Foss. Rec., 18, 81–104, 2015 www.foss-rec.net/18/81/2015/ doi:10.5194/fr-18-81-2015 © Author(s) 2015. CC Attribution 3.0 License. Late Viséan (late Mississippian) ammonoids from the Barnett Shale, Sierra Diablo Escarpment, Culberson County, Texas, USA A. L. Titus1, D. Korn2, J. E. Harrell3, and L. L. Lambert4 1Grand Staircase–Escalante National Monument, 669 S. Highway 89A, Kanab, UT 84741, USA 2Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany 3Noble Energy Inc., Houston, TX 77070, USA 4Department of Geological Sciences, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA Correspondence to: A. L. Titus ([email protected]) Received: 3 February 2015 – Revised: 7 April 2015 – Accepted: 22 April 2015 – Published: 4 June 2015 Abstract. Mid-Carboniferous strata of the Barnett Shale in 1 Introduction the Sierra Diablo region are deep water, offshore sediments deposited in the Marathon Foreland Basin. These strata contain a remarkably complete ammonoid record spanning Late Viséan (Goniatites and Neoglyphioceras genus zones from the Late Viséan to the middle Atokan (Moscovian). sensu Ramsbottom and Saunders, 1985) ammonoids are Late Viséan strata are referred to as the “Folks Member” of widespread in foreland basin settings around the margin of the Barnett Shale and locally yield numerous ammonoids. the North American continent and have been described or Three assemblages can be recognized, which contain, from illustrated from the Chainman Shale of Nevada and Utah oldest to youngest, Goniatites eganensis and Girtyoceras (Miller et al., 1949, 1952; Gordon, 1965, 1971; Furnish and hamiltonense (Goniatites eganensis Zone), Goniatites Saunders, 1971; Titus and Riley, 1997), the Barnett Shale of multiliratus and Girtyoceras meslerianum (Goniatites central Texas (Smith, 1903; Plummer and Scott, 1937; Miller multiliratus Zone), and Choctawites cumminsi and Pachy- and Youngquist, 1948; Miller and Downs, 1950; Plummer, lyroceras cloudi (Choctawites cumminsi Zone). We erect 1950; Elias, 1956; Gordon, 1960, 1965), the Caney Shale the new genera Choctawites and Uralyroceras to accommo- of Oklahoma (Girty, 1909; Miller and Furnish, 1940a; Gor- date, respectively, the North American species “Goniatites don, 1962, 1965; Branson, 1964; McCaleb et al., 1964; Saun- choctawensis Shumard, 1863”, “G. kentuckiensis Miller, ders et al., 1977; Korn et al., 2004), the Moorefield For- 1889” and “G. cumminsi Hyatt, 1893”, and Uralian species mation of Arkansas (Girty, 1911; Gordon, 1965; Saunders formerly attributed to Pachylyroceras. For the material of et al., 1977), the Pride Mountain Shale of Alabama (Dra- “Pachylyroceras cloudi” of the South Urals, the new species hovzal, 2009), the Newman Limestone and equivalent forma- name Uralyroceras arquatum is proposed. tions of Kentucky (Miller and Faber, 1892; Miller and Gur- ley, 1896; Smith, 1903; Miller and Furnish, 1940a; McCaleb ZooBank: http://zoobank.org/References/6C6A1411- et al., 1964; Gordon, 1965; Furnish and Saunders, 1971; Ti- F88F-45C2-BA4A-D97C4CD4B415 tus and Riley, 1997; Work and Mason, 2009b), and the Ste. Genevieve Limestone of Illinois and Indiana (Smith, 1903; Collinson, 1955). Although mentioned repeatedly in the literature and tab- ulated in a 50-year-old faunal list (King, 1965), the Late Viséan ammonoids of the Barnett Shale (Helms Formation of most older papers) in west Texas have never been previ- ously described. Intrigued by this repeated mention in the Published by Copernicus Publications on behalf of the Museum für Naturkunde Berlin. 82 A. L. Titus et al.: Late Viséan (late Mississippian) ammonoids from the Barnett Shale by McCaleb et al. (1964, pl. 2, figs. 8, 9) and a specimen of Pachylyroceras cloudi in Furnish and Saunders (1971, pl. 2, fig. 5). The next year, King (1965) listed eight Viséan species from the Barnett Shale; “Goniatites crenistria Phillips”, “Go- niatites choctawensis Shumard”, “Goniatites sp.”, “Girty- oceras sp. cf. G. meslerianum (Girty)”, “Neoglyphioceras cloudi (Miller and Youngquist)”, “Neoglyphioceras sp.”, and “Lyrogoniatites sp. cf. L. newsomi (Smith)” based on collec- tions made by J. B. Knight, A. K. Miller, and W. M. Fur- nish in the 1930s and 1940s. We have not examined the col- lections that the faunal list was based upon, but it is clear they are stratigraphically mixed; “Goniatites crenistria” and “Girtyoceras sp. cf. G. meslerianum” are from our low- est recognized ammonoid zone (Goniatites eganensis Bio- zone) and the remainder of material from our newly estab- lished Choctawites cumminsi Zone. Because King’s collec- tions were actually tied to a published measured section, we Figure 1. Reference map showing location of the Figure 2 Ranch consider this the only other significant report of Viséan am- King section, Sierra Diablo, Culberson County, Texas. monoids from the Sierra Diablo region. In contrast, there are several mentions that Mississippian ammonoids occur in the Sierra Diablo within faunal descriptions of material literature of abundant late Mississippian ammonoids in the from other localities (Miller and Furnish, 1940a; Miller and Sierra Diablo and the total lack of detailed description of Youngquist, 1948; Youngquist, 1949). the fauna, in 2000 A. L. Titus twice visited the Figure 2 Ranch (then owned by the very gracious Mr Ron Stasny) where the only significant Mississippian ammonoid bearing 3 Stratigraphy of the Sierra Diablo (A. L. Titus, J. E. strata crop out (Fig. 1). It quickly became obvious that the Harrell, L. L. Lambert) Figure 2 Ranch section preserves one of the most important ammonoid-bearing late Mississippian to early Pennsylvanian 3.1 Geological overview sections in North America, and possibly the world. Subse- quently to A. L. Titus’ work on the Figure 2 Ranch, L. L. The Carboniferous stratigraphy of the Sierra Diablo was re- Lambert initiated field studies on the Figure 2 Mississippian cently summarized by Harrell (2007). Virtually every ma- section with J. E. Harrell in 2003 and 2004, measuring sec- jor stratigraphic unit from the Viséan to the Bashkirian has tions and making extensive collections of both Mississippian yielded ammonoids in this region (Harrell, 2007), with the and Pennsylvanian ammonoids. Viséan to late Serpukhovian section being particularly fos- Unfortunately, since the Figure 2 Ranch was sold in 2005, siliferous and rich in ammonoids. All of the Viséan mate- researchers have no longer had access. Harrell (2007) pre- rial in this report came from the “Folks Member” of the sented an overview of the ammonoids they had recovered as Mississippian–Pennsylvanian Barnett Shale, which is ex- part of the stratigraphic revision they were recommending for posed in only three places in the northeast portion of the the Carboniferous of the region. This paper describes for the Sierra Diablo below an imposing escarpment formed out of first time the complete Late Viséan ammonoid succession of the Permian Hueco Formation (King, 1965), entirely within the Barnett Shale at the Figure 2 Ranch, needed now more the Figure 2 Ranch property. Although generally homocli- than ever since there will be no access to this locality in the nal and south-dipping, the Folks Member is locally faulted, foreseeable future. folded, and intruded by small dikes and sills which caused local contact metamorphism. The entire pre-Permian section was folded, faulted, and eroded into a peneplain during the 2 Previous work Ouachita Orogeny before being covered by the sediments of the Permian Paw Paw Formation, which along with the Although Pennsylvanian (Atokan) ammonoids have been Hueco Formation is the source for most of the erosional de- extensively described and figured from the Sierra Diablo bris that covers the non-resistant Folks Member. (Plummer and Scott, 1937; Miller and Furnish, 1940b, 1958), The Folks Member is comprised mostly of mudstone and no systematic analysis of Viséan ammonoids from this re- siltstone, with prominent carbonate concretions, phosphatic gion has ever been published. Prior to this work, only two pebble-rich lags, and thin-bedded pelagic micritic limestone Viséan specimens had been figured from the area; a “Girty- that all point towards a largely sediment-starved depositional oceras meslerianum” (referred to by us as G. hamiltonense) regime during the Late Viséan and early Serpukhovian (Ti- Foss. Rec., 18, 81–104, 2015 www.foss-rec.net/18/81/2015/ A. L. Titus et al.: Late Viséan (late Mississippian) ammonoids from the Barnett Shale 83 Local Ammonoid Zonation STAGE UNIT FORMATION 43 42 41 40 39 38 . barnettense cf 37 00TXCU-31 . sp . 35 00TXCU-28 . 34 sp sp 33 . varians 32 cf ??? 31 29 00TXCU-29 Paracravenoceras ozarkense Syngastrioceras scotti Cravenoceras Tumulites Tumulites Paracravenoceras ? 00TXCU-30 Fayettevillea Tumulites varians 28 27 unzoned 26 24 00TXCU-27 Choctawites cumminsi 22 21a unzoned 20 19 00TXCU-26 17 00TXCU-25 Goniatites multiliratus 16 15 00TXCU-24 Barnett Shale (Folks Member) Pachylyroceras cloudi 14 Choctawites cumminsi 13 00TXCU-23 11 00TXCU-22 Goniatites eganensis 9 00TXCU-21a; 21b Goniatites multiliratus V I S É A NA V I S É N A U K H O V I S E R P 8 Girtyoceras meslerianum ??? 7 6 5 4 Goniatites eganensis Cluthoceras 3 1m Girtyoceras hamiltonense 2 1 0 Silt Mud Pebble Fine S. Crse S. Med. S. Figure 2. Columnar King’s section on the Figure 2 Ranch, Sierra Diablo, Texas, with the position of fossil samples and proposed biostrati- graphic attribution. tus, 1999). This character is generally similar to that of time- detailed analysis when all access to the Figure 2 Ranch to equivalent strata of the Barnett Shale exposed in the Llano researchers was ended. Fortunately the other two sections do Uplift, which is even more condensed than the Sierra Dia- not appear to preserve any fauna or significant horizons not blo section. The Folks Member is abundantly fossiliferous seen at King’s section. and yields a largely pelagic fauna, but also a dwarf, low di- versity benthic assemblage of gastropods and bivalves in the 3.2 King’s section phosphate pebble lag horizons.