ALBERT

Description: In this study, we demonstrate the utility of amino acid geochronology based on single-foraminiferal tests in Quaternary sediment cores from the Queensland margin, Australia. The large planktonic foraminifer Pulleniatina obliquiloculata is ubiquitous in shelf, slope, and basin sediments of north Queensland as well as pantropical oceans. Fossil tests are resistant to dissolution, and retain substantial concentrations of amino acids (2-4 nmol/mg of shell) over hundreds of thousands of years. Amino acid D and L isomers of aspartic acid (Asp) and glutamic acid (Glu) were separated using reverse phase chromatography, which is sensitive enough to analyze individual foraminifera tests. In all, 462 Pulleniatina tests from 80 horizons in 11 cores exhibit a systematic increase in D/L ratios down core. D/L ratios were determined in 32 samples whose ages are known from AMS 14C analyses. In all cases, the Asp and Glu D/L ratios are concordant with 14C age. D/L ratios of equal-age samples are slightly lower for cores taken from deeper water sites, reflecting the sensitivity of the rate of racemization to bottom water temperature. Beyond the range of 14C dating, previously identified marine oxygen-isotope stage boundaries provide approximate ages of the sediments up to about 500,000 years. For this longer time frame, D/L ratios also vary systematically with isotope-correlated ages. The rate of racemization for Glu and Asp was modeled using power functions. These equations can be used to estimate ages of samples from the Queensland margin extending back at least 500,000 years. This analytical approach provides new opportunities for geochronological control necessary to understand fundamental sedimentary processes affecting a wide range of marine environments.

Description: For nearly a century, the Atlantic Coastal Plain (ACP) of the United States has been the focus of studies investigating Pliocene and Pleistocene shorelines, however, the mapping of paleoshorelines was primarily done by using elevation contours on topographic maps. Here we review published geologic maps and compare them to paleoshoreline locations obtained through geomorphometric classification and satellite data. We furthermore present the results of an extensive field campaign that measured the mid-Pliocene (~ 3.3-2.9 Ma) shorelines of the Atlantic Coastal Plain using high-accuracy GPS and digital elevation models. We compare our new dataset to positions and elevations extracted from published maps and find that the extracted site information from earlier studies is prone to significant error, both in the location and, more severely, in the elevation of the paleoshoreline. We also investigate, using geophysical modeling, the origin of post-depositional displacement of the shoreline from Georgia to Virginia. In particular, we correct the elevation of our shoreline for glacial isostatic adjustment (GIA) and then compare the corrected elevation to predictions of mantle flow-induced dynamic topography (DT). While a subset of these models does reconcile the general trends in the observed elevation of the mid-Pliocene shoreline, local discrepancies persist. These discrepancies suggests that either (i) the DT and GIA models presented here do not capture the full range of uncertainty in the input parameters; and/or (ii) other influences, such as sediment loading and unloading or local fault-driven tectonics, may have contributed to post-depositional deformation of the mid-Pliocene shoreline that are not captured in the above models. In this context, our field measurements represent an important observational dataset with which to compare future generations of geodynamic models. Improvements in models for DT, GIA and other relevant processes, together with an expanded, geographically distributed set of shoreline records, will ultimately be the key to obtaining more accurate estimates of eustatic sea level not only in the mid-Pliocene but also earlier in the Cenozoic.

Description: Here we publish simulated Late Cretaceous (~70 Ma) annual mean surface temperatures (tsurf) with different (280-1680 ppm) CO2 levels, annual mean surface temperatures with different gateway configurations between the Arctic Ocean and North proto-Atlantic basin, as well as summer (JJA) and winter (DJF) mean surface temperatures with 840 ppm CO2 level. All data were averaged over the period of 100 years. The climate data has been produced with COSMOS (ECHAM5/MPIOM/OASIS3). The atmosphere component ECHAM5 was run in the resolution of T31/L19, while the ocean model MPIOM in the resolution of GR30 (bipolar orthogonal curvilinear grid with a formal resolution of ~3.0°x1.8°). OASIS3 is responsible for coupling between the atmosphere and ocean components. The Late Cretaceous setup is based on the Markwick and Valdes (2004, doi:10.1016/j.palaeo.2004.06.015) paleogeography. More details about a model setup can be found in Niezgodzki et al. (2017, doi:10.1002/2016PA003055). Additionally, we have prepared the .xlsx file where we provide the details of the locations of data points as well as reconstructed temperatures as used in a model-data comparison. These data are the modified data from Upchurch et al. (2015, doi:10.1130/G36802.1). For more details about the procedure used to modify the original data set, see Niezgodzki et al. (2017, doi:10.1002/2016PA003055).

Description: Studies in the fission yeast Schizosaccharomyces pombe (S. pombe) have done much to inform the view of heterochromatin and its control by the RNA interference (RNAi) machinery. Using cDNA synthesised from poly(A)-enriched RNA samples, numerous novel ncRNA loci were discovered, and the 50 and 30 ends of many other genes were refined in previous studies. Although some of these transcripts may encode novel proteins the function of the majority is yet to be determined. The authors have used strand-specific deep sequencing of RNA, irrespective of poly(A) status, to reveal a highly structured antisense programme that modulates gene expression to dictate cell fate decisions during sexual differentiation. They show that an extensive and elaborate array of ncRNA production accompanies sexual differentiation in the fission yeast S. pombe. Experimental manipulation suggests that these transcripts specifically regulate the function of the target genes.

Description: This spreadsheet contains details on elevation measurements (surveyed with Differential GPS), sea level interpretations and strontium isotope stratigraphy dating described in the manuscript "Pliocene-Pleistocene stratigraphy and sea-level estimates, Republic of South Africa (RSA)" by Hearty et al. (2020), Paleoceanography and Paleoclimatology.