Browsing by Subject "Geology--Texas--Presidio County"
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Item Areal geology of Candelaria area Presidio County, Trans-Pecos Texas(1956) Smith, Joseph Thurston, 1927-; Not availableThe extreme northwestern part of the Candelaria area belongs to the Mexican Highland province; its structure is the result of Laramide orogeny. The rest, consisting of northward trending fault blocks and intervening basins where waste from the fault block accumulates, is characteristic of the Basin and Range province. The Candelaria area stood above the sea in early Cambrian time, probably during late Pennsylvanian-early Permian time, and in post Permian pre-late-Jurassic time when it was a part of the Wichita pale oplain, and it has been emergent since Laramide time. Oil may be trapped at the subsurface unconformities. In early Tertiary time, the area was covered by volcanic material, and in later Tertiary time, epieroganic uplift and normal faulting formed the Basin and Range structure of the present-day surfaceItem Geology of Chinati Peak Quadrangle Trans-Pecos Texas(1953) Rix, Cecil C.; Lonsdale, John T. (John Tipton), 1895-1960; DeFord, Ronald K. (Ronald Kinnison), 1902-1994In the Chinati Mountains, Presidio County, Texas, a stratigraphic sequence of more than 15,000 feet of Paleozoic, Mesozoic, and Cenozoic rocks is exposed. Of five Paleozoic formations, aggregating 8,000 feet, the Cieneguita (Strawn through Cisco), Alta (Wolfcamp), and Cibolo (Leonard), are exposed north of Shafter. The Cibolo is restricted to Leonard age by raising the Alta-Cibolo boundary. The two exposed west of Shafter are respectively correlative with the Word and the Capitan but were mistakenly correlated with the Cibolo formation by previous writers except Skinner; for them the names Ross Mine formation and Mina Grande formation are proposed. Exposures of Paleozoic rocks in the upper Cibolo basin show a thinner, shoreward facies of the formations exposed typically in the vicinity of Shafter. A deep channel, formed during Wolfcamp time and trending southwestward through the quadrangle, is revealed by a 5,415 foot thick Wolfcamp section in the vicinity of Sierra Alta which thins northward to 2,610 feet in the upper Cibolo basin, and southeastward to 2,770 feet in the Argo Oil Corporation's Mitchell Bros.-State No. 1 well. The three Cretaceous formations, the Presidio (Travis Peak-Glen Rose), Shafter (Glen Rose), and "Finlay" (Walnut-Comanche Peak-Edwards), compose a total of 1,000 feet, which is correlative with the Yucca, Bluff, Cox, and Finlay formations, of the Quitman and Finlay mountains about 100 miles northwest. The Shafter is restricted to Trinity age. Extrusive rocks cover more than half the surface area of the quadrangle. The Buck Hill volcanic series is present on the eastern margin. The thick section of lava flows comprising the Chinati Mountains, for which the name Chinati Mountain volcanic series is proposed, lies above the Mitchell Mesa welded tuff of the Buck Hill series at the southern end of the Tierra Vieja and is therefore not older than Oligocene; it is probably Miocene or younger. Pleistocene and recent erosion and deposition has formed the prominent gravel terraces which surround the mountains. Four periods of crustal deformation affected the region: 1) post-Permian-pre-Cretaceous regional uplift and erosion; 2) post-Cretaceous uplift, thrusting, doming, folding, and erosion; 3) late Tertiary doming; and 4) late Cenozoic basin-and-range block faulting. Mineral deposits include ores of silver, lead, copper, zinc, and rare native lead.Item Geology of Pinto Canyon area, Presidio County, Texas(1957) Amsbury, David L.Pinto Canyon area includes the southern Tierra Vieja Mountains and the northern Chinati Mountains. Lower and middle Permian siltstone, limestone, and chert underlie Comanche limestone and sandstone; Gulf rocks were deposited in the area but were eroded from the crest of a north-trending Laramide anticline. Normal faults that trend N30E cut the anticline before burial by silicic middle Tertiary volcanic strata from several sources. Emplacement of silicic intrusions that range from 1-inch dikes to a 27-square-mile granite-syenite complex followed. Large-scale Basin-and-Range normal faults that trend N5W and N85E displaced the volcanic strata to form the Tierra Vieja, Cuesta del Burro, and Presidio bolson. Gravel, sand, and clay deposited in the bolson are being dissected by tributaries to the Rio Grande. In ascending order the lithostratigraphic sequence comprises the Wolfcamp(?) Alta formation and the Leonard and lower Guadalupe Pinto Canyon formation (new name), both in the Permian system; the Yucca formation, Bluff formation (lower Albian), Cox formation, Finlay formation, Bienevides formation (middle Albian; new name), Loma Plata limestone (upper Albian; new name), Del Rio formation, and Buda formation (Cenomanian?), all in the Comanche series of the Cretaceous system; and the Jeff conglomerate, Vieja formation (basal Oligocene), Shely group (Oligocene?; new name), Moonstone rhyolite (new name), Petan trachyte (new name), and Chinati Mountain group (emended), all in the Tertiary system. Six terrace gravels were mapped in the dissected Presidio bolson, plus alluvium in present arroyos and the Rio Grande floodplain.