Date of Award:

5-1986

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geosciences

Department name when degree awarded

Geology

Committee Chair(s)

W. David Liddell

Committee

W. David Liddell

Committee

Peter Kolesar

Committee

Sharon Ohlhorst

Abstract

Recent carbonate sediments from (133-236m) on the northern Jamaican island slope are significantly different from shallower reef zones (l-70m) in grain constituents, textural parameters, and foraminiferal assemblages. The island slope sediment is dominated by coral fragments, calcareous algae, Halimeda plates, and foraminiferal tests. The sediment is characteristically poorly-sorted, nearly-symmetrically skewed, and mesokurtic, with a mean grain size in the fine sand range. Mineralogically, the sediment is predominantly aragonite (66%) and high-Mg calcite (22%), with some calcite (8%), and minor amounts of clays and other insoluble minerals (4%).

Q-mode cluster analyses of sediment constituents, textural parameters, and foraminiferal species and larger group abundances were utilized in the delineation of shelf and island slope depositional environments. Mineralogy proves ineffective for such use.

No significant differences are observed in sedimentological parameters (textures, constituents, and sedimentation rates) between an island slope traverse located below an area with prominant sill reefs and a traverse below an area lacking well-developed sill reefs. It is suggested that the sill reefs have less effect on off-reef transport than was previously believed. Based on the abundance trends of certain sediment grains and the similarity of sediment grains in island slope and deep fore reef/fore reef slope sediment, it is suggested that the deeper reef zones (>30m) are the source of most sediment transported seaward.

Foraminiferal abundances show lateral differences between traverses related to input of shallow water (

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