ERA

Download the full-sized PDF of Origin of island dolostones: case study based on Tertiary dolostones from Cayman Brac, British West IndiesDownload the full-sized PDF

Analytics

Share

Permanent link (DOI): https://doi.org/10.7939/R3W92S

Download

Export to: EndNote  |  Zotero  |  Mendeley

Communities

This file is in the following communities:

Graduate Studies and Research, Faculty of

Collections

This file is in the following collections:

Theses and Dissertations

Origin of island dolostones: case study based on Tertiary dolostones from Cayman Brac, British West Indies Open Access

Descriptions

Other title
Subject/Keyword
dolomitization
dolomite
Cayman Brac
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Zhao, Hongwen
Supervisor and department
Jones, Brian (Earth and Atmpspheric Sciences)
Examining committee member and department
Dix, George (Earth Sciences, Carleton University)
Gingras, Murray (Earth and Atmpspheric Sciences)
Jones, Brian (Earth and Atmpspheric Sciences)
Zonneveld, John-Paul (Earth and Atmpspheric Sciences)
Harris, Nicholas (Earth and Atmpspheric Sciences)
Department
Department of Earth and Atmospheric Sciences
Specialization

Date accepted
2012-11-15T14:47:15Z
Graduation date
2013-06
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Cayman Brac (19 km long, 1.5 to 3 km wide), which is the easternmost of the Cayman Islands, is characterized by a thick Tertiary carbonate succession that has been pervasively dolomitized. The finely crystalline dolostones in the Cayman Formation (Miocene) are fabric-retentive whereas the coarse, sucrosic dolostones in the Brac Formation (Lower Oligocene) are mostly fabric-destructive. Analyses of these dolostones indicate that (1) the dolostones are formed of various mixtures of low-Ca calcian dolomite (LCD – < 55 mol% CaCO3) and high-Ca Calcian dolomite (HCD – > 55 mol% CaCO3), (2) their geochemical signatures (e.g., δ18O and Sr) are heavily influenced by the dolomite stoichiometry, (3) the 87Sr/86Sr ratios point to two phases of dolomitization with Phase I (Late Miocene, 6-8 Ma) that caused partial dolomitization of the upper part of the Brac Formation and basal part of the Cayman Formation and Phase II (Pliocene to Early Pleistocene, 1-5 Ma), that completed dolomitization of the Cayman Formation. Interpretation of these data indicates that dolomitization was probably linked to sea level fluctuations whereas the distribution of the dolomite and evolution of their textures was controlled largely by permeability pathways that governed circulation patterns of the dolomitizing fluids. The large sucrosic dolomite crystals in the Brac Formation probably developed as a result of repeated cycles of limestone matrix dissolution and dolomite precipitation. Rare earth elements (REE) and yttrium (Y) concentrations of carbonates from Cayman Brac are characterized by (1) LREE depletion relative to HREE, (2) positive La anomalies, (3) negative Ce anomalies, and (4) superchondritic Y/Ho molar ratios. Dolomitization did not have a major impact on their REE +Y signatures, which indicates that the dolomitization was probably mediated by seawater-like fluids. The variations in DyN/SmN, LaN/NdN, Ce/Ce*, and Y/Ho with depth reflect the influences of the diagenetic processes (e.g., DyN/SmN ) and possibly, secular changes in the REE+Y composition of seawater (e.g., LaN/NdN, Y/Ho, and Sm/Nd) on the REE+Y signature of carbonates.
Language
English
DOI
doi:10.7939/R3W92S
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication

File Details

Date Uploaded
Date Modified
2014-04-29T15:23:28.055+00:00
Audit Status
Audits have not yet been run on this file.
Characterization
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 4141762
Last modified: 2015:10:12 10:34:24-06:00
Filename: Hongwen_Zhao_Spring2013.pdf
Original checksum: 992c447651d1c409e3ac5490296af828
Well formed: true
Valid: true
Page count: 216
Activity of users you follow
User Activity Date