Clay mineral authigenesis in coal and shale from the Anthracite region, Pennsylvania

Journal Article · · American Mineralogist; (USA)

OSTI ID:6221270

Daniels, E J; Altaner, S P ^[1]

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1. Univ. of Illinois, Urbana (USA)

Textural, chemical, and mineralogical analyses of authigenic clays in anthracite-rank coal and associated shale from eastern Pennsylvania have allowed a better understanding of the parameters controlling diagenesis and perhaps coalification in this region. Minerals in anthracite occur in distinct assemblages associated with the following microenvironments: coal matrix, two orthogonal joint sets (termed systematic and nonsystematic cleat), and a third joint set. Authigenic minerals that replaced preexisting kaolinite during the latest stage of coalification at T > 200C include NH{sub 4}-rich illite, pyrophyllite, and the following minerals, which are primarily restricted to the systematic cleat set: tosudite (R1-ordered, dioctahedral, mixed-layer chlorite/smectite), sudoite (di, trioctahedral chlorite) and rectorite (R1-ordered, mixed-layer chlorite/smectite). Alteration of smectite to illite may be responsible for formation of authigenic illite and Na-bearing illite, which are present only in the shale and coal matrix, and Fe-, Al-rich chlorite and quartz in the third joint set. Minerals in the shale, the coal matrix, and the nonsystematic cleat set are interpreted to represent authigenesis in a low-permeability environment (closed-system alteration); however, the assemblage sudoite + tosudite + rectorite in the systematic cleat set is interpreted to be the result of one or two stages of hydrothermal alteration (open-system alteration). Hydrothermal alteration may be related to large-scale basinal flow induced by Alleghanian-age uplift; such migrating fluids could also have transported heat from depth and thereby significantly increased the rate and rank of coalification in this region.

• OSTI ID: 6221270
• Journal Information: American Mineralogist; (USA), Vol. 75:7-8; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CLAYS
GEOCHEMISTRY
COAL DEPOSITS
MINERALOGY
PENNSYLVANIA
ANTHRACITE
CHEMICAL COMPOSITION
CHLORITE MINERALS
COAL RANK
COALIFICATION
DIAGENESIS
HYDROTHERMAL ALTERATION
ILLITE
KAOLINITE
MATURATION
ORIGIN
OROGENESIS
PERMEABILITY
SHALES
SMECTITE
SOURCE ROCKS
TEXTURE
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BLACK COAL
CARBONACEOUS MATERIALS
CHEMISTRY
COAL
ENERGY SOURCES
FEDERAL REGION III
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
MATERIALS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
USA
011000* - Coal
Lignite
& Peat- Reserves
Geology
& Exploration