Show simple item record

dc.contributor.advisor Droxler, Andre W.
dc.creatorHaddad, Geoffrey Allen
dc.date.accessioned 2009-06-04T00:23:08Z
dc.date.available 2009-06-04T00:23:08Z
dc.date.issued 1994
dc.identifier.urihttps://hdl.handle.net/1911/16729
dc.description.abstract This study presents mineralogic and stable isotopic records generated for piston cores and Ocean Drilling Program holes recovered from intermediate water depths (500 to 2500 meters) near carbonate platforms around the world. Study areas included the Bahamas (western North Atlantic Ocean), the Nicaragua Rise (Caribbean Sea), the Maldives (north equatorial Indian Ocean), and the Queensland Plateau (southwest Pacific Ocean). Mineralogic data includes percent fine aragonite content, percent fine Mg calcite content, pteropod (aragonitic holoplanktonic gastropods) abundance, percent whole pteropods, and for some cores, percent clear pteropods. Carbonate data were interpreted both in terms of carbonate input from the nearby banks and in terms of seafloor dissolution. Planktic foraminiferal $\delta\sp{18}$O records were used as the primary chronostratigraphic tool for all sites. Statistical analyses of four metastable CaCO$\sb3$ dissolution proxies yielded a composite dissolution index (CDI) that displays different dissolution histories for Bahama and Nicaragua Rise sediments over the last 200,000 years. These differences are not predicted by intermediate to deep water nutrient fractionation models (e.g., Boyle, 1988). A good correlation is observed between the Caribbean CDI record (this study) and CaCO$\sb3$ dissolution and benthic $\delta\sp{13}$C records from 4641 meters in the Venezuela Basin, Caribbean Sea (Cofer-Shabica, 1987). It is concluded that during the last 200,000 years, variable cross-equatorial flux of Antarctic Intermediate Water has strongly influenced Caribbean carbon chemistry at water depths greater than 1100 meters. The assumption, therefore, that deep Caribbean sediment cores reliably record nutrient and (CO$\sb3\sp{=}$) variations of average mid-depth Atlantic water may need re-evaluation. Over longer time scales, CaCO$\sb3$ dissolution records from intermediate water depths near the Bahamas, Maldives, and Queensland Plateau are similar to deep-water dissolution records. Dissolution occurred from thermocline to abyssal depths from 500,000 to 300,000 years ago (during the middle Brunhes Chron) and between 1,000,000 and 900,000 years ago revealing that whole-ocean changes in carbonate chemistry have occurred during the Quaternary. Enhanced CaCO$\sb3$ dissolution may be related to decreased Ca$\sp{2+}$ flux to the ocean (decreased glacial weathering) and increased neritic CaCO$\sb3$ production and accumulation during periods of elevated interglacial sea-level highstands.
dc.format.extent 529 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectGeology
Geochemistry
Paleoecology
dc.title Calcium carbonate dissolution patterns at intermediate water depths of the tropical oceans during the Quaternary
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Earth Science
thesis.degree.discipline Natural Sciences
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Haddad, Geoffrey Allen. "Calcium carbonate dissolution patterns at intermediate water depths of the tropical oceans during the Quaternary." (1994) Diss., Rice University. https://hdl.handle.net/1911/16729.


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record