THE LOWER CRETACEOUS in EAST-CENTRAL UTAH—THE CEDAR MOUNTAIN FORMATION and ITS BOUNDING STRATA James I
Total Page:16
File Type:pdf, Size:1020Kb
GEOLOGY OF THE INTERMOUNTAIN WEST an open-access journal of the Utah Geological Association Volume 3 2016 THE LOWER CRETACEOUS IN EAST-CENTRAL UTAH—THE CEDAR MOUNTAIN FORMATION AND ITS BOUNDING STRATA James I. Kirkland, Marina Suarez, Celina Suarez, and ReBecca Hunt-Foster A Field Guide Prepared For SOCIETY OF VERTEBRATE PALEONTOLOGY Annual Meeting, October 26 – 29, 2016 Grand America Hotel Salt Lake City, Utah, USA Pre-Meeting Field Trip October 23–25, 2016 © 2016 Utah Geological Association. All rights reserved. For permission to copy and distribute, see the following page or visit the UGA website at www.utahgeology.org for information. Email inquiries to [email protected]. GEOLOGY OF THE INTERMOUNTAIN WEST an open-access journal of the Utah Geological Association Volume 3 2016 Editors UGA Board Douglas A. Sprinkel Thomas C. Chidsey, Jr. 2016 President Bill Loughlin [email protected] 435.649.4005 Utah Geological Survey Utah Geological Survey 2016 President-Elect Paul Inkenbrandt [email protected] 801.537.3361 801.391.1977 801.537.3364 2016 Program Chair Andrew Rupke [email protected] 801.537.3366 [email protected] [email protected] 2016 Treasurer Robert Ressetar [email protected] 801.949.3312 2016 Secretary Tom Nicolaysen [email protected] 801.538.5360 Bart J. Kowallis Steven Schamel 2016 Past-President Jason Blake [email protected] 435.658.3423 Brigham Young University GeoX Consulting, Inc. 801.422.2467 801.583-1146 UGA Committees [email protected] [email protected] Education/Scholarship Loren Morton [email protected] 801.536.4262 Environmental Affairs Craig Eaton [email protected] 801.633.9396 Geologic Road Sign Terry Massoth [email protected] 801.541.6258 Historian Paul Anderson [email protected] 801.364.6613 Membership Rick Ford [email protected] 801.626.6942 Public Education Paul Jewell [email protected] 801.581.6636 Matt Affolter [email protected] Publications Roger Bon [email protected] 801.942.0533 Publicity Paul Inkenbrandt [email protected] 801.537.3361 Social/Recreation Roger Bon [email protected] 801.942.0533 Society of Vertebrate Paleontology AAPG House of Delegates Editors 2016-2018 Term Craig Morgan [email protected] 801.422.3761 James I. Kirkland (Editor-in-Chief) — Utah Geological Survey State Mapping Advisory Committe ReBecca Hunt-Foster — Bureau of Land Management UGA Representative Jason Blake [email protected] 435.658.3423 Greg McDonald — Bureau of Land Management Martha Hayden — Utah Geological Survey Earthquake Safety Committe Production Chair Grant Willis [email protected] 801.537.3355 Cover Design and Desktop Publishing UGA Website Douglas A. Sprinkel www.utahgeology.org Cover Webmasters Paul Inkenbrandt [email protected] 801.537.3361 Cedar Mountain Formation at the Stikes Quarry Lance Weaver [email protected] 801.403.1636 on Utahraptor Ridge. The Stike Quarry (just below sandstone cliff) is in the upper Yellow Cat Member. UGA Newsletter The underlying Morrison Formation is the reddish Newsletter Editor Bob Biek [email protected] 801.537.3356 slope at the bottom of photograph and the Naturita Become a member of the UGA to help support the work of the Association and Formation caps the ridge. receive notices for monthly meetings, annual field conferences, and new publi- cations. Annual membership is $20 and annual student membership is only $5. Visit the UGA website at www.utahgeology.org for information and membership application. This is an open-access article in which the Utah The UGA board is elected annually by a voting process through UGA Members. Geological Association permits unrestricted use, However, the UGA is a volunteer driven organization, and we welcome your distribution, and reproduction of text and figures that voluntary service. If you would like to participate please contact the current are not noted as copyrighted, provided the original president or committee member corresponding with the area in which you would author and source are credited. like to volunteer. Utah Geological Association formed in 1970 from a merger of the Utah Geological Society, founded in 1946, and the Intermountain Association of Geologists, founded in 1949. Affiliated with the American Association of Petroleum Geologists. i GEOLOGY OF THE INTERMOUNTAIN WEST an open-access journal of the Utah Geological Association Volume 3 2016 The Lower Cretaceous in East-Central Utah—The Cedar Mountain Formation and its Bounding Strata James I. Kirkland1, Marina Suarez2, Celina Suarez3, and ReBecca Hunt-Foster4 1Utah Geological Survey, P.O. Box 146100, Salt Lake City, Utah, 84114; [email protected] 2Department of Geological Sciences, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249; [email protected] 3Department of Geosciences, University of Arkansas, 226 Gearhart Hall, Fayetteville, Arkansas, 72701; [email protected] 4Canyon Country District, Bureau of Land Management, 82 East Dogwood, Moab, Utah, 84532; [email protected] ABSTRACT Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratig- raphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedi- mentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow. INTRODUCTION These stops focus on the eastern exposures of the Ce- dar Mountain Formation including the definition of its This field trip begins in Salt Lake City and proceeds members, their contacts, and how they document active southeast across Utah. During the morning of Day 1 salt tectonics in the northern Paradox Basin during the south of Interstate 70 (I-70) along Yellow Cat Ranch Early Cretaceous (figure 1). The afternoon of Day 1 will Road on lands managed by the Bureau of Land Man- be spent examining the exposures of the Cedar Moun- agement (BLM), northeast of Arches National Park. tain Formation on lands managed by the State of Utah Citation for this article. Kirkland, J.I., Suarez, M., Suarez, C., and Hunt-Foster, R., 2016, The Lower Cretaceous in east-central Utah—the Cedar Mountain Formation and its bounding strata: Geology of the Intermountain West, v. 3, p. 101–228. © 2016 Utah Geological Association. All rights reserved. For permission to use, copy, or distribute see the preceeding page or the UGA website, www.utahgeology.org, for information. Email inquiries to [email protected]. 101 The Lower Cretaceous in East-Central Utah—The Cedar Mountain Formation and its Bounding Strata Kirkland, J.I., Suarez, M., Suarez, C., and Hunt-Foster, R. Figure 1. Map of Utah with location of field trip stops and outcrops of Cedar Mountain Formation. Geology of the Intermountain West 102 2016 Volume 3 The Lower Cretaceous in East-Central Utah—The Cedar Mountain Formation and its Bounding Strata Kirkland, J.I., Suarez, M., Suarez, C., and Hunt-Foster, R. west of Arches National Park where outcrops show con- • Denver Museum of Nature and Science; DMNH# trasting the effects of salt tectonics on either side of the • Dinosaur National Monument; DNM# Salt Valley anticline during the Early Cretaceous. Addi- • Oklahoma Museum of Natural History, Norman, tionally, we will examine the BLM’s Mill Canyon Track- Oklahoma; OMNH# site that has been newly developed as an interpretive • Utah Natural History Museum, Salt Lake City, site. The first and second nights will be spent in Green Utah; UMNH# River, Utah. The morning of Day 2 will be spent exam- • Utah State University Eastern, Prehistoric ining the Cedar Mountain south of Green River. The Museum, Price, Utah: uses locality numbers from afternoon will be spent examining outcrops of the Ce- Utah Paleontological Locality Database (UPLD); dar Mountain Formation between Hanksville and Cap- Utah (County abbreviation)# itol Reef National Park where outcrops display lateral • Utah Geological Survey (UGS): uses numbers changes in the upper and lower contacts of the Cedar from UPLD unless already curated into a recog- Mountain relative to the interface between the Paradox nized Utah repository; Utah (County abbrevia- Basin and the forebulge as expressed by the San Rafael tion) # Swell. Before returning to Salt Lake City on Day 3, we Localities plotted on stratigraphic sections are cor- will proceed west on I-70 to the western side of the San related into the line of