thumbnail

Diagenetic mineralization in Pennsylvanian coals from Indiana, USA: 13C/12C and 18O/16O implications for cleat origin and coalbed methane generation

International Journal of Coal Geology

By:
, , , and
DOI: 10.1016/j.coal.2007.06.002

Links

Abstract

Cleats and fractures in southwestern Indiana coal seams are often filled with authigenic kaolinite and/or calcite. Carbon- and oxygen-stable isotope ratios of kaolinite, calcite, and coalbed CO2 were evaluated in combination with measured values and published estimates of ??18O of coalbed paleowaters that had been present at the time of mineralization. ??18Omineral and ??18Owater values jointly constrain the paleotemperature of mineralization. The isotopic evidence and the thermal and tectonic history of this part of the Illinois Basin led to the conclusion that maximum burial and heat-sterilization of coal seams approximately 272??Ma ago was followed by advective heat redistribution and concurrent precipitation of kaolinite in cleats at a burial depth of < 1600??m at ??? 78 ?? 5????C. Post-Paleozoic uplift, the development of a second generation of cleats, and subsequent precipitation of calcite occurred at shallower burial depth between ??? 500 to ??? 1300??m at a lower temperature of 43 ?? 6????C. The available paleowater in coalbeds was likely ocean water and/or tropical meteoric water with a ??18Owater ??? - 1.25??? versus VSMOW. Inoculation of coalbeds with methanogenic CO2-reducing microbes occurred at an even later time, because modern microbially influenced 13C-enriched coalbed CO2 (i.e., the isotopically fractionated residue of microbial CO2 reduction) is out of isotopic equilibrium with 13C-depleted calcite in cleats. ?? 2007 Elsevier B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Diagenetic mineralization in Pennsylvanian coals from Indiana, USA: 13C/12C and 18O/16O implications for cleat origin and coalbed methane generation
Series title:
International Journal of Coal Geology
DOI:
10.1016/j.coal.2007.06.002
Volume
73
Issue:
3-4
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
International Journal of Coal Geology
First page:
219
Last page:
236
Number of Pages:
18