Telemagmatic metamorphism superimposed on regional metamorphism: Evidence from coals in central China
- Univ. of Kentucky, Lexington, KY (United States). Dept. of Geological Sciences
Coal (Lower Permian No. 1) in north-central Henan province, central China, exhibits a zoned rank distribution. The rank varies between high-volatile bituminous and anthracite. Highest rank coal occurs in a northwest-southeast trending zone that cuts across the center of the study area. Coal rank decreases from this central zone towards both the northeast and southwest. Core data indicate that the anthracite is currently overlain by over 4,600 m of sedimentary cover, which represents more or less continuous sedimentation during the Permian and Triassic. In the lower rank area to the southwest, erosion has removed all but approximately 1,000 m of strata. The rank distribution in this area has been attributed to regional metamorphism by previous workers as the higher coal rank coincides with the thicker strata. However, this study reveals that anthracite in the area has a much higher vitrinite reflectance, between 3--6% (Ro max, in oil), with some locations exhibiting reflectances greater than 6%. Petrographically, the anthracite is characterized by well developed pores (5--10 [mu]m in diameter) and mosaic structure. It is suggested that the higher heat flow is due to the presence of deep-seated plutons. It is proposed that coal metamorphism in this area involved three stages: (1) Pre-orogenic (early Permian-late Triassic). Regional metamorphism produced coals of subbituminous to high-volatile bituminous rank; (2) Orogenic (early Jurassic-late Cretaceous). Telemagmatic metamorphism resulted in zones of higher rank coal (medium volatile through anthracite rank); (3) Post-orogenic (Tertiary-Quaternary). Shallow burial depth due to the tectonic uplift followed by erosion had a negligible effect on coal rank. It is suggested, therefore, that coalification in this area is the result of regional metamorphism overprinted by telemagmatic metamorphism.
- OSTI ID:
- 6109662
- Report Number(s):
- CONF-9303212-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:1; Conference: 27. annual Geological Society of America (GSA) South-Central Section meeting, Fort Worth, TX (United States), 15-16 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTHRACITE
COALIFICATION
PETROGRAPHY
BITUMINOUS COAL
CHINA
COAL DEPOSITS
COAL RANK
GEOLOGIC HISTORY
METAMORPHISM
PERMIAN PERIOD
REFLECTIVITY
VITRINITE
ASIA
BLACK COAL
CARBONACEOUS MATERIALS
COAL
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
MACERALS
MATERIALS
MINERAL RESOURCES
OPTICAL PROPERTIES
PALEOZOIC ERA
PHYSICAL PROPERTIES
RESOURCES
SURFACE PROPERTIES
011000* - Coal
Lignite
& Peat- Reserves
Geology
& Exploration
010600 - Coal
Lignite
& Peat- Properties & Composition