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