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Origin of endogenetic micrite in karst terrains; a case study from the Cayman Islands

Brian Jones and Charles F. Kahle
Origin of endogenetic micrite in karst terrains; a case study from the Cayman Islands
Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes (April 1995) 65 (2): 283-293

Abstract

Cavities in the dolostones of the Cayman Formation (Miocene) on Grand Cayman and Cayman Brae commonly contain spar calcite cements and/or a variety of exogenetic (derived from sources external to the bedrock) and endogenetic (derived from sources in the bedrock) internal sediments. Micrite is a common component in many of these internal sediments. The exogenetic micrite, which is typically laminated and commonly contains fragments of marine biota, originated from the nearby shallow lagoons. The endogenetic micrite formed as a residue from the breakdown of spar calcite crystals by etching, as constructive and destructive envelopes developed around spar calcite crystals, by calcification of microbes, by breakdown of calcified filamentous microbes, and by precipitation from pore waters. Once produced, the endogenetic micrite may be transported from its place of origin by water flowing through the cavities. Endogenetic micrite can become mixed with the exogenetic micrite. Subsequently, it is impossible to recognize the origin of individual particles because the particles in endogenetic micrite are morphologically like the particles in exogenetic micrite. Formation of endogenetic micrite is controlled by numerous extrinsic and intrinsic parameters. In the Cayman Formation, for example, must endogenetic micrite is produced by etching of meteoric calcite crystals that formed as a cement in the cavities or by microbial calcification. As a result, the distribution of the endogenetic micrite is ultimately controlled by the distribution of the calcite cement and/or the microbes--factors controlled by numerous other extrinsic variables. Irrespective of the factors involved in its formation, it is apparent that endogenetic micrite can be produced by a variety of processes that are operating in the confines of cavities in karst terrains


ISSN: 1073-130X
Serial Title: Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes
Serial Volume: 65
Serial Issue: 2
Title: Origin of endogenetic micrite in karst terrains; a case study from the Cayman Islands
Affiliation: University of Alberta, Department of Geology, Edmonton, AB, Canada
Pages: 283-293
Published: 19950403
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 68
Accession Number: 1995-039858
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N19°15'00" - N19°25'00", W81°30'00" - W81°04'60"
Secondary Affiliation: Bowling Green State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199515
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