Lithological and geophysical characteristics of the Pakistan Mineral Development Corporation's THL core hole [microform] : implications for the coal resource potential of the lower and middle part of the Bara Formation in the Lakhra area of Sindh, Pakistan / by Christopher Wnuk ... [et al.] ; report prepared jointly by the Geological Survey of Pakistan and the U.S. Geological Survey under the auspices of the U.S. Agency for International Development