Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Geology
Relationship Between Individual Chamber And Whole Shell Mg/Ca Ratios In Trilobatus Sacculifer And Implications For Individual Foraminifera Palaeoceanographic Reconstructions, Gerald T. Rustic, Pratigya J. Polissar, Ana Christina Ravelo, Peter Demenocal
Relationship Between Individual Chamber And Whole Shell Mg/Ca Ratios In Trilobatus Sacculifer And Implications For Individual Foraminifera Palaeoceanographic Reconstructions, Gerald T. Rustic, Pratigya J. Polissar, Ana Christina Ravelo, Peter Demenocal
School of Earth & Environment Faculty Scholarship
Precisely targeted measurements of trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) reveal inter-chamber heterogeneities in specimens of the planktic foraminifer Trilobatus (Globigerinoides) sacculifer. We find that Mg/Ca ratios in the final growth chamber are generally lower compared to previous growth chambers, but final chamber Mg/Ca is elevated in one of thirteen sample intervals. Differences in distributions of Mg/Ca values from separate growth chambers are observed, occurring most often at lower Mg/Ca values, suggesting that single-chamber measurements may not be reflective of the specimen’s integrated Mg/Ca. We compared LA-ICPMS Mg/Ca values to paired, same-individual Mg/Ca measured via …
Increased Fluvial Runoff Terminated Inorganic Aragonite Precipitation On The Northwest Shelf Of Australia During The Early Holocene, Maximilian Hallenberger, Lars Reuning, Stephen J. Gallagher, Stefan Back, Takeshige Ishiwa, Beth A. Christensen, Kara Bogus
Increased Fluvial Runoff Terminated Inorganic Aragonite Precipitation On The Northwest Shelf Of Australia During The Early Holocene, Maximilian Hallenberger, Lars Reuning, Stephen J. Gallagher, Stefan Back, Takeshige Ishiwa, Beth A. Christensen, Kara Bogus
School of Earth & Environment Faculty Scholarship
Inorganic precipitation of aragonite is a common process within tropical carbonate environments. Across the Northwest Shelf of Australia (NWS) such precipitates were abundant in the late Pleistocene, whereas present-day sedimentation is dominated by calcitic bioclasts. This study presents sedimentological and geochemical analyses of core data retrieved from the upper 13 meters of IODP Site U1461 that provide a high-resolution sedimentary record of the last ~15 thousand years. Sediments that formed from 15 to 10.1 ka BP are aragonitic and characterised by small needles (<5 >µm) and ooids. XRF elemental proxy data indicate that these sediments developed under arid conditions in …
Climate Evolution Across The Mid-Brunhes Transition, Aaron M. Barth, Peter U. Clark, Nicholas S. Bill, Feng He, Nicklas G. Pisias
Climate Evolution Across The Mid-Brunhes Transition, Aaron M. Barth, Peter U. Clark, Nicholas S. Bill, Feng He, Nicklas G. Pisias
School of Earth & Environment Faculty Scholarship
The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100 kyr climate cycles of the past 800 000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels and warmer temperatures than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here, we further characterize changes in the climate system across the MBT …