thumbnail

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

Journal of Sedimentary Research
By: , , and 
https://doi.org/10.1306/D42682D9-2B26-11D7-8648000102C1865D

Links

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 18 O-enriched, saline fluids at temperatures in excess of nearly equal 140 degrees C. 40 Ar/ 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.

Publication type Article
Publication Subtype Journal Article
Title Authigenic feldspar as an indicator of paleo-rock/water interactions in Permian carbonates of the Northern Calcareous Alps, Austria
Series title Journal of Sedimentary Research
DOI 10.1306/D42682D9-2B26-11D7-8648000102C1865D
Volume 66
Issue 1
Year Published 1996
Language English
Publisher Society for Sedimentary Geology
Description 8 p.
First page 139
Last page 146
Google Analytic Metrics Metrics page
Additional publication details