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At least 163 records · Page 9Linked to original sources
USGS1982

Maps showing coal resources of the Big A Mountain Quadrangle, Russell and Buchanan counties, Virginia

The coal-bearing Norton Formation of Early and Middle Pennsylvanian age is at the surface over most of the northwestern two-thirds of the Big A Mountain quadrangle. The southeastern part of the quadrangle, bounded on the northwest and northeast by Buffalo Mountain and Russell Fork faults, consists of highly faulted rocks ranging in age from Early Cambrian to Middle Pennsylvanian (Miller and Meissner, 1977). The coal-bearing rocks in the northwestern two-thirds of the quadrangle are bisected by the Russell Fork fault. The rocks southwest of the fault, which are part of the Cumberland overthrust block (Wentworth, 1921), have been displaced approximately four miles to the northwest (Englund, 1971) along the concealed Pine Mountain overthrust. Because the rocks of the Norton Formation are displaced laterally by the Russell Fork fault, the coal bed sequences across the fault do not match. For this reason the resources are shown separately for the coal beds north and south of the fault (table 1). The stratigraphic section from the Gladeville Sandstone to the Tiller coal bed is thicker to the south of the fault than it is to the north, as illustrated in figures 16 and 17. The Puncheon Camp, a locally important coal bed, is present only south of the fault.

Virginia↗
USGS2015

Mapping of coal quality using stochastic simulation and isometric logratio transformation with an application to a Texas lignite

Coal is a chemically complex commodity that often contains most of the natural elements in the periodic table. Coal constituents are conventionally grouped into four components (proximate analysis): fixed carbon, ash, inherent moisture, and volatile matter. These four parts, customarily measured as weight losses and expressed as percentages, share all properties and statistical challenges of compositional data. Consequently, adequate modeling should be done in terms of a logratio transformation, a requirement that is commonly overlooked by modelers. The transformation of choice is the isometric logratio transformation because of its geometrical and statistical advantages. The modeling is done through a series of realizations prepared by applying sequential simulation for the purpose of displaying the parts in maps incorporating uncertainty. The approach makes realistic assumptions and the results honor the data and basic considerations, such as percentages between 0 and 100, all four parts adding to 100% at any location in the study area, and a style of spatial fluctuation in the realizations equal to that of the data. The realizations are used to prepare different results, including probability distributions across a deposit, E-type maps displaying average properties, and probability maps summarizing joint fluctuations of several parts. Application of these maps to a lignite bed clearly delineates the deposit boundary, reveals a channel cutting across, and shows that the most favorable coal quality is to the north and deteriorates toward the southeast.

International Journal of Coal Geology↗