Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Hayward, B. W. Articles by Shearer, M. Search for Related Content GeoRef GeoRef Citation

Mid-Pleistocene extinction of bathyal benthic foraminifera in the Caribbean Sea

¹ Geomarine Research, 49 Swainston Rd, St Johns, Auckland, New Zealand email: b.hayward{at}geomarine.org.nz, s.kawagata{at}geomarine.org.nz, h.grenfell{at}geomarine.org.nz
² Department of Earth Science, Rice University, P.O. Box 1892, Houston, TX 77251, USA email: andre{at}rice.edu

During the mid-Pleistocene Transition (MPT), 2 families, 14 genera and 41 species of benthic foraminifera (Extinction Group) declined in abundance (8–12 % of early Pleistocene benthic foraminiferal fauna) and finally disappeared at mid-bathyal depths in the Caribbean Sea (ODP Site 1000A, 916m depth), as part of the global extinction of at least 73 deep-water species at this time. At this site, the final phase of pulsed glacial decline, partial interglacial recoveries (0.8–0.67 Ma), and final extinction (0.58 Ma) was essentially the same as the youngest level so far documented elsewhere (0.57 Ma). Extinction Group specimens had smaller average sizes during periods of decline than during favorable periods with higher abundances. Census counts on different size fractions indicate that this extinction event is best recorded by studies of shells in the 150–300µm size range. Pteropod dissolution proxies indicate that intermediate waters in the Caribbean became less corrosive around the onset of the MPT (after c. 1.2 Ma). This is interpreted to be a result of increased input of northern hemisphere-sourced intermediate water at the expense of southern-sourced Antarctic Intermediate Water. Intervals of enhanced Extinction Group decline in intermediate waters in the Caribbean occurred during glacials around the start (1.15–1.05 Ma) and end (0.83–0.65 Ma) of the MPT. During these glacial periods preservation of carbonate was optimal and ä¹³C values high (in source waters at mid-depths in the North Atlantic), suggesting a causal link with enhanced inflow of a less-corrosive, colder, nutrient-depleted, well-ventilated water mass, such as Glacial North Atlantic Intermediate Water.