Size normalized shell weights and measurements for Neogloboquadrina pachyderma and Uvigerina peregrina from the Gulf of Alaska (IODP Exp 341) and associated environmental proxy data ...
Here we use volume density (ρV) measurements as a metric of size-normalized weights for Neogloboquadrina pachyderma, a planktonic foraminifer, from upper OMZ and abyssal depth sites in the Gulf of Alaska over the past ~20,000 years to test for covariation between carbonate preservation and OMZ inten...
| Main Authors: | , |
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| Format: | Dataset |
| Language: | English |
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Dryad
2021
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| Online Access: | https://dx.doi.org/10.5061/dryad.b8gtht7c3 https://datadryad.org/stash/dataset/doi:10.5061/dryad.b8gtht7c3 |
| Summary: | Here we use volume density (ρV) measurements as a metric of size-normalized weights for Neogloboquadrina pachyderma, a planktonic foraminifer, from upper OMZ and abyssal depth sites in the Gulf of Alaska over the past ~20,000 years to test for covariation between carbonate preservation and OMZ intensity. We find that dissolution of N. pachyderma is most intense at the upper OMZ site where oxygenation is generally lower than at the abyssal site. We also examine Uvigerina peregrina, a benthic foraminifer, at the upper OMZ site and find that the lowest ρV measurements in both taxa occur during deglacial and early Holocene dysoxic events. We use computed tomography images to confirm that changes in ρV are related to shell thickness, observe dissolution features, and test for growth influences on ρV. Further, we use stepwise selection of multiple regression models in which co-registered environmental proxies are potential predictors of ρV and find that the best supported models retain negative associations ... : Data are derived from marine seidment cores from IODP Expedition 341 Site U1419 and the co-located EW0408-85JC, IODP Expedition 341 Site U1418 and the co-located core EW0408-87JC. We weighed specimens of each species from each sample in aggregate to the nearest 0.1 μg using a Sartorius Ultramicro Balance to determine the total weight. Individual shell dimensions were digitally measured from 2D images of these same specimens using a Nikon SMZ 1500 stereoscope at 30x and the software program NIS Elements BR 2.10. To calculate shell volume, we approximated N. pachyderma as a sphere using the average of the semi-major axis and semi-minor axis of a hypothetical 2D ellipse that encapsulates the shell as the radius of that sphere and U. peregrina was approximated as a cylinder. Sample weight was then size normalized to volume by dividing total weight by the total volume of the individuals. Computed tomography scans were completed at the University of Texas High-Resolution X-ray Computed Tomography Facility (UTCT). ... |
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