The area under consideration has a dimension of 8 miles east-west and 4 miles north-south, and includes the canyons of Spring Creek and Hobble Creek, Utah County, Utah. These streams flow off the west flank of a southern portion of the Wasatch Range, and have cut canyons to a depth of over 3,000 feet, exposing sections of upper Paleozoic sediments. Pennsylvanian rocks in the vicinity of the southern Wasatch Mountains have received little attention from stratigraphers. In this paper an attempt is made to describe the sequence of Pennsylvanian rocks in the region

Bissell, H. J.

English

Name not available

Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, Utah

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 43 Annual Issue Article 57 1936 Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, Utah H. J. Bissell State University of Iowa Copyright ©1936 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Bissell, H. J. (1936) "Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, Utah," Proceedings of the Iowa Academy of Science, 43(1), 239-243. Available at: https://scholarworks.uni.edu/pias/vol43/iss1/57 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. PENNSYLVANIAN STRATIGRAPHY IN THE SOUTH-ERN WASATCH l\IOUNTAINS, UTAH H. J. BISSELL The area under consideration has a dimension of 8 miles east-west and 4 miles north-south, and includes the canyons of Spring Creek and Hobble Creek, Utah County, Utah. These streams flow off the west flank of a southern portion of the \Vasatch Range, and have cut canyons to a depth of over 3,000 feet, exposing sec-tions of upper Paleozoic sediments. Pennsylvanian rocks in the vicinity of the southern Wasatch Mountains have received little attention from stratigraphers. In this paper an attempt is made to describe the sequence of Penn-sylvanian rocks in the region. PENNSYGVANIAN Svsn:l\r There are exposed about 4,000 feet of Pennsylvanian sediments. In lithology they consist essentially of interbedded limestones and sandstones, with a subordinate amount of shale, and at two hori-zons conglomerates occur. Some of the limestone is siliceous and some of the sandstone is quite quartzitic. These rocks have never been described, but have been briefly referred to the Oquirrh formation, which has its type section in the southern Oquirrh Mountains. 0Ql'IRRH ( ?) FORMATION Lithology -The Oquirrh ( ?) formation has two facies which can be recognized readily. The lower facies is made up of sand-stones, limestones, shales, and conglomerates. The sandstones are generally fine-grained rocks, rather dark gray to grayish-green on fresh fracture and rather reddish brown on weathered surfaces. The cletrital grains of quartz are usually visible to the naked eye. The sandstones themselves are not resistant to erosion, and some of them show distinct laminations. Silica-cemented sandstones predominate over lime-cemented sandstones, and there seems to he no systematic relation between the two varieties of cementing material. The limestones vary greatly in nature, and this has undoubtedly resulted from varying conditions of deposition. l\J any of the limestones are fine-grained, dark bluish-gray on fresh fracture anrl 239 1Bissell: Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, UtaPublished by UNI ScholarWorks, 1936240 IOWA ACADEMY OF SCIENCE [VOL. XLIII light bluish-gray on the weathered surface. Such beds sometimes contain silica, as much as 50%, either in the form of sandy laminae or as chert nodules or chert replacements of fossils. There is some thin-bedded platy limestone which is nearly black on fresh fracture and purplish on weathering. Such beds are frequently fossiliferous and contain large numbers of Fusulinids. The shales are usually chocolate brown to light brown in color and may be sandy or limy. They are generally not very compact. The conglomerates constitute but two stratigraphic beds, one being over 500 feet above the other. These beds are composed of angular blocks of limestone and sandstone. The angular blocks show very little evidence of mechanical wear, and are as large as one foot across a face. This lower facies is predominantly sandstone and limestone interbedded. It is a very pronounced fact that the sandstone is quite calcareous, and the limestone is very siliceous, in some in-stances exceeding 50% quartz grains. There are, of course, many quite pure limestones, and many such sandstones, but the tendency is towards a gradation between the two. The upper facies of the Oquirrh ( ?) formation shows a distinct change from the lower one, this being indicated in four character-istics: ( 1) the upper facies shows a marked increase in thickness of beds of limestone, and also in thickness of beds of sandstone, with some beds in each being in excess of 100 feet thick, as com-pared with 5 to 20 feet thick in many of the beds of the lower facies; (2) there is a lack of both shales and conglomerates; ( 3) many of the limestones change from finely crystalline to coarsely crystalline texture, and sandstones show an increase in the number of sand grains; ( 4) there is a distinct tendency for the limestones to become quite pure in composition, having in some cases 98% soluble material, essentially calcite. The sandstones tend towards an increase in quartz. In the upper facies is exhibited also a change in the color of sediments, the limestones becoming darker, and the sandstones becoming more reddish-brown. The writer feels that the present nomenclature is insufficient for the needs of describing the Pennsylvanian sediments of the south-ern \Vasatch Mountains. The suggestion is here made that in this region the term Oquirrh be elevated to the rank of series to in-clude all the beds from lower to upper Pennsylvanian, and that the lower facies be named the Kelly formation, and the upper facies be named the Hobble formation. 2Proceedings of the Iowa Academy of Science, Vol. 43 [1936], No. 1, Art. 57https://scholarworks.uni.edu/pias/vol43/iss1/571936] PENNSYLVANIAN STRATIGRAPHY 241 TYPE SECTION OF BEDS OF KELLY FORMATION IN HOBBLE CREEK CANYON Central portion of T. 7 S., R. 3 E., Utah Thickness Bed Description in feet 19 Sandstone, friable; some limestone present________________ 122 18 Conglomerate, angular fragments of limestone and sandstone are 1 to 12 inches square---------------------------------- 8 17 Limestone, siliceous, interbedded with sandstone, quartzitic, both gray in color--------------------------------'------- 210 16 Sandstone, light-gray to brown, interbedded with limestone, finely crystalline, light blue to gray color----------------- 215 15 Conglomerate, angular fragments as in bed 18_____________ 20 14 Limestone, siliceous, resistant, gray_______________________ 20 13 Sandstone, soft, friable, interbedded with limestone, siliceous, finely crystalline; bedding 1-4 inches______________________ 195 12 Shale, sandy, chocolate color, beds 1-4 inches_______________ 12 11 Limestone, siliceous, light-gray; bedding 4 inches to 12 feeL- 70 IO Sandstone, slightly calcareous, light brown, interbedded with limestone, highly siliceous, light gray; bedding 1-3 feet____ 290 9 Sandstone, soft, friable, reddish-brown on weathered surface, grayish-green on fresh fracture; bedding 6 inches to 5 feet__ 100 8 Shale, sandy, brown; bedding t inch- 4 inches____________ 50 7 Limestone, siliceous, dark gray, interbedded with sandstone, calcareous; bedding 3 feeL------------------------------- 205 6 Limestone, light-gray, slightly siliceous___________________ 9 5 Sandstone, calcareous, light brown, interbedded with siliceous gray limestone ------------------------------------------- 230 4 Limestone, grades from very cherty below to slightly cherty above --------------------------------------------------- 105 3 Limestone, blue on surface, dark to black on broken or fractured surface ---------------------------------------- 8 2 Sandstone, quartzitic, with lens of siliceous limestone, both light brown to graY------------------------------------- 9 Limestone, finely crystalline and light blue to gray in color -- 6 TotaL___ 1,885 TYPE SECTION OF BEDS OF HOBBLE FORMATION IN HOBBLE CREEK CANYON East-central portion of T. 7 S., R. 3 E., Utah Thickness Bed Description in feet 35 Sandstone, very quartzitic, some lenses of very slightly siliceous limestone, both rocks brown to reddish-brown____ 30 34 Limestone, medium crystalline and very resistant; dark blue in color-------------------------------------------------- 12 33 Sandstone, very quartzitic, light brown____________________ 60 32 Limestone, medium to coarsely crystalline; very resistant, dark blue in color---------------------------------------- 10 3Bissell: Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, UtaPublished by UNI ScholarWorks, 1936242 IOWA ACADEMY OF SCIENCE [VoL. XLIII 11 Sandst-0ne, friable, lenses of limestone, almost pure; both beds gray to brown in color----------------------------- 20 30 Limestone, partly sandy, with interbeddings of quartzitic sandstone ------------------------------------------------ 400 29 Sandstone, quartzitic, interbedded with limestone, slightly siliceous; both light gray to brown in color; have iron oxide coating -------------------------------------------------- 150 28 Limestone, medium crystalline, dark blue in color; has veins of aragonite --------------------------------------------- 25 27 Sandstone, highly quartzitic, light-brown color, interbedded with limestone, slightly siliceous, light-gray in color-------- 350 26 Limestone, medium crystalline, dark blue to black in color__ 4 25 Limestone, slightly siliceous, interbedded with very quartz-itic sandstone; both rocks light gray to brown color-------- 150 24 Sandstone, very quartzitic, light gray; lens of sandy limestone in lower 10 feeL---------------------------------------- 350 23 Limestone, medium crystalline, light gray, lower 15 feet has 3-8 inch bedding_________________________________________ 85 22 Limestone, light gray to blue color, slightly shaly; bedding 3-8 inches ----------------------------------------------- 15 21 Limestone, finely crystalline, massive, has 4 ft. lens siliceous limestone ------------------------------------------------ 50 20 Limestone, medium crystalline, light gray to blue color ; bedding 2-6 feet----------------------------------------- 100 TotaL___ 1,751 The locality to study the type sections of these Pennsylvanian formations is in the central portion of Township 7 South, Range 3 East, east of Springville, Utah County, Utah, in Hobble Creek canyon. DEPOSITION OF THE SEDIMENTS The contact between the limestone and sandstone beds is usually distinct, indicating a rapid change in the conditions of deposition. These Pennsylvanian formations were deposited at the critical point of sedimentation - the boundary line between the arenaceous detrital deposits and those calcareous sediments which derived but part of their material directly from the degradation of the land. The closely alternating beds of these formations does not neces-sarily indicate repeated minor oscillations of the sea bottom during their deposition. The beds containing the elastic rocks were probably worked by currents during their deposition. Yet the fine limestones, which rest directly upon the sandstones and interbed with them might have had an environment free from powerful currents. It appears that in the region of the southern Wasatch Mountains 4Proceedings of the Iowa Academy of Science, Vol. 43 [1936], No. 1, Art. 57https://scholarworks.uni.edu/pias/vol43/iss1/571936] PENNSYLVANIAN STRATIGRAPHY 243 the Oquirrh ( ?) series was deposited in relatively shallow water not far from l~nd and upon an unevenly and constantly sinking sea bottom. DEPARTMENT OF GEOLOGY, STATE UNIVERSITY OF lowA, low A CITY, low A. 5Bissell: Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, UtaPublished by UNI ScholarWorks, 1936

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Pennsylvanian Stratigraphy in the Southern Wasatch Mountains, Utah

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