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Association of coal metamorphism and hydrothermal mineralization in Rough Creek fault zone and Fluorspar District, Western Kentucky

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6561274
The ambient coal rank (metamorphism) of the Carboniferous coals in the Western Kentucky coalfield ranges from high volatile A bituminous (vitrinite maximum reflectance up to 0.75% R/sub max/) in the Webster syncline (Webster and southern Union Counties) to high volatile C bituminous (0.45 to 0.60% R/sub max/) over most of the remainder of the area. Anomalous patterns of metamorphism, however, have been noted in coals recovered from cores and mines in fault blocks of the Rough Creek fault zone and Fluorspar District. Coals in Gil-30 borehole (Rough Creek faults, Bordley Quadrangle, Union County) vary with no regard for vertical position, from high volatile C(0.55% R/sub max/) to high volatile A (0.89%R/sub max) bituminous. Examination of the upper Sturgis Formation (Missourian/Virgilian) coals revealed that the higher rank (generally above 0.75% R/sub max/) coals had vein mineral assemblages of sphalerite, twinned calcite, and ferroan dolomite. Lower rank coals had only untwinned calcite. Several sites in Webster County contain various coals (Well (No. 8) to Coiltwon (No. 14)) with vitrinite reflectances up to 0.83% R/sub max/ and associated sphalerite mineralization. Mississippian and Lower Pennsylvanian (Caseyville Formation Gentry coal) coals in the mineralized Fluorspar District have ranks to nearly medium volatile bituminous (1.03% R/sub max/). The regional rank trend exhibited by the fualt zones is generally higher rank than the surrounding areas. Sphalerite mineralization in itself is not unique within Illinois basin coals, but if it was partly responsible for the metamorphism of these coals, then the fluid temperature must have been higher within the above mentioned fault complexes.
Research Organization:
Univ. of Kentucky, Lexington
OSTI ID:
6561274
Report Number(s):
CONF-8310301-
Conference Information:
Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:9
Country of Publication:
United States
Language:
English