Search

Permian strata containing abundant brachiopods are well developed in the Himalaya Tethys Zone. However, relatively few has been systematically described due to the difficult working condition for collecting. In this paper, we describe the brachiopods from the Qubuerga Formation at the Tulong and Kujianla sections in southern Tibet. The brachiopod faunas consist of 15 species belonging to 11 genera. Among the identified 15 species, Retimarginfera xizangensis, Costiferina indica, Fusispirifer semiplicatus, Spiriferella sinica, Biplatyconcha grandis and Neospirifer (Quadrospina) tibetensis are very common in the equivalents of the Himalaya Tethys Zone including the Selong Group at the Selong Xishan and Qubu sections in southern Tibet, the Senja Formation in northwest Nepal, the Zewan Formation in Kashmir, and the upper part of the Wargal Formation and the Chhidru Formation in the Salt Range, Pakistan. They are all comparable and can be assigned to the Wuchiapingian- early Changhsingian. Since the brachiopods from the Qubuerga Formation at Tulong and Kujianla are all composed of typical Gondwanan, bipolar or cosmopolitan elements, it is conclusive that the Himalaya Tethys Zone in the northern margin of the Indian Plate was still situated at southern high-latitudes under cold palaeoclimatic conditions during most of the Lopingian. The faunal succession at Tulong also recorded a rapid warming at the very end of the Changhsingian in view of the fact that the typical cold-water Lopingian brachiopod, gastropod and bivalve faunas were dramatically replaced by extremely abundant conodonts Clarkina in the basal part of the dolostone unit of the Tulong Formation. This end-Changhsingian warming is comparable with that recorded throughout the Permian-Triassic boundary interval at Selong, Qubu in southern Tibet, the Salt Range, Pakistan and the sections in Kashmir as well as South China.

Volcanism and impact scenarios are two of the most plausible ways of interpreting the causes of the largest biological mass extinction at the end-Permian. Microspherules have previously been widely reported from tens of different Permian-Triassic boundary (PTB) sections in South China and some other regions. These microspherules have been interpreted as either the product of volcanic eruptions or an impact event. In order to test these scenarios, we collected 60 samples from 12 intensively-studied PTB sections in South China. In addition, four soil samples close to these PTB layers were also collected for comparison. Our investigation indicates that abundant microspherules with mosaic or dot shape crystals on rounded surface are present in the surface samples in the PTB layers at Meishan, Meili, and Shatian sections and most soil background samples in South China. Those microspherules consist of four different types based on their main chemical composition, surface features, and internal structure including iron, magnetite-silicate, glassy, pyrite microspherules and framboids. In contrast, microspherules have not been found in a few sections in remote areas such as the Selong Xishan section in Tibet and the Dalongkou section in Xinjiang, Northwest China, in the deeply-excavated samples at the Shangsi section and the hard tuff layers around the PTB at the Xiaochehe Section in Guiyang. Microspherules decrease in abundance with depth in PTB clay beds. All these microspherules except the pyrite microspherules and framboids are found in both the PTB layers and the nearby soil background samples. The iron microspherules are pure iron oxides such as magnetite, hematite or maghemite and contain low concentrations of nickel and chromium, and lack an Ni-Fe core and general extraterrestrial mineral wüstite. All these external and chemical characteristics suggest that most of iron microspherules previously reported from PTB sections in South China are modern industrial fly ashes. A low ratio of Fe3 +/FeTotal in crystals of magnetite-silicate microspherules and high ZnO contents can identify them as industrial contaminants. The pyrite microspherules and framboidal pyrite found from bed 24e and bed 26 at the Meishan sections are of depositional or/and diagenetic origins, and only the rounded quartz and the fragments containing extremely high SiO2 and TiO2 are possibly of volcanic origin. [ABSTRACT FROM AUTHOR]

Previous studies of the end-Permian mass extinction have established that it was geologically rapid, but condensed sections have made it difficult to establish the exact timing of the extinction relative to fluctuations in the ocean carbon cycle, oxygen levels, and temperature. Integrated high-precision U-Pb geochronology, biostratigraphy, and chemostratigraphy from a highly expanded section at Penglaitan, Guangxi, South China reveal a sudden end-Permian mass extinction that occurred at 251.939 ± 0.031 Ma, which is temporally coincident with the extinction recorded in Bed 25 of the Meishan section. Despite the significantly expanded nature of the section and extensive collecting of more than ten major marine fossil groups, there is no evidence of a decline of biotic diversity prior to the extinction interval and no Permiantype species survive the extinction at this location. Fossil range data suggest a nearly instantaneous extinction at the top of a narrow stratigraphic interval limited to 31 ± 31 k.y. The extinction was preceded by and/or accompanied by fluctuations in δ13Ccarb and δ13Corg of 2-3‰, and 3-5 °C in seawater temperature. A larger, more rapid seawater temperature rise of 6-8 °C immediately followed the extinction level at Penglaitan. The extinction is spatially associated with a thick unit of tuff and tuffaceous sandstones (Bed 141) indicating massive pyroclastic input. It is correlative with an ash layer (Bed 25) in the deeper water setting at Meishan, where some Permian-type organisms survived the extinction. Our study reveals that the survivability of Permian taxa after the major extinction pulse is variable and dependent upon the severity of environmental perturbation in different sedimentary settings. The sudden extinction may fit a scenario in which the onset of Siberian Traps and South China intensive volcanism ~420 k.y. before the extinction may have diminished the ecological resilience of communities and reduced ecological functions with little change in diversity. In such an environmentally stressed condition, a single environmental disturbance could trigger the sudden collapse of global ecosystems. [ABSTRACT FROM AUTHOR]

The article discusses research into the chronology and possible causes of the mass extinction event at the end-Permian of the Phanerozoic era. Biodiversity data from sediments in South China was studied, including the mass spectrometric geochronological, isotopic, and biostratigraphic information from several sites. The results indicate that the mass extinction occurred in marine and terrestrial ecosystems 252.28 ± 0.08 million years ago over the course of 20,000 years or more, and point toward thermogenic carbon dioxide or methane emissions as possible causes of the extinction event.