Title

Sedimentology, dolomitization and neomorphism of the upper Debolt Formation (Mississippian) in the Blueberry Field, northeastern British Columbia.

Date of Award

1994

Degree Type

Thesis

Degree Name

M.Sc.

Department

Civil and Environmental Engineering

First Advisor

Al-Aasm, I. S.

Keywords

Geology.

Rights

CC BY-NC-ND 4.0

Abstract

The Mississippian upper Debolt Formation in the Blueberry field of northeastern British Columbia is composed of variably dolomitized grainstone, packstone, wackestone, mudstone, algal laminite and intraclast breccia/conglomerate facies. These lithofacies characterize primarily subtidal deposition in open-, restricted- and protected-marine settings on a shelf platform. Specific depositional environments are shelf-margin, sand shoal and cap, lagoon, mud mound and, rarely, intertidal. Four different generations of dolomite have been identified: (1) early matrix dolomite, (2) pervasive dolomite, (3) pseudomorphic dolomite, and (4) coarse dolomite cement and coarse replacive dolomite. Early matrix dolomite, which replaces the matrix in mud-supported facies, is the earliest formed dolomite and is interpreted to have precipitated from marine fluids. However, its depleted $\delta\sp{18}$O compositions ($-$0.15 to $-$4.18$\perthous$ PDB) and slightly enriched $\sp{87}$Sr/$\sp{86}$Sr ratios (0.7084-0.7086) relative to estimated Mississippian marine dolomite indicate that early matrix dolomite was recrystallized by meteoric fluids. Pervasive dolomite is the most abundant type of dolomite and is associated with reservoir porosity. Petrographic evidence and the vertical and regional distribution of pervasive dolomite suggest a shallow burial origin in a mixed meteoric-marine realm. Carboniferous to Early Permian block faulting in the Peace River Embayment controlled the development and distribution of pervasive dolomite; it is only found on uplifted horsts and decreases towards areas of subsidence (grabens). Therefore, relative sea level fall, and subsequent mixing-zone dolomitization, were controlled by tectonics rather than global eustatic changes. (Abstract shortened by UMI.)Dept. of Geology and Geological Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1994 .D875. Source: Masters Abstracts International, Volume: 34-02, page: 0685. Adviser: Ihgan S. Al-Ansm. Thesis (M.Sc.)--University of Windsor (Canada), 1994.