Neil W. Archbold

Distribution and characteristics of mixed (transitional) mid-Permian (Late Artinskian—Ufimian) marine faunas in Asia and their palaeogeographical implications

Abstract The Permian marine biogeography of the Asian region is characterised by the development of three broad realms (Boreal, Tethyan and Gondwanan). In the early Early Permian (Asselian to Early Artinskian), there seems to have existed sharp biogeographical boundaries with no transitional zones between the realms, presumably due to the effect of Gondwanan glaciation and sharp climatic zonation. The mid-Permian (Late Artinskian to Ufimian) of the Asian region is distinguished by the rise of two broad transitional zones in which mixed marine faunas flourished. The northern transitional zone (north and northeast China, Sikhote Alin, central and northeast Japan) is characterised by an admixture of both warm-water Cathaysian and cold temperate Boreal genera. The southern transitional zone (Arabian Peninsula, Iran, Afghanistan, the Karakorum, southeast and central Pamir, Salt Range, central and northwest Tibet, Shan-Thai terrane, Timor, and western Irian Jaya), on the other hand, is distinguished by incorporating faunal elements of both Gondwanan and Cathaysian origin. The mixed faunas of both transitional zones share several antitropically distributed genera (e.g., Monodiexodina, Lytvolasma and Spiriferella ) and are succeeded by palaeotropical Tethyan faunas of Late Permian age. It has been postulated that the mixed mid-Permian fauna of the northern transitional zone was probably formed in an epicontinental sea which was connected to both the Asian Tethys and the Arctic, which facilitated the migration of Cathaysian and Boreal forms into the epicontinental sea and subsequent faunal mixing. The formation of the mixed faunas of the southern transitional zone, on the other hand, is probably related to the breaking off of the Cimmerian blocks from northern Gondwana and subsequent drifting into a lower latitudinal zone with geographical proximity to both Gondwana and Cathaysia during the mid-Permian.

Unique marine Permian‐Triassic boundary section from Western Australia

A unique marine Permian‐Triassic boundary section containing rich oil source rocks has been continuously cored in a petroleum borehole from the Perth Basin of Western Australia. Such sequences, which provide a biostratigraphic and environmental record at the time of the largest extinction event of the past 500 million years, are globally rare, and this is the first to be documented in Australia. Throughout geological history there have been periods of global marine anoxia that commonly resulted in the widespread deposition of petroleum source rocks, most notably in the mid‐Cretaceous and Late Jurassic. An apparent paradox is that, previously, source rocks have not been recognised in association with the Permian‐Triassic boundary, despite widespread marine anoxia at this time. The Perth Basin source rocks contain abundant and unusual biomarkers, apparently related to the highly specialised and limited biota that flourished in the aftermath of the end‐Permian extinction event. Local conditions may have favoured source‐rock development, either due to higher productivity resulting from coastal upwelling or through enhanced preservation under strongly anoxic conditions.

Permian brachiopods from the Selong Xishan section, Xizang (Tibet), China - Part 1: Stratigraphy, Strophomenida, Productida and Rhynchonellida

Abstract A brachiopod fauna containing some 42 brachiopod species of 30 identified genera and 2 unidentifiable genera is recorded from the Selong Group of the Selong Xishan section in southern Xizang (Tibet). Various species of Strophomenida, Productida and Rhynchonellida from this fauna are described and revised in this paper. New taxa include Neochonetes (Sommeriella) regularis nov. sp., Taeniothaerus densipustulatus nov. sp., Krotovia inflata nov. sp., Retimarginifera xizangensis nov. sp., Costatumulus tazawai nov. sp. and Neopsilocamara laevis nov. gen. et sp. Brachiopods from the Selong Group and the basal 0.07 m of the Kangshare Formation indicate an age ranging from Capitanian to Changhsingian in terms of the lates three-fold Permian timescale. Three brachiopod assemblages at the Selong Xishan section are recognised. The Marginalosia-Composita Assemblage in the lower part of the Selong Group is considered to be of Capitanian to Wuchiapingian age. The brachiopods in the Chonetella nasuta Assemblage suggest a Wuchiapingian to possibly early Changhsingian correlation. The Martinia-Waagenites Assemblage in the basal part of the Kangshare Formation is late Changhsingian in age. The brachiopod succession of the Selong Xishan section indicates that there is no major hiatus present within the Selong Group and the Permian-Triassic boundary beds.

Western Pacific Permian marine invertebrate palaeobiogeography

Data matrices of the presence/absence occurrence data of brachiopod genera from faunal stations throughout the western Pacific region for the Asselian‐Tastubian, Sterlitamakian‐Aktastinian, Baigendzhinian‐Early Kungurian and Kazanian‐Midian time slices of the Permian Period have been analysed by cluster analysis, non‐metric multidimensional scaling and principal coordinate analysis. An evolving pattern of provincialism is recognised for the Permian of the western Pacific with four provinces (Indoralian, Himalayan, Cathaysian and Verkolyma) for the Asselian‐Tastubian, six (Austrazean, Westralian, incipient Cimmerian, Cathaysian, Sino‐Mongolian precursor and Verkolyma) for the Sterlitamakian‐Aktastinian, seven (Austrazean, Westralian, Cimmerian‐with the Sibumasu and Himalayan subprovinces‐Cathaysian, Sino‐Mongolian and Verkolyma) for the Baigendzhinian‐Early Kungurian, and three (Austrazean, Cathaysian and Verkolyma) for the Kazanian‐Midian time slice. The changing pattern of provincialism is best understoo...

An Early Permian brachiopod fauna of Gondwanan affinity from the Baoshan block, western Yunnan, China

The present paper describes and illustrates an Early Permian brachiopod fauna collected from two localities from the upper part of the type Dingjiazhai Formation near Youwang, 30 km south of Baoshan in the Baoshan block, western Yunnan, China. The brachiopod fauna is dominated by Stenoscisma sp. and Elivina yunnanensis sp. nov. and exhibits strong generic and some specific links with faunas from the Bisnain assemblage of Timor and the Callytharra Formation of Western Australia and, to a lesser extent, faunas from the Jilong Formation of southern Tibet, the Tashkazyk Formation of southeastern Pamir, the lower Toinlungkongba Formation of northwestern Tibet, the upper Pondo Group of central Tibet, and the Jimba Jimba Calcarenite of the Carnarvon Basin, Western Australia. Based on these correlations, a Late Sakmarian (Sterlitamakian) age is preferred for the Dingjiazhai brachiopod fauna. Two new species are proposed: Globiella youwangensis sp. nov. and Elivina yunnanensis sp. nov.

Permian Brachiopods from the Selong Xishan section, Xizang (Tibet), China. Part 2: Palaeobiogeographical and palaeoecological implications, Spiriferida, Athyridida and Terebratulida

Brachiopods from the Selong Group at the Selong Xishan section indicate a typical Peri-Gondwanan affinity, but possibly a rapid invasion of tropical/subtropical Tethyan elements into the Himalayan region at the very end of Permian. A brief analysis of taphonomy and composition of the Selong fauna indicate that Selong Xishan lay on the shallow continental shelf near shore and brachiopods suffered substantial abrasion from contemporaneous wave action. Species of Spiriferida, Athyridida and Terebratulida are herein described and revised. New taxa are Nakmusiella selongensis nov. gen. et sp. and ? Bullarina striata nov. sp.

Chonetoidea (Brachiopoda) from the Lopingian (Late Permian) of South China

Ten species of the superfamily Chonetoidea from the Lopingian (Late Permian) of South China are described or revised. A review of all recorded Chonetoidea species from the Lopingian (Late Permian) of South China indicates that some 22 species of five genera can be recognised. Species of Tethyochonetes and Neochonetes are characteristic in the lithofacies dominated by mudstone, siltstone or siliceous rocks in the Lopingian and some argillaceous limestone and clay rock facies near the Permian-Triassic boundary. New taxa are Neochoneles (Zhongyingia) subgen. nov., Neochonetes (Huangichonetes) subgen. nov. and Tethyochonetes flatus sp. nov.

Changhsingian (Late Permian) brachiopod Palaeobiogeography

Detailed statistics show that 141 brachiopod genera from 50 families are known from the Changhsingian, occurring at 21 stations. Calculation of Jaccards coefficient and Simpsons coefficient between all pairs of stations, together with analyses of faunal compositions, reveals the existence of five marine provinces. The extent of the Palaeo‐Equatorial Region apparently expanded, probably owing to global warming, during the later Permian. No Boreal‐type brachiopod faunas are reliably known from the Changhsingian. Gondwa‐nan‐type brachiopod faunas of the Changhsingian seem to be known only from New Zealand, suggesting that the Austrazean Province was still present. Changhsingian brachiopods of the Austrazean Province consist mainly of species of Aperispirifer, Spirif‐erella, Tomiopsis and Notospirifer. The southern Kitakami fauna of Northeast Japan, consisting of Megousia, Tschernyschewia, Orthothrix, Paratnarginifera and Eolyttonia may be the unique vestige of the Sino‐Mongolian Province. The Cathaysian Province is composed of the Yangtze Block, Qiangtang Terrane, Qaidam Basin, Lhasa Terrane, Maizuru Belt of southwest Japan, Thailand and Vietnam. This province is characterized by Peltichia, Perigeyerella and Paryphella. The western Tethyan Province, along the west coast of Tethys, is closely linked with the Cathaysian Province. Its most distinctive genus is Comelicania. The Himalayan Province is of predominantly Gondwanan aspect, with some Tethyan components. The Sino‐Mongolian Province, typified by the Kitakami faunas, occupied a position between Tethys and the Boreal Realm.

Permian brachiopods from the Tupe Formation, San Juan Province, Precordillera, Argentina

The brachiopod fauna from the Tupe Formation at La Herradura Creek, located on the west flank of Perico Hill, San Juan Province, Argentina, palaeogeographically belongs to the western sector of the Paganzo basin (‘Guandacol embayment’). The stratigraphical section of the Tupe Formation at La Herradura Creek is the stratotype of the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone, was previously regarded as being of Late Carboniferous age but here is assigned to the earliest Permian (Asselian). We describe and review the biozone assemblage, which consists of Streptorhynchus inaequiornatus, Tivertonia jachalensis, Kochiproductus sp., Costatumulus sp., Coronalosia argentinensis, Tupelosia paganzoensis, Trigonotreta pericoensis, Septosyringothyris sp. aff. Septosyringothyris jaguelensis and Crurithyris? sp. This brachiopod assemblage is related to Indian and Australian Early Permian faunas and its presence in the La Herradura Creek section provides new evidence in support of an Asselian (Early Permian) age for the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone. This assemblage is also important for intra- and inter-basinal correlation because several of its characteristic species have been identified from other sections of the Paganzo basin and the Río Blanco basin. The proposed age for this biozone is consistent with the age of palynological data from slightly above the marine faunas from the stratotype locality.

The Gondwanan Carboniferous-Permian Boundary Revisited: New Data from Australia and Argentina

Abstract The identification and correlation of the Carboniferous-Permian (Gzhelian-Asselian) boundary within the sedimentary sequences of Gondwana has always been a topic of debate. Type latest Carboniferous and earliest Permian marine sequences are characterised by warm tropical faunas and come from the Uralian Region of Russia and Kazakhstan. Faunas include conodonts and fusulinid foraminiferids which are prime tools for correlation. Such faunal groups are absent from most Gondwanan sequences where reliance for correlations must be placed primarily on brachiopods, bivalve molluscs and palynology. The Western Australian marine sequences, with their contained ammonoids, provide a pivotal link for the dating and correlating of Early Permian Gondwanan sequences with those of the type regions and their palynostratigraphical record is essential for trans-Australian correlations and correlations elsewhere throughout Gondwanaland. New data from the fully cored DM Tangorin DDHl bore hole, drilled in the Cranky Corner Basin, New South Wales, Australia, reveals a sequence of descending faunal zones. The stratigraphically highest zone with Eurydesrna cordaturn, encompasses the Late Sakmarian (Sterlitamakian). The middle zone with Torniopsis elongata, Sulciplica c r a m and Trigonotreta tangorini straddles the Sterlitamakian-Tastubian boundary, with the palynomorphs Pseudoreticulatispora pseudoreticulata high in the zone and Granulatisporites confluens low in the zone. An impoverished fauna with Trigonotreta nov., low in the Granulatisporites confluens Zone, is probably of latest Asselian or Tastubian age. Significant new data from Argentina has revealed marine faunas from below the occurrence of Granulatisporites confluens. These are considered to be of Asselian age. Outcrops of the Tupe Formation, with a marine fauna, at La Herradura Creek in the western Paganzo Basin, San Juan Province, are best regarded as being of mid to late Asselian age. The Tupe Fauna has been recognised as the Tivertonia jachalensis-Streptorhynchus inaequiornatus Zone. Previously, this fauna was considered to be of Late Carboniferous or Stephanian age. Three faunal associations are known from the Rio del Peii6n Formation, Rio Blanco Basin, La Rioja Province. The middle assemblage with Tivertonia, Costaturnulus, Kochiproductus and Trigonotreta, appears to correlate well with the Tupe Formation fauna. The lower assemblage, with Streptorhynchus, Etherilosia, Costaturnulus, Trigonotreta and a punctate spiriferid, as well as indeterminate productids, probably of Early Asselian age. The youngest assemblage includes a species ofRhynchopora that is close to Rhynchopora australasica from the latest Asselian-early Tastubian of Western Australia. The marine biostratigraphical data from Argentina has enabled a much greater understanding of the earliest Permian marine faunas to be achieved - a story that is apparently absent from the other cold and cool temperate regions of Gondwana.