Our study focuses on European loess sequences, particularly the eolian intervals in between the observed pedogenic units. The classical concept of soil formation from parent material is reformulated to estimate of the duration and the associated sedimentation rate (SR) and mass accumulation rate (MAR) of these paleodust intervals. We show that the Greenland Stadial (GS) duration in European loess deposits includes the thickness of the overlying pedogenic unit, which in fact developed downward into the upper part of the eolian unit. The lower stratigraphical limit of the eolian unit overlying the pedogenic unit corresponds to the restart of the dust sedimentation of the younger GS. We illustrate this interpretation first by computing both SRs and MARs first for the Nussloch key sequence, the most complete European series. The correlation between Nussloch and other European loess sequences, located along a 1,800 km longitudinal transect, allows computation of SR and MAR for several identified GS events. Comparing GS from marine and ice core records, our study shows that the two last Bond cycles are preserved in every European eolian record. Bulk SR and MAR are estimated and compared for these two Bond cycles, showing the highest SRs and MARs in western Europe. These indices also indicate that the last stadials, embedding an Henrich event, were not the dustiest in every Bond cycle. Our estimated MAR also differ from previously published computations, which did not take into account the various pedogenic units present in the studied loess sequences. The bulk SR and MAR estimates computed for the two last Bond Cycles from Chinese sequences from the Loess Plateau indicate lower atmospheric dust than in Europe during the Last Glacial Maximum. SR and MAR estimates computed from the fine-grained material for European records fit with Earth System model reconstructions.
Loess sequences are a particular record of paleoenvironments and paleoclimates and show regional peculiarities. Among those, European loess sequences show the occurrence of paleosols and other pedogenic units that have been demonstrated to correspond to the Greenland Interstadials (GIS) or Dansgaard-Oeschger events (DO), for the last climate cycle (Moine et al. 2017), of GIS-like for the penultimate climate cycle (Rousseau et al. 2020).
During the last climate cycle, these paleosols developed synchronously over Europe along a wide longitude transect eastward in Ukraine (Rousseau et al., 2017). More interesting the development of these paleosols or pedogenic units, occurred during a stop of the dust deposition from the top of the most recently deposited eolian unit. Taking into consideration this point in our manuscript, we revisited the stratigraphy of the European loess sequences by considering the paleodust units, equivalent to Greenland Stadials (GS), as associating the lower loess unit and the overlying paleosol or pedogenic unit. Moreover, the close correlation that we established between the paleosols or pedogenic units with GIs, allows us to consider that the paleosol development occurred during the related GI in Greenland (Rousseau et al., 2017). Having the GI durations published by Rasmussen et al (2014), we propose therefore new timescales for the European loess sequences. Moreover, we have assigned the paleosol-loess units doublets to the corresponding Bond cycles defined by Broecker (1994). These cycles group several DO events, of increasing cold amplitude, and end with a Heinrich event that some literature interpreted as the coldest and dustiest time interval over Europe, an interpretation that we are testing in our paper.
In our manuscript, we demonstrate our new method by applying it to the reference sequence of Nussloch that we have investigated for decades. We present a revised detailed record of sedimentation and mass accumulation rates over the 60 ka to 15 ka b2k time interval (TAB. 1). We also apply our method to other key European sequences that we investigated previously at high resolution, allowing us to propose new estimates for the SR and MARs of the most recent Bond cycles, i.e. e. between GI4 and GS3 (29 to 23.2ka b2k) and between GI8 and GS5 (38.2 to 29ka b2k) (TAB. 2). We conclude the LGM as the dustiest interval with the highest values, and presenting a longitudinal pattern along the studied European transect, with the highest values westward. Another finding is that for every Bond cycle, the dustiest interval always happened in the GS prior the last ones corresponding to Heinrich stadials. Expanding the comparison with high-resolution sequences from the Chinese loess plateau (TAB. 3) for the same Bond cycles, our study shows that Europe was dustier than China. A final test of our new method is by considering the SR and MARs for the various grain size categories measured in three key reference sequences. Considering the finest grain size category, which can be assimilated as the closest the mineral aerosols, our estimates fit the dust deposition reconstructed for the LGM in Europe by Earth System models opening new perspectives for future data-model comparisons (TAB. 4).
This dataset contains a compilation of the sulfur isotopic composition of pyrite from outcrop and sediment cores over the past 165 million years. The compilation includes 3754 data points from 94 publications, compiled in 2020, 2021, and 2023. The data was collected in order to investigate the relationship between the sulfur isotopic composition of pyrite and depositional environment over the Cenozoic and Late Mesozoic, and has global spatial coverage. Compiled sediment core data includes the sulfur isotopic composition of pyrite, age, water depth, location, methane content, lithology, and total organic carbon. Compiled outcrop data includes the sulfur isotopic composition of pyrite, age, generalized water depth based on sedimentological criteria, and lithology.
Dieses Projekt ist die Fortsetzung der laufenden Deutsch-Indischen Zusammenarbeit auf dem Gebiet der marinen Geologie und Ozeanographie. Das Hauptziel ist die Untersuchung der Variabilitaet des Partikelflusses in die Tiefsee in Abhaengigkeit vom Monsun im Arabischen Meer und im Golf von Bengalen. Die Feldarbeit beinhaltet die Benutzung von geankerten Sedimentfallen auf jeweils drei Stationen im Arabischen Meer und im Golf von Bengalen. Waehrend der Projektzeit wurden zwei Forschungsfahrten mit den Indischen Forschungsschiffen SAGAR KANYA und NAND RACHIT durchgefuehrt, wobei die sechs Sedimentfallensysteme geborgen und wiederausgesetzt wurden. Ausserdem wurden die Laboruntersuchungen der bisher gewonnenen Proben fortgesetzt und gemeinsame Veroeffentlichungen vorbereitet. Die bisherigen Ergebnisse haben neuere Erkenntnisse ueber die Kohlendioxid (CO2)-Entzugsmechanismen im Meer geliefert, wobei Wind und aeolische Partikel im Arabischen Meer und Fluesse und fluviatile Partikel im Golf von Bengalen eine entscheidende Rolle spielen. Starke Winde und Fluesse liefern Naehrstoffe, die die CO2-Fixierung an der Meeresoberflaeche beguenstigen, waehrend die mit ihnen an die Meeresoberflaeche eingetragenen Partikel als 'Ballast' dienen, und den raschen Entzug der neu-formierten Partikel in die Tiefsee beguenstigen.
Ermittlung der Naturgesetzmaessigkeiten ueber die Entstehung, den Transport und die Ablagerung von Schlick durch Messung hydrologischer, morphologischer, meteorologischer und chemischer Parameter sowie Luftbilder.