| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* U.S. Geological Survey, Reston, Virginia, 20192; now at Department of Geological Sciences, University of South Carolina, Columbia, South Carolina 29208
** U.S. Geological Survey, MS 431, Reston, Virginia 20192
*** Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, United Kingdom
**** School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, United Kingdom
Geothermal convection of seawater deep in carbonate platforms could provide the necessary supply of magnesium for dolomitization at temperatures high enough to overcome kinetic limitations. We used reactive-transport simulations to predict the rates and spatial patterns of dolomitization during geothermal convection in a platform that was 40 km across and 2 km thick. In the simulations, porosity and permeability decrease with depth to account for sediment compaction.
Dolomitization of a platform consisting of medium grained (
0.05 mm) sediments occurred in a broad band ranging from 2.5 km depth near the margin to 1.5 km depth near the platform center. The area of dolomitization is deep enough that temperatures exceed 50°C but not so deep that low permeabilities restrict mass transport. Complete dolomitization in the center of this zone is estimated to require at least 60 my. Incorporation of permeability contrasts, permeable beds, and reactive beds focused dolomitization strongly and reduced the estimated time required for dolomitization by as much as 50 percent. Dolomitization created magnesium-depleted, calcium-rich fluids in less than 10 ky, and results support a link between dolomitization and anhydrite precipitation where adequate sulfate is available.
This article has been cited by other articles:
|
|
 |
|
  H. G. Machel and B. E. Buschkuehle Diagenesis of the Devonian Southesk-Cairn Carbonate Complex, Alberta, Canada: Marine Cementation, Burial Dolomitization, Thermochemical Sulfate Reduction, Anhydritization, and Squeegee Fluid Flow Journal of Sedimentary Research, May 1, 2008; 78(5): 366 - 389. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Hughes, H.L. Vacher, and W. E. Sanford Three-dimensional flow in the Florida platform: Theoretical analysis of Kohout convection at its type locality Geology, July 1, 2007; 35(7): 663 - 666. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. D. Jones and Y. Xiao Geothermal convection in the Tengiz carbonate platform, Kazakhstan: Reactive transport models of diagenesis and reservoir quality AAPG Bulletin, August 1, 2006; 90(8): 1251 - 1272. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. D. Jones and Y. Xiao Dolomitization, anhydrite cementation, and porosity evolution in a reflux system: Insights from reactive transport models AAPG Bulletin, May 1, 2005; 89(5): 577 - 601. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. D. Jones, F. F. Whitaker, P. L. Smart, and W. E. Sanford Numerical analysis of seawater circulation in carbonate platforms: II. The dynamic interaction between geothermal and brine reflux circulation Am J Sci, March 1, 2004; 304(3): 250 - 284. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. G. Machel Concepts and models of dolomitization: a critical reappraisal Geological Society, London, Special Publications, January 1, 2004; 235(1): 7 - 63. [Abstract] [PDF]
|
|
|
|
|
|
F. F. Whitaker, P. L. Smart, and G. D. Jones Dolomitization: from conceptual to numerical models Geological Society, London, Special Publications, January 1, 2004; 235(1): 99 - 139. [Abstract] [PDF]
|
|
|
|
|
|
Numerical modeling of reflux dolomitization in the Grosmont platform complex (Upper Devonian), Western Canada sedimentary basin AAPG Bulletin, August 1, 2003; 87(8): 1273 - 1298.
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
