Late Middle Permian Research Articles

Gigantopteris Schenk ex Yabe in the Capitanian–Wuchiapingian (middle-late Permian) flora of central Shanxi in North China: Palaeobiogeographical and palaeoecological implications

The concept of the Cathaysian Flora was originally based on fossils from the Permian of central Shanxi Province in North China but is now recognized to be valid for the flora of much of East Asia during the Carboniferous and Permian periods. Although Gigantopteris Schenck ex Yabe is characteristic and often distinctive of the Cathaysian Flora in general, it has previously not been recorded in Shanxi Province within the central part of the North China. Recent investigations on the Capitanian–Wuchiapingian (middle-late Permian) flora of the Taiyuan East Hill Coalfield in Shanxi have yielded well-preserved specimens of Gigantopteris dictyophylloides Gu and Zhi within the Upper Shihhotse Formation, contained within continental red-beds interpreted as representing a floodplain environment. Discovery of G. dictyophylloides extends the palaeogeographic distribution of the genus and shows that the Permian flora of Shanxi is more typical of the Cathaysian Flora than previously thought. Results also provide new information on the ecology of G. dictyophylloides based on assessments of its occurrence within depositional sedimentary facies from which we conclude that this species thrived in alluvial–fluvial sediments on the North China Block. We also conclude that the red beds of the Upper Shihhotse Formation that yield gigantopterids most likely formed under a seasonally dry climate rather than a vague statement that these red beds were formed generally under arid conditions as previously thought.

The cranial morphology of the temnospondylAustralerpeton cosgriffi(Tetrapoda: Stereospondyli) from the Middle-Late Permian of Paraná Basin and the phylogenetic relationships of Rhinesuchidae

Stereospondyls are a diverse and morphologically distinctive clade of basal tetrapods that rapidly reached a global distribution and high abundance during the Early Triassic. Yet, the first stereospondyls appeared in the Middle–Late Permian of Gondwana, mostly represented by Rhinesuchidae. Australerpeton cosgriffi is a long-snouted representative of the group and one of the most complete temnospondyls known from the Permian of South America. The elements attributed to Au. cosgriffi were recovered from the Middle-Late Permian deposits of the Rio do Rasto Formation (Parana Basin), in the Serra do Cadeado area of Brazil. Here, we review the cranial anatomy of the species, providing a comparative redescription, new anatomical data and previously unrecognized characters. Australerpeton cosgriffi is nested within Rhinesuchidae based on the anatomy of the tympanic cavity, but its long-snouted condition is unique amongst rhinesuchids. Based on the recovered information and new morphological data, the systematic position of Au. cosgriffi was assessed using a new matrix of 221 characters; of which 196 were selected from previous studies and the remaining are newly proposed. The results show Rhinesuchidae divided into Rhinesuchinae and Australerpetinae. A unique tympanic cavity formed by a well posteroventrally projected tabular horn, stapedial groove, well-developed oblique crest on the pterygoid, and a dorsal pterygoid crest (new term) characterizes the ear region of Rhinesuchidae. Australerpeton cosgriffi is the only undisputed Rhinesuchidae record outside southern Africa and the first long-snouted Stereospondyli, and thus is useful in helping to understand the diversification of the stereospondyls during the Middle/Late Permian of Gondwana.

Palinspastic reconstruction and geological evolution of Permian residual marine basins bordering China and Mongolia

One main feature of the tectono-paleogeographic evolution of the southern branch of the Paleo-Asian Ocean was that there developed residual marine basins in former backarc/forearc regions after the disappearance of oceanic crust. The paper illustrates the viewpoint taking the evolution of Dalandzadgad and Solonker oceanic basins as examples. The Dalandzadgad ocean subducted southwards during the Silurian-Devonian, created an intra-oceanic arc and a backarc basin in southern Mongolia. In addition, a continent marginal arc formed along the national boundary between China and Mongolia, the south of which was a backarc basin. The oceanic basin closed and arc–arc (continent) collision occurred during the early Early Permian, followed by two residual marine basins developing in the former backarc regions, named the South Gobi Basin in southern Mongolia and the Guaizihu Basin in western Inner Mongolia. The Solonker ocean subducted southwards and finally disappeared during the early Middle Permian. Afterwards, two residual marine basins occurred in northern China, the Zhesi Basin being situated in the former backarc region and the Wujiatun Basin in the former forearc region. The late Middle Permian was the most optimum period for the developing residual marine basins, when they covered a vast area. The basin evolution differentiated during the early Late Permian, with a general trend of uplift in the east and of subsidence in the west. The Upper Permian in the South Gobi Basin was characterized by coal-bearing strata hosting economically valuable coal fields. A transgression invaded westwards and the Chandmani-Bayanleg Basin was created in southwest Mongolia during the middle-late stage of the Late Permian. Correspondingly, the coal formation entered a flourishing time, with thick coal beds and sedimentary interbeds. All of these basins, namely, both the marine and nonmarine residual basins, reversed and closed by the end of Permian.

Carboniferous and Permian biostratigraphy by foraminifers and calcareous algae of Bir Mastoura (BMT-1) and related boreholes of southern Tunisia

In South Tunisia, the Bir Mastoura (BMT-1) borehole provides Carboniferous, Permian, and early Triassic foraminifers and carbonate algae which permit to establish a local biozonation which can be correlated with (1) the Capitanian (Late Middle Permian) outcrops of Jbel Tebaga; (2) other Tunisian boreholes; and (3) several stratotypes and/or well-studied Tethyan outcrops. Microfacies, microfaunas and microfloras of BTM-1 reveal subtropical, carbonate, inner platform deposits. As everywhere in the world, the Early Triassic is faunistically very poor. The Upper Permian and Upper Middle Permian microfaunas and microfloras are traditional in Tunisia, but a little poorer than the Tebaga assemblages. The fusulinids of the middle and lower Middle Permian strata are also less numerous than in other Tunisian boreholes. The late Pennsylvanian fusulinids known in some of these boreholes, were not observed in BMT-1; however, these fusulinids are re-discussed here due to their biostratigraphic and palaeobiogeographic importance; they are assigned to two substages, early Gzhelian with Darvasoschwagerina spp. and late Kasimovian with Schwageriniformis petchoricus. Neither early-middle Kasimovian nor late Moscovian microfossils were found, and their absence is probably regional in the whole North Africa. In contrast, the early Moscovian beds yield all the fusulinid biozones of the Urals (Russia) and display diversified microfauna with Profusulinella aff. simplex, Ovatella ex gr. ovata; Depratina timanica, Aljutovella (Tikhonovichella) rhombiformis, Hemifusulina spp., Eofusulina aff. tashlensis, Paraeofusulina trianguliformis, Moellerites cf. praecolaniae and Parabeedeina cf. pseudoelegans. The middle-late Bashkirian seems to be only partially represented, whereas the early Bashkirian is similarly relatively complete, with Varvariella ex gr. varvariensis, Plectostaffella cf. karsaklensis, P.? nauvalia, Semistaffella? sp. and common oolitic microfacies. The Serpukhovian and late Visean appear more developed than in other boreholes. They yield Praedonezella, Eosigmoilina and Endostaffella. As across the North Africa, no older Mississippian foraminifers are not known prior to the late Visean. The palaeogeography is discussed thanks to the regional new data; especially the concept of a Saharan province, or its replacement by multiple aborted rifts during the late Visean-Serpukhovian. From the Bashkirian to Early Permian, affinities with Croatia are frequent. Comparisons with other North African basins, northern Spain, Donets Basin, the Urals basins, Moscow Basin, Taurus and Alborz are also presented.

The Whole‐Rock Geochemical Composition of the Wudaogou Group in Eastern Yanbian, NE China–New Clues to Its Relationship with the Gold and Tungsten Mineralization and the Evolution of the Paleo‐Asian Ocean

AbstractThe late Paleozoic Wudaogou Group, one of the oldest metamorphic units in the eastern Yanbian area, has important tectonic and metallogenic significance. Here, we provide new insights into their protoliths, tectonic setting of the metamorphic rocks and their relationships with the gold and tungsten mineralization, using new petrographic and whole‐rock geochemical data for various lithologies within the Wudaogou Group. The protolith of the metamorphic rocks of the Wudaogou Group was intermediate–basic volcanic rocks (e.g. basaltic andesite, trachyandesite, and basalt) and sedimentary rocks including argillaceous rocks, quartz sandstone, arkose and clayish greywacke, as well as pyroclastic sedimentary rock, covering tuffaceous sandstone. Before undergoing late Paleozoic epidote–amphibolite facies regional metamorphism, these protoliths were formed during the middle–late Permian in an island arc setting within a continental margin collage zone. Combined with the regional tectonic evolution, it can be speculated that the formation and the subsequent metamorphism of the protoliths of the metamorphic rocks from the Wudaogou Group were influenced by the change from subduction to collision of the Paleo‐Asian Ocean. Similarities of the rare earth element (REE) patterns and parameters among the metamorphic rocks within the Wudaogou Group, auriferous ores from the Xiaoxi'nancha gold (copper) deposit, and scheelites from the Yangjingou tungsten deposit, together with the favorable metallogenic element contents within the metamorphic rock series, imply that the Wudaogou Group could provide parts of metallic material for the gold and tungsten mineralization in the eastern Yanbian area, as exemplified by the Yangjingou deposit and Xiaoxi'nancha deposit, respectively. Further, the metamorphic sedimentary rocks, especially the metamorphic sandstones, quartz schists and quartz mica schists within the Wudaogou Group, have closer genetic relationships with the Yangjingou tungsten mineralization. However, the specific lithologies within this group which control the gold mineralization are still uncertain, and need further research.

Revisiting Triassic stratigraphy of the Yanshan belt

Age determinations of the Triassic lithostratigraphic units of the Yanshan belt were previously based on plant fossils and regional correlations of lithologies. The Liujiagou and Heshanggou Formations were assigned as the Lower Triassic, and the Ermaying Formation was regarded as the Middle Triassic. We carried out a geochronologic study of detrital zircon grains from the Triassic sandstone in the Xiabancheng and Yingzi basins in northern Hebei where the Triassic strata are exceptionally well preserved. The results show that the Liujiagou, Heshanggou, and Ermaying Formations are all Late Triassic in age. The ages of detrital zircons also revealed that the upper part of the Shihezi Formation and the overlying Sunjiagou Formation, both of which were thought to be the Middle-Late Permian units, are actually late Early to Middle Triassic deposits. This study combines the upper Shihezi and Sunjiagou Formations into a single unit termed as the Yingzi Formation. We also substitute the widely-used Liujiagou, Heshanggou, and Ermaying Formations with the Dingjiagou, Xiabancheng, and Huzhangzi Formations, respectively. Field observations and facies analysis show that the top of the Shihezi Formation is an erosive surface, marking a parallel unconformity between the Middle Permian and Lower Triassic. The Yingzi Formation is composed mainly of meandering river deposits, indicative of tectonic quiescence and low-relief landform in the Early to Middle Triassic. In contrast, the Dingjiagou, Xiabancheng, and Huzhangzi Formations are interpreted as the deposits of sandy/gravelly braided rivers, alluvial fans, fan deltas, and deep lakes in association with volcanism, thus indicating an intense rifting setting. A new Triassic lithostratigraphic division is proposed according to age constraints and facies analysis, and the results are of significance for understanding the early Mesozoic tectonic evolution of the Yanshan belt.

Middle-Late Permian (Murgabian-Djulfian) foraminifers of the northern Maku area (western Azerbaijan, Iran

Middle-Late Permian (Murgabian-Djulfian) foraminifers of the northern Maku area (western Azerbaijan, Iran

Latest Early Permian granitic magmatism in southern Inner Mongolia, China: Implications for the tectonic evolution of the southeastern Central Asian Orogenic Belt

Latest Early Permian (277–275Ma) magmatic episode is one of the most important tectono-magmatic events in southeastern Central Asian Orogenic Belt (CAOB), recording a tectonic transition from accretionary to post-accretionary evolution of the Paleo-Asian Ocean. The latest Early Permian granitoids along the Solonker suture zone in southern Inner Mongolia were emplaced between 275Ma and 277Ma as determined by SHRIMP zircon U–Pb dating. They are characterized by variable alkali contents, a range from calcic to slightly alkalic compositions, and are magnesian I-type granitoids. Their εNd(t) values from −0.4 to +3.1 record predominantly juvenile crustal sources with moderate involvement of old crustal components. Furthermore, these granitoids show positive zircon εHf(t) values of +7.6 to +10.7 that are also indicative of predominantly juvenile nature. Their high zircon δ18O values of 6.29‰ to 8.13‰, suggest significant involvement of supracrustal materials in their generation. These characteristics imply they were derived from an already hybrid andesitic magma in active continental margin. The resultant composite magmas were finally attached (relaminated) to the lower crust, where they produced segregated melt, to rise with minor assimilation of supracrustal materials, and to form these granitic plutons. The outboard migration of continental arc in response to slab roll-back, from the Late Carboniferous to the latest Early Permian, and tectonic switching from this prolonged extension to the short-lived contraction resulting from slab break-off and final amalgamation of the southeastern CAOB in the Middle-Late Permian lead to efficient continental growth in the southeastern CAOB.

Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution.

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle-Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.

Permian age of the Wudaogou Group in eastern Yanbian: detrital zircon U–Pb constraints on the closure of the Palaeo-Asian Ocean in Northeast China

The Wudaogou Group in eastern Yanbian, Northeast China, plays a key role in constraining the timing and eastward termination of the Solonker–Xra Moron River–Changchun Suture, where the Palaeo-Asian Ocean closed. The Wudaogou Group consists of schist, gneiss, amphibolite, metasedimentary, and metavolcanic rocks, all of which underwent greenschist- to epidote–amphibolite-facies regional metamorphism, with some hornfels resulting from contact metamorphism. To determine the age of deposition, the timing and grade of metamorphism, and the tectonic setting of the Wudaogou Group, we investigated the petrography and geochronology of the metamorphic rocks in this group. Zircons from the metasedimentary rocks of this group can be divided into metamorphic zircons and detrital zircons of magmatic origin. U–Pb ages of metamorphic zircons dated by LA-ICP-MS vary from 249 ± 4 to 266 ± 4 Ma, approximating the age of regional metamorphism in the eastern Yanbian area. Detrital zircons yield U–Pb ages ranging from 253 ± 5 to 818 ± 5 Ma, and indicate that the provenance of the Wudaogou Group experienced four tectonic–thermal events between 818 and 253 Ma: Neoproterozoic (ca. 818–580 Ma), Cambro–Ordovician (ca. 500–489 Ma), Devonian–Carboniferous (ca. 422–300 Ma), and middle–late Permian (ca. 269–253 Ma). The youngest detrital zircon, with a U–Pb age of 253 ± 5 Ma, defines the maximum depositional age of the Wudaogou Group. The presence of the Cambro-Ordovician and Neoproterozoic detrital zircons implies that the source of the Wudaogou Group had an affinity with Northeast China, which leads us to conclude that the Solonker–Xra Moron River–Changchun Suture extends from Wangqing to Hunchun in eastern Yanbian, and that the Palaeo-Asian Ocean may have closed at the end of the Permian or Early Triassic period.

A first record of late Middle Permian actinopterygian fish from Anatolia, Turkey

Abstract The Middle-Upper Permian of the Gomaniibrik Formation, of the Tanin Group, in south-east Anatolia, close to the Iraq border, yielded moderately preserved fish remains. Two species, Palaeoniscum freieslebeni and Pygopterus cf. nielseni, known so far only from the Upper Permian deposits of the Zechstein Basin in western Central Europe, were recognised. This late Middle Permian Anatolian record significantly widens the geographical range of these actinopterygians into the equatorial Palaeotethys Realm.

Gas hydrate contribution to Late Permian global warming

Rapid gas hydrate release (the “clathrate gun” hypothesis) has been invoked as a cause for the rapid global warming and associated negative carbon isotope excursion observed during the Latest Permian Extinction (LPE). We modeled the stability of gas hydrates through a warming Middle to Late Permian world, considering three settings for methane reservoirs: 1) terrestrial hydrates, 2) hydrates on exposed continental shelves during glacial sea level drop, and 3) hydrates in deep marine settings. Model results show that terrestrial hydrates would rapidly destabilize over ∼400 ky after deglaciation for moderate heatflow (40 mW/m2), and more rapidly for higher heat flow values. Exposed continental shelves would lose hydrates even more rapidly, after being flooded due to loss of ice storage on land. These two major hydrate reservoirs would thus have destabilized during the Middle to Late Permian climate warming, well prior to the LPE event. However, they may have contributed to the >2‰ negative C-isotopic shift during the late Middle Permian. Deep marine hydrates would have remained stable until LPE time. Rapid warming of deep marine waters during this time could have triggered destabilization of this reservoir, however given the configuration of one super continent, Pangea, hydrate bearing continental slopes would have been less extensive than modern day. This suggests that any potential gas hydrate release would have had only a minor contributing impact to the runaway greenhouse during the Latest Permian extinction.

The origin and early evolution of Sauria: reassessing the permian Saurian fossil record and the timing of the crocodile-lizard divergence.

Sauria is the crown-group of Diapsida and is subdivided into Lepidosauromorpha and Archosauromorpha, comprising a high percentage of the diversity of living and fossil tetrapods. The split between lepidosauromorphs and archosauromorphs (the crocodile-lizard, or bird-lizard, divergence) is considered one of the key calibration points for molecular analyses of tetrapod phylogeny. Saurians have a very rich Mesozoic and Cenozoic fossil record, but their late Paleozoic (Permian) record is problematic. Several Permian specimens have been referred to Sauria, but the phylogenetic affinity of some of these records remains questionable. We reexamine and review all of these specimens here, providing new data on early saurian evolution including osteohistology, and present a new morphological phylogenetic dataset. We support previous studies that find that no valid Permian record for Lepidosauromorpha, and we also reject some of the previous referrals of Permian specimens to Archosauromorpha. The most informative Permian archosauromorph is Protorosaurus speneri from the middle Late Permian of Western Europe. A historically problematic specimen from the Late Permian of Tanzania is redescribed and reidentified as a new genus and species of basal archosauromorph: Aenigmastropheus parringtoni. The supposed protorosaur Eorasaurus olsoni from the Late Permian of Russia is recovered among Archosauriformes and may be the oldest known member of the group but the phylogenetic support for this position is low. The assignment of Archosaurus rossicus from the latest Permian of Russia to the archosauromorph clade Proterosuchidae is supported. Our revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma. The occurrences of basal archosauromorphs in the northern (30°N) and southern (55°S) parts of Pangea imply a wider paleobiogeographic distribution for the group during the Late Permian than previously appreciated. Early archosauromorph growth strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus.

FORMATION CONDITIONS OF JIMUSAER OIL SHALE AT THE NORTHERN FOOT OF BOGDA MOUNTAIN, CHINA

The Jimusaer oil shale, located in the northern foot of Bogda Mountain, was deposited in the Lucaogou Formation in the Upper Permian. In this paper the effect of paleostructure, paleoclimate and sedimentary environment on the mineralization of oil shale in the study area was inves- tigated. The results show that the Jimusaer oil shale was developed in the stable paralic lacustrine basin formed in the Late Middle Permian, and cropped out with the uplift of Bogda Mountain during the Himalayan orogeny. The Lucaogou Formation, which is composed of six lithologic segments, was deposited in a warm humid to dry hot climate and fresh to brackish water environment indicated by values of Sr/Cu, Sr/Ba and Mn/Fe ratios, which vary segment by segment. There are also similar variety regularities shown, which implicate that the changes of paleoclimate influenced directly water salinity in the study area. The Lucaogou Formation includes two oil shale segments which were developed respectively in the shallow to semi-deep lake and semi-deep to deep lake, and the environment of large-area, moderate saline deep water provided favourable conditions for generation and preservation of oil shale.

Paleo-Heat Flow Anomaly at the End of Middle Permian in NE Sichuan Basin, SW China: Did an Ocean Trough Exist?

It is an issue whether the Kaijiang-Liangping area (in the northeastern Sichuan Basin, SW China) was a controversial ocean trough during Changxing age in the late Permian-early Triassic. Some vitrinite reflectance (Ro) profiles from wells in the northeastern Sichuan Basin show obvious breaks, and the breaks are coincident with the boundary between the middle Permian and late Permian. Based on the Ro data, the heat flow history in the northeastern Sichuan Basin was reconstructed. The result shows that the heat flow reached its peak value at the end of middle Permian (~260Ma). The spatiotemporal feature of the heat flow evolution is not in agreement with the fact that there was a Kaijiang-Liangping Trough existing in the late-Permian to early Triassic. The palaeo-heat flow anomaly was, in fact, a response to the igneous activity in late middle Permian.

Does the Manning Orocline exist? New structural evidence from the inner hinge of the Manning Orocline (eastern Australia)

The map-view structure of the southern New England Orogen in the eastern Gondwanan margin is characterised by four tight orogenic-scale curvatures: Texas, Coffs-Harbour, Manning and Nambucca oroclines. Here we focus on the geometry of the Manning Orocline and examine whether the inner-arc area of the oroclinal structure is expressed within the accretionary wedge rocks of the Tablelands Complex. Our observations from the Tablelands Complex (Armidale–Walcha area) show that rocks were subjected to penetrative deformation (D1), which resulted in a regional slaty cleavage (S1) and related isoclinal folds. This was followed by subsequent deformation (D2) associated with minor gentle folds. In a larger scale, the steeply dipping S1 structural fabric shows a continuous map-view curvature, thus defining a macroscopic fold structure. We interpret this macroscopic fold as the expression of the Manning Orocline within the accretionary wedge complex. This interpretation is consistent with the contorted spatial distribution of other tectonic elements (serpentinite belt, forearc basin terranes and early Permian granitoids), which independently define the structure of the Manning Orocline. Our new structural data support the existence of the Manning Orocline and the quadruple oroclinal geometry of the whole southern New England Orogen. The origin of these oroclines is attributed to multiple stages of bending, possibly associated with an earlier phase of curvature during slab rollback (in the early Permian), followed by a subsequent (middle-late Permian) episode of contractional deformation that tightened the oroclinal structure.

Structural and chronological constraints on a Late Paleozoic shortening event in the Yanshan Tectonic Belt

Early deformation history of the Yanshan Tectonic Belt is an unsolved, important issue. We report early structures and their dating results in basement rocks south of the Kalaqin metamorphic core complex. The basement deformation zone is characterized by WNW-ESE steep gneissosity, WNW-ESE shallow mineral elongation lineation and many intrafolial or isoclinal folds. Many kinematic indicators show that it is a WNW-ESE steep, ductile sinistral deformation zone. LA-ICPMS zircon dating gives a crystallization age of 271 Ma for tatolly transposed, deformed monzonite granite dyke and crystallization ages of 251–250 Ma and 210 Ma for undeformed dyke, stock and pluton. The dating results demonstrate that the deformation related to regional shortening took place between 271 and 251 Ma, i.e. Middle-Late Permian. Combined with previous dating results for post-orogenic magmatism in the Yanshan Tectonic Belt, it is inferred that the shortening-related deformation happened in Middle Permian (271–260 Ma). Recent studies suggest that collision along the Solonker Suture took place in Middle Permian, and is then followed by post-collision extenion in Late Permian. We propose that the intense shortening deformation of the Middle Permian in the Yanshan Tectonic Belt belongs to foreland deformation along the norterhn margin of the North China Craton which is caused by continent-continent collision in the Xing-Meng Orogen. The belt was then oriprinted by shortening deformation of the Yanshanian Movement.

Thermoluminescence in response to the mass extinction event in Penglaitan Section in Laibin, Guangxi

Thermoluminescence (TL) in marine carbonate has been proposed as a potential proxy for reconstruction of paleoceanography history, and has already been used in defining the Quaternary environment. However, its availability in the geological time scale, such as Permian, is still on debate. The mass extinction event caused by drastic changes of global marine environment in Middle-Late Permian provides a typical example to testify the applicability of this proxy. Here we measured the natural thermoluminescence of the carbonate-dominating marine sediments collected from the strata through the Guadalupian-Lopingian mass extinction boundary (G/LB) in the Penglaitan Section in Laibin, Guangxi, China. Our results reveal that TL intensities of carbonate are much higher than those of siliceous rocks, which indicates that the carbonate is the main contributor to the TL. The variation of TL intensities are related with Mn and Fe contents in the carbonate lattices while high Mn and low Fe (e.g., high Mn/Fe ratio) in carbonate will release stronger TL. Due to the better storage of carbonate lattices for original information of Mn and Fe in seawater, thermoluminescence of carbonate-dominating sediments/rocks could sensitively reflect marine environment and biological productivity in geological time scale.

Tapeworm Eggs in a 270 Million-Year-Old Shark Coprolite

Remains of parasites in vertebrates are rare from the Mesozoic and Paleozoic. Once most parasites that live in – or pass through – the gastrointestinal tract of vertebrates, fossil feces (coprolites) or even intestinal contents (enterolites) can eventually preserve their remains. Here we announce the discovery of a spiral shark coprolite from the Paleozoic bearing a cluster of 93 small oval-elliptical smooth-shelled structures, interpreted as eggs of a tapeworm.The eggs were found in a thin section of an elasmobranch coprolite. Most of the eggs are filled by pyrite and some have a special polar swelling (operculum), suggesting they are non-erupted eggs. One of the eggs contains a probable developing larva. The eggs are approximately 145–155 µm in length and 88–100 µm in width and vary little in size within the cluster. The depositional and morphological features of the eggs closely resemble those of cestodes. Not only do the individual eggs have features of extant tapeworms, but their deposition all together in an elongate segment is typical to modern tapeworm eggs deposited in mature segments (proglottids). This is the earliest fossil record of tapeworm parasitism of vertebrates and establishes a timeline for the evolution of cestodes. This discovery shows that the fossil record of vertebrate intestinal parasites is much older than was hitherto known and that the interaction between tapeworms and vertebrates occurred at least since the Middle-Late Permian.

Paleomagnetic data from the Late Carboniferous-Late Permian rocks in eastern Tibet and their implications for tectonic evolution of the northern Qiangtang-Qamdo block

We report paleomagnetic results from the Late Carboniferous-Late Permian strata in eastern Tibet (China), and aim to clarify the tectonic and paleogeographic evolution of the northern Qiangtang-Qamdo block, which is the key to the study of plate boundary between the Gondwanaland and the Eurasia during the late Paleozoic. Two hundred and nineteen samples—including limestone, muddy siltstone, basalt, lava, and tuff—were collected at 24 sites in the Upper Carboniferous and Middle-Upper Permian successions. A systematic study of rock magnetism and paleomagnetism yields three reliable paleomagnetic pole positions. Both hematite and magnetite occurred in the Late Carboniferous limestone samples. The demagnetization curve shows a characteristic double-component, with the remanent magnetization (ChRM) exhibiting a positive polarity (negative inclination). In the Late Permian limestone, tuff, and basalt, magnetic information were recorded primarily in magnetite, although a small fraction of them was found in hematite in basalt. The demagnetization curve illustrates a double or single component, with the ChRM showing a negative polarity (positive inclination), which has passed the classic fold test successfully. The single polarity features of the ChRM directions of the Late Carboniferous and Middle-Late Permian rocks are respectively related to the Kiaman positive and reversed polarities under the stratigraphic coordinates. This, in turn, indicates that both ChRMs directions represent the original remanence directions. By comparison with the previously published paleomagnetic results from the late Paleozoic rocks in the northern Qiangtang Range, we suggest that: (1) Qamdo and northern Qiangtang block were independent of each other during the Late Carboniferous to the Early Permian periods. The north Lancangjiang ocean basin between the two blocks may have closed before the Middle Permian and been involved in the continent-continent collision stage in the Late Permian-Early Triassic periods. (2) The northern Qiangtang-Qamdo Block paleogeographically was situated at low to intermediate latitudes in the Southern Hemisphere in the Late Carboniferous-Late Permian periods, and began to displace northward in the Early Triassic, with an amount of more than 5000 km northward transport from its current location.