Marine Jurassic Gastropods, Central and Southern Utah GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-D Marine Jurassic Gastropods, Central and Southern Utah By NORMAN F. SOHL CONTRIBUTIONS TO PALEONTOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-D A descrzption of I9 species of gastropods from the Ba;"ocian to Callovian rocks of Utah, supplemented by a discussion of the Jurassic gastropodfauna of North America UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1965 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 45 cents (paper cover) CONTENTS Page Abstract------------------------------------------------------------------- I>1 Introduction_______________________________________________________________ 1 Analysis of the gastropod fa una_ _ _ _ _ __ _ _ _ __ __ _ _ _ __ _ _ _ __ __ _ _ _ _ __ _ _ _ _ __ _ _ _ _ __ _ _ 4 Abundance_____________________________________________________________ 5 Preservation of the fossils, and notes on ecology____________________________ 6 Geographic and stratigraphic distribution__________________________________ 7 Survey of Jurassic gastropods of North America________________________________ 8 ~exico________________________________________________________________ 8 United States (conterminous)_ _ _ _ _ _ __ __ _ _ _ _ __ _ _ __ _ _ _ _ _ _ __ __ _ _ _ _ _ _ _ __ _ __ _ _ 8 Gulf coast_ _ _ _ _ _ _ _ __ _ _ _ __ _ _ _ _ __ _ _ _ __ _ __ _ _ _ _ _ _ __ _ _ __ __ __ __ _ __ _ _ _ __ _ _ 8 VVestTexas-------------------------------------------------------- 9 VV estern interior_ _ _ _ _ __ __ __ __ _ _ __ _ _ __ _ _ _ __ __ _ _ _ _ _ __ _ __ __ __ _ _ _ __ _ _ __ _ 9 Pacific coast------------------------------------------------------- 12 Canada---------------------------------------------------------------- 12 Alaska________________________________________________________________ 12 SummarY-------------------------------------------------------------- 13 Systematic paleontology_____________________________________________________ 15 References cited_ __ __ _ _ _ _ __ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ __ __ __ __ _ _ __ __ _ _ __ _ 24 Index--------------------------------------------------------------------- 27 ILLUSTRATIONS [Plates follow index] PLATE 1. Trochacea?, Teinostomopsis?, Ooliticia?, Pleurotomaria?, Nododelphinula?, Amberleya?, Cylindrobullina?, Neri- domus?, and Symmetrocapulus? 2. Lyosoma. 3. Rhabdocolpus, Pseudomelania?, Procerithium? and Neritina? 4. Cossmannea, Globularia?, Tylostoma? 5. Specimens of Carmel limestone. Page FIGURE 1. Index map of central and southwestern Utah____________________________________________________________ ]) 2 2. Geographic and stratigraphic distribution of the Gastropoda of the Carmel Formation________________________ 5 TABLES Page TABLE 1. Localities at which marine gastropods of Jurassic age have been collected in central and southern Utah__________ I>3 2. Abundance of the Gastropoda of the Carmel Formation_ _ _ _ __ __ _ _ _ __ __ _ _ _ __ __ __ __ _ __ __ _ _ __ _ _ _ _ __ _ _ _ __ _ __ _ 6 ni CONTRIBUTIONS TO PALEONTOLOGY MARINE JURASSIC GASTROPODS, CENTRAL AND SOUTHERN UTAH By NoRMAN F. SoHL ABSTRACT geologists of the U.S. Geological Survey, during recent This ,paper describes a gastropod fauna of 19 species assigned years has provided sufficient collections and detailed to 17 genera from the lower limy units of the Carmel Forma­ stratigraphic information to make a study of this fauna tion and from the Twelvemile Canyon Member of the Arapien especially profitable. Shale (Bajocian to Callovian) in central and southwestern This report on the gastropods of the Carmel Forma­ Utah. These descriptions constitute the first report for most tion and the Twelvemile Canyon Member of the Arapien of the genera from the Jurassic of North America. The Carmel gastropod fauna is a shallow-water one dominated by Archaeo­ Shale supplements the report by Imlay (1964) on the gastropoda and Mesogastropoda, primarily the cerithiaceans, pelecypods. He provided an outline of the stratigraphy, naticaceans, and neritaceans such as Lyosmna. Neogastropoda age, and correlation of the Carmel Formation and dis­ are absent, and Euthyneura are represented only by the nerineids cussed the relationships of the collecting localities. The and the cephalas,pid genus OylindrobulUna. Of special note is stratigraphy and lithology of the units of the formation the neritid Lyoswna, which heretofore has been thought to lack an inner lip septum. Silicified specimens retain such a lip and were described by Baker, Dane, and Reeside (1936) and show that its loss is probably due to differential replacement of summarized by Wright and Dickey ( 1958, 19,63). shell layers. The Carmel Formation may be divided into two units. Gastropods are most common in the central area of outcrop A lower limy unit is dominated by gray limestone and of the Carmel Formation and lessen in diversity and abundance shale and, according to Imlay ( 1964, p. C3-C5), is of in the thinner sandier, nearer shore sediments to the east. Bajocian age. An upper unit is dominated by clay­ The fauna is most similar to that found in member B of the Twin Creek Limestone of Utah, Idaho, and Wyoming; but it also stone, siltstone, and gypsum but locally includes some has a close relationship to that in the Gypsum Spring Formation sandstone. The whole formation becomes thinner, and "Lower Sundance Formation" of Wyoming. sandier, and redder toward the east and finally changes A survey of the Jurassic gastropods of North America indi­ into reel beds. Frmn the featheredge in southeastern cates that they are not so diverse as are those of Europe. lTtah, the formation thickens and becomes increasingly Taxonomically, they are dominated by the Archaeogastropoda calcareous to the northwest, and in Sanpete and Juab (especially Neritacea and Amberleyacea) and Mesogastropoda (primarily Pseudomelaniacea and Ceritheacea). No Neogas­ Counties the total thickness of the equivalent Arapien tropoda are present. Shale may reach 3,000 feet or more (Wright and Dickey, The Jurassic gastropods are very provincial. The gulf coast 1963). and west Texas gastropod faunas are similar in some respects, All the gastropods have come from the lower limy but have no species in common with those of the western interior. unit of the Carmel Formation, and like the pelecypods Similarly, the Alaskan gastropod fauna is distinct from those faunas to the south. Such differences are seen even at the (Imlay, 1964), they are most abundant in the middle family level where the Neritidae and Nerineacea, so common in area (fig. 1), which is approximately 40 miles wide and the southern faunas, are absent or poorly represented in Alaska. trends southwestward along the west side of the San In Alaska the Purpurinidae and Amberleyiidae are common Rafael Swell. Abundance of fossils diminishes to the but decrease in abundance southward to Mexico. east as the units thin and to the west as they thicken. In terms of age the Late Jurassic is the time of greatest The Arapien Shale consists of a lower gray cal­ gastropod diversity in the gulf coast and west Texas, but in the western interior and Alaska, the Middle Jurassic (Bathonian­ careous shale called the Twelvemile Canyon Member lower Callovian) interval shows the greatest flowering of and an upper red and gray siltstone and shale member gastropod faunas. called the Twist Gulch Member. In aggregate thick­ ness they may reach 10,000 feet. Gastropods are rare INTRODUCTION in the formation and occur only in the Twelverriile Little information on the nature of the 1nolluscan Canyon Member. Correlation with the Carmel Forma­ fauna of the Carmel Formation of central and southern tion must rest primarily on fauna other than gastropods. Utah has been published. Fieldwork, primarily by The gastropod fauna of the Carmel Formation is D1 D2 CONTRIBUTIONS TO PALEONTOLOGY small, consisting of 19 species assigned to 17 genera. tions, many representing different stratigraphic levels There are a few other gastropods in the fauna, but they at the 42 localities, are reported on herein. are too poorly preserved to merit even generic assign­ Special thanks are due my colleague R. W. Imlay ment. The gastropods all come from the lower limy of the U.S. Geological Survey, who first interested me unit of the Carmel Formation (Imlay, 1964) and from in the present study. He has not only aided as a critical equivalent units of the Arapien Shale. This unit of the reviewer but has also guided me to many of the collect­ Carmel Formation has yielded an abundance of fossils, ing localities and tutored me in Jurassic stratigraphy. but the gastropods usually are poorly preserved.- James C. Wright, also of the Survey, whose fieldwork As is· shown on figure 1 and table 2, gastropods have precipitated the present paper, is also due many thanks been collected at 42 localities in the Carmel Formation for serving as a field companion, guide, and technical and Arapien Shale. (See table 1.) Sixty-one collec- reviewer. 113° J U A B C 0 U N T Y COUNTY M L L A R B E A V E R C R 0 N C 0 0 U N T Y 37° --------------- FIGuRE 1.-Map of central and southwestern Utah showing localities at which Carmel and Arapien gastropods have been found. Numbers indicate collection localities referred to in text. MARINE JURASSIC GASTROPODS, CENTRAL AND SOUTHERN UTAH D3 TABLE !.-Localities at which marine gastropods of Jurassic age TABLE !.-Localities at which marine gastropods of Jurassic age have been collected in central and southern Utah have been collected in central and southern Utah-Continued usns usns Locality Mesozoic Collector, year of collection, description of locality, and Locality Mesozoic Collector, year of collection, description of locality, and on fig.