ALBERT

Description: Initial detrital composition and authigenic alterations during diagenesis of three sandstone types are related to their mechanical properties. Sandstones were prepared for geotechnical standard tests [density, uniaxial compressive strength (UCS), Young’s modulus (E), strain at failure (ε)] and thin sections for petrographic analyses (point counting). UCS ranges from 3 to 62 MPa and positively correlates with density (1.75–2.35 g/cm〈sup〉3〈/sup〉) and E (0.3–12.7 GPa). Optical porosity is controlling these mechanical parameters and was linked to diagenetic alterations. Diagenetic alterations affecting porosity reduction are the abundance of clay minerals, and the intensity of mechanical and chemical compaction. The latter is controlled by clay mineral coatings on contacts between detrital grains, and the occurrence of authigenic quartz and dolomite. Horizontal contact lengths of grains normalized to their respective particle diameter (effective contact ratio, ECR) and porosity are identified as a control on the mechanical properties UCS and E, reflected by the rock strength index SR. The results of this pilot study suggest that SR is able to predict UCS and E based on petrographic information obtained from the studied samples. These results enhance the understanding of the coupling between mineralogy and geomechanics and highlight the impact of diagenesis on geomechanical behavior.

Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Description: Projekt DEAL

Description: Carbonate was micro-sampled from representative listvenite and serpentinite core sections of Hole BT1B for carbonate stable isotope analysis (δ13C, δ18O) and clumped isotope thermometry. This sample subset includes matrix and vein magnesite, vein dolomite from the Upper Serpentinite (BT1B 43–02 and 44–03) and listvenite. The majority of listvenite carbonate samples are from the Lower Listvenite, comprising green, light red and dark red listvenite, plus one additional light red listvenite from the Upper Listvenite. Listvenite matrix carbonate is mainly magnesite except for matrix dolomite from core sections BT1B 72–04 and BT1B 77–03. Listvenite vein dolomite was sampled from the Upper Listvenite (BT1B 32–02) and Lower Listvenite (BT1B 67–04). Carbonate was sampled by using a micro drill with 3.8 mm inner diameter and a handheld Dremel tool from thin-section billets at sites selected based on the petrography. The relatively large diameter of the drill compared to the typical grain size and vein diameter, required sampling of the most homogeneous matrix areas and veins that were macroscopically devoid of crosscutting relationships. Carbonate samples were further crushed to a fine powder using an agate mortar and pestle prior to the analysis. Stable isotope analyses were performed at the GeoLab, Utrecht University, The Netherlands. Before isotope analysis, the mineralogy of each sample powder was constrained by XRD. The duration of acid digestion was adjusted to either dolomite or magnesite according to the dominant carbonate species in the sample powder. Dolomite samples were digested in 103% phosphoric acid at 70°C for 20 minutes and the released CO2 was continuously collected in a liquid nitrogen trap using a Kiel IV carbonate device, coupled to a 253 Plus isotope ratio mass spectrometer (both instruments from Thermo Scientific) and analyzed in Long-Integration Dual-Inlet mode (Müller et al., 2017a, doi: 10.1002/rcm.7878; with 600 seconds integration time per aliquot). The weight of individual aliquots of reference materials and unknown samples ranged between 75–95 µg. Magnesite samples were digested offline, using 10–20 mg solid powder and 1–2 ml 103% phosphoric acid at 100°C for 15–16 hours in individual, sealed vials using a custom-built vacuum line containing a cold trap with liquid nitrogen acetone slush (-96°C) to remove H2O trace quantities from the CO2 gas. The analyses were conducted using the Dual Inlet of a Thermo Fisher Scientific MAT 253 in the traditional way by 8 alternating reference gas-sample gas cycles (208 seconds sample gas integration time per measurement). All analyses were carried out in sequences with intermittent analyses of the carbonate (calcite) reference materials ETH-1, ETH-2, ETH-3. Each unknown sample was analyzed 4 to 14 times. A separate dataset contains the complete summary of all individual analyses of unknown samples and reference materials (Beinlich et al., 2019; doi:10.1594/PANGAEA.908649).

Description: The presented serpentine and fuchsite (Cr-muscovite) data were derived from representative carbonate-bearing serpentinite and listvenite samples from Hole BT1B, OmanDP. Electron microprobe analysis was conducted using the JEOL 8530F FE electron microprobe at Centre for Microscopy, Characterization and Analysis (CMCA), The University of Western Australia, using an acceleration voltage of 15 keV and a fully focused beam. The general analytical procedure and application of reference materials follow the method described in Beinlich et al. (2018; doi:10.1038/s41467-018-03039-9).

Description: This dataset contains X-ray diffraction data of powder drilled from the shell of A. benedeni benedeni specimen SG-125. This measurement was carried out in order to determine whether the originally aragonitic shell of this specimen contained any calcite of diagenetic origin. The spectrum of this specimen was compared to that of a modern aragonitic shell measured in-house (XRD_Fresh_Aragonite_Cerastoderma_edule.csv), and a calcite mineral from an external database (RRUFF database, ID R040070; Lafuente et al. 2015). The bivalve shells were collected in 2013 from a shell bed at the top of the Oorderen Member of the Lillo Formation of the Pliocene in Belgium. The collection site was a construction-related temporary outcrop at the Deurganck Dock Lock (now Kieldrecht Lock) in the city of Antwerp, located at 51°16′44″N 4°14′52″E. X-ray diffraction analysis was carried out in spring 2021 at the department of Earth Sciences at Utrecht University, the Netherlands, on a Bruker D8 diffractometer that was calibrated with a corundum crystal. Measurement conditions were as follows: 40 kV voltage, 40 mA current, 1.5418 Å (CuKα) radiation, 0.165 mm divergence slit, 2.5° primary soller slit, no secondary soller slit, 15-70° 2theta measuring range, 0.02° 2theta step-size, 0.85 s counting time, 15 rpm sample rotation. Reported are the angle (in degrees 2theta) and the corresponding intensity (in counts per second).

Description: This dataset (XRF_Benedeni_benedeni_SG-125_126_127_crosslines_cal.csv) contains micro-X-ray fluorescence elemental data of the shell of A. benedeni benedeni specimens SG-125, SG-126, and SG-127. The bivalve shells were collected in 2013 from a shell bed at the top of the Oorderen Member of the Lillo Formation of the Pliocene in Belgium. The collection site was a construction-related temporary outcrop at the Deurganck Dock Lock (now Kieldrecht Lock) in the city of Antwerp, located at 51°16′44″N 4°14′52″E. These measurements were carried out in order to screen for diagenetic alteration, which results in enrichment of certain elements (e.g., Fe and Mn). The specimens were measured in spring 2021 at the Analytical, Environmental, and Geochemistry Research Group (AMGC) of the Vrije Universiteit Brussel, Belgium), on a Bruker M4 Tornado µXRF scanner. This instrument is equipped with a 30 W Rh anode metal-ceramic X-ray tube operated at 50 kV and 600 µA, and polycapillary lens focussing. The measurement was carried out following the methods described in de Winter and Claeys (2017) and Kaskes et al (2021), and consisted of multiple line scans oriented perpendicular to the growth direction. Also provided is an image file (XRF_Benedeni_benedeni_crosslines_locations.png) which shows the location of these line scans on the shell cross sections.

Description: The Agulhas Plateau composite (APcomp) is a stratigraphic framework made up of sediment core sites MD02-2588 (41 19.90'S, 25 49.7'E, 2907m) and IODP Site U1475 (41 25.6'S, 25 15.6'E, 2669m). Stable isotope measurements were performed on 2-3 Cibicidoides wuellerstorfi specimens (250-315μm size fraction) and made on a Thermo Finnigan MAT 253 mass spectrometer linked online to a Carbo Kiel carbonate preparation device at Cardiff University with long-term precision of ±0.05‰ for δ18O and ±0.021‰ for δ13C (±1σ). Results are calibrated to an internal laboratory standard (BCT63) and presented relative to the Vienna Pee Dee Belemnite scale. IRD is defined as detrital mineral grains (excluding volcanic ash) 〉150μm. IRD is normalized to sample weight (IRD concentration in #/g) and then multiplication by apparent bulk mass accumulation rate derived from estimates of dry bulk density and linear sedimentation rate.

Description: Age-depth model for the Agulhas Plateau composite (APcomp), a stratigraphic framework made up of sediment core sites MD02-2588 (41 19.90'S, 25 49.7'E, 2907m) and IODP Site U1475 (41 25.6'S, 25 15.6'E, 2669m).

Description: The Agulhas Plateau composite (APcomp) is a stratigraphic framework made up of sediment core sites MD02-2588 (41 19.90'S, 25 49.7'E, 2907m) and IODP Site U1475 (41 25.6'S, 25 15.6'E, 2669m). Stable isotope measurements were performed on 2-3 Cibicidoides wuellerstorfi specimens (250-315μm size fraction) and made on a Thermo Finnigan MAT 253 mass spectrometer linked online to a Carbo Kiel carbonate preparation device at Cardiff University with long-term precision of ±0.05‰ for δ18O and ±0.021‰ for δ13C (±1σ). Results are calibrated to an internal laboratory standard (BCT63) and presented relative to the Vienna Pee Dee Belemnite scale. IRD is defined as detrital mineral grains (excluding volcanic ash) 〉150μm. IRD is normalized to sample weight (IRD concentration in #/g) and then multiplication by apparent bulk mass accumulation rate derived from estimates of dry bulk density and linear sedimentation rate.

Description: The interoceanic transfer between the Indian and the Atlantic Oceans known as 'Agulhas leakage' is of global significance as it alters the Atlantic Meridional Overturning Circulation (AMOC) on different time scales. Variability in the Agulhas Current regime is key in shaping hydroclimate on the adjacent coastal areas of the African continent today as well as during the past. However, the lack of long, continuous records from the Agulhas Current core region dating beyond the last glacial cycle prevents elucidation of its role in regional and wider global climate changes. This is the first continuous record of hydrographic variability (SST; δ18Osw) from the Agulhas Current core region spanning the past 270,000 years. The data set is analytical sound and provides a solid age model. As such, it can be used by paleoclimate scientists, archaeologists, and climate modelers to evaluate e.g. linkages between the Agulhas Current system and AMOC dynamics, as well as connections between ocean heat transport and Southern African climate change in the past and its impact on human evolution.