Galina P. Nestell

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.

High influx of carbon in walls of agglutinated foraminifers during the Permian-Triassic transition in global oceans

The Permian–Triassic mass extinction is postulated to be related to the rapid volcanism that produced the Siberian flood basalt (Traps). Unrelated volcanic eruptions producing several episodes of ash falls synchronous with the Siberian Traps are found in South China and Australia. Such regional eruptions could have caused wildfires, burning of coal deposits, and the dispersion of coal fly ash. These eruptions introduced a major influx of carbon into the atmosphere and oceans that can be recognized in the wall structure of foraminiferal tests present in survival populations in the boundary interval strata. Analysis of free specimens of foraminifers recovered from residues of conodont samples taken at a Permian–Triassic boundary section at Lung Cam in northern Vietnam has revealed the presence of a significant amount of elemental carbon, along with oxygen and silica, in their test wall structure, but an absence of calcium carbonate. These foraminifers, identified as Rectocornuspira kalhori, Cornuspira mahajeri, and Earlandia spp. and whose tests previously were considered to be calcareous, are confirmed to be agglutinated, and are now referred to as Ammodiscus kalhori and Hyperammina deformis. Measurement of the 207Pb/204Pb ratios in pyrite clusters attached to the foraminiferal tests confirmed that these tests inherited the Pb in their outer layer from carbon-contaminated seawater. We conclude that the source of the carbon could have been either global coal fly ash or forest fire-dispersed carbon, or a combination of both, that was dispersed into the Palaeo-Tethys Ocean immediately after the end-Permian extinction event.

Magnetostratigraphy susceptibility for the Guadalupian series GSSPs (Middle Permian) in Guadalupe Mountains National Park and adjacent areas in West Texas

Abstract Here we establish a magnetostratigraphy susceptibility zonation for the three Middle Permian Global boundary Stratotype Sections and Points (GSSPs) that have recently been defined, located in Guadalupe Mountains National Park, West Texas, USA. These GSSPs, all within the Middle Permian Guadalupian Series, define (1) the base of the Roadian Stage (base of the Guadalupian Series), (2) the base of the Wordian Stage and (3) the base of the Capitanian Stage. Data from two additional stratigraphic successions in the region, equivalent in age to the Kungurian–Roadian and Wordian–Capitanian boundary intervals, are also reported. Based on low-field, mass specific magnetic susceptibility (χ) measurements of 706 closely spaced samples from these stratigraphic sections and time-series analysis of one of these sections, we (1) define the magnetostratigraphy susceptibility zonation for the three Guadalupian Series Global boundary Stratotype Sections and Points; (2) demonstrate that χ datasets provide a proxy for climate cyclicity; (3) give quantitative estimates of the time it took for some of these sediments to accumulate; (4) give the rates at which sediments were accumulated; (5) allow more precise correlation to equivalent sections in the region; (6) identify anomalous stratigraphic horizons; and (7) give estimates for timing and duration of geological events within sections.

Species of Hollinella (Palaeocopida: Ostracoda: Crustacea) as stratigraphical indices of the Late Permian–Early Triassic post-extinction interval

Members of the ostracod order Palaeocopida, except three very rare genera (Puncia, Manawa and Promanawa), disappeared from the stratigraphical record close to the Permian–Triassic boundary (PTB) event. Species of the genus Hollinella are often present just after the end-Palaeozoic mass extinction event, in latest Permian and earliest Triassic beds. They are among the last representatives of Palaeocopida, the typical Palaeozoic straight dorsal border ostracods. The Early Triassic species have been assigned by most authors to Hollinella tingi (Patte, 1935), but this assignment is incorrect. This species is present in the latest Permian and the earliest Triassic, and therefore is considered a biostratigraphical index fossil of the post-mass extinction interval. A revision of Hollinella species from this interval is presented here. Three Hollinella species occur in the earliest Triassic: H. panxiensis Wang, 1978; H. magninoda Wang, 1978; and Hollinella (Hollinella) lungcamensis Crasquin sp. nov. The new species of the post-PTB event is present in strata exposed in the northern part of Vietnam. All three species of Hollinella cross the PTB and H. (H.) lungcamensis is characteristic of the post-extinction period (latest Changhsingian–earliest Induan). http://zoobank.org/urn:lsid:zoobank.org:pub:C8BA4418-B7FE-4B28-ADA0-28BE317687A4

New jalodontid chondrichthyans from the Middle Permian of West Texas, USA

The teeth of two new genera of jalodontid sharks have been found in the strata of the Middle Permian in the Guadalupe Mountains area of West Texas. Isacrodus marthae gen. et sp. nov. occurs in the Williams Ranch Member, Cutoff Formation, Roadian. A second taxon Texasodus varidentatus gen. et sp. nov. is found in beds of the Hegler and Pinery Members, Bell Canyon Formation, Upper Wordian–Lower Capitanian. The family Jalodontidae includes Jalodus, Adamantina and the two new genera; Isacrodus and Texasodus.

New results of microfaunal and geochemical investigations in the Permian–Triassic boundary interval from the Jadar Block (NW Serbia)

Abstract Detail results of microfaunal, sedimentological and geochemical investigations are documented from a newly discovered section of the Permian–Triassic boundary (PTB) interval in the area of the town of Valjevo (northwestern Serbia). The presence of various and abundant microfossils (conodonts, foraminifers, and ostracodes) found in the Upper Permian “Bituminous limestone” Formation enabled a determination of the Changhsingian Hindeodus praeparvus conodont Zone. This paper is the first report of latest Permian strata from the region, as well as from all of Serbia, where the PTB interval sediments have been part of a complex/integrated study by means of biostratigraphy and geochemistry.