Dolomite: occurrence, evolution and economically important associations

被引:1072
作者
Warren, J [1 ]
机构
[1] Univ Brunei Darussalam, Dept Petr Geosci, Bandar Seri Begawan, Brunei
关键词
dolomite; brine; models; porosity; permeability; oil and gas; base metal;
D O I
10.1016/S0012-8252(00)00022-2
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Dolomite is not a simple mineral; it can form as a primary precipitate, a diagenetic replacement, or as a hydrothermal/metamorphic phase, all that it requires is permeability, a mechanism that facilitates fluid flow, and a sufficient supply of magnesium. Dolomite can form in lakes, on or beneath the shallow seafloor, in zones of brine reflux, and in early to late burial settings. It may form from seawater, from continental waters, from the mixing of basinal brines, the mixing of hypersaline brine with seawater, or the mixing of seawater with meteoric water, or via the cooling of basinal brines. Bacterial metabolism may aid the process of precipitation in settings where sulfate-reducing species flourish and microbial action may control primary precipitation in some hypersaline anoxic lake settings. Dolomite is a metastable mineral, early formed crystals can be replaced by later more stable phases with such replacements repeated a number of times during burial and metamorphism. Each new phase is formed by the partial or complete dissolution of an earlier dolomite. This continual re-equilibration during burial detracts from the ability of trace elements to indicate depositional conditions and resets the oxygen isotope signature of the dolomite at progressively higher temperatures. Because subsurface dolomite evolves via dissolution and reprecipitation, a bed of dolomite can retain or create porosity and permeability to much greater burial depths and into higher temperature realms than a limestone counterpart. Dolomitization also creates new crystals, with new rhomb growth following the dissolution of less stable precursors. Repetition of this process, without complete pore cementation, can generate intercrystalline porosity a number of times in the rock's burial history. Intercrystalline porosity is a highly interconnected style of porosity that gives dolomite reservoirs their good fluid storage capacity and efficient drainage. The fact that many dolomite reservoirs formed via brine reflux means that they sit beneath an evaporite seal in both platform and basinwide evaporite settings. The same association of evaporites (sulfate source) and entrained hydrocarbons means that burial conditions are also suitable for thermochemical sulfate reduction and the precipitation of base metals. This tends to occur at higher temperatures (> 60 degreesC-80 degreesC) and so the resulting dolomites tend to be ferroan and consist of saddle-shaped crystals. (C) 2000 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:1 / 81
页数:81
相关论文
共 371 条
[1]  
Adams J.E., 1960, AAPG BULL, V44, P1912, DOI DOI 10.1306/0BDA6263-16BD-11D7-8645000102C1865D
[2]   DOLOMITIZATION OF ATOLLS BY SEA-WATER CONVECTION FLOW - TEST OF A HYPOTHESIS AT NIUE, SOUTH-PACIFIC [J].
AHARON, P ;
SOCKI, RA ;
CHAN, L .
JOURNAL OF GEOLOGY, 1987, 95 (02) :187-203
[3]   RECENT HOT BRINE DOLOMITIZATION IN SOLAR LAKE, GULF OF ELAT, ISOTOPIC, CHEMICAL, AND MINERALOGICAL STUDY [J].
AHARON, P ;
KOLODNY, Y ;
SASS, E .
JOURNAL OF GEOLOGY, 1977, 85 (01) :27-48
[4]   DOLOMITE SEDIMENTATION IN THE SOUTH-EAST OF SOUTH-AUSTRALIA [J].
ALDERMAN, AR ;
SKINNER, HCW .
AMERICAN JOURNAL OF SCIENCE, 1957, 255 (08) :561-567
[5]   A DOLOMITE REACTION SERIES [J].
ALDERMAN, AR ;
BORCH, CCV .
NATURE, 1963, 198 (487) :465-&
[6]   FACIES AND SEDIMENTARY ENVIRONMENT OF THE PERMIAN CARBONATES (KHUFF FORMATION) IN THE UNITED-ARAB-EMIRATES [J].
ALSHARHAN, AS .
SEDIMENTARY GEOLOGY, 1993, 84 (1-4) :89-99
[7]  
AMTHOR JE, 1994, AAPG BULL, V78, P1541
[8]  
AMTHOR JE, 1993, B CAN PETROL GEOL, V41, P164
[9]  
ANDREASON MW, 1992, AAPG BULL, V76, P1735
[10]  
[Anonymous], SEPM SPECIAL PUBLICA