Palaeontological aspects of the Permian Broughton Formation, Sydney Basin, Australia

An abundant, low diversity cool-water macroinvertebrate fauna from the Middle Permian Broughton Formation in the Sydney Basin, eastern Australia, was investigated. The fauna was described and identified, which assisted in regional and global correlation of the Broughton Formation, as well as palaeogeographical and palaeontological research.

Zoophycos composite ichnofabrics and tiers from the Permian neritic facies in South China and south-eastern Australia

Zoophycos composite ichnofabrics (ZCI) comprising two or more suites of the same form of Zoophycos are widespread and densely distributed in Early and Middle Permian (Cisuralian–Guadalupian) neritic limestones (Qixia and Maokou Formations) of palaeotropical origin in the Laibin area, Guangxi, South China. Similar ZCI also occur in neritic greywackes of glaciomarine origin from the Middle Permian (Guadalupian) Westley Park Sandstone Member (Broughton Formation) in the southern Sydney Basin, southeastern Australia. Zoophycos from both regions consists of planar spreite with major and minor lamellae and a cylindrical tunnel interpreted as a marginal tube and ⁄ or axial shaft. The cylindrical tunnel is herein considered to be an essential component of Zoophycos, and thus can be used to define and characterize the morphological variability of Zoophycos. It is suggested that the variation of spreite and major and minor lamellae originated from the different morphologies and migration manners of the cylindrical tunnel. The shallowest, shallow, middle and deepest Zoophycos tiers have been distinguished in ZCI on the basis of cross-cutting relationships, the soft-sediment deformation and the contrast in colour between Zoophycos and its host rock. The multiple tiers may represent the substrate consistency spectrum from a softground through a stiffground to a firmground.The different Zoophycos tiers may have been constructed by tracemakers of either different or the same taxonomic affinities in response to the gradual accretion and lithification of sediment layers on the seafloor. The tracemakers appeared to be very sensitive to neither climate nor lithology. The width of the planar spreiten of Zoophycos decreases slightly with the depth of tiering in ZCI

Controls on body size during the Late Permian mass extinction event

This study examines the morphological responses of Late Permian brachiopods to environmental changes. Quantitative analysis of body size data from Permian–Triassic brachiopods has demonstrated significant, directional changes in body size before, during and after the Late Permian mass extinction event. Brachiopod size significantly reduced before and during the extinction interval, increased for a short time in more extinction-resistant taxa in the latter stages of extinction and then dramatically reduced again across the Permian ⁄ Triassic boundary. Relative abundances of trace elements and acritarchs demonstrate that the body size reductions which happened before, during and after extinction were driven by primary productivity collapse, whereas declining oxygen levels had less effect. An episode of size increase in two of the more extinction-resistant brachiopod species is unrelated to environmental change and possibly was the result of reduced interspecific competition for resources following the extinction of competitors. Based on the results of this study, predictions can be made for the possible responses of modern benthos to present-day environmental changes.

Palaeobiogeography and palaeogeographical implications of Permian marine bivalve faunas in Northeast Asia (Kolyma–Omolon and erkhoyansk–Okhotsk regions, northeastern Russia)

The paper considers the biogeography and palaeogeographic implications of the Permian marine bivalve faunas of Northeast Asia, with a focus on the dynamic relationships between biotic similarities and palaeogeographic distance through an interval of ca. 50 million years. A stage-by-stage time series analysis of the biotic similarities between two previously recognized biochores in Northeast Asia, the Kolyma–Omolon and Verkhoyan–Okhotsk provinces, has been carried out using both the Jaccard and Dice similarity indices based on the spatio-temporal distributions of 355 Permian marine bivalve species in Northeast Asia. The outcome of this analysis, combined with other empirical data and previously published tectonic, sedimentological and palaeontological information, suggests that (1) the bivalve faunas from these two provinces were distinctive from one another as two separate biochores throughout all but the earliest (Asselian) Permian stages and (2) the biotic similarities between the Verkhoyan–Okhotsk and Kolyma–Omolon provinces remained consistently low since Sakmarian, all falling well below the minimum threshold of the Jaccard index of 0.42 required for distinguishing marine biotic provinces. We interpret these below-threshold Jaccard biotic similarities as an indication of significant palaeogeographic separation between the Verkhoyan-Okhotsk and Kolyma–Omolon provinces, which is in turn considered to indicate rifting and seafloor spreading of the Omolon microcontinent and associated terranes and island arcs away from the North Asian craton, at least from the Sakmarian to the beginning of the Late Permian.
Palaeo-distance separation appears to be the primary and most significant biogeographic determinant in accounting for the differences in the spatial distribution of most Permian bivalve species in Northeast Asia. Several other variables also appear to have played a significant role, including regional climate conditions, ocean currents and merged island chains as geographic barriers. In particular, the relatively high biotic similarity between the Verkhoyan–Okhotsk and Kolyma–Omolon provinces during the Late Wuchiapingian and Changhsingian may have been related to the shallowing of the deep-water basins (Oimyakon, Ayan-Yuryakh, Balygychan and Sugoi basins) that had previously separated the two provinces and the flooding (submergence) of the Okhotsk–Taigonos volcanic arc system, thus allowing the invasion of lower latitude warm-water Palaeotethyan and even Gondwanan species into Northeast Asia.

Late Middle Permian (Guadalupian) fusuline fauna from the Gyanyima area of Burang County, Tibet, China and its paleobiogeographic implications

Numerous Permian limestone blocks exposed along the Yarlung-Zangbo Suture Zone have been named Tibetan facies exotic limestone blocks or Chitichun-type Permian deposits.The Gyanyima limestone block,one of those limestone blocks,is located in Burang County,southwestern Tibet.Fusulines are abundant in the Gyanyima limestone block especially for Middle Permian Xilanta Formation.The fusuline fauna comprises 10 genera,respectively Neoschwagerina, Yangchienia, Armenina, Verbeekina, Paraverbeekina, Kahlerina, Lantschichites, Codonofusiella,Chusenella, Nankinella.This fauna indicates a Midian age(Late Guadalupian or Lengwuan age of South China) in terms of the coexistence of Kahlerina, Lantschichites, Codonofusiella and Neoschwagerina.

The Carboniferous and Permian sequences in north and south of the Longmucuo-Shuanghu suture zone in Tibet

The location of the Palaeo-tethys suture in Tibet has been in great dispute for past two decades. The Longmucuo-Shuanghu suture has long been considered as the Palaeo-tethys in Tibet. Restudy of the Carboniferous and Permian sequences in the north and south of this suture reveal that: (1) the Carboniferous and Permian sequence of the North Qiangtang Block is characterized by containing compound corals and intact fusulinids zones from Moscovian Fusulinella, Fusulina to Changhsingian Palaeofusulina zones; (2) the Early Permian of the South Qiangtang Block is

Late Guadalupian (Middle Permian) Fusuline fauna from the Xiala formation in Xainza county, central Tibet : implication of the rifting time of the Lhasa Block

A fusuline fauna consisting of 9 species of 4 genera from the Xiala Formation of the Mujiucuo section, Xainza County, Tibet, China is described. The fusuline fauna is dominated by Nankinella and Chusenella and indicates a Midian (Late Guadalupian) age. The earliest record of fusuline fauna during the Midian in the Lhasa Block suggests that the block rifted later than the Qiangtang Block to the north and the Baoshan and Tengchong blocks to the east, all of which yield much earlier fusuline faunas of Yakhtashian (Artinskian) age, but had drifted away from Gondwana to a relatively warm temperate zone in the Late Guadalupian (Middle Permian).

Geological features of Permian ophiolite in the Jiaomuri area, Qiangtang, Tibet, and its tectonic significance

During the regional geological mapping of the 1∶250000 Mayigangri Sheet, a very complete ophiolite was discovered in the Jiaomuri area, which consists of radiolarian chert, pillow basalt, gabbro, diabase and metaperidotite. This ophiolite is the most intact and complete one in the central Qiangtang area.

Restudy on the late Permian strata in Northern Qiangtang area, Tibet.

The Late Permian strata, namely Raggyorcaka Formation, is distributed along the line from Shuanghu agency to Raggyorcaka area. The Formation comprises two parts divided by fault. The lower part is mainly composed of shale and carbonate containing fusulinids and brachiopods while the upper part is dominated by flora-bearing sandstone and mudstone. Acording to the new materials got from 1∶250 000 scale Mayigangrimap, the upper terrestrial flora-bearing deposits conformably overlie the lower marine fusulinids-bearing deposits. So, based on the analysis of paleon to logy and litho stratigraphy, the original Raggyorcaka Format ion are divided in to two parts. The lower is Raggyorcaka Formation standing for fusulinids-bearing marine deposits and the upper is Heitugou Formation (P3h), a new lithostratigraphic name represen ting flora-bearing deposits.

Earliest Wuchiapingian (Lopingian, Late Permian) brachiopods in southern Hunan, South China : implications for the Pre-Lopingian crisis and onset of Lopingian recovery / radiation

The uppermost 5-15 m of the Douling Formation in the southern Hunan area. South China, yields a diverse fauna comprised of ammonoids, bivalves, and brachiopods. The brachiopods reported in this paper consist of 51 species in 34 genera and are dominated by the Lopingian (Late Permian) species associated with a few species persisting from the underlying Maokouan (Late Guadalupian). This fauna is of earliest Wuchiapingian in age as precisely constrained by the associated conodont Clarkina postbitteri postbitteri and the Guadalupian-type ammonoid fauna of the Roadoceras-Doulingoceras Zone in the brachiopod horizon. The discovery of the Lopingian species-dominated brachiopod fauna in the earliest Wuchiapingian in southern Hunan suggests a much less pronounced effect of the pre-Lopingian crisis (end-Guadalupian mass extinction) than the end-Changhsingian mass extinction in terms of brachiopods, a contemporaneous onset of the Lopingian recovery/radiation during the pre-Lopingian crisis period, and taxonomic selectivity of the pre-Lopingian crisis in terms of different fossil groups. New taxa are Echinauris doulingensis n. sp., Pararigbyella quadrilobata n. gen. and n. sp. and P. doulingensis n. gen. and n. sp.