ALBERT

Description: The evolution of permeability and its effective stress behavior is related to inelastic deformation and failure mode. This was systematically investigated in Indiana and Purbeck limestones with porosities of 16% and 14%, respectively. High‐pressure compression tests were conducted at room temperature on water‐saturated samples. At relatively high confinement shear‐enhanced compaction was observed to initiate at a critical stress, accompanied by significant permeability reduction of up to a factor of ~3. Overall, the permeability reduction due to inelastic compaction in our limestones is smaller than that observed in sandstones. At relatively low confinement, dilatant failure was observed, which was accompanied by a decrease and increase of permeability in Indiana and Purbeck limestones, respectively. There seems to be a trend for the correlation between porosity and permeability changes to switch from positive to negative with increasing porosity. The void space of both limestones has significant proportions of macropores and micropores. The effective stress behavior of such a limestone with dual porosity has been documented to be different from the prediction for a microscopically homogeneous assemblage, in that its effective stress coefficients for permeability and pore volume change may attain values significantly 〉1. In contrast, our investigation of damaged samples consistently showed effective stress coefficients for both permeability and pore volume change with values 〈1. This suggests that the behavior in the damaged samples is akin to that of a microscopically homogeneous assemblage, possibly due to pervasive collapse of macropores that would effectively homogenize the initially bimodal pore size distribution.

Description: The dataset contains foraminifera images of over 1,000 forams taken under 16 different lighting directions with an optical microscope. The species and locations of the samples are also specified. It also contains manual segmentation of over 400 samples from the images described above. The segmentation labels are matched by their name. To capture these images, a visual identification system was developed in order to automate the identification of target microorganisms. The visual system incorporates a controllable LED lighting ring used to capture images by illuminating the specimens from several directions, mimicking an important step in the traditional identification process. The dataset was originally used for foraminifera identification and segmentation with machine learning and computer vision techniques. This work is a collaboration between the Dr. Edgar Lobaton (Associate Professor at the North Carolina State University), Dr. Thomas Marchitto (Associate Professor at the University of Colorado Boulder) and Dr. Ritayan Mitra (Assistant Professor at IIT Bombay). Please refer to https://research.ece.ncsu.edu/aros/foram-identification/ for more information about the datasets, related studies and downloading the dataset.

Description: We reconstruct the environmental evolution of the East China Sea in the past 14 kyr based on glycerol dialkyl glycerol tetraethers (GDGTs) in a sediment core from the subaqueous Yangtze River Delta. Two primary phases are recognized. Phase I (13.8-8 cal kyr BP) reflects a predominantly continental influence, showing distinctly higher concentrations of branched GDGTs (averaged 143 ng/g dry sediment weight, dsw) than isoprenoid GDGTs (averaged 36 ng/g dsw), high BIT index (branched vs. isoprenoid tetraethers) values (〉0.78) and a fluctuating GDGT-0/crenarchaeol ratio (R0/5, varied from 0.52 to 3.81). Within this interval, temporal increases of terrestrial and marine influence are attributed to Younger Dryas (YD) (ca. 12.9-12.2 cal kyr BP) cold event and melt-water pulse (MWP) -1B (11.5-11.1 cal kyr BP), respectively. The prominent transition from 8 to 7.9 cal kyr BP shows a sharp decrease in BIT index value (〈0.4) and increase in crenarchaeol, which marks the beginning of phase II. Afterwards, the proxies remain relatively constant, which indicates that phase II (7.9 cal kyr BP-present) is a shelf sedimentary environment with high stand of sea level. Overall, the BIT index in our record serves as a good marker for terrestrial influence at the site, and likely reflects the flooding history of the region. The TEX86 (TetraEther Index of tetraethers consisting of 86 carbons) proxy is not applicable in phase I because of an excess terrestrial influence; but it seems to be valid for revealing the annual SST in phase II (21.6±0.9°C, n=49). In contrast, the MBT'/CBT (Methylation of Branched Tetraethers and Cyclization of Branched Tetraethers) proxy appears to faithfully record the annual mean air temperature (MAT) (14.3±0.63°C, n=68) and presents an integrated signal over the middle and lower Yangtze River drainage basin.

Description: The Multi-GNSS observations from an onboard receiver were retrieved using kinematic Precise Point Positioning (PPP) method. The solution using only Global Positioning System (GPS) observations is the GPS-only solution; and the one using GPS, GLONASS, and Galileo observations together, is the GRE PPP solution. R is short for the Russian system GLONASS, and E is short for Europe system Galileo. The GNSS data was collected by a GNSS receiver on R/V Lance. It is used by the Norwegian Polar Institute (NPI) for regular monitoring and research related to ocean and sea ice properties in Fram Strait. During the Fram Strait 2016 cruise from day-of-year (DOY) 238 to DOY 257, a geodetic JAVAD TR_G3TH GNSS receiver was installed on the ship bow, which is about 6 m above the water surface. This receiver collected multi-GNSS data at a sampling of 1-Hz, including GPS, GLONASS, and Galileo.

Description: Authigenic carbonate deposits have been sampled with the remotely operated vehicle 'MARUM-QUEST 4000 m' from five methane seeps between 731 and 1823 m water depth along the convergent Makran continental margin, offshore Pakistan (northern Arabian Sea). Two seeps on the upper slope are located within the oxygen minimum zone (OMZ; ca. 100 to 1100 m water depth), the other sites are situated in oxygenated water below the OMZ (below 1100 m water depth). The carbonate deposits vary with regard to their spatial extent, sedimentary fabrics, and associated seep fauna: Within the OMZ, carbonates are spatially restricted and associated with microbial mats, whereas in the oxygenated zone below the OMZ extensive carbonate crusts are exposed on the seafloor with abundant metazoans (bathymodiolin mussels, tube worms, galatheid crabs). Aragonite and Mg-calcite are the dominant carbonate minerals, forming common early diagenetic microcrystalline cement and clotted to radial-fibrous cement. The delta18O carbonate values range from 1.3 to 4.2 per mil V-PDB, indicating carbonate precipitation at ambient bottom-water temperature in shallow sediment depth. Extremely low delta13Ccarbonate values (as low - 54.6per mil V-PDB) point to anaerobic oxidation of methane (AOM) as trigger for carbonate precipitation, with biogenic methane as dominant carbon source. Prevalence of biogenic methane in the seepage gas is corroborated by delta13C methane values ranging from - 70.3 to - 66.7per mil V-PDB, and also by back-calculations considering delta 13C methane values of carbonate and incorporated lipid biomarkers.