REFLECTIVITY AND ANISOTROPY OF VITRINITES IN SOME COAL SCARES FROM THE COAL MEASURES OF NORTHUMBERLAND

Publisher Website
Google Scholar
Abstract
Summary: The pattern of variation of reflectivities and bireflectances in vitrinites of low bituminous rank in coal scares from the Middle Coal Measures (Westphalian) of Northumberland has been examined in relation to the angle which the scares and the vitrinite banding make with the sedimentary bedding. The normal uniaxial negative optical character of the vitrinites is maintained when the scare margins and the edges of the vitrinite bands are parallel to the stratification, with the isotropic section in the plane of the bands. However, when the scare and the banding are in a vertical position, the optical properties of the vitrinites appear similar to those of biaxial materials. This pattern of variation can be attributed primarily to overburden pressure which, when the vitrinite bands depart from parallelism with the stratification, distorts both the form anisotropy and the specific anisotropy of the aromatic lamellae that constitute the greater part of the molecular structures of the vitrinites at this level of coalification.

This publication has 3 references indexed in Scilit: