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At least 109 records · Page 6Linked to original sources
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↗
USGS1979

Maps showing coal resources of the Honaker Quadrangle, Russell, Tazewell, and Buchanan counties, Virginia

The Honaker quadrangle lies in two physiographic provinces. The northern half of the quadrangle is part of the Appalachian Plateaus province, where the coal-bearing formations of Pennsylvanian age are nearly flat lying or very gently dipping. Diagonally extending east-northeastward across the middle of the quadrangle are several belts of faulted, overturned, and steeply dipping rocks of Mississippian and Pennsylvanian age which are in the fault system that separates the Appalachian Plateaus from the Valley and Ridge provinces. Several belts of Pennsylvanian rocks in this area contain coal beds that are exposed at the surface. South of the faulted and overturned belts of Mississippian and Pennsylvanian rocks is an area of older faulted and folded noncoal-bearing rock formations, which are also part of the Appalachian Valley and Ridge province and which form much of the southern half of the Honaker quadrangle.

Virginia↗