Bruce R. Wardlaw

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

Abstract 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.

The record of Pliocene sea-level change at Enewetak Atoll

Abstract Detailed seismic stratigraphy, lithostratigraphy, and chemostratigraphy indicate that atoll-wide subaerial exposure surfaces (major disconformities) developed during major sea-level lowstands form prominent seismic reflectors and are coincident with biostratigraphic breaks in the Plio-Pleistocene on Enewetak Atoll. Sea-level models based on the stratigraphic position and age of major disconformities suggest a maximum sea-level highstand elevation of 36 m above present sea level and a maximum sea-level lowstand elevation of 63 m below present sea level for the Pliocene.

Evolution and distribution of the conodonts Sweetognathus and Iranognathus and related genera during the Permian, and their implications for climate change

Abstract The conodont genus Sweetognathus , which is characterized by pustulose ornamentation on a wide, flat-topped carina, originated in the earliest Permian as S. expansus from Diplognathodus edentulus . The Asselian through Artinskian part of the Sweetognathus lineage is well represented in Kansas by the successive evolution of S. expansus , S. merrilli , S. aff. S. merrilli , S. whitei and S. bucaramangus . Sweetognathus and Iranognathus lineages were mainly confined to tropical areas from the Kungurian onward. The Kungurian and Guadalupian part of the Sweetognathus lineage is well represented in South China by the successive evolution of S. whitei (Artinskian), S. guizhouensis (lower Kungurian), S. subsymmetricus (upper Kungurian), S. iranicus hanzhongensis (Roadian) and S. fengshanensis (Capitanian). An additional lineage in West Texas is represented by the evolution of S. sulcatus to S. aff. adjunctus to S. adjunctus and to S. bicarinum . In the Urals and northwestern Pangea, the late part of the Sweetognathus lineage is represented by rare specimens of S. bogoslovskajae (upper Artinskian–lower Kungurian). During the late Artinskian, S. whitei radiated into S. toriyamai and S. bucaramangus , and also gave rise to Neostreptognathodus pequopensis and probably Pseudosweetognathus costatus . Neostreptognathodus ? exsculptus may have evolved from Adetognathus paralautus through Adetognathus ? telfordi sp. nov. Iranognathus , characterized by a narrow carina with poorly developed denticles and bearing subtle and smaller pustulose micro-ornament, replaced Sweetognathus at or near the Guadalupian/Lopingian boundary. It probably also evolved from Diplognathodus in the topmost Guadalupian. A lineage of Iranognathus ? sp. nov. A to I. erwini can be recognized for the Guadalupian and Lopingian boundary interval. A lineage of Iranognathus ? sp. nov. A to I. movschovithschi to I. sosioensis to I. tarazi is found throughout the Guadalupian and Lopingian boundary interval and the Wuchiapingian of South China. Sweetognathus and Iranognathus tend to develop homeomorphic accessory nodes iteratively during lowstand periods of global sea level near the Artinskian/Kungurian and Guadalupian/Lopingian boundaries and in the late Wuchiapingian. Sweetognathus and Iranognathus seem to be equatorial warm-water inhabitants. Distribution patterns reflect glaciation in Gondwana during the Asselian and Sakmarian, a warm climate during the Artinskian, cooling in North Pangea during the Kungurian and later Permian, slight amelioration during the Guadalupian, warming during the Wuchiapingian, and cooling during the Changhsingian in the peri-Gondwana region. Definitions for most of the important Sweetognathus species are refined. Three new species and subspecies, Iranognathus ? sp. nov. A , Adetognathus ? telfordi sp. nov., Gullodus duani sp. nov., are described.

The Permian of Pakistan

The Permian of Pakistan has been well known, yet poorly understood. Pakistan represents one of the few places where the Permian of the Paleotethys (Northern Hemisphere) and the Permian of Gondwana both occur. This chapter will review the stratigraphy of Pakistan that represents the northern part of the Indian/Pakistan plate. The Permian of the Paleotethys is in many structural blocks to the north and east of the Kohistan island arc terrane (Fig. 1). Talent et al. (1981) summarize what is known of these barely accessable rocks. South of the Kohistan island arc terrane, in several thrust sheets, are Permian strata that were deposited along the northern part of Gondwana in a rift flank basin. Apparently, the southern margin (craton), basin, and northern margin (rift flank) are preserved in these thrust sheets. The detailed conodont biostratigraphy is important for developing a better understanding of the timing and correlation of these rocks to each other and to the parts of Asia that resided in the Northern Hemisphere in the Permian.

Paleozoic and Mesozoic stratigraphy of the Peshawar basin, Pakistan: Correlations and implications

The most complete Paleozoic sequence described from Pakistan is exposed in bedrock inliers and in ranges fringing the eastern Peshawar basin. Interbedded quartzite and argillite of the Precambrian and Cambrian Tanawal Formation is overlain unconformably by the Cambrian(?) Ambar Formation. The Misri Banda Quartzite unconformably overlies the Ambar and contains Ordovician Cruziana ichnofossils. New conodont discoveries restrict the ages of overlying formations as follows: Panjpir Formation, Llandoverian to Pridolian; Nowshera Formation, Lochkovian to Frasnian; and Jafar Kandao Formation, Kinderhookian to Westphalian. The Karapa Greenschist, consisting of metamorphosed lava flows, separates the Jafar Kandao from Upper Triassic (Carnian) marbles of the Kashala Formation. The Upper Triassic and Jurassic(?) Nikanai Ghar Formation forms the top of the section. Correlatives to the Peshawar basin stratigraphy are present locally in the Sherwan synclinorium of Hazara and in the Khyber Pass region. The sequence contrasts markedly with the Paleozoic and Mesozoic section exposed south of the Khairabad thrust in the Attock-Cherat Range. This thrust and its northeastern continuation in Hazara north of Abbottabad thus form the boundary in Pakistan between the Lesser Himalayan and Tethyan Himalayan sections, a function performed by the Main Central thrust (MCT) in the central Himalaya of India and Nepal. The newly dated Carboniferous to Triassic horizons provide the first firm age constraints on the protoliths of the high-grade Swat metasediments. The dating of the metasediments has, in turn, provided age constraints on pre-Himalayan tectonism and associated intrusions. Two major tectonic episodes during the Late(?) Cambrian and Carboniferous produced positive areas north of the Peshawar basin that provided coarse detritus to the Misri Banda Quartzite and Jafar Kandao Formation.

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 relation- ships 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.

Upper Permian conodonts from Hydra, Greece

Conodont faunas recovered from the upper 80 m of Late Permian limestones on the Greek island of Hydra (Idhra) include Neogondolella leveni (Kozur, Mostler, and Pjatakova), Neogondolella orientalis (Barskov and Koroleva), Hindeodus julfensis Sweet, Xaniognathus hy- draensis n. sp., and Ellisonia sp. The conodonts occur with a rich assemblage of silicified bra- chiopods, fusulines, and other invertebrates. Diagnostic fusulines include Reichelina media Mik- lukho-Maklai and Palaeofusulina cf. P. prisca Deprat. The conodont and fusuline faunas are correlative with well-known faunas described from the lower part of the Ali Bashi Formation of the Djulfa region of Iran, and with similar faunas described from other regions of Central Asia. The presence of conodonts from the Neogondolella orientalis Zone of Kozur indicates that the age of the upper part of the Permian sequence on Hydra is early-middle Dzhulfian (Baisalian Substage).

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.

Permian and Triassic rocks near Quinn River Crossing, Humboldt County, Nevada

Permian and Triassic rocks near Quinn River Crossing, Humboldt County, Nevada, consist of four structural blocks: (1) a Lower Permian volcanic block; (2) a Permian(?) chert-arenite block; (3) a Lower Permian limestone block; and (4) a Permian and Triassic block. The contacts between the Permian volcanic block and the others are interpreted as thrust faults or glide surfaces. None of these rocks are metamorphosed, in contrast to those of the surrounding mountain ranges. Each of the blocks is lithically similar in some respects to rocks of the Osgood Mountains area 80 km to the southeast. The fusulinid and brachiopod faunas of two of the blocks display affinities to those of the McCloud Limestone of northern California and the Coyote Butte Limestone of central Oregon, and the fauna of another block has elements in common with autochthonous rocks of eastern Nevada and Utah. All four blocks probably are allochthonous with respect to the rocks exposed in the surrounding mountain ranges, but their points of origin remain obscure. The rocks at Quinn River Crossing provide a link among the Permian rocks of north-central Nevada, northern California, and central Oregon and a possible key to their original relations, but more comparative data are needed.

Heating, cooling, and uplift during Tertiary time, northern Sangre de Cristo Range, Colorado

Paleozoic sedimentary rocks in a wide area of the northern Sangre de Cristo Range show effects of heating during Tertiary time. Heating is tentatively interpreted as a response to burial during Laramide folding and thrusting and also to high heat flow during Rio Grande rifting. The regional extent of heating is shown by the distribution of low-grade metamorphic minerals, altered conodonts, and reset fission-track ages throughout much of the study area. Alteration of conodonts to a conodont alteration index (CAI) of 4.0 suggests that temperatures reached ∼200 °C in the central part of the area. Temperatures may have reached 300 °C beneath Laramide thrusts on the west side of the range, where conodonts were altered to a CAI of 5.0, and where chloritoid and andalusite are found in sedimentary rocks of Pennsylvanian age. The lowest temperatures that were determined by conodont alteration (CAI = 1.0–2.0, Fission-track ages of apatite across a section of the range show that rocks cooled abruptly below 120 °C, the blocking temperature for apatite, ∼19 Ma ago. Cooling was probably in response to rapid uplift and erosion of the northern Sangre de Cristo Range during early Rio Grande rifting.