102 



UNITED STATES MINERAL RESOURCES 



thus far none have been developed commercially. 

 In California, the bitumen resources in only seven 

 deposits, the largest being in the Edna district, San 

 Luis Obispo County, are about 300 million barrels. 



Kansas. — The principal deposits of bituminous 

 rocks in Kansas are in the east-central and south- 

 eastern part of the State and are of Pennsylvanian 

 age. The bitumen is in beds of porous sandstone and 

 limestone in a stratigraphic sequence exposed across 

 several counties in a band 15-40 miles wide. A core 

 from an area in the southeastern part of the State 

 shows a bitumen-impregnated sandstone 100 feet 

 thick containing 65,000 barrels of oil per acre in 

 situ. 



Kentucky. — In west-central Kentucky sizable de- 

 posits of bitumen-bearing rocks occur, and in a few 

 counties of eastern Kentucky minor accumulations 

 occur. The asphalt-bearing strata are predominantly 

 sandstone of Pennsylvanian and Mississippian age 

 and have reported bitumen content of as much as 

 10 percent by weight. Estimates of bitumen re- 

 sources for three areas in Kentucky are given in 

 table 19. 



Missouri. — Known deposits of bitumen are widely 

 distributed in 21 counties in western Missouri. The 

 deposits occur in both sandstone and limestone of 

 Mississippian and Pennsylvanian age, but mostly 

 in Pennsylvanian sandstones. The impregnated rocks 

 of Mississippian age are mostly limestones located 

 in the zinc-lead mining area in the southwestern 

 part of the State. Maximum reported thickness of 

 impregnated rocks is 30 feet, and maximum bitu- 

 men content is 15 percent by weight. No bitumen 

 resource estimates have been made for Missouri, 

 although some deposits are known to be extensive. 



New Mexico. — One economically important tar- 

 sand deposit occurs in New Mexico, and that is in 

 the Santa Rosa Sandstone (Triassic) in Guadalupe 

 County. The bitumen-bearing zone is as much as 

 60 feet thick and contains as much as 8 percent 

 hydrocarbon by weight. A resource estimate for the 

 Santa Rosa Sandstone is given in table 19. 



Oklahoma. — Ball Associates, Ltd. (1965, p. 227- 

 231) listed 80 areas containing petroleum-impreg- 

 nated rock located in 21 Oklahoma counties. The 

 largest deposits are in sandstones and limestones of 

 Ordovician age in Murray County. The sandstone 

 contains as much as 14 percent bitumen by weight. 

 Other bitumen deposits are found in rocks ranging 

 in age from Ordovician to Cretaceous. 



Texas. — Cretaceous rocks, in a northeast-trending 

 area that extends across the middle one-third of 

 Texas, contain most of the known bitumen deposits 

 of the State. The largest deposits, in the Uvalde I 



district (table 19), are in the Anacacho Limestone. 

 The bitumen-bearing sequence is as much as 200 

 feet thick, and its maximum hydrocarbon content 

 is 20 percent by weight. 



Utah. — Outcrops of tar sand are found in many 

 sections of eastern Utah. The largest outcrops are 

 situated around the margin of the Uinta Basin and 

 in a triangle-shaped area west of the confluence of 

 the Green and Colorado Rivers. The deposits in the 

 Uinta Basin are, for the most part, in rocks of Ter- 

 tiary age. Some impregnated zones extend through 

 several hundred feet of sandstone and related rocks. 

 Asphaltic zones in the "Tar Sand Triangle" are ex- 

 tensive and are as much as 250 feet thick. They 

 occur in rocks of Permian and Triassic age. The 

 estimate of nonfluid bitumen in Utah has been 

 greatly increased as a result of recent studies by the 

 Utah Geological and Mineralogical Survey. 



Gilsonite is the only solid hydrocarbon produced 

 in appreciable quantities. Utah has all the major 

 deposits. The deposits are not large enough, how- 

 ever, to contribute greatly to the total energy needs 

 of the United States. Original reserves of gilsonite 

 are estimated to have been 45 million tons, and much 

 ore has been mined from the widest veins. All op- 

 erating mines are in Utah. 



PROSPECTING TECHNIQUES 



Discovery of most of the larger known occurrences 

 of bitumen-bearing rocks has been due to visible 

 indications of impregnations, such as discolored 

 rocks and tar seeps. Other deposits have been found 

 as a result of mineral-mining operations and ex- 

 ploratory drilling for oil and gas. Because there 

 has been no rapid depletion of known tar-sand de- 

 posits, little attention has been given to developing 

 sophisticated tools for prospecting. If the need 

 arises for tar-sand exploration, some methods now 

 employed in searching for liquid petroleum could 

 be adapted to prospecting for nonliquid bitumen. In 

 the near future, however, increases in the estimated 

 amount of United States tar-sand resources will 

 probably be a result of investigations of known 

 deposits that have not been evaluated. 



PROBLEMS FOR RESEARCH 



Large reserves of relatively high-grade material 

 occurring in a small area are required for large- 

 scale economic development of bitumen-bearing 

 rocks. In North America, the Canadian tar sands 

 are, by far, the deposits best suited for exploitation. 

 Development of the Canadian deposits has brought 

 great advancement in the technology used in mining 

 and processing enormous tonnages of tar sand, but 



