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GEOREF RECORD

Cation site occupancy in chlorites and illites as a function of temperature

M. Cathelineau
Cation site occupancy in chlorites and illites as a function of temperature (in Special issue devoted to some papers read at the sixth meeting of the European Clay Groups, D. C. Bain (editor))
Clay Minerals (December 1988) 23 (4): 471-485

Abstract

The relationships between the composition and the crystallization temperature of chlorites and illites have been investigated in different geothermal fields and in particular the Los Azufres system in Mexico, considered to be a natural analogue to experimental laboratories, as the main changes in physical and chemical conditions and mineralogy are related to progressively increasing temperature with depth. Temperature was estimated from combined geothermometric approaches, and especially from fluid inclusion studies on quartz coexisting with clays. The Al (sub (IV)) content in the tetrahedral site of chlorites, and the K content and total interlayer occupancy of illites increase with temperature. These chemical changes are mainly related to the marked decrease in the molar fraction of the Si (sub (IV)) -rich end-members (kaolinite for chlorites, and pyrophyllite for illites) which become negligible at approximately 300 degrees C. Other chemical changes, such as the variation in Fe and Mg contents, are partly influenced by temperature, but are strongly dependent on the geological environment, and consequently on the solution composition. The empirical relationships between chemical variables and temperature were calibrated from 150-300 degrees C, but extrapolations at lower and higher temperatures seem possible for chlorites. Such geothermometers provide tools for estimating the crystallization temperature of the clays, and are important for the study of diagenetic, hydrothermal and low-T metamorphic processes.


ISSN: 0009-8558
Coden: CLMIAF
Serial Title: Clay Minerals
Serial Volume: 23
Serial Issue: 4
Title: Cation site occupancy in chlorites and illites as a function of temperature
Title: Special issue devoted to some papers read at the sixth meeting of the European Clay Groups
Author(s): Cathelineau, M.
Author(s): Bain, D. C.editor
Affiliation: CREGU, Vandoeuvre-les-Nancy, France
Affiliation: Macaulay Land Use Res. Inst., Craigiebuckler, United Kingdom
Pages: 471-485
Published: 198812
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
Meeting name: Euroclay 87 conference ; sixth meeting of the European Clay Groups
Meeting location: Seville, ESP, Spain
Meeting date: 19870907Sept. 7-10, 1987
References: 41
Accession Number: 1989-050615
Categories: Mineralogy of silicatesGeochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N17°58'00" - N20°25'00", W103°46'60" - W100°15'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 1989
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