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GEOREF RECORD

Subsurface dolomites, San Salvador, Bahamas

P. R. Supko
Subsurface dolomites, San Salvador, Bahamas
Journal of Sedimentary Petrology (September 1977) 47 (3): 1063-1077

Abstract

The carbonates from a 168-meter well on the north coast of San Salvador, Bahamas consist mostly of stratal and massive dolomite below 37 meters. Stratal dolomites are thinly bedded (<15 cm) and laminated, contain a poor fauna, and have occasional intraclasts and bird's eye structure. They are interpreted as supratidal. In places they are capped by a thin reddish, iron-rich crust, which may indicate soil forming conditions. Most of the section is massive dolomite, which formed as replacement of grain supported sediments or rocks of backreef or lagoonal facies. Multiple stages of dolomitization are indicated. The mean delta O (super 18) value of the dolomite is +2.1 per thousand relative to PDB and it is enriched in O (super 18) by nearly equal 3 per thousand relative to presently forming sediment and nearly equal 5 per thousand to associated limestone. The mean delta C (super 13) is + 1.8 per thousand roughly the same as presently forming sediment but nearly equal 8 per thousand heavier than associated calcite. The mean Sr value for limestone is 564 ppm, for dolomite 170 ppm. Stratal dolomites are lower in O (super 18) and mol % MgCO (sub 3) than are the massive dolomites, and crystal structures are more poorly ordered. This may indicate that the two dolomite types formed in different fluids (i.e., that different processes operated) or that they reflect differing susceptibility to dolomitization. Our present state of knowledge does not allow an unequivocal answer as to the nature of the fluid(s) responsible for dolomitizing the San Salvador rocks.


ISSN: 0022-4472
Coden: JSEPAK
Serial Title: Journal of Sedimentary Petrology
Serial Volume: 47
Serial Issue: 3
Title: Subsurface dolomites, San Salvador, Bahamas
Author(s): Supko, P. R.
Affiliation: Scripps Inst. Oceanogr., La Jolla, Calif., United States
Pages: 1063-1077
Published: 197709
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 53
Accession Number: 1978-009241
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. table, sketch map
N24°04'60" - N24°10'00", W74°30'00" - W74°25'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1978
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