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The intensification of Northern Hemisphere glaciations at the end of the Pliocene epoch marks one of the most substantial climatic shifts of the Cenozoic. Despite global cooling, sea surface temperatures in the high latitude North Atlantic Ocean rose between 2.9–2.7 million years ago. Here we present sedimentary geochemical proxy data from the Gulf of Cadiz to reconstruct the variability of Mediterranean Outflow Water, an important heat source to the North Atlantic. We find evidence for enhanced production of Mediterranean Outflow from the mid-Pliocene to the late Pliocene which we infer could have driven a sub-surface heat channel into the high-latitude North Atlantic. We then use Earth System Models to constrain the impact of enhanced Mediterranean Outflow production on the northward heat transport in the North Atlantic. In accord with the proxy data, the numerical model results support the formation of a sub-surface channel that pumped heat from the subtropics into the high latitude North Atlantic. We further suggest that this mechanism could have delayed ice sheet growth at the end of the Pliocene., Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1237

The modern oceanographic setting off northern-central Chile is characterized by highly productive waters and an extensive Oxygen Minimum Zone (OMZ), both resultant from coastal upwelling induced by the Humboldt Current System. However, oscillations of upwelling and OMZ properties during the Neogene are still poorly understood. Here, we assess palaeoceanographic conditions based on benthic foraminifera assemblage data of marine sediments from the Bahía Inglesa Formation (Upper Miocene-Pliocene), recovered from the Quebrada Tiburón outcrop (27°42' S, 70°59' W). Quantitative paleoenvironmental analyses of benthic Foraminifera >250 µm from 6 samples are currently conducted. Preliminary results show shifts in both, the diversity and abundance of hyaline species over the studied interval. High abundances of planospiral (predominantly epifaunal) morphotypes in sandy, heavily bioturbated parts of the studied section alternate with diatom-rich sediments bearing predominantly serial (infaunal) taxa such as Bolivina aenariensis and Uvigerina peregrina/striata. The observed changes in assemblage composition imply significant changes in biological productivity, bottom-water oxygenation, and ultimately, coastal upwelling off Chile in the Neogene. Further refinements of the stratigraphic model for the studied section will clarify the timing of the here described preliminary observations of paleoenvironmental fluctuations. This study contributes to project A4 “Land‐ocean coupling between the Humboldt Current System and Atacama palaeoclimate in the Neogene” of CRC 1211 “Earth-evolution at the dry limit”.

Global warming and changes in precipitation patterns are of increasing concern for populations in the Mediterranean region. Exploiting regional paleoenvironmental archives helps to understand how climatic parameters changed regionally in past periods which serve as future climate analogues. Prominently, benthic foraminifera serve as proxy carriers to unravel variability of paleo-temperature, -salinity, -pH, -productivity and –oxygenation. Besides the faunal composition of a defined sediment sample, the geochemical signature recorded in the shells is a constantly investigated proxy signal. Recently, the Ba/Ca has been proposed to track changes in barium content of marine bottom waters. In fact, barium concentrations in the benthic (shallow) marine environment either reflect directly riverine input or export productivity via barite as part of the organic matter sinking to the seafloor. We use core-top material of dead and live (Rose Bengal stained) specimens from a water depth range of 600-1500 m throughout the Northern Aegean Sea, to quantify variability of Ba/Ca across two different species with hyaline shells (Melonis baarleanus and Uvigerina mediterranea) and different sediment sampling depths. Using Laser Ablation ICP-MS we can further assess the intratest variability of Ba/Caforam. Moreover, we compare the Ba/Caforam to measured bottom water [Ba/Ca] from the same locality and consider a multitude of factors for approaching this novel core-top calibration. First results show that the species-specific partition coefficients are matching those of published laboratory experiments and core-top calibrations for hyaline benthic foraminifera. We show the application of high-resolution sampling techniques in the benthic environment to assess the complex present-day situation.

Magnetic polarity stratigraphy and magnetic palaeointensity stratigraphy is often used on sedimentary rocks to correlate outcrops and establish chronologies. The concept is based on the assumption that dipolar geomagnetic variations are globally synchronous and independent of climate and depositional conditions. The strengths of the method include the wide dating range and the applicability to a large variety of sediments and rocks. Best results are gained if long continuous sequences with high and uniform sedimentation rates are available. In the Atacama Desert, however, these perfect conditions are rare, as the landscape is strongly influenced by tectonic processes and extreme climatic conditions. Within the CRC1211 “Earth Evolution at the Dry Limit” magnetic stratigraphy is used to improve the age control of long drill cores from the claypans PAG, Huara, and Paranal, and of discrete samples from the marine Bahia Inglesia Formation. In addition, a first methodological attempt is being made to validate the potential of gypsum wedges as possible palaeomagnetic archive. The analyses are particularly carried out in order to specify the time covered by these geoarchives. Challenges for the palaeomagnetic analysis of the different archives arise from the often quite brittle nature of the unconsolidated sediments, the weak magnetizations and the complex magnetic mineralogy, potentially biased by diagenesis. Here we present challenges of the ongoing studies, as well as first results and perspectives.

Meereswissenschaftliche Berichte No 116 2021 - Marine Science Reports No 116 2021, Das deutsch-chinesische Verbundvorhaben Megacity’s fingerprint in Chinese marginal seas: Investigation of pollutant fingerprints and dispersal (MEGAPOL) geht nach drei Jahren intensiver Zusammenarbeit (01.08.2017-31.07.2020; verlängert bis 31.12.2020) zu Ende. MEGAPOL hatte zwei regionale Schwerpunkte. Der eine konzentrierte sich auf den Mündungsbereich des Perlflusses im Südchinesischen Meer und der andere auf das Gelbe Meer mit dem Yangtse Fluss sowie auf die Bohai See mit dem Gelben Fluss. Die Verbundpartner auf deutscher Seite sind das Leibniz-Institut für Ostseeforschung Warnemünde, das Institut für Geologie und das Institut für Meereskunde der Universität Hamburg, sowie das Institut für Küstenforschung des Helmholtz Zentrums Geesthacht. Auf chinesischer Seite sind die Verbundpartner der Guangzhou Marine Geological Survey, die School of Oceanography der Shanghai Jiao Tong Universität, das Second Institute of Oceanography SOA, Hangzhou, das National Marine Environmental Monitoring Centre, SOA, Dalian und das Yantai Institute of Coastal Zone Research, CAS, Yantai. Die Prozessstudien wurden von Deutschland durch das BMBF (03F0786A/B/C) im Rahmen der Wissenschaftlich- Technischen Zusammenarbeit (WTZ) mit China finanziert sowie von China durch die State Ocean Organisation (SOA). Der Verbund hatte zum Ziel, die Umweltveränderungen in den genannten Schelfregionen und den Randmeeren zu untersuchen und damit die Folgen der Entstehung von Megastädten für das marine Ökosystem abzuschätzen. Die Untersuchungsgebiete stellen ideale Modellsysteme dar, um Austauschprozesse zwischen Land und Ozean, Veränderungen der physikalischen Antriebe (Monsun, Zirkulation), anthropogene Stoffflüsse (u.a. Mikroplastik, Schadstoffe) und somit die Effekte von Ballungszentren auf die Wechselwirkung Land-Küste- Ozean sowie die Auswirkungen von klimatischen Änderungen in sensiblen marinen Ökosystemen besser zu verstehen. Die Probennahme im Südchinesischen Meer wurde auf drei mehrwöchigen Expeditionen mit chinesischen Forschungsschiffen (HAI YANG DI ZHI SHI HAO 2015, HAI YANG DI ZHI SHI HAO 2018) und dem deutschen Forschungsschiff SONNE (2019) durchgeführt. Die Beprobung in der Bohai See und im Gelben Meer fand im April und August 2018 mit dem chinesischen Forschungsschiff R/V DONG FANG HONG 2 statt. Flussproben wurden im Mai und Juli bis November im Gelben Fluss genommen sowie im November aus dem Daliao, Hai, Luan und Xiaoqing Fluss. Für beide regionalen Schwerpunkte lieferten die physikalischen, bio-geochemischen und ökosystemaren Modellierungen zusätzliche Erkenntnisse zum Einfluss von wechselnden Umweltparametern auf die marinen Stoffkreisläufe (N, P, C) und ermöglichten Aussagen zu der zeitlichen und räumlichen Variabilität der ozeanischen Prozesse. Der MEGAPOL Verbund wurde durch die Aktivitäten des BMBF Verbundes Südchinesisches Meer-Natürliches Laboratorium unter klimatischen und anthropogenen Stress (FKZ 03G0269A-B, SOCLIS) erweitert, in dessen Rahmen die Expedition mit dem deutschen Forschungsschiff SONNE (SO269) im August 2019 im Untersuchungsgebiet am nördlichen Schelfrand des Südchinesischen Meeres im Mündungsbereich des Perlflusses stattfand. Auf der Expedition wurde u.a. eine Verankerung für einen Zeitraum von 2 Jahren am nördlichen Kontinentalhang des Südchinesischen Meeres ausgesetzt, wodurch die wissenschaftlichen Fragestellungen und die Infrastruktur von MEGAPOL erweitert wurden. Diese Arbeiten wurden durch das TRAN Projekt (Zeitliche Muster anthropogener und natürlicher Partikel am Kontinentalhang des Südchinesischen Meeres, FKZ 01DO17038) auf der deutschen Seite finanziert. In diesem Bericht fassen wir die ersten Ergebnisse der Untersuchungen in Form erweiterter Kurzbeschreibungen deutscher und chinesischer KollegInnen zusammen, die in einer Online- Konferenz am 28. und 29. Oktober 2020 vorgestellt wurden., The bilateral Sino-German joint project Megacity's fingerprint in Chinese marginal seas: Investigation of pollutant fingerprints and dispersal (MEGAPOL) comes to an end after three years of intensive cooperation (01.08.2017-31.07.2020; extended until 31.12.2020). MEGAPOL had two regional focuses, one at the mouth of the Pearl River in the South China Sea and one on the Yellow Sea with the Yangtse River and on the Bohai Sea with the Yellow River. The Leibniz Institute for Baltic Sea Research Warnemünde, the Institute of Geology and the Institute of Oceanography of the University of Hamburg, the Institute for Coastal Research of the Helmholtz Centre Geesthacht from Germany and the Guangzhou Marine Geological Survey, the School of Oceanography of the Shanghai Jiao Tong University, the Second Institute of Oceanography SOA, Hangzhou, the National Marine Environmental Monitoring Centre, SOA, Dalian and the Yantai Institute of Coastal Zone Research, CAS, Yantai from China cooperated in this network. The process studies were financed on the German side by the BMBF (03F0786A/B/C) within the framework of the WTZ China Initiative, whereas the State Oceanic Administration (SOA) financed the studies on the Chinese side. The aim of the network was to investigate environmental changes in the aforementioned marginal seas and their shelf areas in order to understand the effects of anthropogenic and natural changes, as a consequence of the formation and development of megacities, on the marine ecosystem. The study areas represented an ideal model system to better understand land-ocean exchange processes, changes in physical drives (monsoon, circulation), anthropogenic matter fluxes (including microplastics, pollutants), the effects of urban agglomerations on the land-coast-ocean interaction, and the effects of climatic changes in a very sensitive marine ecosystem. Sampling was carried out on three expeditions lasting several weeks on Chinese research vessels (HAI YANG DI ZHI SHI HAO 2015, HAI YANG DI ZHI SHI HAO 2018) and the German research vessel SONNE (2019) in the South China Sea. Sampling in the Bohai and Yellow Sea was carried out in April and August 2018 by the research vessel R/V DONG FANG HONG 2. River samples were taken in May, July to November from the Yellow River, and in November from Daliao River, Hai River, Luan River and Xiaoqing River. For both regional foci, physical, bio-geochemical and ecosystem modelling provided additional insights into the influence of varying environmental parameters on changes in biogeochemical cycles of elements (N, P, C) and allowed the assessment of the temporal and spatial variability of oceanic processes. The MEGAPOL consortium was expanded by the activities of the BMBF project South China Sea Natural Laboratory under Climatic and Anthropogenic Stress (FKZ 03G0269A-B, SOCLIS). The central activity in SOCLIS was the expedition with the German research vessel SONNE (SO269) in August 2019 in the working area at the northern shelf edge of the South China Sea in the research area of the Pearl River. During the expedition, among other things, a mooring was deployed for a period of 2 years on the northern continental slope of the South China Sea, thus expanding the scientific questions and infrastructure of MEGAPOL. This work was financed by the TRAN project (Temporal Patterns of Anthropogenic and Natural Particles on the Continental Slope of the South China Sea, FKZ 01DO17038) on the German side. In this report we summarize the first results of the investigations in the form of extended short descriptions presented by German and Chinese colleagues, which were presented in an online conference on 28 and 29 October 2020.

Bottom current-induced sediments such as contourites contain fundamental information for reconstructions of water mass properties and ocean circulation. The distinction between contourites and other deposits on continental slopes is particularly complex in areas where downslope and along-slope sedimentary processes co-occur. Clear and easily applicable diagnostic criteria for properly distinguishing between contourites and other coarse-grained and/or graded deep-water deposits such as turbidites are still limited (e.g., de Castro et al., 2020) and mainly focus on sedimentological data. The present study investigates Pleistocene contouritic (~0.5 Ma) and turbiditic (~0.9 Ma, ~1.1 Ma) sequences from the SW Iberian Margin in the Gulf of Cádiz (IODP Site U1389), where thick contourite drift bodies with extensively intercalated turbidites are preserved (Stow et al., 2013). The aim of the study is to define diagnostic criteria based on benthic foraminiferal assemblage composition in order to differentiate between normally graded contourites and turbidites as well as reworked turbidites. The revealed “foraminiferal fingerprint” will allow for improving paleoceanographic interpretations of sedimentary archives from complex depositional environments along continental margins. References: De Castro, S., Hernández-Molina, F.J., de Weger, W., Jiménez-Espejo, F.J., Rodríguez-Tovar, F.J., Mena, A., Llave, E., Sierro, F.J., 2020. Contourite characterization and its discrimination from other deep‐water deposits in the Gulf of Cadiz contourite depositional system. Sedimentology. Stow, D.A.V., Hernández-Molina, F.J., Llave, E., Bruno, M., García, M., Díaz del Rio, V., Somoza, L., Brackenridge, R.E., 2013. The Cadiz Contourite Channel: Sandy contourites, bedforms and dynamic current interaction. Mar. Geol. 343, 99–114.

Benthic foraminifera inhabit diverse marine environments, including areas of persistent bottom currents and contourite drift deposition. Certain highly adapted epibenthic foraminifera colonize contourite deposits as opportunistic suspension feeders. A correlation between these assemblages and high bottom current velocities has been highlighted in previous studies from the Iberian Margin (e.g. Schönfeld, 2002), suggesting their applicability as reliable proxy for reconstructing bottom currents. Our ongoing project aims to document biogeographic patterns of benthic foraminifera from extended contourite drift systems in the Atlantic Ocean. The results will provide a framework to evaluate the applicability of foraminifera-based proxy methods for reconstructing bottom currents in different Atlantic contourite deposits. Existing data from the mid-latitude Iberian Margin are complemented by new faunal data from surface samples at high (50-62°N; Björn and Gardar Drifts, Iceland Basin; Eirik Drift, southern Greenland Margin) and low latitudes (10°-22°S Campos Drift, Brazilian Margin). Preliminary results show variations in faunal composition along gradients of current intensity. Low current velocities at Björn and Gardar Drifts (max. 10 cm/s) favor tubular agglutinated taxa such as Rhabdammina abyssorum and Saccorhiza ramosa. An association of hyaline attached species including Cibicides refulgens and Cibicidoides wuellerstorfi preferentially settle in intermediate flow speeds at the Eirik Drift (12-22 cm/s). Communities of Campos Drift dwell at higher current velocities (up to 80 m/s) and show increased abundances of Cibicides lobatulus, Globocassidulina subglobosa, and Planulina ariminensis. Reference: Schönfeld, J., 2002. Recent benthic foraminiferal assemblages in deep high-energy environments from the Gulf of Cadiz (Spain). Mar. Micropaleontol. 44, 141–162. https://doi.org/10.1016/S0377-8398(01)00039-1

Mediterranean–Atlantic exchange through the Strait of Gibraltar plays a significant role in the global ocean–climate dynamics in two ways. On one side, the injection of the saline and warm Mediterranean Outflow Water (MOW) contributes to North Atlantic deep-water formation. In return, the Atlantic inflow is considered a sink of less saline water for the North Atlantic Ocean. However, while the history of MOW is the focus of numerous studies, the Pliocene Atlantic inflow has received little attention so far. The present study provides an assessment of the Mediterranean–Atlantic exchange with a focus on the Atlantic inflow strength and its response to regional and global climate from 3.33 to 2.60 Ma. This time interval comprises the mid-Pliocene warm period (MPWP; 3.29–2.97 Ma) and the onset of the Northern Hemisphere glaciation (NHG). For this purpose, gradients in surface δ18O records of the planktonic foraminifer Globigerinoides ruber between the Integrated Ocean Drilling Program (IODP) Hole U1389E (Gulf of Cádiz) and Ocean Drilling Program (ODP) Hole 978A (Alboran Sea) have been evaluated. Interglacial stages and warm glacials of the MPWP revealed steep and reversed (relative to the present) W–E δ18O gradients suggesting a weakening of Mediterranean–Atlantic exchange likely caused by high levels of relative humidity in the Mediterranean region. In contrast, periods of stronger inflow are indicated by flat δ18O gradients due to more intense arid conditions during the severe glacial Marine Isotope Stage (MIS) M2 and the initiation of NHG (MIS G22, G14, G6–104). Intensified Mediterranean–Atlantic exchange in cold periods is linked to the occurrence of ice-rafted debris (IRD) at low latitudes and a weakening of the Atlantic Meridional Overturning Circulation (AMOC). Our results thus suggest the development of a negative feedback between AMOC and exchange rates at the Strait of Gibraltar in the latest Pliocene as it has been proposed for the late Quaternary.