The Nam Co Drilling Project (NamCore) is a multinational and interdisciplinary research initiative designed to understand long-term climatic variability and associated environmental change on the Tibetan Plateau. The project primarily targets the timing and magnitude of Indian/East Asian monsoon variability and its interplay with the Westerlies. Thereby, the glacial-interglacial history and dynamics at high altitude; the impact of geological and environmental changes on (micro-)biological processes; the evolution and resilience of high-altitude ecosystems, including the deep biosphere; and geomagnetic variations during the Quaternary are of special interest.For in-depth investigations regarding the outlined research purposes, the (mostly) calcareous sediments of Nam Co, one of the largest and deepest lakes on the Tibetan Plateau, were targeted within the framework of the International Continental Scientific Drilling Program (ICDP) and cored in May-July 2024 (ICDP Expedition 5073). Altogether, 1415.45 m was drilled and 1175.99 m cored, with 950.77 m of sediment recovered (core recovery of 80.8 %) from seven holes at one site (5073_1) situated at a water depth of similar to 93 m, reaching a maximum depth of 510.2 m below the lake floor. Initial results from core descriptions and preliminary core catcher analyses suggest that the sediments of Nam Co reflect the evolution of a dynamic high-altitude lake system over multiple glacial-interglacial cycles. Four major lithologies are observed in the drill cores (calcareous mud, non-calcareous mud, calcareous mud with ferric staining and sand) and grouped into five major lithological units based on their physicochemical characteristics obtained from core catcher material. Micropaleontological results from core catcher material reveal a general absence of diatoms, due to unsuitable growing and/or preservation conditions, while ostracods abundances, preservation, and species composition vary, which might be linked to environmental changes and/or changing preservation conditions. Shifts in n-alkane chain length might be attributable to lake-level variations and/or glacial-interglacial cycles.

The formation of asymmetric submarine channels and canyons is the result of multiple processes, including bottom currents, Coriolis forcing, and centrifugal forces, acting on turbidity flows. Despite increasing studies of asymmetric submarine canyons and channels and recognition of the influence of bottom currents on turbidity flows, the relative contributions of these factors remain poorly constrained, often resulting in contradictory interpretations. In this study, we investigate whether morphometric characteristics of submarine canyons and channels – specifically relief and width asymmetries, and cross-sectional slope angles – can indicate the most likely processes responsible for their asymmetry, such as Coriolis effect versus bottom currents. We systematically analysed 24 asymmetric canyons and channels from diverse settings, integrating their morphometric data with environmental parameters including latitude, water depth, slope angle, and bottom current intensity and direction.Our results reveal substantial variability in channel asymmetry along their lengths: the positions of the higher margin, thalweg, steeper margin, and the degree of asymmetry often change within a system, so that a single channel cannot be consistently described with one asymmetry value. Depth-dependent variations in slope, water-mass structure, turbidity current dynamics, and bottom-current intensity, combined with temporal variability in both turbidity-current characteristics and bottom-current velocities, create locally coherent, but non-predictive asymmetry. Thus, our observations suggest that morphological characteristics alone are insufficient to identify the main forces controlling channel asymmetry. We propose a classification scheme to aid interpretation of channel asymmetry and potential bottom current interactions, emphasizing the complexity of channel formation.

The Bengal Fan, the world’s largest and among the few deep-sea fans still active today, has long been thought to have its active channel reaching the lower fan. Our findings reveal a middle-fan avulsion that shifted the terminal sediment sink 1,800 km landward, forming the modern terminal lobe complex. The lobes, dominated by sandy turbidites, are relatively thin (<20 m), but cover large areas (up to 1,350 km2). Their evolution is strongly related to inherited topography and probably autogenic processes while external factors (e.g., monsoon and sea-level variation) control sediment supply and types of gravity flows. These lobes represent a small portion of the channel-levee-lobe system, as sediments mainly accumulated on the levees during Holocene highstand. Identifying the modern sink of the Bengal Fan provides a closure point for the Earth’s largest source-to-sink system, with implications for present-day fluxes of sediments, carbon, and marine litter across a vulnerable coastal region. “The currently active lobe complex and modern sediment sink of the Bengal Fan are constrained to the middle fan, where an avulsion of the active channel shifted its location 1,800 km landward, establishing a critical closure point for the world’s largest source-to-sink system”

The student training cruises of the Faculty of Geosciences at the University of Bremen took place in 2021 during the Cruise AL566. The cruise was dedicated to master and bachelor students. The master students took part in the frame of the course “Advanced marine geophysical survey project”, which is part of the module “Field and Lab Practice” within the internationally oriented postgraduate study program Master of Science "Marine Geosciences". The module is mandatory for students in the first year of the curriculum. The data collected during the cruise are used for small scientific projects carried out by the students after the cruise. Additionally, the collected data are available for master theses. For the bachelor students, the cruise is the “Seegeophysikalische Geländeübung” as part of the module “Projektkurs”. This module is mandatory for students in their third academic year. The “Seegeophysikalische Geländeübung” is addressed to students which enrolled the core subject “angewandte Geophysik”. Within this core subject, the module “Marine Geophysik” is a major component of the second academic year of the students, and the content communicated in the module „Marine Geophysik“ should be applied during the cruise. The collected seismic data are used by the participating students in the third academic year in the courses “Seismische Exploration” and “Seismisches Datenprozessing”. During the cruise, seismo-acoustic data were collected by means of a multichannel seismic system, a multibeam system, a sidescan sonar, and the hull mounted echosounders SES2000 and EK80. Additionally, magnetic data were gathered along profiles, and CTD measurements were carried out during stations. (Alkor-Berichte AL566)

Valdivia Bank (VB) is an oceanic plateau in the South Atlantic that formed from hotspot‐ridge volcanism during the Late Cretaceous at the Mid‐Atlantic Ridge (MAR). It is part of Walvis Ridge (WR), a quasi‐linear seamount chain extending from offshore Namibia to Tristan da Cunha and Gough Islands. To understand Valdivia Bank evolution, we interpret the seismic stratigraphy from multichannel seismic data paired with coring results from International Ocean Discovery Program (IODP) Expedition 391, which recovered mostly pelagic nannofossil ooze and chalks. The seismic section can be divided into three seismic units (SU), a lower transparent interval which is faulted and conforms to basement, a middle, moderate to high amplitude interval which is thick in local depocenters such as rifts, and an upper, subparallel transparent interval. Notable features include regional unconformities, dipping clinoforms, mass transport and contourite deposits, and volcanic structures. Additionally, three infilled rifts are observed across the plateau. Our analysis implies that following a period of sedimentation in the Campanian, the edifice was faulted through the Paleocene, coinciding with a South Atlantic tectonic reorganization. Local depocenters formed as a result of rifting. Subsequently, the plateau experienced thermal rejuvenation and regional uplift during the Eocene. Volcanic mounds were emplaced atop Cretaceous sediments and intrusives were emplaced within the sediments. During the Cenozoic, sedimentation was punctuated, likely in response to changes in the carbonate compensation depth and bottom current intensification. VB sedimentation was complex and largely influenced by the paleoceanographic context of the plateau, as well as thermal rejuvenation and tectonism.

The Advanced Marine Geophysical Survey Cruise AL581 took an international group of 10 scientists from the University of Bremen, including six Msc Marine Geosciences students, in September 2022 on the RV ALKOR to the German Baltic Sea, between Kiel and the eastern side of Rügen Using a variety of geophysical methods, the seafloor was imaged for training purposes in order to analyze geological structures and features, but also to detect anthropogenic influences, like submarine cables, pipelines, construction sites, traces of fishing and possible ammunition remnants from past wars. Students were involved in planning, data acquisition, data processing and interpretation in the 24-hour shift work. Using Multichannel Seismic (MCS), Sediment Echosounder (SES), Multibearn Echo-sounder (MBES), Side Scan Sonar and Magnetometer, the cruise provided students with the opportunity to develop a deep understanding of the application of the various methods through hands-on experience. (Alkor-Berichte AL581)

Over the Tertiary, the uplift of the Himalaya combined to the development of the monsoon generated the largest erosion basins of the planet. More than 80% of the erosion is exported to the Bay of Bengal by the Ganga-Brahmaputra river system and generates turbidity currents which convey detrital sediment building the Bengal Fan. In the modern Himalaya, the monsoon rainfall and tectonic processes shape the erosion pattern. The monsoon seasonal precipitation ensures efficient transport of sand-rich sediments in the basin despite long distances through a very flat floodplain and delta. Rapid transport also acts as a limiting factor for weathering as it reduces residence time in the floodplain but favors efficient carbon burial. The IODP Expedition 354 drilled the Bengal Fan with seven sites over a 320 km E-W transect at 8°N. This construcs a composite sedimentary record of Himalayan erosion over the Neogene and Quaternary. Sediments are predominantly composed of turbidites generated from the Ganga-Brahmaputra delta. Turbiditic sediments show mineralogical, geochemical and isotopic characteristics which reveal a close analogy with those of the modern Ganga-Brahmaputra river. Sand deposition is dominant and is present in several meters thick sand lobe as well as in levee turbidite (Bergmann et al. 2020). Sand was used to determine average erosion rates of the Himalaya using quartz in situ concentrations of cosmogenic 10Be. Those show stable rate in spite of the onset of a more unstable climate from the Pliocene to the Pleistocene (Lenard et al. 2020). Major element concentrations and Sr-Nd isotopic compositions of turbidite samples reflect combined effects of geological sources exposed to erosion, weathering and mineral sorting during transport. Deciphering these controls, based on the comparison between turbidite samples and modern river sediments of the Ganga and Brahmaputra basin reveals evolution from Miocene to present. Changes appear in the abundance of detrital carbonates likely reflecting decreasing exposition of the Tethys Himalaya to erosion since Miocene. Clear increase in the silicate Na and Ca concentrations from Miocene to Pleistocene indicates major change in the weathering conditions in the basin which can be related to longer residence time of the sediment in the floodplain and lower erosion ratesin the Miocene. Bergmann et al. 2020, G. cube 10.1029/2019gc008702Lenard et al. Nat Geosc. 2020, doi:10.1038/s41561-020-0585-2

Located in the heart of the Tibetan Plateau, Nam Co is a closed lake spanning over 2,000 square kilometers and situated at an elevation exceeding 4,700 meters. The sediment thickness within the lake exceeds 700 meters, providing comprehensive insights into the climate and environmental conditions covering several glacial and interglacial cycles. With the support of the International Continental Scientific Drilling Program (ICDP) and China's Second Tibet Integrated Expedition Project (STEP), the Namcore drilling project aims to achieve: (1) Reconstructing the long-term climate change history across multiple glacial-interglacial stages and elucidating its relationship with global atmospheric circulation patterns; (2) Investigating the evolution and resilience of high-altitude terrestrial and lacustrine ecosystems under glacial and interglacial climate conditions; (3) Understanding the metabolic factors influencing lake sediment microbial communities in various glacial-interglacial environments; (4) Providing fundamental observation data on paleomagnetic changes to simulate the paleomagnetic field prior to the Holocene epoch. Depending on a stable and wind-resistant drilling barge manufactured in China, and a skilled drilling team as well as the long-term used drilling equipment provided by ICDP, the field campaign was successfully conducted from June 6 to July 17 of 2024, resulting in the retrieval of a total length of 950 meters of lake core. The deepest depth reached by the drill exceeded 510 meters. Based on seismic survey data, it is anticipated that the age of the lake core surpasses MIS 13 stage (approximately 550,000 yrs BP). Furthermore, the average resolution achieved is as high as 10 yrs cm-1. A combination of multiple dating methods will be employed in order to establish a robust deposition time series. 14C will be utilized for sediments less than 50,000 yrs BP while OSL and post-IR IRSL method will be employed to date back approximately 200,000 yrs BP. For more older deposits, amino acid racemization (AAR), uranium/thorium ratio (U/Th), cosmic ray Beryllium isotope (10Be/9Be), as well as geomagnetic polarity analysis, thermochronology assessment and cyclic stratigraphy will be integrated to obtain reliable chronological sequences of cores. Proxies will be utilized to indicate climate and environmental changes, such as geochemical indicators, pollen, biomarkers, sedaDNA, environmental magnetic indicators, etc. for reconstructing paleo-temperature, precipitation, water level, vegetation, aquatic biodiversity and other changes in the lake basin. The relationship between these changes and atmospheric circulation changes and glacial activities in the lake basins will be also discussed.

The Argentine Basin is a deep-sea basin located in the South Atlantic Ocean that contains sedimentary deposits derived from different provenances. It is characterized by complex ocean dynamics encompassing diverse spatial and temporal dimensions. The northward subantarctic Malvinas Current and southward subtropical Brazil Current converge at the western margin of the Argentine Basin, resulting in the formation of the Brazil-Malvinas Confluence region. Bottom currents, particularly currents flowing alongslope and horizontal eddies, are crucial in shaping the seafloor and in the formation of sedimentary features (e.g., contourites). The poorly understood strength and variability of bottom currents leave the processes that control sedimentation in deep environments unclear. High-resolution (1/12 degrees) reanalysis was used to analyze near-bottom flows and bottom dynamics were compared with seafloor sedimentary characteristics obtained from geophysical datasets and sediment cores. High speeds, up to 3.5 m/s at the surface and up to 1.4 m/s at the bottom, reveal the presence of intense flows in this area. The Zapiola Drift, an similar to 1,200 m high sedimentary deposit located in the central part of the Argentine Basin, is bounded by a zone of high bottom eddy kinetic energy (EKE) that resulted in the erosion of the seafloor and in the accumulation of sandy mud. The Malvinas Current is distinguished by strong and constant currents flowing northwards along the continental slope and by minimal EKE at the bottom. The area of the continental slope along which the Malvinas Current flows corresponds to a contourite terrace, a relatively flat surface composed almost entirely of sandy sediments and with abundant erosional features. The regions of highest EKE activity in the bottom layer is the overshoot of the Brazil Current and the abyssal plain. Our study highlights the impact of bottom-current dynamics on contouritic sedimentation. In certain regions, the process of sedimentation is subject to the influence of sporadic events that occur between periods of intense and weak flow. These events are regarded as intermittent processes. While sedimentation in other areas is controlled by constant flows. A better understanding of the strength and variability of bottom currents will improve paleoceanographic reconstructions based on the sedimentary record.

The inundated Doggerland in the North Sea Basin has been a coveted research target for many years owing to its key location with respect to geological evolution since the last glaciation and its archaeological potential related to prehistoric hunter-gatherer populations. Still, many uncertainties related to glacial and sea-level forcing on erosion and deposition remain, and the first discovery of submerged settlements is yet to be reported. In this study, we present a range of seismic morphologies and facies characteristic for the late glacial and Holocene succession near a major drainage system at the eastern Dogger Bank. Five of these facies are dominant in the area while two facies can be associated with a terrestrial-fluvial landscape buried 0-22 m below the seafloor. We detect various erosion levels of the terrestrial-fluvial landscape that are greatest towards the south where sediment has been removed, probably owing to combined terrestrial-fluvial and marine erosion. We find that five subareas show geo-archaeological potential in terms of (1) the preservation degree of terrestrial strata based on erosion estimates, (2) the accessibility of terrestrial strata based on burial depths and (3) the palaeo-landscape configuration based on the spatial setting in relation to the drainage system and the palaeocoastlines. We further document a geological evolution of the study area, which is comparable with the evolution at the western Dogger Bank. However, we find more evidence for an extended flooding period because of the vicinity to the major drainage system and the Elbe Paleo Valley. We propose that our approach can be used as a workflow for marine investigations that focus on submerged hunter-gatherer heritage.

Off the Northwestern Iberian Peninsula, the vigorous bottom-current regime interacts with a complex seafloor topography inside the Galicia Interior Basin (GIB), which was tectonically shaped during the opening of the North Atlantic Ocean basin in Cretaceous times. The evolving North Atlantic Ocean circulation determined the depositional pattern of the basin fill over time, which can, in turn, be utilized as palaeoceanographic archive. This study reconstructs the evolution of the GIB sedimentary system since the mid-Eocene, namely, resulting from interplay between down- and along-slope sediment-transport processes, using high-resolution multichannel seismic data. Six major depositional stages are identified and connected to the evolution of the North Atlantic Ocean circulation. 1) Levelling of topography shows that the influence of contourparallel bottom currents on the depositional pattern steadily intensified since the mid-Eocene; 2) The strengthening of Northern Component Water (NCW), associated with the opening of the Faeroe-Shetland Basin in the late Eocene, is documented along the southwestern European continental margin for the first time by the onset of a plastered contourite drift; 3) A shift in the depocenters provide evidence that the closure of the Tethys-Indian Seaway led to Tethys Outflow Water into the Atlantic Ocean at intermediate ocean depths in the Miocene; 4) Until the mid-Miocene, the tectonic stress regime initially associated with the Pyrenean Orogeny and the following Betic Orogeny led to both sets of small-scale faulting systems as well as submarine mass wasting indicated by slope scarps and mass-transport deposits; 5) The onset of modern-style Mediterranean Outflow Water (MOW) after the Messinian Salinity Crisis (5.3 Ma) caused a distinct change in the depositional dynamics from combined along- and down-slope transport processes towards predominantly contouritic deposition, which is evident from the construction of several separated mounded contouritic drifts that formed during Pliocene and early Pleistocene times; and 6) The contourite drift growth continued during the middle and late Pleistocene, but under a gaining influence of down-slope processes.

The Ewing Terrace is a relatively flat surface formed by the action of bottom currents and part of a contourite depositional system (CDS) at the Argentine continental slope. It is situated in a highly complex oceanographic setting at the Brazil-Malvinas Confluence Zone. Located in water depths of similar to 1000-1200 m and incised by the Mar del Plata Canyon, the Ewing Terrace is separated into the Northern Ewing Terrace (NET) and the Southern Ewing Terrace (SET). The long-term variations in ocean circulation led to a complex internal architecture of the terrace. As a result, this region represents a unique archive for studying sedimentary features that were eroded, transported, and deposited by along-slope and down-slope processes. An in-depth data analysis of high-resolution multichannel seismic profiles exhibits a complex sequence of erosional and depositional contouritic features, namely buried moat-drift systems identified in depths of similar to 370-750 m below the seafloor. They are arranged in migrating sequences and clustered in the early Oligocene to middle Miocene. This pattern is probably attributable to the vertical shift of water masses and to a highly dynamic oceanographic setting with spatial changes influenced by the Brazil-Malvinas Confluence Zone over this particular geological time. The moat-drift systems reveal significant lateral changes from north to south. In the southern area of the SET the moats are constructional and the associated separated mounded drifts are well developed. In contrast, the northern area exhibits two types of moats, reminiscent of cut-and-fill structures that mirror the significant and rapid changes in bottom-current dynamics. With these new insights, this study contributes to a better understanding of moat-drift systems and improves the knowledge about past oceanographic dynamics and sediment deposition at the northern Argentine margin.

Seafloor depressions (SD) are features commonly observed on the ocean floor. They often occur as circular, small-sized (up to 10 s of m) incisions caused by fluid expulsion. Larger depressions (100s m to km) are considerably less abundant, and their origin and development have been scarcely studied. This study investigated two giant morphological depressions (>5 km) using recently acquired multibeam bathymetry and backscatter, sediment echosounder, and high-resolution seismic data. An arc-shaped (SD-N) and a sub-circular depression (SD-S) are located on the Ewing Terrace at the Argentine Continental Margin north and south of the Mar del Plata Canyon, respectively. The study area is influenced by the Brazil-Malvinas Confluence, where major counterflowing ocean currents affect sedimentation, and northward flowing currents form a large contourite depositional system. Using an existing seismo-stratigraphy, the onset of SD-N was dated to the middle Miocene (∼15–17 Ma), whereas SD-S started developing at the Miocene/Pliocene boundary (∼6 Ma). Acoustic anomalies indicate the presence of gas and diffuse upward fluid migration, and therefore seafloor seepage is proposed as the initial mechanism for SD-S, whereas we consider a structural control for SD-N to be most likely. Initial depressions were reworked and maintained by strong and variable bottom currents, resulting in prograding clinoform reflection patterns (SD-N) or leading to the build-up of extensive cut-and-fill structures (SD-S). Altogether, this study highlights the evolution of two unique and complex seafloor depressions throughout the geologic past under intense and variable bottom current activity in a highly dynamic oceanographic setting.

ABSTRACTThe interaction of sedimentary systems with oceanographic processes in deep‐water environments is not well understood yet, despite its importance for palaeoenvironmental reconstructions, and for a full understanding of source‐to‐sink sediment transport. The aim of this study is to improve the understanding of how contourite moats, elongated depressions formed by bottom currents associated with contourite drifts, develop and of the link between moat‐drift system morphology and bottom current dynamics. This study provides a systematic comparison of 185 cross‐sections of moat‐drift systems distributed at 39 different locations worldwide, and a detailed analysis of the morphology of six moats that cover a wide range of typical geological and hydrodynamic settings. Additionally, in situ measured current data were analysed to better link hydrodynamics to moat morphology. The median of all profiles across all moat‐drift systems reveals a 50 m relief, a width of 2.3 km, a relief to width ratio of 0.022, a slope angle of 6°, a drift angle of 3° and a concave‐up shaped morphology. Moats can be over 100 km long. Some moats are driven by sediment erosion while others are depositional and primarily exist due to differential sedimentation inside the moat compared to the drift alongside the moat. A new sub‐classification of moat‐drift systems based on their stratigraphy is proposed. This classification distinguishes moats depending on the degree of erosion versus deposition. No relation is found between latitude and moat‐drift morphology or stratigraphy in the analysed examples. The combined data indicate that a steeper slope focuses the current more than a gentle slope, resulting in an increase of the relief–width ratio and drift angle. Thus, this study provides new insights into the interaction of ocean currents with sedimentary morphology, which thereby affects the evolution of a poorly understood deep‐water sedimentary system.

A set of 2D high resolution seismic lines was acquired near the Kerch Peninsula during R/V Meteor Cruise M72/3 in March/April 2007 to the Eastern Black Sea. The high resolution seismic data were used for analysis of seismic facies and seismic sequences to gain insight into the sedimentary evolution of the study area. Seven seismic facies types were identified and six seismic units could be mapped. Based on seismic line interpretation, isopach and seismic facies distribution maps, a chronostratigraphic framework could be established for the study area. The study reveals that the sediment deposits were influenced by syndepositional tectonic movements, sea level and climate. During the late Miocene and the early Pliocene, possible slope fan deposits developed. At the boundary between the Miocene and Pliocene, the Messinian erosional truncation surface was observed. After the Messinian sea level fall, accompanied by a major transgressional phase during the Pliocene, the Paleo-Don and Kuban Rivers delivered a large terrigenous input to the Black Sea from the uplifted Crimean Mountains. This formed thick submarine fan deposits near the mouth of Kerch Strait during the late Pliocene. Facies variations within the seismic units are related to the sea-level and climate curves, and are reflected by grain size variations in the sediments and the shift of the river mouth. During the Quaternary, hemipelagic sediments interbedded with coarse-grained fluvial sediments developed in the study area, along with slumps, river channels and fan deposits.

02.10.2020 – 15.10.2020, Kiel (Germany) – Kiel (Germany) GeophysPracUniBremen

Summary Marine reflection seismic data acquisition for inversion of near surface targets, which is restricted to the first 30–100m of the earth’s surface, is both a challenging and important task. Nevertheless, there are no comprehensive acquisition and quality control guidelines for this type of data set. In order to determine the requirements and boundary conditions for near surface seismic inversion, the soil property ranges of sediments in the North Sea and Baltic Sea have been established as a first step. Then the typically used seismic source signals have been analyzed. A range of synthetic models was generated and analyzed to develop optimum acquisition parameters. Source, receiver, positioning and recording parameters have been found to be most relevant. So, very exact corrections e.g. in terms of gun delay, positioning errors or source and receiver directivity have been identified to be substantial. Also, offsets greater than about three times the target depth and a channel spacing smaller than 2 m to avoid aliasing for high resolution signals have been found to be necessary. Further establishment of near surface seismic inversion in industrial and academic work flows has the great potential to reduce cost and enhance knowledge.

The structure of a caldera may influence its activity, making its understanding crucial for hazard assessment. Here, we analysed high-resolution seismic profiles in the Campi Flegrei (southern Italy) offshore sector. We recognised two main fault systems, including those associated with the formation of the caldera and those affecting the resurgent dome. The former system comprises three broadly concentric fault zones (inner, medial and outer ring fault zones) depicting a nested caldera geometry. Considering the relations between faults and seismic units that represent the marine and volcaniclastic successions filling the caldera, all ring faults were formed during the Campanian Ignimbrite eruption (40 ka) and subsequently reactivated during the Neapolitan Yellow Tuff eruption (15 ka). In this last caldera-forming event, the inner and medial fault zones accommodated most of the collapse and were episodically reactivated during the younger volcano-tectonic activity. The second fault system occurs in the apical zone of the resurgent dome and comprises dominantly high-angle normal faults that are mainly related to the volcano-tectonic collapse that followed the Agnano-Monte Spina Plinian eruption (4.55 ka). Finally, we provide a volcano-tectonic evolutionary model of the last 40 kyr, considering the interplay among ring and dome faults activity, volcaniclastic sedimentation, ground deformation and sea-level changes.

The southeastern North Sea was a sub-aerially exposed periglacial environment during the late Weichselian. At that time, the approximately 210 km long and 40 km wide SE-NW trending Elbe Palaeovalley (EPV) was the main conduit for meltwater from the southern margin of the Scandinavian ice sheet and rivers draining the North European plain. Only few studies investigated the environmental organization of the Northwest European shelves during deglacial sea level rise resulting in vague reconstructions of the drainage systems. Here, a detailed analysis of sediment echo-sounder data and core samples are presented to study the EPV morphology and stratigraphic infill. The valley base is about 65 m below the present sea-level. This SE-NW palaeo-drainage with its braided system developed during the MIS 2 sea level fall and lowstand in a periglacial environment. During deglacial sea-level rise, the EPV evolved into an estuary with tributaries, intertidal and subtidal flats. After the early Holocene (similar to 10 cal ka BP), ongoing sea-level rise drowned the EPV system which became the major sedimentary trap in the southern North Sea. Successive sea level rise and associated changes in the hydrodynamic regime led to three stages of shelf organization that were recorded in the valley infill successions: (1) shallow basin with restricted connections to Atlantic water; (2) the southwestern connection with the Dover Strait; (3) the open marine environment at 5.8 cal ka BP after the drowning of Dogger Bank. (C) 2022 Elsevier Ltd. All rights reserved.