Publication Date

2010-01-01

Availability

Open access

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Marine Geology and Geophysics (Marine)

Date of Defense

2010-11-19

First Committee Member

Gregor P. Eberli - Committee Chair

Second Committee Member

Donald F. McNeill - Committee Member

Third Committee Member

Paul M. (Mitch) Harris - Outside Committee Member

Abstract

The present day Bahamian archipelago was deposited during sea level highstands when carbonate production was high enough to overfill accommodation space. This study unravels the complex stratigraphy and heterogeneity created by island accretion during and across the most recent Pleistocene highstands (MIS 5e, 9, and 11) using New Providence Island as a case study. Building upon the work of previous researchers, field based mapping was completed to understand the spatial relationships between ages, environments of deposition, and grainstone compositions across the island. Using the vertical and lateral relationships gained from detailed mapping, the depositional history of New Providence Island has been reconstructed for the Pleistocene MIS 5e, 9, and 11 sea level highstands. To map all of the environments of deposition, detailed criteria were created to recognize each environment observed on New Providence Island. Ages were estimated with field techniques and confirmed with dating done in previous studies and in this study, including both U-series techniques and amino acid racemization (AAR). Hand samples and short (< 1 m) cores were collected in the field and were used for petrographic analyses in the laboratory as well as whole rock AAR sampling for age determination. Detailed outcrop drawings were created, showing the lateral and vertical relationships of environments within outcrops. Meanwhile, maps and cross-sections were drafted to better understand island-wide relationships of environments, ages, and compositions. Based on age maps, New Providence formed by vertical and lateral accretion during the last three Pleistocene highstands (MIS 5e, 9, and 11), with a majority of deposition occurring during the most recent interglacial (MIS 5e, ~125 ka). Environment of deposition mapping revealed that island deposition occurred within shallow marine to eolian environments. Because of the abundance of MIS 5e deposits, the sedimentological complexity of an individual highstand (MIS 5e) reveals sub-orbital scale sea level changes. With mid-highstand sea level fluctuations apparent within the MIS 5e deposits on New Providence Island, a high level of lithofacies complexity could be expected within any individual sea level highstand. This study documents the complex vertical and lateral facies patterns associated with island building between and within sea level highstands.

Keywords

Eolianite; Marine Isotope Stage; Facies Heterogeneity; Geomorphology; Carbonatesedimentology

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