API src

Found 11 results.

Other language confidence: 0.9698100041707478

BrGDGT-based temperature evolution through an Eocene hyperthermal event

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) from maar sediments were analyzed in order to reconstruct continental air temperatures across a middle Eocene (47.2 Ma) hyperthermal event. Additionally, carbon isotopes of total organic carbon (δ13C TOC) were measured from the same samples to reconstruct changes in global and local carbon cycle. Measurements for both, brGDGTs and carbon isotopes, were carried out between beginning of 2021 and end of 2022. Based on the current age model the temporal resolution of the samples is millennial to sub-millennial. Sediment samples (organic-rich pelites) are from the FB2001 drill core, recovered from the Messel Fossil Site located in the vicinity of Frankfurt, Germany. The brGDGTs were solvent extracted by Soxhlet apparatus and further analyzed by high-performance liquid chromatography (HPLC-) - atmospheric pressure chemical ionization (APLCI-) - mass spectrometry (MS). Aliquots for total organic carbon isotope measurements were decalcified with HCl (10%) prior analyses on a Flash Elemental Analyzer.

Estimated adjusted depth of CO2 of FB2001 drill core from Messel

This table contains atmospheric CO2-estimates based on stomata retrieved in the Messel fossil pit and published by Grein (2010) and Grein et al. (2011). The data is based on leaves retrieved from the Messel fossil pit (earliest Middle Eocene; 47.66 to 47.22 Ma). The leaves were microscopically analysed for their stomata density and which was then converted into atmospheric CO2 content (cf. Grein 2010, Grein et al., 2011 for details about the algorithm). The plant fossils were listed with their original outcrop depth which was marked down relative to marker beds. We projected the outcrop depth (m) onto the FB2001 drill core depth using the marker beds as reference horizons. The age (Ma) as well as mean, maximum and minimum of the CO2 estimates are reported as well as the respective plant species.

Recurrence times of siderite layers of FB2001 drill core from Messel

To investigate variability and drivers of extreme precipitation events under high greenhouse gas concentrations prevalent during the Eocene we computed recurrence times of Fe/Ti peaks in the XRF scanning record of FB2001, reflecting siderite layers that are interpreted to reflect strong precipitation events. Fe/Ti-peaks were detected based on a peak-detection algorithm, followed by counting over a sliding window. Recurrence times were calculated based on the number of Fe/Ti peaks per 5 ka window. Upper and lower boundaries of recurrence times are calculated based on bootstrapping. The record covers the period 47.66 to 47.22 Ma

Mean Annual Air Temperatures of FB2001 drill core from Messel

This table contains Mean Annual Temperatures (MAT) reconstructed using branched GDGTs obtained on core FB2001 from Messel (earliest Middle Eocene; 47.66 to 47.22 Ma), relative to the core depth and age. The error given reflects the calibration error. Samples from the depth interval 17.38 to 30.88 m were analyzed in Frankfurt by high-performance liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS) on a Shimadzu UFLC device coupled to an AB Sciex 3200QTrap. Samples from the interval between 35.94 to 70.94 m core analyzed at RWTH Aachen University, Aachen (Germany), using an Agilent 1260 Infinity II HPLC coupled to an Agilent LC/MSD XT mass spectrometer.

XRF Fe/TI and K/Ti ratios of FB2001 drill core from Messel

The data contains Fe/Ti and K/Ti ratios obtained via XRF core scanning of drill core FB2001 from the Messel fossil pit (earliest Middle Eocene; 47.66 to 47.22 Ma) versus core depth and age. Scanning was performed at the Institute of Institute of Earth Sciences, Heidelberg University (Germany), with an Avvatech (Gen. IV) X-Ray Fluorescence Scanner. The purpose of this analysis was to objectively detect and quantify the occurrence of siderite layers in the Messel oil shale. These siderite layers are interpreted to represent extreme precipitation events.

Reconstruction of continental temperatures and oxygen isotope compositions of precipitation based on clumped and oxygen isotope analysis of pedogenic siderites

Earth's climate sensitivity – defined as the temperature increase for a doubling of pCO2 – and the mechanisms responsible for amplification of high latitude warming remain controversial. The latest Paleocene/earliest Eocene (LPEE; 57-55 million years ago) is a time when pCO2 peaked between 1400 and 4000 ppm, which allows us to evaluate the climatic response to high pCO2. Here, we present a reconstruction of continental temperatures and oxygen isotope compositions of precipitation – reflective of specific humidity – based on clumped and oxygen isotope analysis of pedogenic siderites. We show that continental mean annual temperature reached 41 °C in the equatorial tropics, and summer temperatures reached 23 °C in the Arctic. The oxygen isotope compositions of precipitation reveal that compared to the present-day the hot LPEE climate was characterized by an increase in specific humidity and the average residence time of atmospheric moisture and by a decrease in the subtropical-to-polar specific humidity gradient. The global increase in specific humidity reflects the fact that atmospheric vapor content is more sensitive to changes in pCO2 than evaporation and precipitation, resulting in an increase in the residence time of moisture in the atmosphere. Pedogenic siderite data from other super-greenhouse periods support the evidence that the spatial patterns of specific humidity and warmth are related providing new means to evaluate Earth's climate sensitivity.

Middle to late Eocene carbonate accumulation rates in the Pacific, Atlantic, Indian, and Southern Oceans

Sedimentary records from the equatorial Pacific show that the deepening of the carbonate compensation depth (depth below which the calcium carbonate flux to the seafloor is balanced by dissolution) at the Eocene/Oligocene boundary (~33.9 Ma) was preceded by several episodes of high and low carbonate accumulation rates. However, data from other basins are scarce. Here, we report middle-late Eocene carbonate accumulation rates from sites located in the Pacific, Atlantic, Indian, and Southern Oceans. Our results show that the calcium carbonate burial was geographically, bathymetrically, and temporally heterogenous suggesting the fundamental role of surface calcium carbonate production in driving middle-late Eocene carbonate accumulation rates. Our data also suggest that an increase in ocean ventilation might have influenced calcium carbonate preservation at depths > 2500 m.

Cenozoic TEX86-derived global SST compilation including new data from ODP/DSDP Sites 72-516, 90-588, 108-667, 114-704, 117-730, 121-754, 184-1146 and 208-1263

Cenozoic global TEX86-derived sea surface temperature (SST) compilation from all published marine TEX86 records and new data measured in this study (ODP/DSDP Sites 516, 588, 667, 704, 730, 754, 1146 and 1263). This table contains all GDGT measurements, calculated indices, SSTs and SST gradients.

Paleomagnetic data of the Balzes Anticline

This dataset is built from data published in two different articles (Rodríguez-Pintó et al. 2012 and 2016). The main scientific goal described in the articles is the quantification of vertical axis rotations (VAR) around the bended axis of the Balzes anticline in the South Pyrenean frontal thrust (External Sierras). 74 sites and one short magnetostratigraphic section were sampled following standard paleomagnetic field procedures; in total 984 oriented cores were drilled in the field. Paleomagnetic sites are evenly distributed along strike changes of the fold and were drilled in Eozene rock of the Ypresian (Cuisian), Lutetian and Bartonian rocks. Lithologies and affinity may vary; some rocks are marine limestones and marls (Boltaña, Paules and Guara Formations), others (sandy limestones and marls) represent transitional environments (Belsué-Atarés Formation) while the remaining are continental siltstones and sandstones from the Campodarbe Formation. Every site contains an average out of 9.6 standard cores (stand. dev. 5.8) but varies between 3 and 35. For the small magnetostratigraphic section 65 cores were sampled. Thermal demagnetization was the main laboratory analysis performed searching for VAR values at the site scale. The analyses were performed in the laboratories of the Universities of Barcelona and Burgos. 2G magnetometer were used to measure the magnetization in both laboratories and MMTD80 (Magnetic Measurements) and TD-48 SC (ASC Scientific) furnaces, respectively.

LPEE reconstructions of oxygen and hydrogen isotope compositions of precipitation based on the analysis of pedogenic siderites and published records of plant wax n-alkanes

1 2