41 research outputs found
Photic zone euxinia in the central Rhaetian Sea prior the Triassic-Jurassic boundary
No full textShortly after the deposition of black shales in the Rhaetian Sea (Central European Basin, CEB), the Triassic/Jurassic (TO) boundary witnessed one of the Big Five mass extinction events in Earth's history. Aiming at a better understanding of paleoenvironmental changes in the (geochemically) less well-known middle to late Rhaetian (German subdivision), we studied samples from a cored borehole from the central Rhaetian Sea in NW Germany (Hebelermeer 2). Biomarkers, palynomorphs and bulk geochemistry all support a marine/brackish setting with inputs from terrestrial plants. Dinosteranes were found throughout the core, most likely suggesting the spread of dinoflagellates. It is widely accepted that volcanic exhalations during the development of the Central Atlantic Magmatic Province (CAMP) had a major impact on marine and terrestrial environments in the earliest Jurassic e.g., the development of photic zone euxinia and H2S poisoning of benthic life. There is evidence from the studied core, however, that comparable conditions already thrived in the central Rhaetian Sea during the middle Rhaetian. A first indication of euxinia/anoxia is evident from low to very low total organic carbon versus total sulfur (TOC/TS) ratios (similar to<1) with a minimum preceding the Tr/J boundary (0.03). The latter very low value hints at a decoupling of S and C cycles and eventually abiogenic pyrite formation. Water-column anoxia during the middle Rhaetian is indicated by the occurrence of the biomarker gammacerane, which records ciliates living at the O-2-H2S chemocline. The strongest support for a stratified water column even with photic zone euxinia comes from high abundances of isorenieratane. This biomarker is a pigment of anoxygenic phototrophic green sulfur bacteria, which use H2S for photosynthesis. Our data point to perturbations in the biogeochemical cycles of sulfur and carbon already in the middle Rhaetian, which are possibly linked to early volcanic activities and SO2, H2S, and CO2 eruptions. (C) 2016 Elsevier B.V. All rights reserved
Stable oxygen record, sea surface temperatures (Uk37) and total organic carbon content oof sediment core SO139-74KL
No full textStable oxygen record, sea surface temperatures (Uk37) and total organic carbon content oof sediment core SO139-74K
(Figure 3) Oxygen isotopes and reconstructed salinity records of sediment core SO90-39KG from the northeastern Arabian Sea during the late Holocene
No full textAge scale is in calendar years from varve counting (see von Rad et al., 1999, datasets: doi:10.1594/PANGAEA.735718
(Table 1) Age determination of sediment core SO139-74KL
No full textA multiproxy record has been acquired from a piston core (SO139-74KL) taken offshore southern Sumatra, an area which is situated in the southwestern sector of the tropical Indo-Pacific Warm Pool. The high-resolution data sets (X-ray fluorescence, total organic carbon, and C37 alkenones) were used to track changes in paleoproductivity, freshwater budget, and sea surface temperature (SST) of the tropical climate system at orbital time scales over the past 300 ka. Our paleoclimatic data show that enhanced marine paleoproductivity was directly related to strengthening of coastal upwelling during periods of increased boreal summer insolation and associated SE monsoon strength with a precessional cyclicity. Changes in freshwater supply were primarily forced by precession-controlled changes in boreal NW winter monsoon rainfall enclosing an additional sea level component. SST variations of 2°-5°C occurred at eccentricity and precessional cyclicity. We suggest that the sea surface temperature variability off southern Sumatra is predominantly related to three major causes: (1) variations in upwelling intensity; (2) an elevated freshwater input into the southern Makassar Strait leading to reduced supply of warmer surface waters from the western Pacific and increased subsurface water transport via the Indonesian Throughflow into the Indian Ocean; and (3) long-term changes in the intensity or frequency of low-latitude climate phenomena, such as El Niño-Southern Oscillation
(Figure 3) Sea surface temperature estimates of sediment core SO90-56KA from the northeastern Arabian Sea during the late Holocene
No full textAge scale is in calendar years from varve counting (see von Rad et al., 1999, datasets: doi:10.1594/PANGAEA.735718
Bulk geochemistry and biomarker concentrations and isotopic compositions of lignites spanning the PETM from Stenkul Fiord (Ellesmere Island), early Eocene
No full textThis dataset contains bulk geochemical information (TOC, S, Tmax, Hydrogen and Oxygen Indices), relative and absolute abundances of selected plant wax and bacterial hopanoid biomarkers as well as stable carbon and hydrogen isotope signatures of selected compounds. Samples were analysed with a Leco C/S analyser, a Rock-Eval 6 pyrolysis unit, a gas chromatograph-triple quad mass spectrometer and gas chromatograph isotope ratio mass spectrometer (for d13C and d2H). The samples originate from two onshore outcrops at the Stenkul Fiord (Ellesmere Island) and are mostly coal samples of the lignite thermal maturity stage. The age of the samples are Paleogene and cover the Paleocene Eocene Thermal Maximum (PETM; Margaret Formation), and they were taken in 2017 (BGR CASE 19 expedition). The data were generated to reconstruct the terrestrial paleovenvironment in this high-latitude setting. More information on the studied sections can be found elswhere (Reinhardt et al., 2022)
Bulk geochemistry and biomarker concentrations and isotopic compositions of lignites spanning the PETM from Stenkul Fiord (Ellesmere Island), Paleocene
No full textThis dataset contains bulk geochemical information (TOC, S, Tmax, Hydrogen and Oxygen Indices), relative and absolute abundances of selected plant wax and bacterial hopanoid biomarkers as well as stable carbon and hydrogen isotope signatures of selected compounds. Samples were analysed with a Leco C/S analyser, a Rock-Eval 6 pyrolysis unit, a gas chromatograph-triple quad mass spectrometer and gas chromatograph isotope ratio mass spectrometer (for d13C and d2H). The samples originate from two onshore outcrops at the Stenkul Fiord (Ellesmere Island) and are mostly coal samples of the lignite thermal maturity stage. The age of the samples are Paleogene and cover the Paleocene Eocene Thermal Maximum (PETM; Margaret Formation), and they were taken in 2017 (BGR CASE 19 expedition). The data were generated to reconstruct the terrestrial paleovenvironment in this high-latitude setting. More information on the studied sections can be found elswhere (Reinhardt et al., 2022)
Compilation of organic carbon distribution and sedimentology in the surface sediments on the continental margin offshore southwestern Africa
No full textIn this study we demonstrate the relevance of lateral particle transport in nepheloid layers for organic carbon (OC) accumulation and burial across high-productive continental margins. We present geochemical data from surface sediments and suspended particles in the bottom nepheloid layer (BNL) from the most productive coastal upwelling area of the modern ocean, the Benguela upwelling system offshore southwest Africa. Interpretation of depositional patterns and comparison of downslope trends in OC content, organic matter composition, and 14C age between suspended particles and surface sediments indicate that lateral particle transport is the primary mechanism controlling supply and burial of OC. We propose that effective seaward particle transport primarily along the BNL is a key process that promotes and maintains local high sedimentation rates, ultimately causing high preservation of OC in a depocenter on the upper slope offshore Namibia. As lateral transport efficiently displaces areas of enhanced OC burial from maximum production at highly productive continental margins, vertical particle flux models do not sufficiently explain the relationship between primary production and shallow-marine OC burial. On geologic time scales, the widest distribution and strongest intensity of lateral particle transport is expected during periods of rapid sea-level change. At times in the geologic past, widespread downslope lateral transport of OC thus may have been a primary driver of enhanced OC burial at deeper continental slopes and abyssal basins
Geochemical analysis in SW Morocco (Core S13)
No full textGeochemical analysis in SW Morocco (Core S75
