms as responsive to their environments on neontological timescales, and able to readily change size or shape due to selection pressures (as exemplified by the famous case of Galápagos finches). But since 1863, it has been well established that Pleistocene animals and plants show limited morphologic change in response to the glacial-interglacial cycles. Rancho La Brea tar pits in Los Angeles, California, preserves a large and diverse fauna from many well-dated deposits, spanning 37,000 years. Pollen evidence shows that climate changed from oak-chaparral about 37 ka to snowy piñon-juniper-ponderosa pine forests during the peak glacial about 18 ka, then returned to the modern chaparral since the glacial-interglacial transition. We have studied all the sufficiently abundant mammals (dire wolves, saber-toothed cats, giant lions, Harlan’s ground sloths, camels, bison, and horses) and all the common birds (28 species, ranging from eagles, hawks, vultures, condors, owls, to yellow-billed magpies, ravens, and Western meadowlarks). We found complete stasis in size and robustness as measured by the major limb bones in all 28 species. There was no significant response even at 20 ka to 18 ka, during the peak glacial period, when climate and vegetation were very different at La Brea. The larger species might be so wide-ranging and versatile that they would not respond to environmental changes, but this is inadequate to explain stasis in even the smallest birds, such as meadowlarks and burrowing owls. While the Galápagos finch model suggests rapid morphological change in response to environmental change, the fossil record shows that such small-scale changes are transient and do not accumulate to result in speciation.
How to cite: Prothero, D. R.: Patterns of Evolution in late Pleistocene Mammals and Birds from La Brea Tar Pits, California, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21959, https://doi.org/10.5194/egusphere-egu25-21959, 2025.
Posters on site: Thu, 1 May, 16:15–18:00 | Hall X3
Interpretion of the 2D seismic data set revealed the depositional history and structural forming processes in the southwestern margin of the Ulleung Basin, East Sea. Based on the seismic facies and sediment succession with various unique structures in the study area, they were divided into five depositional sequences (DS1 to DS5), separated by erosional unconformities (H1–H5). The lower two depositional sequences (DS1-DS2) show deformed succession with faults and folds, whereas the upper three depositional sequences (DS3-DS5) indicate non-deformed succession. DS1 and DS2, regarded as the late Miocene strata, comprise hummocky and chaotic seismic facies. During the late Miocene, the Dolgorae Thrust Belt (DTB) and Gorae Structure (GS) were created sequentially and are strongly associated with the creation of the DS1 and DS2. On the other hand, the upper three sequences (DS3–DS5), which are part of the Plio-Quaternary strata, are acoustically distinguished by reflection configurations that are both well-stratified and progressive. Since the Pliocene, the tectonic movement associated with the regional structures (US, DTB, and GS) has been nearly stopped. On the other hand, a portion of the GS has been developed until now. As a result of these findings, it was determined that DS1 and DS2 were mainly controlled by tectonic activity. The sedimentation of the upper three sequences (DS3-DS5) after the Pliocene was driven primarily by periodic and repeated sea-level changes rather than by tectonic activity.
How to cite: Lee, B.-R., Yoo, D.-G., Jung, S.-K., and Cho, J.-H.: Seismic stratigraphy and depositional history in the SW margin of the Ulleung Basin, East Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7783, https://doi.org/10.5194/egusphere-egu25-7783, 2025.
The study of astronomical climate forcing and the application of cyclostratigraphy grew spectacularly over the last decades. In cyclostratigraphy a wide range in methods are used to assess cyclicity and orbitally forced cyclicity. However, comparative studies between these different approaches remain too rare. Different geological datasets clearly require specific approaches. With the growing importance of the field, questions arise about reproducibility, uncertainties and standardization of methods and reporting of results. To address these questions, we initiated a framework for analysing and comparing cyclostratigraphic investigations within the community. The aims are to investigate and quantify reproducibility of, and uncertainties related to, cyclostratigraphic studies and to provide a platform to discuss the merits and pitfalls of different methodologies, and their applicability. After a successful first Cyclostratigraphy Intercomparison Project (CIP) workshop in 2018, activities shifted online during Covid-19 with the development of the www.cyclostratigraphy.org website that hosts a growing suite of cyclostratigraphy-related educational and communication materials. In 2024, a second intercomparison workshop took place in-person during the summer in Brussels, Belgium. Participants analysed real cyclostratigraphic data before and during the meeting. The compiled results were presented and discussed during the workshop, state-of the art keynote lectures were given followed by topical debates. One relevant outcome of these efforts to be discussed in this session is that spectral analysis must always be considered in the context of background knowledge, and complementary data analyses are often needed to reach a conclusion.
Literature:
Sinnesael, M., De Vleeschouwer, D., Zeeden, C., Batenburg, S. J., Da Silva, A.-C., de Winter, N. J., Dinarès-Turell, J., Drury, A. J., Gambacorta, G., Hilgen, F. J., Hinnov, L. A., Hudson, A. J. L., Kemp, D. B., Lantink, M. L., Laurin, J., Li, M., Liebrand, D., Ma, C., Meyers, S. R., Monkenbusch, J., Montanari, A., Nohl, T., Pälike, H., Pas, D., Ruhl, M., Thibault, N., Vahlenkamp, M., Valero, L., Wouters, S., Wu, H., and Claeys, P.: The Cyclostratigraphy Intercomparison Project (CIP): consistency, merits and pitfalls, Earth-Sci. Rev., 102965, https://doi.org/10.1016/j.earscirev.2019.102965, 2019.
How to cite: Zeeden, C., Sinnesael, M., De Vleeschouwer, D., Da Silva, A.-C., Crucifix, M., and Claeys, P.: Initial Results of the Cyclostratigraphy Intercomparison Project 2, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13786, https://doi.org/10.5194/egusphere-egu25-13786, 2025.
The Pliensbachian-Toarcian boundary interval has attracted great scientific interest over the last decade, because it comprises carbon cycle disturbances of magnitudes rarely observed else during the Phanerozoic, and because it is accompanied by well-documented biotic changes. This interval covers lithostratigraphically the basal part of the Posidonia Shale Formation and the top of the Amaltheen Clay Formation. The Posidonia Shale is one of the most pronounced black shales and hydrocarbon source rocks in western Europe and the North Sea. Carbon cycle changes have previously been recorded in organic and inorganic carbon isotope data from various terrestrial and marine settings.
In our contribution, we will present results from recent drill cores along (i) a SW-NE transect across the South German Basin and (ii) a NW-SE transect along the Hils Syncline in the Lower Saxony Basin. In addition to detailed sedimentary descriptions, all cores have been studied using high-resolution XRF core scanning and organic carbon isotope stratigraphy. These new results will be compared to the Mochras key site in Wales, as well as other records from Germany, in order to identify differences and potential stratigraphic gaps in the sedimentary successions.
How to cite: Bornemann, A., Blumenberg, M., Littke, R., Mann, T., and Erbacher, J.: New carbon isotope records from the Pliensbachian-Toarcian boundary interval in Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8188, https://doi.org/10.5194/egusphere-egu25-8188, 2025.
The Opalinuston-Formation in Southern Germany comprises a thick sequence of Late Toarcian to Early Aalenian claystones. In parts of Bavaria and Baden-Württemberg, the formation has the potential for hosting high-level radioactive waste. However, in contrast to Switzerland where the Opalinuston-Formation has been studied in detail, there is a general lack of coherent geological data in Germany. We present new data from the research project "Sequence Stratigraphy of the Aalenian in Southern Germany" (SEPIA) on the geological variability of the Opalinuston-Formation based on four drill cores, each of which penetrated through the entire formation, and parts of the over- and underlying rock strata. In order to investigate different depositional environments of the Opalinuston-Formation on a basin scale, the drill cores obtained constitute a transect through the entire Southern German basin in the Middle Jurassic, from the eastern edge of the Black Forest in the Wutach area to the western boundary of the Bohemian Massif in Upper Franconia. Cores were examined in high resolution for their petrophysical properties and element distribution using non-destructive analytical tools such as XRF core scanner and multi-sensor core logger. Furthermore, one sample per core meter was taken for a precise biostratigraphic classification of the rocks and a geochemical-mineralogical and sedimentological characterization. Initial results show that the Opalinuston-Formation in Southern Germany, which appears often homogeneous in macroscopic terms, exhibits notable variability. Particularly with regard to the element distribution (especially Si/Al ratio), a distinct cyclicity becomes visible, which is interpreted as changes in grain size due to relative sea-level fluctuations during deposition. In summary, our preliminary results highlight the geological variability of the Opalinuston-Formation in Southern Germany and allow for a discussion of the possibilities of a sequence stratigraphic approach in order to finally identify the most suitable parts of sub-areas in claystone formations, elsewhere.
How to cite: Erbacher, J., Mann, T., Zimmerli, G. N., Blumenberg, M., Bornemann, A., and Dohrmann, R.: The Late Toarcian to Early Aalenian Opalinuston-Formation in Southern Germany – a sequence stratigraphic approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10774, https://doi.org/10.5194/egusphere-egu25-10774, 2025.
The Gadvan Formation of Barremian to Aptian age, is considered as a subordinate oil reservoir with proven oil-bearing intervals, in some well-known field structures, in the Persian Gulf. However, this formation has received limited geoscientific attention, with relatively few studies and data available so far. In the offshore area, regional geological and stratigraphic understanding has primarily been based on reports from drilled wells and limited industrial subsurface data, along with correlations to outcrop exposures. In this study, we investigate the Gadvan Formation using multiple stratigraphic approaches, including biostratigraphy, and both sample-based and log-based sequence stratigraphy. Our analysis reveals that the formation can be consistently interpreted to consist of two 3rd-order sequences, in the studied locations. By correlating data, we provide generalized sequence stratigraphic interpretations that can help predict the distribution of key reservoir layers, in inter-well areas in this region. These findings contribute to a more comprehensive understanding of the Gadvan Formation stratigraphy, in the Persian Gulf.
How to cite: Yari Nejad, A., Farahpour, M. M., Yousefi Yeganeh, B., Wagreich, M., and Yosefpour Kejani, M.: Sequence stratigraphy of Gadvan Formation (Barremian-Aptian) in the Persian Gulf, Iran, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18388, https://doi.org/10.5194/egusphere-egu25-18388, 2025.
In this work, 44 isolated small theropod teeth from different microsites of “El Gallo” formation, Baja California, Mexico are studied. Isolated theropod teeth constitute important evidence to analyse their diversity, since they are quite common in the fossil record. For their identification, a morphological comparison and multivariate and cladistic analyses were performed, comparing them with previously described small theropod teeth from Late Cretaceous North America formations. This dental material can be assigned mainly to two families: Dromaeosauridae, Troodontidae; and one subfamily: Saurornitholestinae. Also, some of the teeth were assigned to Richardoestesia and two specimens were indeterminate. Dromaeosaurids represent the most abundant group of theropods in “El Gallo” followed by the Richardoestesia dental morphotype. This diversity pattern is similar to the one reported in the Aguja Formation of Texas for the same period of time. The use of multivariate statistical techniques and cladistic analyses allowed us to evaluate the similarity between specimens, however, taxonomical assignments are difficult due to the lack of knowledge of intraspecific morphological and / or ontogenetic variation that can lead to misinterpretations. Even so, the sample of 44 specimens yields valuable information that allows suggesting the presence of certain taxa and providing knowledge of the diversity of the continental Cretaceous fauna in Mexico.
How to cite: López-Miguel, M., Torices, A., García-Gil, V. A., and Montellano-Ballesteros, M.: Isolated teeth of small theropods from the “El Gallo” formation, Baja California, Mexico., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19350, https://doi.org/10.5194/egusphere-egu25-19350, 2025.
The Paleocene/Eocene Thermal Maximum (PETM) marks a short but intense climate warming that occurred 56 million years ago and lasted for about ca.100 - 200 k years. It represents a significant change in the carbon cycle and Earth’s climate.
PETM sites from the Arabian Platform occupy an important low latitude site for recording this excursion. However, to date, specific information about the PETM event in the region is relatively rare as the previous studies have mostly focused on hydrocarbon production and related investigative approaches to biostratigraphy, diagenesis, mineralogy, and geochemistry. High-resolution and integrated approaches are necessary to understand how the low latitude and shallow marine deposits respond to abrupt climatic changes such as the PETM, and therefore to tie regional stratigraphy to the global stratigraphic models and correlate the shallow marine to different depositional environments.
The objective of the study is to use a multidisciplinary approach and integration of field observations, sedimentology, paleontology and stable isotopes analyses to record the depositional and sedimentological changes of the Paleocene-Eocene interval within the Muthaymimah Formation in the UAE, for the first time. In this study four stratigraphic sections of Muthaymimah Formation have been analysed, Qarn El Barr, Malieha & Thanyes outcrops in the central region of Sharjah Emirate and Mundassah section, southeast of Al Ain city, Abu Dhabi Emirate.
We examined sedimentological changes across the Muthaymimah Formation using field observations and stratigraphic logging. Initially 64 samples were analyzed for their calcareous nanoplanktons content to determine calcareous nanoplankton assemblages and the age of each stratigraphic section and in order to identify a biozonation and to locate the Palaeocene/Eocene boundary. According to previously published work in the region, the Paleocene/Eocene boundary is located between biozones NP9b and NP10. Our preliminary investigation showed that biozones NP7/8, NP9a and NP10 are represented in Mundassah section, bracketing the PETM. Biozones NP3 and NP7/8 are described in the lower part of the Malieha section. Biozone NP10 was located at Qarn El Barr, while Paleocene sediments have been tentatively identified above the well-defined late Cretaceous sediments at Thanyes.
Based on the findings of this lower resolution preliminary data set, we carried out a further detailed investigation to better constrain the Paleocene/Eocene boundary in the studied sections. A total of 213 samples from four logged sections are used to produce a high-resolution biozonation of the calcareous nannoplankton analyses for Muthaymimah Formation. In addition, we constructed the first chemostratigraphic sections using Carbon and Oxygen stable isotope ratio analysis of the Muthaymimah Formation in the UAE. A total of 534 further samples have been collected from the key four outcrops in November 2024. We focused on the Mundassah stratigraphic section, where the PETM has already been bracketed by our lower resolution analysis, collecting 403 samples. In addition, 51 samples from the Qarn El Barr stratigraphic section, 23 from the Malieha stratigraphic section, and 57 samples from Thanyes stratigraphic section were collected.
Based on these analyses, we establish the first detailed record of the PETM from the field outcrops in the UAE.
How to cite: Al Ali, A., Whittaker, A., Price, G., Abdelghany, O., Faris, M., Davies, M., Reynolds, R., and Abu Saima, M.: New Insights into the Paleocene-Eocene Thermal Maximum (PETM) in the UAE: Geological and Paleoclimatic findings from the Muthaymimah Formation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14944, https://doi.org/10.5194/egusphere-egu25-14944, 2025.
Recent studies on early Eocene climate have established that climatic fluctuations characterized by negative carbon isotopic excursions (CIE, hyperthermals) in the atmosphere associated to global warming, are responsible for drastically changes in the terrestrial sedimentary record of sub-tropical basins. Here we present a key sedimentary record to understand geological and climatological changes in order to evaluate the impact of hyperthermals on sediment transport and deposition in alluvial setting during Early Eocene Climatic Optimum (EECO). Based on an integrative study combining sedimentology, sequential stratigraphy, magnetostratigraphy and chemostratigraphy (δ13C), we propose a detailed constrained chronostratigraphic framework of continental sedimentary series of the French Minervois Basin. Using facies association analysis, the sedimentary succession is divided into three continental sequences bounded by subaerial unconformity deposited through the development of an endoreic underfilled basin. Sequences are composed of cyclically siliciclastic fluvial and carbonated palustrine-shallow lacustrine deposits. Palustrine-shallow lacustrine systems reflect arid climate conditions during EECO which are interrupted by sudden arrivals of detrital fluxes reflecting intense and extreme rainfall events in the hinterland. The latter coincide to CIEs corresponding to transient hyperthermals identified as C24n.1nH1/K/ETM3, C23rH2/M, and C23n.2nH1/N-C23n.2nH2/O interval. Extreme monsoon-type events triggered by intense warm-ups during hyperthermals are proposed to explain sudden detrital inputs in the basin. Finally, we present a new model in which variation in continental stratigraphic architecture enable us to emphasize hydrological changes associated to transient hyperthermals, and that the corresponding sedimentary response is almost identical to that of more intense events such as the PETM.
How to cite: Boyrie, C., Girard, F., Yans, J., Ballas, G., Lihoreau, F., Benammi, M., Bourget, H., Garcia, G., Leredde, C., Pellissier-Tanon, A., Valentin, X., and Tabuce, R.: Rapid changes in continental sedimentation triggered by monsoon-type event during EECO hyperthermals, Minervois Basin, Southern France, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5891, https://doi.org/10.5194/egusphere-egu25-5891, 2025.
Traces of large extraterrestrial impacts preserved in distinct sedimentary layers can be used as event horizons for stratigraphic correlation and to assess relationships, e.g., to extinctions in the fossil record and to paleoenvironmental changes associated with the event [1]. During the Late Eocene, the two largest post-K/Pg impact structures - Popigai (Russia; ~100 km diameter) and Chesapeake Bay (USA; ~85 km diameter) - are thought to have formed as a result of nearly simultaneous impact events ca. 35–36 Mya [1–3] and may have caused significant biotic disruptions and altered climate conditions on a global scale [3,4]. A more detailed assessment of the exact timing of these events and impact-induced effects, however, requires high-resolution stratigraphic correlation and more accurate age data than currently available.
The two Late Eocene impacts have been stratigraphically associated with two distinct impact layers identified in contemporaneous deposits around the globe: (a) Chesapeake Bay with the North American tektite layer, and (b) Popigai with the clinopyroxene (cpx)-bearing spherule layer [2,3]. The occurrence of cpx-spherules at several deep-sea Southern Ocean sites drilled by the Ocean Drilling Program (ODP) was previously correlated to the Popigai impact [3]. However, a lack of geochemical data at some sites, as well as an absence of absolute age data, hitherto prevented rigorous verification that recovered spherules derived from the same or possibly multiple events.
Here, we report new geochemical data (major oxide compositions) of cpx-spherules and glassy microtektites collected from ODP Hole 689D (Maud Rise, South Atlantic) and from ODP Hole 738B (Kerguelen Plateau, Southern Indian Ocean). Site 738 previously had not been evaluated compositionally. The investigated samples from both sites display similar compositional ranges for Al2O3, MgO, FeO, CaO, Na2O, K2O and TiO2 versus SiO2 compared to reported literature data [3,5] for the cpx-spherule layer associated with the Popigai impact. Hence, our results confirm the provenance of the impacto-clastic layer at the studied Southern Ocean sites. Additionally, large glassy microtektites (200–700 µm in diameter) were recovered from these sites and are currently being prepared for high-precision 40Ar-39Ar analysis. This continuing direction of research will potentially yield the first radiometric ages for the impact layer and provide a new geochronological framework for assessing the timing and effects of Late Eocene impact events.
[1] Glass, B.P. and Simonson, B.M. (2013), Distal Impact Layers: Springer, 716 pp. [2] Koeberl, C. (2009), Geol. Soc. Am. Spec. Pap. 452: 17-26. [3] Liu, S. et al. (2009), Geol. Soc. Am. Spec. Pap. 452: 37-70. [4] Vonhof, H.B. et al. (2000), Geology 28: 687-690. [5] Glass, B.P. et al. (2004), Geochim. Cosmochim. Ac. 68: 3971-4006.
How to cite: Vogt, M., Trieloff, M., and Bohaty, S. M.: Late Eocene impact layers in the Southern Ocean: A geochemical and geochronological archive of the Popigai impact event, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9179, https://doi.org/10.5194/egusphere-egu25-9179, 2025.
Key Words: Stratigraphy, Upper Miocene, Pannonian Basin, Seismic Attributes, Lithotype Analysis, Palynology
The Upper Miocene deposits in the southeastern part of the Pannonian Basin can be categorized into three sedimentary and tectonic cycles based on the regional Neogene stratigraphy (Horváth et al., 2015). The first cycle is characterized by deep-water marlstones, claystones, and sandstone turbidites corresponding to the regional Endrőd and Szolnok formations. Overlying these, the second cycle includes sediments deposited in a delta plain environment, represented by the clastic and marly progradational series of the Algyő Formation (Magyar et al., 2013). Finally, the third cycle consists of shallow-water, transitional, and terrestrial deposits attributed to the Újfalu Formation.
The primary objective of this research was to determine progradational directions and identify sedimentary bodies within the Upper Miocene characterized by distinct lithological properties. A significant challenge involved the geological interpretation of seismic data, which, being in the time domain, has a much lower vertical resolution compared to well data. Detailed lithological analysis of well data was performed using cluster (lithotype) analysis, which groups rocks based on the physical characteristics observed in well logs. Since seismic data also reflect variations in rock physical properties, combining cluster analysis with seismic facies maps provided a robust foundation for the development of an initial 3D lithofacies model. The ultimate goal of this approach was to produce seismic facies maps that, when integrated with lithotype analysis, enhance the petroleum system model with detailed lithological and spatial distribution data. Calibration of the results culminated in the creation of final lithology facies maps.
This multidisciplinary study also incorporated palynological and sedimentological analyses of the Algyő and Újfalu formations. Sedimentological investigations involved analyzing sedimentary bodies delineated using interpreted horizons and seismic attributes. The studied sedimentary sequences, stratigraphically dated to the Upper Miocene-Pliocene (second and third cycle deposits), were characterized using seismic attributes such as "mean amplitude" and "RMS amplitude." These attributes facilitated the identification of sedimentary bodies and corroborated their characteristics as determined by lithotype analysis.
References:
- Magyar, I., Radivojević, D., Sztanó, O., Synak, R., Ujszászi, K., & Pócsik, M. (2013). Progradation of the paleo-Danube shelf margin across the Pannonian Basin during the Late Miocene and Early Pliocene. Global and Planetary Change, 103, 168–173.
- Horváth, F., Musitz, B., Balázs, A., Végh, A., Uhrin, A., Nádor, A., Koroknai, B., Pap, N., Tóth, T., & Wórum, G. (2015). Evolution of the Pannonian Basin and its geothermal resources. Geothermics, 53, 328–352.
How to cite: Gajić, V., Dulić, I., Sovilj, J., Bogićević, G., and Savić, I.: Geological Characterization of Seismic Data, Lithofacies Delineation within the Stratigraphic Framework of Upper Miocene Sediments in Northern Banat, Serbia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3085, https://doi.org/10.5194/egusphere-egu25-3085, 2025.
On the basis of high-resolution seismic and sediment data, the late Quaternary transgressive deposits in this area consist of five sedimentary units deposited during the post-glacial transgression between about 15 and 6 ka BP: ancient beach/shoreface complex (unit P1), estuarine deposits (unit P2), mid-shelf sand sheet (unit M1), sand ridge system (unit M2), and inner-shelf sand sheet (unit M3). They are paralic and marine separated by a ravinement surface. The lower paralic component below the ravinement surface consists of two sedimentary units (P1 and P2) preserved from shoreface erosion. The top surface of the paralic unit is truncated by a sharp erosional surface. This surface is overlain by three sedimentary units (M1, M2, and M3), which were produced by shoreface erosion that shifted landward during transgression. The transgressive deposits in this area, considering geometries and distribution patterns, can be divided into three types (I, II, and III). Type I overlying the lowstand systems tract is confined to the shelf margin, and consists of a thick paralic unit P1 and a relatively thin marine unit M1. Type II on the mid shelf has no paralic component and the marine units M1 or M2 directly overlies the sequence boundary. Type III, found in the inner shelf, includes a thick paralic (unit P2) and a thin marine (unit M3) component. It is completely covered by the highstand systems tract.
How to cite: Yoo, D.-G., Lee, G.-S., Hong, S.-H., Kim, G.-Y., Lee, B.-R., Jung, S.-K., and Cho, J. H.: Late Quaternary transgressive systems tract in a low-gradient environmental setting: Korea Strait shelf, SE Korea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14761, https://doi.org/10.5194/egusphere-egu25-14761, 2025.
The MIS 6 deposits in coastal regions are important in determining evolution of depositional systems over one cycle in response to sea-level changes. It is known to be the most extensive glaciation with weathering and erosional processes since about 400 ka. However, it is difficult to preserve whole deposits, despite weathering and erosional processes during the glacial periods. We carefully conducted core analyses of sedimentary facies, grain size, and age dating from two cores. This study reconstructed the development of an incised-valley fill in response to sea-level changes since the late Pleistocene. Seven facies associations are defined in the cores: braided river, tributary channel and land swamp, mud flat to marsh, fluvial channel and floodplain, central basin to bayhead prodelta, bayhead delta front, and bayhead delta plain. Stratigraphy and evolution of the Nakdong incised-valley fill can be divided into five stages since the Penultimate Glacial Maximum. Over all sedimentary analyses indicate that depositional environments of each stage are corresponding to relationships between sediment supplies and accommodation spaces in response to the sea-level changes in the Nakdong incised-valley system. The Nakdong incised-valley fills also note that fluvial environments occurred in an incised-valley system during Last Glacial Maximum periods. It can be possible to reveal a fully depositional history more than one cycle through two glacial traces. Additionally, the biased geomorphology influenced the architecture and preservation of the Nakdong incised-valley deposits characterized by asymmetric development of depositional successions since the Penultimate Glacial Maximum.
How to cite: Hong, S.-H., Yoo, D.-G., Lee, G.-S., Ryang, W. H., and Kim, J. C.: Evolution of fluvio-estuarine system in response to sea-level changes since MIS 6, southeastern Korea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14829, https://doi.org/10.5194/egusphere-egu25-14829, 2025.
