The influence of microfossil content on the physical properties of calcareous sediments from the Ontong Java Plateau

Date

1995

Contributor

Advisor

Department

Instructor

Depositor

Speaker

Researcher

Consultant

Interviewer

Narrator

Transcriber

Annotator

Journal Title

Journal ISSN

Volume Title

Publisher

Volume

Number/Issue

Starting Page

Ending Page

Alternative Title

Abstract

This work is based on results from Ocean Drilling Program Leg 130, which drilled the Ontong Java Plateau, a broad submarine plateau in the western equatorial Pacific. The Ontong Java Plateau has a unique combination of geographic location and bathymetry that makes it ideally suited for paleoceanographic studies. This study addresses several aspects of plateau sediment physical properties (e.g., porosity, velocity, acoustic impedance, compression and expansion indexes, and rebound) within the broad framework of establishing relationships between physical properties and microfossil content and preservation. Samples obtained in Hole 803D were analyzed to determine their microfossil constituents. The resulting data are compared to shipboard-measured physical properties data to assess the relationships between small-scale fluctuations in physical properties and microfossil content. Impedance was found to increase with increasing grain size and planktonic foraminifera content. Variations in the coarse fraction constituents appear to have a more significant effect on the physical properties than do variations in the fine fraction constituents, though the fine fraction make up greater than 85% of the samples by weight. Many of the seismic reflectors identified by shipboard scientists could be related to changes in the relative percentages of microfossil constituents. The consolidation behavior of Ontong Java Plateau sediments was observed to relate to sediment composition. In general, consolidation test parameters from this study are consistent with those of other researchers for sediments of similar carbonate contents. We found that both compression and expansion indices decrease with increasing carbonate content and with increasing foraminifer content. Rebound curves derived from consolidation tests on Ontong Java Plateau samples yield porosity rebounds of 1% to 4%for these sediments at equivalent depths of 200 to 1200 meters below seafloor (mbsf), The exception is a radiolarian-rich sample that has 6% rebound. We combined the rebound correction derived from the porosity rebound vs. depth data with the correction for pore-water expansion to correct the shipboard laboratory porosity data to in-situ values. The rebound-corrected laboratory data can be used as in situ data in place of missing or erroneous downhole logging data.

Description

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995.
Includes bibliographical references (leaves 138-148).
Microfiche.
xiii, 148 leaves, bound ill., maps 29 cm

Keywords

Sediments (Geology) -- Pacific Ocean, Ocean bottom -- Pacific Ocean

Citation

Extent

Format

Geographic Location

Time Period

Related To

Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Geology and Geophysics; no. 3149

Related To (URI)

Table of Contents

Rights

All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.

Rights Holder

Local Contexts

Email libraryada-l@lists.hawaii.edu if you need this content in ADA-compliant format.