--> Abstract: Timing of Turbidite Input and Late Quaternary Sea Level: Comparison Between Siliciclastic (Western Gulf of Mexico), Carbonate (Northern Nicaragua Rise), and Mixed Carbonate-Siliciclastic (Pandora Trough, Coral Sea) Systems, by Gianni Mallarino, Andre W. Droxler, and Richard Fitton; #90039 (2005)

Datapages, Inc.Print this page

Timing of Turbidite Input and Late Quaternary Sea Level: Comparison Between Siliciclastic (Western Gulf of Mexico), Carbonate (Northern Nicaragua Rise), and Mixed Carbonate-Siliciclastic (Pandora Trough, Coral Sea) Systems

Gianni Mallarino, Andre W. Droxler, and Richard Fitton
Rice University, Houston, TX

This study focuses on linking the turbidite input to an independently constrained late Quaternary sea-level curve for two siliciclastic and carbonate end-members. The chronostratigraphy was based on coupled oxygen isotope and planktonic foraminiferal stratigraphies.

In the siliciclastic system of mini-Basin 4 (offshore Texas-Louisiana shelf) deposition of sandy and muddy turbidites occurred mostly during lowstands at the subglacial and glacial scale, Marine Isotope Stage (MIS) 5d and 5b, late MIS 3, and MIS 2. The maximum amount of sand was delivered to mini-Basin 4 during MIS 2. In contrast, in the carbonate system of two mini-basins (northeast of Pedro Bank) deposition of turbidites occurred mostly during highstands at the glacial scale, MIS 5, early MIS 3 and MIS 1. With this in mind one would expect that in a mixed carbonate-siliclastic system, siliciclastic and calci-turbidites would alternate between times of sea-level lowstands and highstands respectively. The Pandora Trough is such a mixed system in which two cores were acquired. Sediments in the lower 10 m of these cores represent mostly MIS 2 and consist of numerous quartz-rich sandy turbidites up to 20 cm in thickness interbedded with dark grey mud. The uppermost 2 m, corresponding to MIS 1, are made of light grey mud with one 30 cm-thick calciturbidite layer.

As predicted for a mixed carbonate-siliciclastic system, siliciclastic sandy turbidites dominated during MIS 2 lowstand whereas calciturbidites occurred at the end of the following transgression as soon as the adjacent carbonate platform tops (Ashmore, Eastern Fields and Portlock Reefs) were reflooded.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005