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GEOREF RECORD

Authigenic feldspar as an indicator of paleo-rock/water interactions in Permian carbonates of the northern Calcareous Alps, Austria

Christoph Spoetl, Martin Kralik and Michael J. Kunk
Authigenic feldspar as an indicator of paleo-rock/water interactions in Permian carbonates of the northern Calcareous Alps, Austria
Journal of Sedimentary Research (January 1996) 66 (1): 139-146

Abstract

Dolostones interbedded with Upper Permian evaporites at the base of the Northern Calcareous Alps contain abundant authigenic K-feldspar. Two petrographically, structurally, and isotopically distinct generations of K-feldspar can be distinguished: crystals composed of an inclusion. rich core and a clear rim, and optically unzoned, transparent crystals. Both feldspar types have essentially identical K-feldspar end-member compositions with >= 99.5 mole % Or component. Low oxygen isotope ratios (+16.1 per thousand to +18.1 per thousand SMOW) suggest precipitation from (super 18) O-enriched, saline fluids at temperatures in excess of nearly equal 140 degrees C. (super 40) Ar/ (super 39) Ar plateau-age spectra of five samples range from 145 + or - 1 to 144 + or -1 Ma (Early Berriasian) and suggest that both types of feldspar were formed within an interval that did not exceed nearly equal 2 m.y. Rb/Sr model ages range from 152 to 140 Ma, assuming that the burial diagenetic regime was buffered with respect to strontium by the associated marine Permian evaporites. Authigenic K-feldspar records two distinct events of hot brine flow, most likely triggered by tectonic movements (detachment) and by an increase in the subsurface temperature in response to thrust loading.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 66
Serial Issue: 1
Title: Authigenic feldspar as an indicator of paleo-rock/water interactions in Permian carbonates of the northern Calcareous Alps, Austria
Affiliation: Universitaet Innsbruck, Institut fuer Geologie und Palaeontologie, Innsbruck, Austria
Pages: 139-146
Published: 199601
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 57
Accession Number: 1996-020803
Categories: Sedimentary petrologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
N47°00'00" - N48°22'00", E09°33'00" - E16°19'60"
Secondary Affiliation: Geotechnisches Institut, AUT, AustriaU. S. Geological Survey, USA, United States
Source Note: Section A: Sedimentary Petrology and Processes
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199608
Program Name: USGSOPNon-USGS publications with USGS authors
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