Permian and Triassic Radiolaria from Northwest Thailand: paleogeographical implications

Well-preserved radiolarians were recovered from seven sections in the Mae Hong Son-Mae Sariang area, northwestern Thailand. 51 species assigned to 34 genera are identified, including 1 new species (Triassospongosphaera erici Feng sp. nov.) and 19 unidentified species. They are divided into the Late Permian, late Ladinian and middle Carnian radiolarian assemblages. Newly identified radiolarian assemblages, together with the published radiolarian biostratigraphic data from this region, indicate that there was a pelagic basin during the Late Paleozoic and Triassic. This basin was joined to the Chiang Dao and Changning-Menglian oceanic basins, and they represent the main oceanic basin of the Paleotethyan Archipelago Ocean. This main oceanic basin was situated in the traditional “Shan-Thai Block”. Therefore, “the Shan-Thai Block” was not a single block during that stage, but composed of the Paleotethyan Ocean and two continental terranes that were affiliated with the Gondwana and Cathaysian domains, respectively.     

Palynological evidence of Early Carboniferous sedimentation in the Llanos Orientales Basin, Colombia

Early Carboniferous palynological assemblages from the SM-4 well located in the Llanos Orientales Basin constitute the only definitively geological evidence of Carboniferous strata in this Basin. Stratigraphically significant species include: Anapiculatisporites concinnus, Apiculiretusispora mutiseta, Grandispora spiculifera, Indotriradites dolianitii morphon, Spelaeotriletes pretiosus and Prolycospora rugulosa. The presence of scarce acritarchs indicates a shallow marine environment. A Tournaisian age, probably reaching the Viséan, is proposed for the interval 2010-2340 ft based on the presence of distinctive spore species with previous records in the Viséan and Tournaisian of Western Europe and Western Gondwana. This report increases the knowledge about the distribution and composition of the Early Carboniferous palynological assemblages in Northern Gondwana.     

Late Devonian - Early Carboniferous vertebrate microremains from the Carnic Alps, northern Italy

Vertebrate microremains from the Late Devonian-Early Carboniferous of the Carnic Alps are predominantly chondrichthyan, with minor placoderm and actinopterygian remains. The faunas are sparse and, with very few exceptions, occur only in conodont-rich pelagic limestones (Pramosio Limestone) representative of the palmatolepid-bispathodid conodont biofacies. Phoebodont and jalodont chondrichthyans, also reflecting open-ocean environments, predominated during the Famennian, and eventually symmoriids seem to predominate during the Early Carboniferous. The presence of Siamodus in this assemblage gives a new locality for this genus known from few regions in the world and allows confirming its stratigraphical range (limpidus Zone) and its relation to deep-water environments. The Late Devonian vertebrate faunas are tropical and cosmopolitan, having much in common with coeval taxa from the North-Gondwanan margins and Asian terranes. Composition of the vertebrate faunas is consistent with the Carnic Alps terrane having occupied a position intermediate between Gondwana and Laurussia, as hypothesized by various authors, but because of sparsity of the taxa represented and the pronounced cosmopolitan nature of both the conodont and vertebrate faunas, the data are not compelling.     

Radiizonates arcuatus, a distinctive new miospore species from the Lower Carboniferous of Western Gondwana

A new species of trilete zonate miospores, Radiizonates arcuatus, is established for Lower Carboniferous Western Gondwanan forms hitherto ascribed misguidedly to Radiizonates genuinus (Jushko) Loboziak and Alpern (1978), a Russian Lower Carboniferous species. The latter binomen is, moreover, not a valid combination and is more correctly designated as Vallatisporites genuinus (Jushko) Byvsheva, 1980. R. arcuatus is, from records to date, confined to westerly parts of Gondwana (Brazil, North Africa and Middle East), in which it is characteristic of Early Carboniferous strata, albeit with some slightly older and slightly younger occurrences.     

Palynostratigraphy and palaeogeography of the Padeha, Khoshyeilagh, and Mobarak formations in the eastern Alborz Range (Kopet-Dagh region), northeastern Iran

A total of 113 surface samples collected from the Padeha, Khoshyeilagh, and Mobarak formations of Kuh-e-Ozum, northeast of Jajarm town were processed for palynomorphs, in order to determine age relationships. Well-preserved and abundant palynomorphs dominated by organic-walled-marine microphytoplankton (acritarchs and prasinophyte phycomata), miospores and subordinate chitinozoans, and scolecodonts were recovered. Seven species of prasinophyte phycomata (four genera), 19 acritarch species (14 genera), one species of chitinozoa, and 26 miospore species (19 genera) were recorded and assigned to eight local Assemblage Zones. Assemblage Zones I-IV occur in the Padeha Formation and suggest an Early Late Devonian (Frasnian) age whilst assemblages zones V-VII are present in the Khoshyeilagh Formation and indicate Late Devonian (Famennian) ages. Assemblage zone VIII, which occurs in the basal part of Mobarak Formation, suggests a Lower Mississippian (Tournaisian) age for this formation. Many of the palynomorph groups encountered are closely comparable with coeval assemblages recorded from Western Australia, southwest Ireland, England, Turkey, Saudi Arabia, North Africa, and South America, indicating the close relationship of the Iranian Platform to other parts of the northern Gondwana Domain during the time interval represented by these strata. The presence of marine palynomorphs (acritarchs/prasinophyte phycomata, chitinozoans, and scolecodonts), and shelly macrofauna (brachiopods, gastropods, and corals) in Member c of the Padeha Formation (as well as the Khoshyeilagh and Mobarak formations), together with associated miospores, indicate an open marine (moderately nearshore) depositional environment for the Upper Devonian and Lower Carboniferous deposits in northeastern Alborz Range (Kopet-Dagh region) of Iran.     

New data on the Tournaisian bryozoans (Lower Carboniferous) from Azerbaijan and Armenia

Three new bryozoan species of the order Trepostomata are described from the Tournaisian sedimentary rocks of Azerbaijan (Nakhichevan) and Armenia: Nikiforopora arpaensis sp. nov., Tabuliporella nakhichevanica sp. nov., and Anisotrypa kjarkiensis sp. nov. The sequential change in the bryozoan associations in southern Transcaucasia during the Tournaisian age is considered. Some taxa are shown to belong also to the Early Carboniferous bryozoan assemblages of the shelf seas of the Paleotethys.     

FOSSIL WOODS IN INTERGLACIAL SEDIMENTS FROM THE CARBONIFEROUS HOYADA VERDE FORMATION, SAN JUAN PROVINCE, ARGENTINA

Abstract:  Fossil woods are described and assigned to Cuyoxylon multipunctatus gen. et sp. nov. The woods were deposited in shales from an interglacial period, and are the first to be described in detail from the Carboniferous glaciation of western Gondwana. They have the primitive characters of Early Carboniferous woods, such as mesarch protoxylem and numerous contiguous pits in an alternate arrangement. They are the oldest fossil woods to have been described from South America. The growth ring characteristics are consistent with a seasonal cool climate.     

Pangea Megasequences of Tethyan Gondwana-margin reflect global changes of climate and tectonism in Late Palaeozoic and Early Triassic times—A review

The maximum concentration of continental crust at the Pangea stage is characterized by a specific depositional sequence generally referred to as the Pangea Megasequence. Extending in time from the Late Carboniferous to the middle of the Triassic, the succession exhibits similar trends across the whole of Gondwana. Invariably, the sequence was initiated by Late Carboniferous to Early Permian glacial and periglacial deposits. Deglaciation occurred in Early Sakmarian time, evidenced by a typical, commonly transgressive facies. The succeeding formations comprise, in ascending order, coal measures, redbeds, some more coal measures and again redbeds with an intercalation of fluviatile sands in the Early Triassic.After deglaciation the basic depositional theme was modified, depending on postglacial adjustments of climate and on the type of regional tectonic regimes. Extension of the tropical climatic belt after deglaciation was one factor that governed the resulting sediment facies. Coal deposition that prevailed in central Gondwana in the Early Permian gave way to dominance of redbeds in the Middle and Late Permian and, in more distal positions, evaporitic deposits were laid down, following deglaciation. Within marine realms, coralline limestones were formed.Within Gondwana the depositional period of the Pangea Megasequence was governed by three distinctive tectonic regimes: collision dominated the Panthalassa margin, transpressional sag controlled the interior basins, and extension and rifting was experienced along the entire Tethyan margin. In the Early Permian, large and complex graben structures commenced to develop between Africa and India (Malagasy Trough) and between India and Australia (West Australian Trough), giving access to Tethyan waters during deglaciation, commencing in the late Early Sakmarian.Rifting along the Tethyan margin commenced in the Early Permian and was associated with active volcanism between Cashmere and Yunnan and in north-western Australia. Spreading of Neo-Tethys and the formation of oceanic crust, leading to the separation of the Cimmerian Blocks from Gondwana, commenced in the late Early Permian and continued into the Triassic. Thus two facies realms developed, an intracratonic rift facies comprising the Cashmere, Lhasa and Baoshan blocks and a facies controlled by detachment, comprising more distal blocks, such as Tengchong, Malay and Sumatra. The present distribution of individual blocks was governed by fold movements of the Himalayan Orogeny, complicated by transpression along the eastern Himalayan Syntaxis.     

Mississippian (early Carboniferous) radiolarian biostratigraphy of northern Thailand (Chiang Dao area)

Well-preserved Carboniferous radiolarian faunas were obtained from ribbon-bedded siliceous sediments (radiolarites) north of Chiang Dao city, Chiang Mai province, northern Thailand. These sediments are rich in identifiable radiolarian faunas, including more than 44 species and sub-species belonging to 15 genera. Among them, Albaillellaria and Latentifistularia are dominant, but few Entactinaria are present. Five Early Carboniferous radiolarian assemblage zones are recognised and compared to those of Germany, France and North America. They are, in ascending order: the Albaillella paradoxa gr. assemblage; the Albaillella indensis gr. assemblage: the Albaillella cartalla-Albaillella furcata furcata assemblage which includes the Palaeolithocyclia rota subassemblage; and the A. furcata rockensis-Latentifistula impella gr. assemblage. The age assignment of each assemblage is well-controlled by co-occurring conodonts, which are abundant during this time interval in the area. The Thai radiolarian assemblage zones are rather similar to those of Germany and North America, indicating that the albaillellarian form has a global distribution and can be readily used as a world key indicative fauna. These results also provide an additional data set indicating that distal oceanic deposits are present in northern Thailand from the Devonian to the Late Triassic, which provides evidence for a long-lived oceanic realm between the Indochina and Shan-Thai continental terranes (nearly 200 My).     

Miospore assemblages from the Silurian–Devonian boundary,in borehole A1-61, Ghadamis Basin,Libya

Well preserved and diversified miospore assemblages have been recorded from a relatively continuous sequence in borehole A1-61 which spans the Silurian–Devonian boundary in the northwestern part of the Ghadamis Basin, Libya. The sequence is represented by early Devonian Lochkovian beds of the Tadrart Formation that transgress onto the Silurian Ludlow-Pridoli beds of the upper part of the ‘Alternances Argilo-gréseuses’ Formation. The present work demonstrates a succession of miospore assemblages from closely sampled layers that have been stratigraphically dated as Ludlow–middle Pridoli and early Lochkovian by chitinozoans and acritarchs. Over 80 species of cryptospores and trilete spores have been identified. Modified detailed morphological interpretations are given. The miospore assemblages are correlated with miospore zonation schemes established for the type sequences of the Welsh Borderland, and those previously described from Libya. Early occurrences of some species as Streelispora newportensis on the western Gondwana plate, are put forward by comparison with the Old Red Sandstone continent. Phytogeographic and palaeobotanic implications based on these observations are discussed.     

全球石炭纪和二叠纪植物地理分区

早石炭世由于全球气候分带不明显,无显著植物分区现象,全球为一个一致性的植物区,即拟鳞木植物区[WT5”BX](Lepidodendropsis [WT5”BZ]floral province)。晚石炭世和二叠纪,全球存在4个植物区,即华夏植物区(Cathaysian floral province)、欧美植物区(Euramerican floral province)、安加拉植物区(Angaran floral province)和冈瓦纳植物区(Gondwanan floral province)。华夏、欧美和安加拉植物区皆位于北半球的劳亚古陆(Laurasia), 冈瓦纳植物区位于南半球的冈瓦纳古陆(Gondwana)。本文通过对全球石炭纪二叠纪植物地理分区的一些焦点问题的综合评述和分析,试图为古大陆再造研究提供古植物学方面的证据。     

Fossil Plants and Their Assemblages from the Early Carboniferous in Guangdong

This paper deals with the Lower Carboniferous fossil plants, 19 genera and 41 species including 10 new species, such as Sublepidodeneron wcwgtanense, Lepidodendron sophoroides, Adiantites lianpingensis, A. matouensis, Archaeopteridium shaoguanense, Rhacopteris angusta, Rhodeites lanceolata, Neuropteris shaoguanensis, Potoniea turbinata and P. racemicarpa. According to the distributive regularity of those fossils in stratigraphic section of Early Carboniferous from Guangdong area, the authors propose to divide the flora into three assemblages from lower to upper, namely, 1, Sublepidodendron mirabile assemblage; 2. Cardiopteridium spetsbergense-Adiantites gothanii assemblage; 3. Archaeopteridium-Sphenopteris obtusiloba assemblage, which separately represent the dispositions of Dahu Formation (the 1st assemblage), the lower part of Ceshui Formation (the 2nd assemblage) and upper part of Ceshui Formation or middle part of Zhongxin Formation (the 3rd assemblage).     

Global deglaciation and the re‐appearance of microbial matground‐dominated ecosystems in the late Paleozoic of Gondwana

The extensive matgrounds in Carboniferous‐Permian open‐marine deposits of western Argentina constitute an anachronistic facies, because with the onset of penetrative bioturbation during the early Paleozoic microbial mats essentially disappeared from these settings. Abundant microbially induced sedimentary structures in the Argentinean deposits are coincident with the disappearance of trace and body fossils in the succession and with a landward facies shift indicative of transgressive conditions. Deposits of the Late Carboniferous–Early Permian glacial event are well developed in adjacent basins in eastern Argentina, Brazil, South Africa and Antarctica, but do not occur in the western Andean basins of Argentina. However, the deglaciation phase is indirectly recorded in the studied region by a rapid rise in sea level referred to as the Stephanian‐Asselian transgression. We suggest that an unusual release of meltwater during the final deglaciation episode of the Gondwana Ice Age may have dramatically freshened peri‐Gondwanan seas, impacting negatively on coastal and shallow‐marine benthic faunas. Suppression of bioturbation was therefore conducive to a brief re‐appearance of matground‐dominated ecosystems, reminiscent of those in the precambrian. Bioturbation is essential for ecosystem performance and plays a major role in ocean and sediment geochemistry. Accordingly, the decimation of the mixed layer during deglaciation in the Gondwana basins may have altered ecosystem functioning and geochemical cycling.     

全球石炭纪和二叠纪植物地理分区

早石炭世由于全球气候分带不明显,无显著植物分区现象,全球为一个一致性的植物区,即拟鳞植物区（Ｌｅｐｉｄｏｄｅｎｄｒｏｐｓｉｓ ｆｌｏｒａｌ ｐｒｏｖｉｎｅｃｅ）。晚石炭世和二叠纪,全球存在４个植物区,即华夏植物区（Ｃａｔｈａｙｓｉａｎ ｆｌｏｒａｌ ｐｒｏｖｉｎｃｅ）、欧美植物区（Ｅｕｒａｍｅｒｉｃａｎ ｆｌｏｒａｌ ｐｒｏｖｉｎｃｅ）、安加拉植物区（Ａｎｇａｒａｎ ｆｌｏｒａｌ ｐｒｏｉｎｃｅ）     

河南固始下石炭统杨山组华夏木一新种

描述河南固始杨山煤矿下石炭统杨山组的一个华夏木新种Cathaysiodendronyangshanensesp.nov.,这是近年来继在甘肃靖远早石炭世臭牛沟组中发现华夏木之后该属在早石炭世地层中的又一发现。华夏木属是华夏植物群的特有分子,它在早石炭世的发现对探讨华夏植物群的起源有重要意义。     

A new Carboniferous equisetale from western Gondwana

Upper Paleozoic sphenopsids from western Gondwana are little known. New finds were made from the Upper Carboniferous of the San Juan province (Argentina). The specimens include vegetative and fertile characters that allow the definition of a new genus and species: Gondwanites subtilis. They are characterized by slender branches bearing whorls of very thin, simple or divided leaves. Simple fertile organs are borne in whorls just below the verticel of leaves. The presence of dichotomized leaves and bractless fertile organs in the new taxon suggests its probable primitive condition.     

Siphonodella leiosa (Conodonta), a new unornamented species from the Tournaisian (lower Carboniferous) of Puech de la Suque (Montagne Noire,France)

A new conodont species, Siphonodella leiosa, is described from the lower Carboniferous pelagic limestones of the Montagne Noire (France), deposited in North Gondwana on a outer platform environment. Specimens were obtained from one level dated to the Siphonodella jii conodont Zone. The major difference from other siphonodellid conodonts known in this area is that the elements of this new species have a practically entirely smooth and unornamented platform, apart from the development of one or two low rostral ridge-like nodes. Similar morphologies were generally observed in shallow marine deposits of the same time frame from China, Russia and East and Central European areas. The new discovery reinforces the idea that ornamentation of siphonodellids is not only related to bathymetry, but that temperature could play an important role in the diversification and radiation of unornamented species during the Siphonodella jii conodont Zone.     

Anisian foraminifers from allochthonous limestones of the Tanoura formation (Kurosegawa Terrane, West Kyushu, Japan)

Thirty-five species belonging to 21 genera of foraminifers are distinguished from allochthonous limestone blocks contained within the autochthonous mudstones and sandstones of the Carnian Tanoura Formation, Kurosegawa Terrane of West Kyushu (SW Japan). These blocks are considered to be Anisian in age, based on the occurrence of two foraminifers widely distributed in the Anisian of the Tethyan Realm, Pilammina densa and Meandrospira dinarica; they are associated with Involutinid-like forms, such as Triadodiscus and Aulotortus, and with other foraminifers. The allochthonous limestones are mostly composed of oolites, abundant bioclasts and detrital quartz grains. They are thought to have been redeposited during the Carnian on the shelf slope of the South Kitakami-Kurosegawa Old Land. Palaeogeographically, this terrane was part of the North Gondwana margin, then isolated eastwards before its Early Cretaceous amalgamation with South China. Three foraminiferal species, Triadodiscus eomesozoicus (Oberhauser), Triadodiscus? tanourensis, n. sp., and Triadodiscus? sp. are described from the Anisian allochthonous blocks.     

Caradoc strophomenoid and plectambonitoid brachiopods from Wales and the Welsh Borderland

Abstract: Ordovician strophomenoidean and plectambonitoidean brachiopods are reviewed and partially redescribed from the Caradoc (Sandbian to Early Katian) age rocks of Wales and the Welsh Borderland of England, then forming part of the Avalonia Terrane. There are 51 nominal species available, of which 12 are synonymised here and many transferred to different genera. Strophomenoids occurred sporadically, often rarely but occasionally abundantly, particularly in mid‐shelf benthic assemblages, and 21 named species and subspecies are noted, including the new Kiaeromena (Kiaeromena) harperi, as well as six in open nomenclature. The common genus Kjaerina, with six species known from the area, is revised in detail. In contrast to the strophomenoids, plectambonitoids were more common in shallow and mid‐shelf assemblages, including Eoplectodonta (Eoplectodonta) abigailae sp. nov., with Sowerbyella in particular dominating many bedding planes, and 17 named species are reviewed, as well as three in open nomenclature. The distinctive Gunningblandella, hitherto known only from Australia and Kazakhstan, is recorded for the first time from Europe. The Avalonian strophomenides are compared with those from neighbouring terranes, particularly Laurentia and Baltica, during a time when the seas between those terranes were narrowing, and the faunas from the three terranes are found to be largely similar at the generic level, although there are few species in common. In contrast, there are few genera in common between those three terranes and the Mediterranean Province of Northwestern Gondwana.     

河北唐山西域山晚寒武世长山组的树形笔石

本文对东秦岭南部湖北郧西地区早石炭世四射珊瑚进行了研究,系统描述了11科中的24属和39种,其中包含2新属和21新种。本区早石炭世四射珊瑚拟划分为4个组合带:范家坪组上部Palaeosmilia-Lithostrotion组合带,下部Yuanophyllum组合带。袁家沟组上部Shennongia majus组合带,下部Zaphrentoides组合带。范家坪组是新建的组名。文中也讨论了Cystophrentis的分布时限,及其与Shennongia的亲缘关系。此外,Neoclisiophyllum在本区与岩关期的Shennongia共生,出现的时间早于华南各地。