Late Pleistocene biogenic flux in the tropical Atlantic, a response to climate change.
Item
-
Title
-
Late Pleistocene biogenic flux in the tropical Atlantic, a response to climate change.
-
Identifier
-
AAI9218284
-
identifier
-
9218284
-
Creator
-
Verardo, David Joseph.
-
Contributor
-
Adviser: Andrew McIntyre
-
Date
-
1992
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Geology | Geochemistry
-
Abstract
-
Cyclic changes in the flux of the biogenic components; organic carbon, nitrogen, calcium carbonate, and opal, to the seafloor are documented in cores from a zonal/meridional/depth transect in the Equatorial Atlantic Ocean. The largest concentrations of organic carbon, nitrogen, and opal occur in glacial stages of the Late Pleistocene, 0-300 Ka B.P. These changes in biogenic flux are a function of orbitally paced variations in primary production modified by fluctuations in oxygen and carbonate ion concentration at depth which enhance/diminish organic carbon preservation and calcium carbonate dissolution. Variations in sedimentary flux in the equatorial region of divergence is a function of orbital forced variation in trade wind zonality which modulates divergence. When perihelion is aligned with boreal winter, trade wind stress and upwelling are at maximum and surface productivity is increased. This imprints a pure orbital signal centered on precessional periods (19 & 23 Kyrs). The other major control is due to variation in the corrosive character of advected intermediate and deep water from high latitudes--a function of orbitally paced high latitude ice. The relative proportion of signal variance within the precessional band decreases while those of obliquity (41 Kyrs) and eccentricity (100 Kyrs) increase with depth. The signal of destruction dominates that of production.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
