Li C.,CAS Institute of Vertebrate Paleontology and Paleoanthropology |
Jiang D.-Y.,Peking University |
Cheng L.,Wuhan Institute of Geology and Mineral Resources |
Wu X.-C.,CAS Institute of Vertebrate Paleontology and Paleoanthropology |
And 2 more authors.
Geological Magazine | Year: 2014
Largocephalosaurus polycarpon Cheng et al. 2012a was erected after the study of the skull and some parts of a skeleton and considered to be an eosauropterygian. Here we describe a new species of the genus, Largocephalosaurus qianensis, based on three specimens. The new species provides many anatomical details which were described only briefly or not at all in the type species, and clearly indicates that Largocephalosaurus is a saurosphargid. It differs from the type species mainly in having three premaxillary teeth, a very short retroarticular process, a large pineal foramen, two sacral vertebrae, and elongated small granular osteoderms mixed with some large ones along the lateral most side of the body. With additional information from the new species, we revise the diagnosis and the phylogenetic relationships of Largocephalosaurus and clarify a set of diagnostic features for the Saurosphargidae Li et al. 2011. Largocephalosaurus is characterized primarily by an oval supratemporal fenestra, an elongate dorsal 'rib-basket', a narrow and elongate transverse process of the dorsal vertebrae, and the lack of a complete dorsal carapace of osteoderms. The Saurosphargidae is distinct mainly in having a retracted external naris, a jugal-squamosal contact, a large supratemporal extensively contacting the quadrate shaft, a leaf-like tooth crown with convex labial surface and concave lingual surface, a closed dorsal 'rib-basket', many dorsal osteoderms, a large boomerang-like or atypical T-shaped interclavicle. Current evidence suggests that the Saurosphargidae is the sister-group of the Sauropterygia and that Largocephalosaurus is the sister-group of the Saurosphargis-Sinosaurosphargis clade within the family. Copyright © Cambridge University Press 2013.
Song H.,Wuhan University |
Tong J.,Wuhan University |
Algeo T.J.,Wuhan University |
Algeo T.J.,University of Cincinnati |
And 8 more authors.
Geochimica et Cosmochimica Acta | Year: 2014
The marine sulfur cycle is intimately linked to global carbon fluxes, atmospheric composition, and climate, yet relatively little is known about how it responded to the end-Permian biocrisis, the largest mass extinction of the Phanerozoic. Here, we analyze carbonate-associated-sulfate (CAS) from three Permo-Triassic sections in South China in order to document the behavior of the C-S cycle and its relationship to marine environmental changes during the mass extinction and its aftermath. We find that δ34SCAS varied from +9‰ to +44‰ at rates up to 100‰Myr-1 during the Griesbachian-Smithian substages of the Early Triassic. We model the marine sulfur cycle to demonstrate that such rapid variation required drawdown of seawater sulfate concentrations to ≤4mM and a reduction in its residence time to ≤200kyr. This shorter residence time resulted in positive covariation with δ13Ccarb due to strong coupling of the organic carbon and pyrite burial fluxes. Carbon and sulfur isotopic shifts were associated with contemporaneous changes in climate, marine productivity, and microbial sulfate reduction rates, with negative shifts in δ13Ccarb and δ34SCAS linked to warming, decreased productivity, and reduced sulfate reduction. Sustained cooling during the Spathian re-invigorated oceanic overturning circulation, reduced marine anoxia, and limited pyrite burial. As seawater sulfate built to higher concentrations during the Spathian, the coupling of the marine C and S cycles came to an end and a general amelioration of marine environmental conditions set the stage for a recovery of invertebrate faunas. Variation in seawater sulfate during the Early Triassic was probably controlled by climate change, possibly linked to major eruptive phases of the Siberian Traps. © 2013 Elsevier Ltd.
Cheng L.,Wuhan Institute of Geology and Mineral Resources |
Chen X.-H.,Wuhan Institute of Geology and Mineral Resources |
Shang Q.-H.,CAS Institute of Vertebrate Paleontology and Paleoanthropology |
Wu X.-C.,Canadian Museum of Nature
Naturwissenschaften | Year: 2014
The Luoping fauna (Anisian, Middle Triassic) is probably the oldest of Triassic faunas in Guizhou-Yunnan area, China. The reptilian assemblage is comprised of ichthyosaurs, a number of sauropterygians (pachypleurosaur-like forms), saurosphargids, protorosaurs, and archosauriforms. Here, we report on a peculiar reptile, newly found in this fauna. Its dentition is fence or comb-like and bears more than 175 pleurodont teeth in each ramus of the upper and lower jaws, tooth crown is needle-like distally and blade-shaped proximally; its rostrum strongly bends downward and the anterior end of its mandible expands both dorsally and ventrally to form a shovel-headed structure; and its ungual phalanges are hoof-shaped. The specializations of the jaws and dentition indicate that the reptile may have been adapted to a way of bottom-filter feeding in water. It is obvious that such delicate teeth are not strong enough to catch prey, but were probably used as a barrier to filter microorganisms or benthic invertebrates such as sea worms. These were collected by the specialized jaws, which may have functioned as a shovel or pushdozer (the mandible) and a grasper or scratcher (the rostrum). Our preliminary analysis suggests that the new reptile might be more closely related to the Sauropterygia than to other marine reptiles. © 2014 Springer-Verlag Berlin Heidelberg.
Timing and genesis of the adakitic and shoshonitic intrusions in the Laoniushan complex, southern margin of the North China Craton: Implications for post-collisional magmatism associated with the Qinling Orogen
Ding L.-X.,Wuhan University |
Ding L.-X.,Wuhan Institute of Geology and Mineral Resources |
Ma C.-Q.,Wuhan University |
Li J.-W.,Wuhan University |
And 4 more authors.
Lithos | Year: 2011
The NWW-striking Qinling Orogen formed in the Triassic by collision between the North China and Yangtze Cratons. Triassic granitoid intrusions, mostly middle- to high-K, calc-alkaline, are widespread in this orogen, but contemporaneous intrusions are rare in the southern margin of the North China Craton, an area commonly considered as the hinterland belt of the orogen. In this paper, we report zircon U-Pb ages, elemental geochemistry, and Sr-Nd-Hf isotope data for the Laoniushan granitoid complex that was emplaced in the southern margin of the North China Craton. Zircon U-Pb dating shows that the complex was emplaced in the late Triassic (228±1 to 215±4Ma), indicating that it is part of the post-collisional magmatism in the Qinling Orogen. The complex consists of, from early to late, biotite monzogranite, quartz diorite, quartz monzonite, and hornblende monzonite, which span a wide compositional range, e.g., SiO2=55.9-70.6wt.%, K2O+Na2O=6.6-10.2wt.%, and Mg# of 24 to 54. The biotite monzogranite has high Al2O3 (15.5-17.4wt.%), Sr (396-1398ppm) and Ba (1284-3993ppm) contents and relatively high La/Yb (mostly 14-30) and Sr/Y (mostly 40-97) ratios, but low Yb (mostly 1.3-1.6ppm) and Y (mostly14-19ppm) contents, features typical of adakitic rocks. The quartz monzonite, hornblende monzonite and quartz diorite have a shoshonitic affinity, with K2O up to 5.58wt.% and K2O/Na2O ratios averaging 1.4. The rocks are characterized by strong LREE/HREE fractionation in chondrite-normalized REE pattern, without obvious Eu anomalies, and show enrichment in large ion lithophile elements but depletion in high field strength elements (Nb, Ta, Ti). The biotite monzogranite (228Ma) has initial 87Sr/86Sr ratios of 0.7061 to 0.7067, εNd(t) values of -9.2 to -12.6, and εHf(t) values of -9.0 to -15.1; whereas the shoshonitic granitoids (mainly 217-215Ma) have similar initial 87Sr/86Sr ratios (0.7065 to 0.7075) but more radiogenic εNd(t) (-12.4 to -17.0) and εHf(t) (-14.1 to -17.0). The Sr-Nd-Hf isotope data indicate that the rocks were likely generated by partial melting of an ancient lower continental crust with heterogeneous compositions, as partly confirmed by the widespread presence of early Paleoproterozoic inherited zircons. Mafic microgranular enclaves (MMEs), characterized by fine-grained igneous textures and an abundance of acicular apatites, are common in the Laoniushan complex. Compared with the host rocks, they have lower SiO2 (48.6-53.7wt.%) and higher Mg# (51-56), Cr (122-393ppm), and Ni (24-79ppm), but equivalent Sr-Nd isotope compositions, indicating that the MMEs likely originated from an ancient enriched lithospheric mantle. The abundance of MMEs in the granitoid intrusions suggest that magma mixing plays an important role in the generation of the Laoniushan complex. Collectively, it is suggested that the Laoniushan complex was a product of post-collisional magmatism related to lithospheric extension following slab break-off. Formation of the adakitic and shoshonitic intrusions in the Laoniushan complex indicates that the Qinling Orogen had evolved into a post-collisional setting by about 230-210Ma. © 2011 Elsevier B.V.
Deng X.,Wuhan University |
Deng X.,Wuhan Institute of Geology and Mineral Resources |
Wu K.B.,Wuhan University |
Yang K.G.,Wuhan University
Science China Earth Sciences | Year: 2013
The Shigujian pluton is a gneissic quartz monzonite located in Tiantangzhai area in central part of the Dabie orogen. Anisotropy of magnetic susceptibility (AMS) data show that most magnetic foliations dip steeply to southeast. About 85% of sampling points dip from 40° to 90°. Magnetic foliations are generally parallel to the foliations measured in the field. The pluton has NWW-SEE trending lineations in the southeast and NE-SW trending lineations in central part and north, but the lineations plunge to SW in central part and to NE in the north. All plunges are moderate. The anisotropy degree (P) is between 1.065 and 1.532 and the shape parameter (T) is between 0.005 and 0.694. A Flinn diagram of the magnetic fabrics shows that the value of K is less than 1. The analysis of AMS suggests that the pluton was emplaced and deformed under a SE-NW compressional stress regime. The analysis of quartz C-axis fabrics indicates that the pluton was deformed under compressional stress and deformation temperatures range from 400 to 500°C. Microstructures indicate that the pluton is deformed in near solidus conditions and the pluton is a synkinematic intrusion. The emplacement of the Shigujian granite is inferred to have taken place syntectonically. The zircon U-Pb dating of the granite suggests that the pluton was intruded at 141±2.3 Ma. By synthesizing all data, it seems that the Shigujian pluton was emplaced in a compressional environment and the transformation time of the Dabie orogen from compression to extension took place after 141 Ma. The structural evolution of the Dabie orogen was controlled by the Pacific tectonic domain when the Shigujian pluton was emplaced, whereas the adjacent Tiantangzhai complex massif is the result of an extensional environment. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.
Li X.,Wuhan Institute of Geology and Mineral Resources |
Li X.,Nanjing University |
Cai Y.,Nanjing University
Cretaceous Research | Year: 2013
We have used diffuse reflectance spectroscopy to investigate the colouration mechanisms of hematite in Cretaceous Oceanic Red Beds (CORBs). Data for samples of CORBs from the Chuangde section in Tibet, Vispi Quarry section in Italy, and Core 12X of Ocean Drilling Program Hole 1049C in the North Atlantic were compared with calibration datasets obtained for hematite in different crystalline forms (kidney and specular hematite) and calcite matrix. Spectra for hematite in either pure form or in calibration datasets show that the centre of the reflection peak shifts to a longer wavelength and depth (D) decreases as the crystallinity of the hematite increases. Compared with specular hematite, the presence of just 0.5% of kidney hematite can cause a much deeper absorption peak and greater redness value, which indicates that kidney hematite has a higher colouration capacity than specular hematite. However, both kidney and specular hematite exhibit a good correlation between the redness value for each calibration dataset and the absorption peak depth. In all three studied sections, hematite is the main iron oxide mineral responsible for colouration. Spectral features such as absorption peak depth and peak centre reveal that hematite crystallinity gradually decreases from red shale to limestone to marl. Based on a spectral comparison of red shale in the Chuangde section before and after citrate-bicarbonate-dithionite (CBD) treatment, we found that two forms of hematite are present: a fine-grained and dispersed form, and a detrital form. The former is relatively poorly crystalline hematite, which has a much stronger colouration capacity than the detrital form. In the Vispi Quarry section and Core 12X of ODP Hole 1049C, a good correlation between the absorption peak depth of hematite and redness value indicates that the red colouration is caused by hematite of similar crystallinity in each section. © 2013 Elsevier Ltd.
Hagdorn H.,Muschelkalkmuseum Ingelfingen |
Wang X.-F.,Wuhan Institute of Geology and Mineral Resources
Palaeoworld | Year: 2015
The morphology of the pseudoplanktonic crinoid Traumatocrinus from the early Late Triassic (Carnian) Xiaowa Formation of Guanling County (South China, Guizhou Province) is described based on articulated and disarticulated material. Juvenile individuals of less than 10. mm crown height with 20 isotomously branching arms prove the encrinid ancestry of the family Traumatocrinidae. However, even the smallest individuals have five large interradials. Endotomous branching commences at crowns of slightly more than 10. mm at the outer arms of the rays. All brachial articulations are ligamentary (granosyzygies). The assignment of the Chinese material to one of the nominal species of Traumatocrinus is still left open. The diagnosis of the genus Traumatocrinus is emended. Traumatocrinus lived attached to driftwood and was widespread across the Palaeo-Tethys. In contrast to its benthic encrinid ancestors, Traumatocrinus fixed its distal column with countless anastomosing radicular cirri to its substrate, preferentially to the ends of the driftwood logs. Depending on the state of the hypothesized mutable collagene tissue, the columns are preserved in straight positions or curved like a rope. Crowns are preserved in star position with radially splayed arms or in lateral bell position with the cup disrupted in interbrachial position. As usual in black shales, the exposed upper sides of the crinoids are in a more or less progressive state of decomposition whereas the embedded lower sides are intact. © 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS.
Sander P.M.,University of Bonn |
Chen X.,Wuhan Institute of Geology and Mineral Resources |
Cheng L.,Wuhan Institute of Geology and Mineral Resources |
Wang X.,Wuhan Institute of Geology and Mineral Resources
PLoS ONE | Year: 2011
Background: Ichthyosaurs were an important group of Mesozoic marine reptiles and existed from the Early Triassic to the early Late Cretaceous. Despite a great diversity in body shapes and feeding adaptations, all share greatly enlarged eyes, an elongated rostrum with numerous conical teeth, and a streamlined body. Methodology/Principal Findings: Based on new material from China and the restudy of Shastasaurus pacificus, we here reinterpret the classical large-bodied Late Triassic ichthyosaur genus Shastasaurus to differ greatly from the standard ichthyosaurian body plan, indicating much greater morphological diversity and range of feeding adaptations in ichthyosaurs than previously recognized. Phylogenetic analysis indicates a monophyletic clade consisting of the giant Shonisaurus sikanniensis, Guanlingsaurus liangae, and Shastasaurus pacificus to which the genus name Shastasaurus is applied. Shastasaurus liangae comb. nov. is from the Late Triassic (Carnian) Xiaowa Formation of Guizhou Province, southwestern China. The species combines a diminutive head with an entirely toothless and greatly reduced snout. The species also has by far the highest vertebral count among ichthyosaurs (86 presacral vertebrae and >110 caudal vertebrae), a count that is also very high for tetrapods in general. A reduced toothless snout and a diminutive head is also apparently present in the giant S. sikanniensis and presumably in S. pacificus. Conclusions/Significance: In analogy to many modern odontocetes, Shastasaurus is interpreted as a specialized suction feeder on unshelled cephalopods and fish, suggesting a unique but widespread Late Triassic diversification of toothless, suction-feeding ichthyosaurs. Suction feeding has not been hypothesized for any of the other diverse marine reptiles of the Mesozoic before, but in Shastasaurus may be linked to the Late Triassic minimum in atmospheric oxygen. © 2011 Sander et al.
Zhang R.H.,Wuhan Polytechnic University |
Yang X.L.,Wuhan Institute of Geology and Mineral Resources |
Liu J.,Wuhan Polytechnic University |
Cheng X.Z.,Wuhan Polytechnic University
Advanced Materials Research | Year: 2012
A simple solid phase extraction procedure for adsorption and preconcentration of manganese(II, VII) in environmental water samples has been proposed prior to inductively coupled plasma mass spectrometry. The procedure presented based on quantitative recoveries of manganese >95%. In this work, the potential use of eggshell membrane(ESM), a typical biomaterial, as solid-phase extraction (SPE) adsorbent is evaluated for analysis of trace manganese. The analytical variables, pH, flow rate, sample volume, elution, coexisting ions for optimum recoveries of manganese (II) and manganese (VII) were investigated. The preconcentration factor was 60. The detection limit (3σ) of manganese was 0.031 ng L -1. The relative standard deviations of determination was found to be 3.21%. The procedure was successfully applied to the adsorption and determination of manganese in environmental water samples. © (2012) Trans Tech Publications.
Wang L.,Wuhan Institute of Geology and Mineral Resources |
Long W.-G.,Wuhan Institute of Geology and Mineral Resources |
Zhou D.,Wuhan Institute of Geology and Mineral Resources
Geology in China | Year: 2013
LA- ICP- MS U-Pb dating was conducted for zircons from four gneissic granites in Yunkai area, which were assigned to Precambrian basement rocks or Neoproterozoic intrusion in 1:250000 geological survey. The dating yielded 206Pb/238U weighted mean of 443.3±2.6 Ma (sample 1009, Lutou Reservoir in Luchuan City), 445.7 ±2.3Ma (sample 1010, Yuedong in Luchuan city), 441.1 ±2.0Ma (sample 1012, Xieji in Gaozhou city) and 443.7±1.7Ma (sample 1018, Zhusha in Xinyi city), suggesting that these rocks are Caledonian products rather than Precambrian basement or Neoproterozoic intrusive rocks. In combination with previous studies, the authors hold that these granites probably resulted from partial melting of the Proterozoic materials due to the Caledonian orogeny in South China. These results and recently published data (Caledonian) for the so-called Precambrian basement rocks, such as the crystallization age or metamorphic age of gneissic granite and gneiss, indicate that Yunkai area has undergone extensive reformation by the Caledonian orogeny. Actually, the Precambrian basement of Yunkai area mainly consists of gneissic rocks and meta-sedimentary rocks, which serve as the representative of the Gaozhou complex and the Yunkai Group, respectively. The Gaozhou complex was formed during the Mesoto Neo-proterozoic and the Yunkai Group might have been formed in the Neoproterozoic. The Paleo- to Meso -Proterozoic crystallized basement does exist in Cathaysia Block, however, which is not so widely distributed as previously thought.