MN183-3 detailed chronology

Published: 26 May 2022| Version 1 | DOI: 10.17632/4b8vhb45z2.1
Contributors:
Tiberiu Bogdan Sava,
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Description

The sampling point is located on the slope of the NW Black Sea continental platform at the exact location described by 43.925.917 N, 30.758.911 E and at a water depth of 658 m in the anoxic/euxinic environment, which starts below the surface at around 150 m depth. Here, we publish the final data of our case study as an intermediate product, which set the base and come in handy for creating a high-resolution sedimentation model spanning the last 5500 years. The AMS radiocarbon dated material is the bulk organic matter. We present the series of 25 radiocarbon ages on the sampled layers of organic matter, each two centimeters. The radiocarbon raw data files (.dat files) work with BATS 4.06 data reduction software. The final output file is written for web browser visualisation (.xhtml files). There are three data files for each of the AMS measurements performed on 1.10.2020, 19.03.2021 and 24.03.2021. For the identification of the reservoir sources of the organic matter in sediments we've resorted to measure the δ13C (#12 samples) and C/N atomic ratio (files: "Experimental_data_13C.xlxs" and "Experimental_data_C-N.xlxs"; the raw data for the 13C measurements is found in "raw_exp_data_13C.pdf"). The XRF files are compatible with Bruker Instrument Tools 1.6.0.110 software (.pdz files). These results are also transcripted in MS Excel files. We attach also the TOC measurement taken on all the 25 depths (Experimental_data_TOC.xlxs") and the radioactivity levels for 210Pb and 137Cs found in "Experimental_data_210Pb-137Cs.xlxs".

Files

Steps to reproduce

For 14C dating: sample preparation implied acidification of the organic matter for carbonates removal. For the AMS measurements on the 1MV Tandetron (High Voltage, The Netherlands), all the samples were normalized to the modern radiocarbon level using the international standard Oxalic Acid II (NIST 1983), while the blank level was estimated using old charcoal of an unknown source. The experimental data obtained for all the samples were corrected for the isotopic fractionation introduced during the sample preparation and spectrometer measurement using AMS δ13C. The radiocarbon ages were calculated according to Stuiver and Pollach, 1977. The atomic C/N ratio was estimated using Vario MicroCube elemental analyser (Elementar, Germany) on the pretreated samples from the 14C dating. The sample pretreated samples went to 13C measurement. The stable carbon isotope (13C) was determined using an isotope ratio mass spectrometer (IRMS) (Delta V Advantage, Thermo Fisher Scientific). The resulting δ 13C was normalized to Vienna Pee Dee Belemnite (VPDB) international standard, (Brand et al., 2014) and calibrated against the International Atomic Energy Agency (IAEA) references material, NBS-22 oil. The bulk (untreated) sediment samples were pressed to create the tablets for the XRF analysis. In our study, a Bruker Tracer S1 Titan Spectrometer was used, whose beam with energy of 40 keV was passed through an 8 mm collimator before reaching the samples. The spectra were taken using a silicon drift detector (Amptek, USA) positioned backward at 45° with respect to the Rh anode tube. The same bulk sample was sent to chemical pretreatment and to total carbon/organic carbon/inorganic carbon analysis using a Primacs analyser from Skalar (The Netherlands). For gamma-ray spectrometry a gamma spectrometer with an HPGe semiconductor detector, 30% relative efficiency, model Ortec GMX-30-70-S, equipped with a 0.5 mm Be window was used to measure the levels of the 137Cs and 210Pb isotopes present in the cores.

Institutions

Institutul National de Cercetare Dezvoltare pentru Tehnologii Izotopice si Moleculare, Horia Hulubei National Institute of Physics and Nuclear Engineering, Institutul National de Cercetare-Dezvoltare pentru Geologie si Geoecologie Marina

Categories

Geochemistry, Geochronology

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