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Numerical modelling of geothermal and reflux circulation in Enewetak Atoll: Implications for dolomitization

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, , , and
DOI: 10.1016/S0375-6742(00)00010-8

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Abstract

Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80??? can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls. (C) 2000 Elsevier Science B.V. All rights reserved.Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80 per mil can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls.

Additional Publication Details

Publication type:
Conference Paper
Publication Subtype:
Conference Paper
Title:
Numerical modelling of geothermal and reflux circulation in Enewetak Atoll: Implications for dolomitization
DOI:
10.1016/S0375-6742(00)00010-8
Volume
69-70
Year Published:
2000
Language:
English
Publisher:
Elsevier Science Publishers B.V.
Publisher location:
Amsterdam, Netherlands
Larger Work Title:
Journal of Geochemical Exploration
First page:
71
Last page:
75
Number of Pages:
5
Conference Title:
Geofluids III - 3rd International Conference on Fluid Evolution, Migration and Interaction in Sedimentary Basins and Orogenic Belts
Conference Location:
Barcelona, Spain
Conference Date:
12 July 2000 through 14 July 2000