Nature and origin of minerals in anthracite from eastern Pennsylvania

Textural, chemical, and mineralogical analyses of authigenic clays in anthracite-rank coal from eastern Pennsylvania have allowed a better understanding of parameters controlling diagenesis and relationships among mineral authigenesis, coalification, and tectonic deformation. Minerals in anthracite occur as distinct assemblages associated with the following microenvironments: coal matrix, two orthogonal joint sets restricted to coal beds (termed systematic and non-systematic cleat), a third joint set (J$\sb3)$ which is systematic and permeates adjacent lithologies, and slip surfaces. Systematic and non-systematic cleat sets, and kaolinite within the cleat sets, formed during bituminization. All other authigenic clay minerals in cleat replaced pre-existing kaolinite ($\pm$quartz) during the latest stage of coalification (anthracitization) at T $>$ 200$\sp\circ$C and different replacement assemblages are often observed in co-existing orthogonal cleat sets. In localities from all four anthracite fields, kaolinite in the systematic cleat was replaced by rectorite, sudoite, and tosudite, which are clay minerals primarily associated with hydrothermal veins and ore deposits, as well as by berthierine, NH$\sb4$-illite, and pyrophyllite. Replacement minerals in associated non-systematic cleat consist primarily of NH$\sb4$-illite or pyrophyllite. J$\sb3$ assemblages typically consist of quartz + Fe-rich chlorite veins which precipitated from solution during the early stages of anthracitization and deformation (T = 200$\sp\circ$C). Slip surfaces formed during regional tectonic deformation, and minerals observed in slip surfaces include NH$\sb4$-illite, pyrophyllite, Fe-rich chlorite, and kaolinite. The chemical components for clay mineral authigenesis appear to have multiple sources: Al and Si from pre-existing kaolinite and quartz; N from local organic matter; Mg, Fe, Mn, and perhaps Cr, Ni, and Zn, largely from metasomatic hydrothermal fluids.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Geology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Daniels, Eric Joseph

Contributors dc:contributor

• Altaner, Stephen P.

• Mineralogy
• Geochemistry

Statement dc:rights

• Copyright 1992 Daniels, Eric Joseph

Language dc:language

eng

Identifier

AAI9215801
(UMI)AAI9215801

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/22568