Rick Hennekam

Royal Netherlands Institute for Sea Research

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Gert‐Jan Reichart

Royal Netherlands Institute for Sea Research

Gert J. de Lange

Utrecht University

Stefan Schouten

Royal Netherlands Institute for Sea Research

Geert-Jan A Brummer

Royal Netherlands Institute for Sea Research

Chris I Munday

Royal Netherlands Institute for Sea Research

Catarina Guerreiro

University of Lisbon

Dirk Jong

Vrije Universiteit Amsterdam

Michèlle van der Does

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Laura F Korte

International Union for Conservation of Nature (Bangladesh)

Jan-Berend W Stuut

Vrije Universiteit Amsterdam

Cooperative Institutions

Utrecht University

Royal Netherlands Institute for Sea Research

Centre National de la Recherche Scientifique

Australian National University

University of Bremen

ETH Zurich

Vrije Universiteit Amsterdam

Chinese Academy of Sciences

Woods Hole Oceanographic Institution

Centre de Recherche et d’Enseignement de Géosciences de l’Environnement

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Calibrated XRF-scanning data (mm resolution) for elements Al, Ba, Mo, Ti, and U in Mediterranean core MS66PC

Rick Hennekam Bregje van der Bolt Egbert H. van Nes Gert J. de Lange Marten Scheffer

10.1594/pangaea.923193

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Organic carbon burial in Mediterranean sapropels intensified during Green Sahara Periods since 3.2 Myr ago

Communications Earth & Environment (2022)

Katharine Grant Udara Amarathunga Jessica D. Amies Pengxiang Hu Yao Qian

Abstract Dark organic-rich layers (sapropels) have accumulated in Mediterranean sediments since the Miocene due to deep-sea dysoxia and enhanced carbon burial at times of intensified North African run-off during Green Sahara Periods (GSPs). The existence of orbital precession-dominated Saharan aridity/humidity cycles is well known, but lack of long-term, high-resolution records hinders understanding of their relationship with environmental evolution. Here we present continuous, high-resolution geochemical and environmental magnetic records for the Eastern Mediterranean spanning the past 5.2 million years, which reveal that organic burial intensified 3.2 Myr ago. We deduce that fluvial terrigenous sediment inputs during GSPs doubled abruptly at this time, whereas monsoon run-off intensity remained relatively constant. We hypothesize that increased sediment mobilization resulted from an abrupt non-linear North African landscape response associated with a major increase in arid:humid contrasts between GSPs and intervening dry periods. The timing strongly suggests a link to the onset of intensified northern hemisphere glaciation.

Terrigenous sediment

Sapropel

myr

Precession

10.1038/s43247-021-00339-9

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Citations (37)

Geochemistry (Sr/Ca, d18O, d18Osw) of Porites coral D3 from the Cocos Keeling Islands (Australia)

Rick Hennekam Jens Zinke Erik van Sebille Malou Ten Have Geert-Jan A Brummer

Porites

10.1594/pangaea.883834

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Comment on cp-2022-14

Rick Hennekam Katharine Grant Eelco J. Rohling Rik Tjallingii David Heslop

In eastern Mediterranean Sea sediments, the titanium to aluminum ratio (Ti/Al) captures relative variability in eolian to riverine derived material, and predominantly integrates climate signals over the Saharan and Sahel regions. Long Ti/Al time series can, therefore, provide valuable records of North African humidity/aridity changes. X-ray fluorescence core scanning (XRF-CS) can generate near-continuous Ti/Al records with relatively modest effort and in an acceptable amount of time, provided that accurate Ti/Al values are acquired. Calibration of the raw XRF-CS data to those of established analytical methods is an important pathway to obtain this required accuracy. We assess how to obtain reliable XRF-CS Ti/Al calibration by using different sets of calibration reference samples for a long sediment record from ODP Site 967 (eastern Mediterranean). The accuracy of reference concentrations and the number of reference samples are important components for reliable calibration. The acquired continuous Ti/Al record allows detailed time-series analysis over the past 3 Ma. A near-direct control of low-latitude insolation on the timing and amplitude of North African aridity/humidity is observed from 3 to ~1.2 Ma. It is evident from our Ti/Al record that the most arid North African intervals (i.e., with longest period and highest amplitude) occur after the mid-Pleistocene transition (MPT; ~1.2–0.7 Ma). Concurrently, correlation between North African aridity/humidity (Ti/Al) and higher latitude climate signals (ice-volume variability) increases around the MPT. These findings support the growing consensus that African climate became more sensitive to remote high-latitude climate when a threshold ice volume was reached during the MPT.

10.5194/cp-2022-14-rc2

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Inter-comparison of XRF core scanning results from 7 labs

Ann G. Dunlea Richard W. Murray Ryuji Tada Carlos A. Alvarez Zarikian C. H. Anderson

10.1594/pangaea.922043

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Integral view of Holocene precipitation and vegetation changes in the Nile catchment area as inferred from its delta sediments

Quaternary Science Reviews (2015)

Rick Hennekam Timme H. Donders Karin Zwiep Gert J. de Lange

Nile delta

River delta

10.1016/j.quascirev.2015.05.031

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Calibrated XRF-scanning data (mm resolution) and calibration data (ICP-OES and ICP-MS) for elements Al, Ba, Mo, Ti, and U in Mediterranean cores MS21, MS66, and 64PE406E1

Rick Hennekam Bregje van der Bolt Egbert H. van Nes Gert J. de Lange Marten Scheffer

Sediment cores were collected using a piston corer at three sites in the eastern Mediterranean Sea. Piston cores MS21 (32°20.7'N, 31°39.0'E; 1022 m water depth; 751.5 cm in length) and MS66 (33°1.9'N, 31°47.9'E; 1630 m water depth; 630 cm in length) were recovered during the MIMES cruise with the R/V Pelagia in 2004. Piston core 64PE406E1 (33°18.1'N, 33°23.7'E; 1760 m water depth; 920.5 cm in length) was recovered during the Eastern Mediterranean part of the 64PE406 (NESSC) cruise with the R/V Pelagia in 2016. The cores were opened and then prepared for X-Ray Fluorescence (XRF) core scanning by carefully flattening the sediment and covering it with a 4-μm SPEXCerti Ultralene foil. Subsequently, the sediments were XRF-scanned with a 1-mm resolution using four settings (10 kV-no filter, 20 kV-Al filter, 30 kV-Pd-thick filter, and 50 kV-Cu filter). The produced XRF-core-scanner data were calibrated using a subset of the discrete samples taken from the same core material. These samples were digested with an acid mixture and partially measured by inductively coupled plasma mass spectrometry (ICP-MS) and partially measured by ICP-optical emission spectroscopy (ICP-OES). The main purpose of our data collection was to reconstruct in detail (~10-50 yr resolution) the deoxygenation and anoxia in the eastern Mediterranean Sea during the last 300 ka BP; we focused on elements and elemental ratios of Al, Ba, Mo, Ti, and U.

10.1594/pangaea.923197

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Suborbital Hydrological Variability Inferred From Coupled Benthic and Planktic Foraminiferal‐Based Proxies in the Southeastern Mediterranean During the Last 19 ka

Paleoceanography and Paleoclimatology (2020)

Sandrine Le Houëdec Meryem Mojtahid Erica Bicchi Gert J. de Lange Rick Hennekam

Abstract We present a high‐resolution study covering the past 19 ka from the southeastern Mediterranean Sea, based on benthic foraminiferal faunas and their stable oxygen and carbon isotopes. These data are integrated with previously published and newly acquired planktic foraminiferal data from the same sediment core in order to investigate the benthic‐planktic coupling and its response to past suborbital climate variability. On a millennial timescale, foraminiferal communities and their isotopic signatures vary following three main time periods (late glacial, sapropel S1 [~10.1–6.5 ka], and mid‐Holocene to Late Holocene). Within these intervals, we identified short‐timescale changes related to the carbon export and hydrological conditions. During the deglaciation, and except for the Younger Dryas, the coupled benthic‐planktic data indicate an overall poorly mixed water column with a low productivity. During S1 event, our data confirm the presence of a highly stratified water column, with enhanced primary productivity export to the deep sea, being associated to high Nile River activity. While the foraminiferal ecosystem is strongly driven by the combined influence of overturning circulation and the Nile River activity until the end of the African humid period, we suggest a more regional eastern Mediterranean climatic‐driven response of the foraminiferal community over the mid‐Holocene to Late Holocene. A strong multicentennial variability, probably associated to solar forcing, was found for both benthic and planktic records, and a supplementary 1,600‐year mode was found for the benthic data, suggesting a potential overturning circulation‐driven forcing for the latter.

Deglaciation

paleoceanography

Sapropel

10.1029/2019pa003827

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Comment on egusphere-2023-2981

Babette Hoogakker Catherine V. Davis Yi Wang Stepanie Kusch Katrina Nilsson-Kerr

Abstract. A growing body of observations reveals rapid changes in both the total inventory and distribution of marine oxygen over the later half of the 21st century, leading to increased interest in extending oxygenation records into the past. Use of paleo-oxygen proxies have the potential to extend the spatial and temporal range of current records, bound pre-anthropogenic baselines, provide datasets necessary to test climate models under different boundary conditions, and ultimately understand how ocean oxygenation responds beyond decadal scale changes. This review seeks to summarize the current state-of-knowledge about proxies for reconstructing Cenozoic marine oxygen: sedimentary features, sedimentary redox-sensitive trace elements and isotopes, biomarkers, nitrogen isotopes, foraminiferal trace elements, foraminifera assemblages, foraminifera morphometrics, and benthic foraminifera carbon isotope gradients. Taking stock of each proxy reveals some common limitations in that the majority of proxies function best at low-oxygen concentrations and many reflect multiple environmental drivers. We also highlight recent breakthroughs in geochemistry and proxy approaches for constraining pelagic (in addition to benthic) oxygenation that are rapidly advancing the field. In light of both the emergence of new proxies and the persistent multiple driver problem, the need for multi-proxy approaches and FAIR data storage and sharing is emphasized. Continued refinement of proxy approaches and both proxy-proxy and proxy-model comparisons are likely to support the growing needs of both oceanographer and paleoceanographers interested in paleo-oxygenation records.

10.5194/egusphere-2023-2981-rc2

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Supplementary material to "Reviews and syntheses: Review of proxies for low-oxygen paleoceanographic reconstructions "

Babette Hoogakker Catherine V. Davis Yi Wang Stepanie Kusch Katrina Nilsson-Kerr

Ca. Scalindua profunda' anammox hypoxia/anoxia, O 2 <20µmol

10.5194/egusphere-2023-2981-supplement

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