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B. R. Wardlaw

Publications and source records attributed to B. R. Wardlaw.

At least 19 recordsLinked to original sources
USGS2016

Streptognathodus isolatus new species (Conodonta): Proposed index for the Carboniferous-Permian boundary

Davydov et al. (1995) recently proposed the Aidaralash Creek section in northern Kazakhstan (Figures 2 and 3) as the Global Stratotype Section and Point (GSSP) for the base of the Permian System. The proposed boundary is the level in an evolutionary sequence where Streptognathodus wabaunsensis Gunnell gives rise to a descendent with an isolated node field on the inside of the upper platform surface. This morphotype constitutes a new and distinct species for which we propose the name Streptognathodus isolatus new species.

Journal of Paleontology↗
USGS2016

Bryozoa of the Murdock Mountain formation (Wordian, Permian), Leach Mountains, northeastern Nevada

A thin limestone tongue in the upper part of the Murdock Mountain Formation of northeastern Nevada contains abundant bryozoans of earliest Wordian age. This bryozoan fauna is close to the Kungurian-Kazanian boundary in Russia. These bryozoans are younger than those found in the Kaibab Formation of southern Nevada and slightly older than those in the Gerster Limestone of northern Nevada. This limestone tongue, herein referred to as the Stenodiscus beds, lies below the Thamnosia beds described by Wardlaw in the Murdock Mountain section of the Leach Mountains. This bryozoan-rich limestone tongue serves as a marker unit for mapping the Murdock Formation in the Leach Mountains. Nine new species of bryozoans occur in the Stenodiscus beds of the Murdock Mountain Formation: Hinganella felderi, Neoeridotrypella schilti, Stenopora parvaexozona, Stenodiscus murdockensis, Dyscritella acanthostylia, Pseudobatostomella irregularis, Streblotrypa ( Streblotrypa ) elongata, Morozoviella praecurriensis, and Thamniscus erraticus, Hinganella felderi, Neoeridotrypella schilti, Dyscritella acanthostylia, and Streblotrypa ( Streblotrypa ) elongata are very similar to species described from Russia.

Journal of Paleontology↗
USGS2007

Conodont index fossil Hindeodus changxingensis Wang fingers greatest mass extinction event

The marine conodont fossil species, Hindeodus changxingensis Wang, that has a distinctive morphology, is restricted to a very narrow stratigraphic interval essentially from the Permian-Triassic extinction event through the internationally recognized boundary and into the very earliest Triassic. The species is geographically widespread in the Tethyan Region, from Italy to South China, and serves as a characteristic index fossil to reliably identify this short but critical interval that encompasses the greatest mass extinction of life on earth and the boundary between the Paleozoic and Mesozoic Eras. ?? 2007 Nanjing Institute of Geology and Palaeontology, CAS.

Palaeoworld↗
USGS2007

Mesogondolella and Jinogondolella (Conodonta): Multielement definition of the taxa that bracket the basal Guadalupian (Middle Permian Series) GSSP

Multielement definitions are presented here for Mesogondolella and Jinogondolella based on species that bracket the basal Guadalupian (Middle Permian Series) GSSP. Distinctive apparatus characters that appear with the first Jinogondolella include several details of P2 element dimorphism and process bifurcation in S3 elements. The sequential expression of these multielement characters is traced through M. idahoensis, M. lamberti, and J. nankingensis. The resulting multielement definition of Jinogondolella serves to distinguish it from all other closely related genera. Mesogondolella lamberti is recognized as a distinct species, and J. serrata is formally designated a junior synonym of J. nankingensis. ?? 2007 Nanjing Institute of Geology and Palaeontology, CAS.

Palaeoworld↗
USGS2007

Upper triassic continental margin strata of the central alaska range: Implications for paleogeographic reconstruction

Remnants of a Late Triassic continental margin and ocean basin are scattered across central and southern Alaska. Little is known about the fundamental nature of the margin because most remnants have not been studied in detail and a protracted period of terrane accretion and margin-parallel translation has disrupted original stratigraphic and structural relationships. Three new conodont collections were recovered from a sequence of Upper Triassic calcareous sedimentary rocks in the central Alaska Range. One of the three localities is north of the Denali fault system in an area previously thought to be underlain by an uninterrupted sequence of metamorphic rocks of the parautochthonous Yukon-Tanana terrane. Structural relations in the immediate vicinity of this conodont locality indicate that mid-Cretaceous(?) thrust faulting imbricated Paleozoic metaigneous rocks with the Triassic sedimentary rocks. This may reflect a closer pre-Cretaceous relationship between the Yukon-Tanana terrane and Late Triassic shelf and slope deposits than previously appreciated. Reexamination of existing conodont collections from the central Alaska Range indicates that Upper Triassic marine slope and basin rocks range in age from at least as old as the late Carnian to the early middle Norian. The conodont assemblages typical of these rocks are generally cosmopolitan and do not define a distinct paleogeographic faunal realm. One collection, however, contains Epigondolella multidentata sensu Orchard 1991c , which appears to be restricted to western North American autochthonous rocks. Although paleogeographic relations cannot be determined with specificity, the present distribution of biofaces within the Upper Triassic sequence could not have been the result of simple accordion-style collapse of the Late Triassic margin.

Special Paper of the Geological Society of America↗
USGS2006

The Global Boundary Stratotype Section and Point (GSSP) for the base of Changhsingian Stage (Upper Permian)

The Global Stratotype Section and Point (GSSP) for the base-Changhsingian Stage is defined at the First Appearance Datum (FAD) of the conodont Clarkina wangi within the lineage from C. longicuspidata to C. wangi at a point 88 cm above the base of the Changxing Limestone in the lower part of Bed 4 (base of 4a-2) at Meishan D section, Changxing County, Zhejiang Province, South China. This level is consistent with the first appearance of Changhsingian index fusulinid Palaeofusulina sinensis and tapashanitid ammonoids. The speciation event from Clarkina longicuspidata to C. wangi occurs just above the flooding surface of the second parasequence in the Changxing Limestone. In addition, the boundary interval is clearly recognizable by the depletion of isotopic carbon ratios and the normal polarity zone appearing above the Late Wuchiapingian reversed polarity zone. Section C, about 300 m to the west of Section D, exposes more of the upper Longtan Formation. It clearly shows the transitional nature of deposition across the Longtan/Changxing formational boundary, and thus is described as a supplementary reference section.

Episodes↗
USGS2006

Integrated biostratigraphy of foraminifers, radiolarians and conodonts in shallow and deep water Middle Permian (Capitanian) deposits of the "Rader slide", Guadalupe Mountains, West Texas

A diverse assemblage of microfossils is present in a 6m thick sequence of three debris flow deposits interbedded with thin turbidite limestone beds and fine grained siliciclastics exposed above the megaconglomerate in a section (known as the "Rader Slide" in numerous guidebook stops) of the Rader Limestone Member of the Bell Canyon Formation of Capitanian age (Middle Permian) in the Guadalupe Mountains of West Texas. Each debris flow, derived from nearby Capitan Reef shelf-margin and slope deposits, contains a distinct microfossil assemblage. Small foraminifers and fusulinaceans, conodonts, radiolarians, sponge spicules, fish dermal plates and teeth, and other fragmental fossils are present in this sequence. Conodonts are relatively scarce in the first (or lowest) debris flow, except in its upper part, but they are common to abundant in the other two debris flows, and very abundant in several of the thin turbidite limestone beds. All of the conodonts present appear to be morphotypes of one population of the species Jinogondolella postserrata, except for one new conodont species, and the Jinogondolella postserrata Zone is clearly documented in this sequence. The debris flows contain the fusulinaceans Rauserella, rare Codonofusiella, Polydiexodina, Leella? and various species of the small foraminifers Globivalvulina, Hemigordius, Baisalina, Abadehella, Deckerella, Neoendothyranella, Vachardella, Geinitzina, and Polarisella. Some of the thin turbidite limestone beds contain a foraminiferal assemblage similar to that found in the debris flows, but with lower diversity. Many small foraminiferal species appear to be endemic, although a few are closely related to species known in Permian age strata in Italy, Greenland, the Russian Far East, northeastern part of Russia (Omolon massif), and the Zechstein of Germany and the Baltic area. Two thin limestone beds above the second debris flow contain primarily radiolarian species known from the Follicucullus japonicus Zone of Japan. Nine new species of small foraminifers (Bisphaera? improvisa, Vissariotaxis? nativus, Multidiscus raderensis, Baisalina miscella, Agathammina minuscula, Polarisella globosa, Geinitzina jucunda, Robustopachyphloia texana and Spireitlina capitanensis) and one new conodont species Jinogondolella gladirobusta are described.

Stratigraphy↗
USGS2002

Latest Guadalupian (Middle Permian) conodonts and foraminifers from West Texas

Clarkina, which characterizes Upper Permian (Lopingian Series) strata, evolved from Jinogondolella altudaensis in the Delaware basin of West Texas as demonstrated by transitional continuity. The West Texas section is significantly more complete in the uppermost Guadalupian interval than that of the probable GSSP reference section in South China, and clarifies the phylogenetic relationships among other conodont taxa as well. Jinogondolella granti clearly evolved into J. artafrons new species, both characterized by Pa elements with a distinctive fused carina. Representatives of Jinogondolella crofti are limited to the uppermost part of the altudaensis zone, and are interpreted as terminal paedomorphs. The associated foraminifer (non-fusulinid) fauna has some species in common with Zechstein faunas, possibly presaging the evaporitic basin that would develop following this latest Guadalupian marine deposition in West Texas.

Micropaleontology↗
USGS2000

A paleoecologic reconstruction of the history of Featherbed Bank, Biscayne National Park, Biscayne Bay, Florida

Using multiple-proxy biological indicators, a paleoecological history of the past 550 years of Featherbed Bank, Biscayne Bay, has been reconstructed from a short (2.26 m) sediment core. Paleoecological changes in ostracode, mollusc, and foraminifer assemblages show that core SEI297-FB-1 can be divided into three distinctly different zones, which together provide evidence for distinct changes in historical environmental conditions at Featherbed Bank. Assemblages from fossil biotic communities within zone 1, representing approximately 1440 to 1550 AD, are characterized by open-marine biota with relatively limited numbers of epiphytic biota. Molluscan faunal indicators suggest the sediment was capable of supporting infaunal organisms and that faunal richness was relatively limited during this time period. A change in the biotic community occurred around 1550 AD and continued until the late 1800's distinguishing zone 2. Fossil biotic indicators from zone 2 show a strong dominance of epiphytic organisms within all of the biotic communities examined. Foraminifers, molluscs, and ostracodes capable of subsisting in salinities slightly lower than normal marine begin to flourish in this time period, and there is a marked decline in infaunal molluscs. Zone 2 assemblages are replaced around 1900 AD by increased numbers of organisms that typify open-marine conditions and a return to decreased epiphytic assemblages, similar to zone 1. Zone 3 assemblages, however, show some strong dissimilarities from zone 1, including limited infaunal molluscs, increased abundances of the ostracode Malzella floridana, and a significant increase in molluscan faunal richness.

Florida↗
USGS2000

A deep water turbidity origin for the Altuda Formation (Capitanian, Permian), Northwest Glass Mountains, Texas

The Altuda Formation (Capitanian) in the northwestern Glass Mountains is comprised of thin, even bedded limestones, dolostones, mixed clastic-carbonates, and silt/sandstones interbedded with basin-ward dipping wedge-shaped clinoforms of the Captian Limestone. The formation is characterized by graded bedding, planar laminations, flame structures, contorted/convolute bedding, horizontal branching burrows, and shelf-derived normal marine fauna. A detailed study of the Altuda Formation north of Old Blue Mountain, Glass Mountains, reveals that the formation in this area was deposited by turbidity currents in slope to basinal settings.

Texas↗
USGS2000

Guadalupian studies in West Texas

Murchison established the Permian System in the Ural Mountains of Russia in 1841. The first North American Permian fossils were discovered by Hall (1856) about 15 years later. The fossils, which were collected in New York State, were initially described as Carboniferous (Hall, 1856) but were subsequently recognized as Permian by Girty (1902). Benjamin F. Shumard (1858), however, was the first to place an unequivocal Permian designation on some North American fossils, which has been collected by his brother George G. Shumard from the Guadalupe Mountains in Texas. A half a century passed before Girty (1908) made known an extensive Guadalupian fauna, although his field work in Texas and his study of this fauna already lead him to propose a Guadalupian "period" (Girty, 1902). Girty's suggestion was accepted only when it was formalized as the Guadalupe Series by Adams et al. (1939). The "Guadalupian fauna" was based upon fossils that Girty collected in 1901 on an expedition headed by Robert T. Hill, a revered figure in Texas geology.

Smithsonian Contributions to Earth Sciences↗
USGS2000

Guidebook to the Gaudalupian symposium

Compared to the Guadalupe Mountains of Texas and New Mexico the depositional environments of the Permian strata of the Glass Mountains (and adjacent Del Norte Mountains) are less well known. In general, the Guadalupian facies in the the Glass and Del Norte mountains changes from predominantly carbonate facies in the northeast to thicker clastic facies in the southwest. Philip B. Kind (1931) originally considered this trend to reflect an uplifted clastic source to the southwest, with carbonate facies developing away from the source area. Ross (1986) interpreted the eastern portion of the Road Canyon and Word formations to consist the shelf, shelf-edge bioherm, and reef facies, and the southwest area to consist of deeper water siliceous shale, clastic limestone, and basinal sandstone facies. Probably the best known controversy in the Glass Mountains involves the depositional environment of the Skinner Ranch Formation (Leonardian according to Ross, 1986; Wolfcampian according to Cooper and Grant, 1972) at its type section on Leonard Mountain. Cooper and Grant (1964) identified in situ patch reefs at the base of the section, which were subsequently interpreted as displaced limestone blocks deposited in a slope environment (Rogers, 1972; Cys and Mazzullo, 1978; Ross, 1986). Later Flores, McMillan, and Watters (1977) interpreted the same units as subtidal and intertidal deposits. The Skinner Ranch Formation illustrates the complexities involved in interpreting the paleogeography of the Glass Mountains. If the Sinner Ranch contains displaced blocks, some eroded from older units, it explains the occurrence of Wolfcampian fossils in the Skinner Ranch (Ross, 1986).The slop facies interpretation also is used to place the shelf edge at that time between Skinner Ranch outcrops at Leonard Mountain and the lagoonal, backreef deposits of the Hess Formation to the east, although most of the actual shelf edge is not preserved (Ross, 1987:30). Similar conflicting interpretations exist in younger rocks in the western facies of the Leonardian Guadalupian to the southwest in the Del Norte Mountains. Ross (1986, 1987) considered the western facies of the Road Canyon and Word formations to be basinal shales and turbidites. Wardlaw et al. (1990) and Rohr et al. (1987) have interpreted this area to be shallow intertidal to lagoonal environments adjacent to an uplifted area to the south. The type section of the Road Canyon Formation is also a subject of disagreement and will be discusses in more detail later.

Texas↗
USGS2000

Geology and depositional environments of the Guadalupian rocks of the northern Del Norte Mountains, West Texas

The Guadalupian rocks of the northern Del Norte Mountains were deposited in a foreland basin between land of the Marathon orogen and a carbonate shoal established on the geanticline separating the foreland basin from the Delaware basin. Deposition was alternately influenced by coarse clastic input from the orogen and carbonate shoal, which interrupted shallow basinal siltstone depletion. Relatively deeper-water deposition is characterized by carbonate input from the shoal, and relatively shallow-water deposition is characterized by sandstone input from the orogen. Deposition was in five general transgressive-regressive packages that include (1) the Road Canyon Formation and the first siltstone member and first sandstone member of the Word Formation, (2) the second siltstone member, Appel Ranch Member, and limy sandy siltstone member of the Word Formation, (3) the Vidrio Formation, (4) the lower and part of the middle members of the Altuda Formation, and (5) part of the middle and upper members of the Altuda Formation.

Texas↗
USGS1999

Lithostratigraphy, geophysics, biostratigraphy, and strontium-isotope stratigraphy of the surficial aquifer system of eastern Collier County and northern Monroe County, Florida

In 1997, ten cores were drilled in eastern Collier County and northern Monroe County, within the limits of the Big Cypress National Preserve. These cores represent a continuation of the study of seven cores in western Collier County begun in 1996 and reported in Weedman and others (1997) and Edwards and others (1998). This joint U.S. Geological Survey and Florida Geological Survey project is designed to acquire subsurface geologic and hydrologic data in southwest Florida to extend current ground-water models, thereby expanding the utility of these models for land and water management. In this report we describe the lithostratigraphy, geophysical logging, sedimentological analysis, dinocyst biostratigraphy, and strontium-isotope stratigraphy of these ten cores. The three geophysical logs (natural gamma-ray, induction conductivity, and neutron porosity) assumed to be related to formation lithology and water quality show that a number of clay-rich zones are present in all of the boreholes, and that pore-water conductivity increases with depth. The clay-rich zones are confirmed by visual examination of core material and sedimentological analysis. The relative transmissivity calculated at 10-foot-thick intervals shows that in six of the boreholes, high values are associated with the shallow aquifer in the 0-40 ft interval. Two of the boreholes (the most northerly and the most easterly) showed relatively higher values of transmissivity in permeable zones at or somewhat below 100 ft in depth. Core geology and logs indicate that the deeper aquifers are not more permeable than similar deeper zones in the other boreholes, but rather that the shallow aquifer appears to be less permeable in these two coreholes. The Arcadia (?) Formation was only penetrated in the deepest core where it is late Miocene in age. The Peace River Formation was penetrated in all but the two westernmost cores. It yields a late Miocene age, based on both dinocysts and strontium-isotope stratigraphy. The top is an irregular surface. Age and stratigraphic relations suggest that the upper part of the Peace River and lower part of the unnamed formation are at least partially equivalent laterally. The unnamed formation was recovered in every core. It is thinnest in the northernmost core and thickest to the west. Ages calculated from strontium isotopes range from 6.9 to 4.6 million years ago (late Miocene to early Pliocene). The top of the unnamed formation is deepest to the north and it becomes shallower to the southwest. The Tamiami Formation also was recovered in every core and consistently yields early Pliocene ages; it yields late Pliocene ages near the top in two cores. The age and lateral relations strongly suggest that the lower part of the Tamiami Formation and the upper part of the unnamed formation are lateral facies of each other. The Fort Thompson (?) Formation, Miami Limestone, and undifferentiated siliciclastic sediments and limestone at the very top of the cores were not dated.

Florida↗
USGS1998

A refined succession of Changhsingian and Griesbachian neogondolellid conodonts from the Meishan section, candidate of the global stratotype section and point of the Permian-Triassic boundary

A detailed study of new conodont collections from the Changxing Formation at the Meishan section has resulted in taxonomic refinement of several important neogondolellid species. Most of the previously erected species are much more strictly redefined, mainly based on the denticulation of the holotypes, and the stratigraphic ranges attributed to key conodont taxa are modified. Three new species and two new subspecies, all of which are form-species, are tentatively erected and described mainly for the purpose of taxonomic explanation. As a result of the taxonomic refinement, six neogondolellid conodont zones are recognized for the Changxing Formation and the Permian-Triassic boundary interval.

Conference Paper↗