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Regional diagenetic patterns in the St. Peter Sandstone; implications for brine migration in the Illinois Basin

Bulletin 2094-A

By:
, ,

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Abstract

Diagenetic minerals and alteration patterns in the Ordovician St. Peter Sandstone, Illinois Basin, record varied hydrologic and chemical conditions during the basin?s long and complex geologic history. Major diagenetic events modifying the St. Peter Sandstone include (1) mechanical compaction, (2) early K-feldspar overgrowth and dolospar precipitation, (3) burial quartz, dolospar, anhydrite, and calcite cementation, and (4) carbonate-cement and K-feldspar grain dissolution. Radiometric age dates of authigenic K-feldspar and illite in combination with the reconstructed burial history of the St. Peter reveal that early-diagenetic K-feldspar and dolospar precipitated at shallow to moderate depths in the Devonian, whereas late-diagenetic quartz, dolospar, anhydrite, and calcite formed during deep burial in the Late Pennsylvanian to Early Permian. Stable-isotope geochemistry and fluid-inclusion paleothermometry suggest that burial cements precipitated from saline fluids over a wide temperature range. In the southern part of the basin, burial cements preserve a record of diagenetic effects that were in part controlled by fractures and hydrothermal-fluid circulation. Baroque dolospar cementation is the most significant of these effects.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Regional diagenetic patterns in the St. Peter Sandstone; implications for brine migration in the Illinois Basin
Series title:
Bulletin
Series number:
2094
Chapter:
A
Edition:
-
Year Published:
1997
Language:
ENGLISH
Publisher:
U.S. G.P.O.,
Description:
iii, p. A1-A17, ill., maps ;28 cm.