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Show Surface Exploration Governs Search For Oil In Uintah Basin By Ray E. Colton Petroleum Geologist Recent field exploration, i.e., surface geologic study of the geographical confines of Duchesne Du-chesne and Uintah counties indicates in-dicates that owing to the complex com-plex geological structural conditions con-ditions of the Utah side of the Basin, that a system of surface geological fundamentals must be worked out for future searches for petroleum areas as yet undiscovered. un-discovered. The Uintah Basin covers approximately ap-proximately 13,600 square miles in west-central Colorado and east-central Utah, being largely a major structural basin lying between major uplifts such as the Uinta mountains to the north, 1 and the Wasatch mountains on the west. It is believed on the basis of recent geophysical operations oper-ations conducted in both Duchesne Du-chesne and Uintah counties, that approximately 20,000 feet of ex-plorable ex-plorable strata are present in the deep parts of the Uintah Basin. These strata of sand, sandstone, limestone, anhydrites, dolomites, etc., range in geologic antiquity from the Cambrian period pf the major Paleozoic geologic era to the Miocene period of the major Cenozoic geologic era. The Paleozoic Pal-eozoic section underlying the Roosevelt-Duchesne areas consists con-sists largely of thick continental sandstone, and shale, marine limestone and some local evaporates evapo-rates (from ancient Lake Uinta). The Mesozoic section which over lies the Paleozoic section in geologic geo-logic sequence, consists largely according to geophysical readings, read-ings, of continental sandstone with shale at the top and bottom and intervening shale zones. The Tertiary section overlying the Mesozoic consists of continental contin-ental sandstone and shale zones. Thus we have three major periods per-iods of the prehistoric geologic record represented here, with an estimated geologic age of 300,-000,000 300,-000,000 years. Within the sections discussed are many actual producing oil sands such as the Shinarump and Weber, and potentials lying in the limestone zones fi the Paleozoic Paleo-zoic Mississippian and Pennsyl-vanian Pennsyl-vanian strata, overlying the basement base-ment granite complex. Geologists in future searches 1 for petroleum potential areas of both Duchesne and Uintah counties, coun-ties, will divide these areas of the Uintah Basin into three catagor-:ies catagor-:ies as follows: 1. The impossible areas for petroleum bearing rocks; 2. Possible petroleum, producing pro-ducing areas; 3. Petroleum (favorable (fav-orable exploration) areas. These categories will be subdivided sub-divided according to their surface sur-face appearance or sub-surface geology. Impossible areas for petroleum will be cataloged as follows: (a) The more extensive areas of igneous ig-neous rocks appearing in Uintah and Duchesne counties, and especially es-pecially those of the ancient prc-Cambrian prc-Cambrian shields; excepting the smaller dikes; (b) All pre-Cam-brian rocks; (c) All decidedly folded mountaineous tracts older old-er than the Cretaceous period of the major Mesozoic geologic record, rec-ord, excepting domes and block- faulted mountains; (d) All regionally reg-ionally metamorphosed strata; (e) All continental or fresh-water strata deposits; (f) All marine formations which are thick and uniform in rock character and that are devoid of interbedded dark ,shales, thin-bedded dark impure limestones, dark marls or thin-bedded limy and fossil-iferous fossil-iferous sandstones. The possible petroleum areas should be classed as follows: (a) Highly folded marine and brackish-water strata; (b) Strata which is of marine type of Tertiary geologic time; (c) Cambrian and Ordovician gently folded strata; (d) Lake deposits such as Lake Uinta which was formed under arid or semi arid climatic conditions; con-ditions; (e) Green River (Eocene) deposits (oil shale areas of Uintah Uin-tah and Duchesne counties. Note: This discussion will be continued in another article of this series. |