The study of marine terraces, which include a paleo-shoreline record, provides information on global sea level fluctuations and crustal uplift rates during the Late Quaternary period. This data is helpful in preparing for sea level rise in the upcoming 'Global boiling'. Currently, widely recognized sea level fluctuation curves are derived from oxygen isotope stages in ice cores and deep-sea cores. The data shows a 30-50m sea level fall during Marine Isotope Stage (MIS) 5d-5a. However, some studies conducted in various parts of the world have reported smaller declines in sea level than is commonly known. For instance, studies on the marine terraces of the east coast of the Korean Peninsula suggest that sea level may have been as low as -5 to -10 m during MIS5a and MIS5c. In this study, we investigated the marine deposits in Haenam, located on the southwestern coast of the Korean Peninsula. We found deposits in the sedimentary layers that correspond to MIS5c, which were located beneath layers formed during MIS5e. The age of the sediments was determined using optically stimulated luminescence (OSL) dating. Based on the altitude, formation process, and absolute age of the sediments, it is inferred that sea level was similar to the present during MIS5c in Haenam. Recent research on the southwestern coast of the Korean Peninsula has accumulated data on marine deposits formed during MIS5a and MIS5c. This paper presents the results of studies on sea level during MIS5a and MIS5c on the west and south coasts of the Korean Peninsula. This study suggests one perspective for MIS5a and MIS5c sea level across East Asia and to raise new questions. Specifically, the paper questions why sea levels are similar to present during what is known to be a glacial period. This study offers a fresh perspective on sea level fluctuations in East Asia and can improve our comprehension of the intricate correlation between sea level and climate change.

How to cite: Ryu, H., Lee, J.-H., Jung, H. S., and Shin, J.: The Sea Level during MIS5a, MIS5c in the Southwestern Coast of South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4885, https://doi.org/10.5194/egusphere-egu24-4885, 2024.

TerraceM is an open-source software written in MATLAB for mapping and analyzing marine terraces. In this latest release, TerraceM-3 has undergone significant evolution, which leverages the capabilities of machine learning to introduce an automated marine terrace mapping feature. This new version includes a neural network that has been meticulously trained with over 1000 mapped marine terraces. This allows TerraceM-3 users to effortlessly map marine terraces and precisely determine their elevation through the automated mapping of their shoreline angles. In addition, TerraceM-3 incorporates two new functionalities: 1) Photon profile mapping, which includes mapping of satellite LiDAR profiles from the IceSat-2 mission, which broadens the applicability of TerraceM-3 beyond the availability of topographic data. 2) Indicative meaning calculator that accounts for the factors that can alter the initial sea-level position using global datasets (wave conditions and tidal ranges). This method facilitates the direct assessment of uncertainties in the reconstructions of the paleo-sea-level based on marine terraces. TerraceM-3 is a complete toolkit for researchers and students engaged in marine terrace analysis by offering a unique blend of numerical methods, statistical analyses techniques and additional enhanced functionalities to precisely map marine terraces and using them as markers of tectonic deformation.

How to cite: Jara Muñoz, J., Mey, J., Freisleben, R., Pedoja, K., and Melnick, D.: TerraceM 3.0: Advancing marine terrace mapping through integrated machine learning methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5716, https://doi.org/10.5194/egusphere-egu24-5716, 2024.

The degree to which the Last Interglacial (Marine Isotope Stage 5e; ~125,000 Before Present) can serve as an analog for future sea-level rise caused by anthropogenic climate change is a matter of great importance. Refining knowledge of factors such as glacio-hydro-isostatic conditions and ice-sheet histories leading up to and since the Last Interglacial will help resolve this question, and well-constrained, well-dated indicators of relative sea level will provide crucial data towards this end. We conducted stratigraphic surveys on several well-exposed outcrops along the Intercoastal Waterway canal near Myrtle Beach, South Carolina, on the East Coast of the United States. In addition to photogrammetry records of the outcrop, optically stimulated luminescence analysis has produced new dates that provide information about sea level history during the Last Interglacial and subsequent interstadials, while also helping to clarify the complex local stratigraphic context, which consists of a series of coastal beach ridges and paleoshorelines left by highstands. The dates are linked to precisely constrained DGPS elevations referenced to the local hydrographic datum, a technique which has not been widely used in the study area. The new data will be preserved as sea-level index points in the format specified by the World Atlas of Last Interglacial Shorelines as part of the WARMCOASTS project and are an especially important contribution since they add additional points in a passive margin area considered to be tectonically stable since the investigated time period.

How to cite: Dean, S., Georgiou, N., Poirier, R. K., Doar III, W. R., Brill, D., Chauveau, D., Cerrone, C., and Rovere, A.: OSL Dated Sea-Level for MIS 5e Interglacial in South Carolina, United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15894, https://doi.org/10.5194/egusphere-egu24-15894, 2024.

Geological sea-level proxies, such as fossil intertidal or foreshore deposits, store fundamental information that allow reconstructing past changes in sea level, which may be used to evaluate the volume of ice sheets during past warm periods. Studies on Last Interglacial (LIG; Marine Isotope Stage 5e, ~ 125 ka) sea-level proxies are particularly important, as this highstand is a process analogue for the current interglacial, including warming caused by human greenhouse gas emissions. In fact, the LIG was characterized by slightly higher temperatures than the pre-industrial, that caused higher global sea level and, in turn, smaller ice-sheets.

This work was done in the framework of the WARMCOAST Project funded by the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovative Program (Grant Agreement No. 802414). This part of the project aims at surveying new geological sea-level proxies along the western Atlantic Brazilian coast, from Rio Grande do Sul to São Paulo and in southern Bahia State. Classical geological and geomorphological surveys were carried out in the field. We collected several samples for OSL dating and micropaleontological analysis. Samples consist mostly of shallow-water marine sands of supposed LIG age. The elevation of each proxy has been measured by a GNSS RTK station with centimetric precision and referred to a local geoid model (MAPGEO2015).

In this work, we report the results of the field campaign along the Brazil coast and, the new data are interpreted in terms of Glacio-Isostatic Adjustment processes affecting the coasts since the Last Interglacial. 

How to cite: Cerrone, C., Lämmle, L., Scicchitano, G., Perez Filho, A., Chauveau, D., Georgiou, N., Dean, S., and Rovere, A.: Last Interglacial sea-level proxies along the Brazilian western Atlantic coasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16538, https://doi.org/10.5194/egusphere-egu24-16538, 2024.

Geological indicators of past relative sea level changes are fundamental to reconstruct the extent of former ice sheet during past interglacials, which are considered analogs for future climate conditions. Four interglacials, dating from Holocene to Pliocene, have left sea-level imprints in the proximity of the coastal town of Camarones in Central Patagonia, Argentina. Sea-level index points were preserved as beach ridges deposited by storm waves above modern sea level. We used highly accurate survey techniques to measure the elevation of these deposits. Satellite-derived wave measurements and wave runup models were then employed to calculate their indicative meaning (i.e., their elevation with respect to sea level at the time of deposition). The paleo relative sea levels (i.e., uncorrected for post-depositional vertical land motions) associated with the four interglacials (with 1σ uncertainties) are 6±1.5 m (Holocene); 8.7±2.1 m (MIS 5e); 14.5±1.5 m (MIS 9 or 11); and 36.2±2.7 m (Early Pliocene). Ages have been obtained using both published (U-series, Electron Spin Resonance, and Radiocarbon) and new (Amino Acid Racemization and Radiocarbon) dating constraints. We compare our results with published glacial isostatic adjustment and mantle dynamic topography predictions, and we highlight that refining these models before calculating the global mean sea level for the interglacials mentioned above is necessary. Our high-resolution data provide a significant benchmark for paleo relative sea-level studies in the Southwestern Atlantic.

How to cite: Rovere, A., Rubio Sandoval, K., Ryan, D. D., Richiano, S., Giachetti, L. M., Hollyday, A., Bright, J., Gowan, E. J., Pappalardo, M., Austermann, J., and Kaufman, D. S.: Quaternary and Pliocene sea-level changes at Camarones, central Patagonia, Argentina, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17200, https://doi.org/10.5194/egusphere-egu24-17200, 2024.

Corals have been used as proxies of relative sea-level (RSL) change and key inputs in refining glacial isostatic adjustment (GIA) models globally. Along subduction zones, interseismic, coseismic, and postseismic processes act as local drivers of relative sea-level changes, which can also be used to elucidate past tectonic deformation. In this study, we present new radiometric (Th-230) ages of marine-limiting sea-level proxies (i.e., emerged fossil coral reefs) along the coasts of Southwest Panay Peninsula and Nogas Island facing the Negros Trench forearc. Real-time kinematic (RTK) GNSS and drone surveys were conducted to determine the elevations relative to the tide datum and the extent of the emerged fossil coral reefs. In the Southwest Panay Peninsula, emerged fossil coral reefs were observed at 4.20 m and 3.967–4.647 m above mean low low water (amllw), with Th-230 ages of 12.44 kya and 8.65–8.82 kya BP, respectively. About 15 km from the trench forearc, Mid-Holocene emerged fossil coral reefs dated 6.37–7.55 kya BP with elevations 1.596–2.810 m amllw. Late Holocene emerged fossil coral reefs were dated 4.33–1.48 kya BP with elevations 1.256–2.280 m amllw. On the western side of Nogas Island facing the trench forearc, emerged fossil coral reef platforms dated 1.08–1.66 kya BP with elevations 1.446–1.960 m amllw. The calculated RSL of these marine-limiting sea-level indicators is generally higher compared to the ICE-6G C and ICE-7G NA sea-level curve models and other coral proxies in Southeast Asia and Palawan that have relatively low tectonic deformation activities. In this study, we highlight the spatiotemporal variability of RSL coral proxies in local scales along the trench forearc. These initial results further imply active tectonic deformation induced along the Negros Trench since the Holocene. 

Keywords: fossil coral reefs, relative sea level, Holocene, Negros Trench forearc, Southwest Panay Peninsula, Nogas Island, Philippines

How to cite: Nawanao, L., Ramos, N., Mangahas, R., Hu, H.-M., and Shen, C.-C.: Early-to-Late Holocene Emerged Fossil Corals along the Negros Trench Forearc, Philippines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17311, https://doi.org/10.5194/egusphere-egu24-17311, 2024.

During past Interglacial periods, global ocean volume increased as a result of the higher temperatures and the melting of ice sheets, consequently leading to a rise in global sea levels. However, on timescales ranging from years to a few decades, regional sea level variability deviates from the global pattern, due to a combination of vertical land movements (earth’s crust viscoelastic response to glacial and ice sheet melting, tectonics), thermohaline circulation, wind forcing and land water storage. Therefore, decoding the regional sea-level variability during Interglacial periods is crucial for advancing climate models’ precision, especially for vulnerable coastlines.

Beach ridge plains are valuable fossil geological archives, offering significant potential for the analysis of sea-level fluctuations, climatic shifts and catastrophic events. The extraction of these information can be achieved through the measured elevation of the dune-beach contact and the beach berm, the analysis of the fossil beach ridge orientation, the geometry of the internal stratigraphy and by dating of the beach deposits using optically stimulated luminescence (OSL) signals from quartz.

In this study, we present results from our fieldwork campaign in the northern Gulf of Mexico, where we utilized a GNSS RTK station to obtain centimeter-level precision in measuring the elevation of the beach ridge sets, originally detected through freely available LIDAR datasets. Concurrently, a Ground Penetrating Radar (GPR) was employed to determine the stratigraphy of the beach ridge plains. Both surveyed areas, Apalachicola and Pensacola, contain fossil beach ridge sets varying in elevation from +2.5m up to a maximum of +7.5-8m above mean sea level, detected in more inland locations. Recent studies suggest that during the Last Interglacial period sea level in the area reached up to ~5m. The exact timing of the formation of the more elevated inland beach ridges remains uncertain, as does the question of whether their present elevation is attributable to post-Last Interglacial vertical land movements. Through in-depth analysis of the data collected during the WARMCOASTS ERC project, we aim to unravel the formation processes of these beach ridges and trace their development and evolution over time.

How to cite: Georgiou, N., Dean, S., Simms, A. R., Chauveau, D., Cerrone, C., and Rovere, A.: Interglacial beach ridge plains across the northern Gulf of Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20690, https://doi.org/10.5194/egusphere-egu24-20690, 2024.