Diagenesis: Cementation, dolomitization, and dedolomitization, including petrophysical characteristics of carbonate rocks.
Item
-
Title
-
Diagenesis: Cementation, dolomitization, and dedolomitization, including petrophysical characteristics of carbonate rocks.
-
Identifier
-
AAI9417467
-
identifier
-
9417467
-
Creator
-
Guo, Baiying.
-
Contributor
-
Adviser: Gerald M. Friedman
-
Date
-
1994
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Geology | Mineralogy | Geochemistry
-
Abstract
-
On the basis of subsidence- and accumulation rate, water depth, and sediment supply, the carbonate shelf of the Sauk Sequence in eastern New York can be divided into two subprovinces: (1) central (Wappinger Group, {dollar}\epsilon\sb1{dollar} to O{dollar}\sb1),{dollar} confined to the Appalachian fold-thrust belt, and (2) western (Beekmantown Group, {dollar}\epsilon\sb3{dollar} to O{dollar}\sb1),{dollar} underlying the Saratoga Platform.;In the Wappinger Group, I recognize three stages of dolomite and one episode of dedolomite which postdated the second-stage dolomite: (1) early, including very-fine crystalline and the cores of some dolomite rhombs {dollar}(\delta\sp{18}{dollar}O {dollar}-{dollar}5.6 to {dollar}-{dollar}6.7{dollar}\perthous){dollar} that formed syndepositionally; (2) second, which constitutes 80 to 90% of the massive regional-scale dolostones, including fine- to coarsely crystalline dolomite and some cement {dollar}(\delta\sp{18}{dollar}O {dollar}-{dollar}6.1 to {dollar}-{dollar}7.4{dollar}\perthous){dollar} that formed at shallow-burial depth (0.5 to 1 km) during the initial episode of subsidence associated with the passive-margin tectonic regime; and (3) late (deep-burial), including non-saddle- and saddle dolomite that filled fractures and pores {dollar}(\delta\sp{18}{dollar}O {dollar}-{dollar}8.5 to {dollar}-{dollar}12.2{dollar}\perthous){dollar} and that formed during the deep burial (5- to 7 km) of the ensuing convergent-margin episode(s). Dedolomite {dollar}(\delta\sp{18}{dollar}O {dollar}-{dollar}7.9{dollar}\perthous){dollar} formed during post-Early Ordovician emergence (post-Sauk, pre-Tippecanoe surface of unconformity). Dedolomite, which is confined to the topmost three formations, displays progressive degrees of replacement from intercrystalline through pseudomorphic to massive.;During deep burial, the kerogen matured to beyond crude oil, but still within the conditions for thermogenic methane. I found residue of oil in the pores of the Galway Formation {dollar}(\epsilon\sb3){dollar} in the Finnegan boring, which proves that during shallow burial, oil (and gas) was generated and migrated (estimated porosity 10%). After deeper burial, most porosity was lost (porosities from 0.1% to 4.64%). Three borings found gas shows: Columbia Gas No. 1 Finnegan, the Crom-Wells No. 1 Fee, and ARCO No. 1 Susi. The study of the stratigraphic sequences and associated surfaces of unconformity also implies that the general geologic requirements for forming subtle hydrocarbon traps have been fulfilled.;No matter how diagenesis destroyed primary porosity, the petrophysical properties of the studied Sauk rocks still show a clear relationship with depositional facies as in the studied modern beachrocks. Oolitic dolostone presents the best porosity, skeletal grainstone follows, and fine- to very-fine dolostones show very low porosity.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
