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The Origin of the Faults, Anticlines, and Buried "Granite Ridge" of the Northern Part of the Mid-Continent Oil and Gas Field

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The Origin of the Faults, Anticlines, and Buried THE ORIGIN OF THE FAULTS, ANTICLINES, AND BURIED "GRANITE RIDGE" OF THE NORTHERN PART OF THE MID-CONTINENT OIL AND GAS FIELD. By A. E. FATH. INTRODUCTION. feature of considerable significance in this The structural geologist is ever confronted region is a buried " granite ridge" trending by the problem of the origin of the geologic northeastward from Butler County, Kans., to features with which he deals. An understand­ Pawnee County, Nebr. ing of their fundamental causes permits a better The alinements of these three features-the interpretation of their significance, which iJ?­ major anticlines, the fault belts, and the buried studies of natural resources, such as oil and "granite ridge "-are remarkably parallel, and gas, has a direct economic bearing. In regions to the writer this parallelism indicates a gen­ where the rock folds and faults are of large etic relationship. It is the purpose of this magnitude the structural mechanics are gen­ paper to point out this relationship and to erally apparent, at least in part, but in the Mid­ present an interpretation of its meaning. Continent field, where but few of the anticlines REGIONAL GEOLOGY. and faults represent elevations of more than Before the structural features are described 200 feet, the origin of these fea.tures is more in detail, a brief summary o:f the regional geol­ obscure. These small rock folds and fractures ogy will be presented as a background for the have commonly been considered the distant ef­ discussion. Rocks of undoubted ·pre-Cambrian fects of forces originating in the Ozark Moun­ age, such as granites and quartzites, crop out at tains, the dominating structural feature of the numarous places around the northern part of region, but the difficulty of applying this ex­ the Mid-Continent field, .in the St. Francis planation to the features that have come under Mountains of southeastern Missouri, the Ar­ the writer's observation has led to other con­ buckle and Wichita mountains o:f southern siderations, which are presented in this ·paper. Oklahoma, the Rocky Mountains of New Mex­ The need of understanding the origin and ico, Colorado, and Wyoming, the Black Hills mechanics of the structural features in the Mid­ in southwestern South Dakota, and the Sioux Continent oil and gas field may be inferred quartzite area of southeastern South Dakota, from the fact that much of the oil and gas in southwestern Minnesota, and northwestern this region occurs in localities where the struc­ Iowa. These outcrops probably do not repre­ ture of the containing rocks is favorable for sent rocks of precisely the same age, but its accumulation-that is, where there are anti­ they represent the ancient basement complex clinal or domal flexures. In searching for new upon which all the Paleozoic stratified rocks oil and gas pools it is therefore of paramount of the Mid-Continent region were deposited. importance not only to know the structure of Within the oil-field region of eastern Kansas the surface rocks in the regions to be prospected similar crystalline rocks have been found at but also to understand how the structural fea­ comparatively shallow depths in holes drilled tures exposed at the surface may differ from for oil.1 (See Pl. XIV.) Such drill holes are those which govern the accumulation of oil 1 Taylor, C. H., The granites of Kansas: Southwestern and gas in the deep-lying strata. Assoc. Petroleum Geologists Bull., vol. 1, pp. 111-126, Feb­ In addition to the anticlines and domes there ruary, 1917. Powers, Sidney, Granite in Kansas: Am. Jour. Sci., 4th ser., vol. 44, pp. 146-150, August, 1917. Wright, are, in places, many faults of the en echelon or Park, Granite in Kansa.s wells: Am. Inst. Min. Eng. Bull. offset type, grouped into remarkable parallel 128, pp. 1113-1120, August, 1917. Moore, R. C., and Haynes, W. P., The crystalline rocks of Kansas, in Oil and belts or series, the study of which suggested gas resources of Kansas : Kansas Geol. Survey Bull. 3, pp. the fundamental principles on which the pres­ 140-173, 1917. Moore, R. C., Geologic history of the crys­ talline rocks of Kansas : Am. Assoc. Petroleum Geologists ent discussion is based. Still another geologic Bull. 2, pp. 98-113, 1918. 75 76 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1920. Generalized section of formations in eastern Kansas. Thickness Geologic age. Group. Formation. Principal character. (feet). Wellington shale. Shale ...................... 500-800 Sumner group ..... Marion formation ........... Shale, limestone and con- 150 glomerate. Winfield formation ........ Limestone and shale ...... 8-25 Doyle shale ................ Shale ..............- ........ 60-90 Permian •.•......... Chase group ....... Fort Riley limeetone ....... Limestone ................. 40-50 Florence flint .............. Cherty limestone..... -...... 20-35 Matfield shale ............. Shale ...................... 57-70 Wreford limestone ......... Limestone .... .'............ 28-50 "lG Garrison formation ......... Shale and thin limestones .. 135-150 Councl rove group Cottonwood limestone ....... Limestone ......... -... ----- 5-12 Eskrid~e shale. ~ .......... Shale ...................... 30-40 Neva limestone ............ Limestone ................. 10 Elmdale formation ......... Shale and thin limestones .. 130 Americus limestone ....... Limestone ................. 8 Wabaunsee group ... Admire shale ............. Shale ...................... 300 Emporia limestone ........ Limestone ................. 9 Willard shale ............. Shale ...................... 45-55 Burlingame limestone ...... Limestone ................. 7-12 Scranton shale ............ Shale ...................... 160-200 Howard limestone ........ Limestone ................. 3-7 Severy shale .............. Shale ...................... 40-60 Topeka limestone .... ~ ..... Limestone ................. 20-25 Shawnee group .... Calhoun shale ............. Shale ........... ~ .......... 25-50 Deer Creek limestone ...... Limestone ................. 20-30 Tecumseh shale ........... - Shale ...................... 40-70 Lecompton limestone ...... Limestone ................. 15-30 Kanwaka shale ........... Shale ...................... 50-100 Oread limestone........... Limestone................... 50-70 D Lawrence shale ........... - Shale....................... 150-300 · oug1 as group.····· Iatan limestone ........... - Limestone.................. 3-15 Pennsylvanian...... Weston shale .............. Shale....................... 60-100 --1----- Stanton limestone .......... Limestone.................. 20-40 L · p Vilas shale. Shale........... 0-125 ansmg grou · · · · · · Plattsburg limestone ...... - - Lii~testone ... -- ·. -.- ---· - -.. 4-80 Lane shale.. Shale............. 50-150 lola limestone ............. Limestone ................. 0-40 Chanute shale ............ Shale ...................... 25-100 Drum limestone ........... Limestone .....- ............ 0-80 Cherryvale shale .......... Shale ................ _-_ .... 25-125 Kansas City group .. Winterset limestone ....... Limestone ................. 5-30 Galesburg shale ........... Shale ...................... 5-60 Bethany Falls limestone ... Limestone ................. 4-23 Ladore shale .............. Shale ..............•........ 3-40 Hertha limestone ......... Limestone ................. 0-22 Dudley shale. Shale .................... 160 Pleasanton group... Parsons formation. Shale and limestone ....... 80 Bandera shale ............. Shale .................... 60-140 Pawnee limestone. Limestone ................. 45-52 Henrietta group..... Labette shale. Shale ...... ~ ....... _....... 20-120 Fort Scott limestone ........ Limestone ................. so Cherokee shale...... Shale .... '.................. 350-700 Unconiormity------II----------------I-------------------1---------------------!--------- Mississippian ........ Boone limestone ........... Limestone ................. 300-500 Unconformity------I----------------I----------------------I------------------------1---------- 0rdovician and Cam- Dolomite and sandstone..... 1, ooo-2, 200 brian. Unconfonnuy------~-------------------·------------------I-----------------------1----------- Pre-Cambrian ..........•..................................... , . Granite ................... FAULTS, ANTICLINES, AND BURIED "GRANITE RIDGE" OF MID-CONTINENT FIELD. 77 generally termed "granite wells." The crys­ as a part of the Ozark uplift itself but as the talline basement thus encountered is much shal­ Prairie Plains monocline. lower than had previously been thought possi­ Cambrian, Ordovician, and Mississippian ble. In places it lies less than 1,000 feet below strata were involved in both phases of this the surface, and in these localities it is directly widespread Ozark deformation, but the over­ overlain by upper Pennsylvanian rocks, and lying Pennsylvanian and Permian formations these in turn by Permian rocks. In the light of were affected only by the post-Paleozoic dis­ available evidence it now seems probable that turbance. The time occupied by the first de£­ the granite thus discovered indicates the pres­ ormational period is represented in an exten­ ence of a buried " ridge " (named the Nemaha sive erosional unconformity, with no marked Mountains by Moore and Haynes), which prob­ angular divergence between the Mississippian ably formed a low island in the early Pennsyl­ and Pennsylvanian series. Although the first vanian sea and was entirely covered by later phase of the Ozark deformation took place be­ sediments. fore the deposition of the Pennsylvanian strata, The
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