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<br />2. deep-basin deposits which range in depth from
<br />200 to 5,000 feet, and are mined solely by in
<br />situ recovery methods.
<br />
<br />The principal deposits of near-surface lignite occur in the
<br />Wilcox Group and are classified by Kaiser according to origin
<br />as iluvial, deltaic, or lagoonal. Fluvial lignites are associated
<br />with overbank deposits of stream systems and have a high percentage
<br />of woody material but low sulfur ~ontent. Deltaic deposits
<br />of lignite occur in association with delta-front sequences,
<br />interdistributary deposits, and meanderbeltdeposits. The most
<br />commercially significant deposits are associated with the delta
<br />plain. Primarily nonwoody, deltaie lignite results from a
<br />marsh environment. Lagoonal lignite has a high sulfur and ash
<br />content, possibly reflecting a salt marsh environment (Kaiser,
<br />1974).1' ,
<br />
<br />Deep-basin lignite resources have not been extensively studied
<br />but apparently are related to fluVial systems in the Wilcox
<br />Group.
<br />
<br />Surface and subsurface coal deposits occur in the Pennsylvanian
<br />rocks of North-Central Texas. The coal deposits are associated
<br />with fluvial-deltaic facies tracts in the Straw~ Canyon and
<br />Cisco Groups. As defined by T.J. Evans (1974)_/bituminous c,oa1
<br />contains approximately 86% fixed carbon (dry basis) and has
<br />heating values of 11,000 btu/lb, In the late 1800's, a coal mine
<br />was producing from the Cisco Group :!.n'Montague County; 'however,
<br />abundant oil and gas undercut the coal market and most mines were
<br />closed by 1928.
<br />
<br />At present, there are two active or recently active uranium mines
<br />in the region. These deposits are small, off..urring in the
<br />Triassic redbeds. According to F1awn, (1967)_the uranium was most
<br />probably deposited by precipitation from circulating ground
<br />water in conglomeratic sandstone.
<br />
<br />The petroleum and natural gas p~oduction in the Arkansas-White-Red
<br />region comprises 5% and 18% respectively of the State's total
<br />production. During 1972, several deep gas fields, 18,000 to
<br />21,000 feet in depth, were discovered in the Anadarko Basin,
<br />Wheeler County. The majority of the petroleum production
<br />is in the Levelland-Slaughter_San Andres trend in Cochran and
<br />Hockley Counties ~exas Gulf Region), and' in the Anadarko' Basi,n
<br />along the Red River, , ,
<br />
<br />11
<br />
<br />Kaiser, W, R" 1974, Texas Li~nite: Near-Surfaee and
<br />Deep Basin Resourc~s, Bureau of Economic Geology, University
<br />of Texas at Austin, Report of Investigations, 76.
<br />
<br />Evans, T. J" 1974, Bituminous Coal in Texas, Bureau of
<br />Economic Geology, University of Texas at Austin, Handbook 4.
<br />
<br />F1awn, P. T., 1967, Uranium in,Texas-1967, Bureau of
<br />Economic Geology, University of Texas at Austin, Geological
<br />Circular 67-1. 136
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