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News Article | June 30, 2017
Site: www.eurekalert.org

Understanding modern biodiversity and extinction threats is important. It is commonly assumed that being large contributes to vulnerability during extinction crises. However, researchers from the University of Bristol and the Chengdu Center of the China Geological Survey, have found that size played no role in the extinction of fish during the largest mass extinction of all time. The study focused on the evolution of bony fishes during the Permian-Triassic mass extinction 252 million years ago. During this crisis, as many as 90 percent of all species on Earth were killed by massive climate change triggered by huge volcanic eruptions in Russia. The erupted gases led to worldwide acid rain and atmospheric warming of as much as 20 degrees centigrade. This killed plants, and soil was stripped by rainfall and washed into the sea. Oceans were also heated and life fled from the tropics. It was expected that a key feature in extinction would have been body size: the large animals would suffer heat and starvation stress first. However, in the new paper, published today in Palaeontology, it is shown that larger fish were no more likely to go extinct than small fish. The study used a detailed summary of all information on fossil fish through a span of over 100 million years, from well before to well after the disaster. Body size information was identified for over 750 of these fishes, and multiple calculations were carried out to allow for variations in the shape of the evolutionary tree and the exact dating of all the species. The result was clear - body size did not provide any advantages or disadvantages to fish during the crisis. Lead researcher Dr Mark Puttick from the Natural History Museum and University of Bristol's School of Earth Sciences, explained: "These results continue the trend of recent studies that suggest body size played no role in determining which species survive or go extinct. This is the opposite result we would expect, but provides increasing support for previous studies that show body size plays no role in extinction selectivity." The team explored the largest dataset used in an analysis of this type and applied a range of computational evolutionary models to understand these patterns in deep time. The models take account of uncertainties in the quality of the fossil data and the reconstructed evolutionary tree, and the result was clear. Professor Michael Benton, also from the University of Bristol, added: "These are exciting results. What is important also is that we were able to deploy new methods in the study that take greater account of uncertainties. "The methods are based around a detailed evolutionary tree so, unlike most previous work in the field, we paid attention to the relationships of all the species under consideration." Professor Shixue Hu, leader of the China Geological Survey: "It's great to see this new analytical work. We were able to include many new fossils from our exceptional biotas in China, and we can see the full impact of the extinction and the subsequent recovery of life during the Triassic."


Zhu Y.-D.,Southwest Petroleum University | Zhang D.-H.,China University of Geosciences | Wang L.-L.,China University of Geosciences | Dai Y.-P.,Chengdu Center | Xi A.-H.,Southwest Petroleum University
International Geology Review | Year: 2017

The northwest Zhejiang Province is a key domain for providing deep insight into the crust–mantle interaction and tectonic evolution of the South China block. In this paper, we collect geochemical, geochronological, and isotopic data of the Jurassic porphyries in this region, and investigated the Huangbaikeng ore-bearing porphyry in the Tongcun Mo–Cu deposit, using it as an example to uncover the porphyry petrogenesis and evaluate their metallogenic potential. Two varieties of the Huangbaikeng porphyry were distinguished: the medium- to coarse-grained type and medium- to fine-grained type. Zircon Sensitive High-Resolution Ion Microprobe U–Pb dating indicates that they were emplaced at 161.8 ± 2.8 and 162.7 ± 3.5 Ma, respectively, which are consistent with the molybdenite Re–Os ages of 163.9–161.8 Ma. The inherited zircons age spectrum significantly recorded a series of geological events, for example, assembly and breakup of the Columbia and Rodinia supercontinent, and the Triassic collision of Yangtze and North China blocks. Whole rock Sr–Nd and Jurassic zircon Hf isotopic data yield mostly negative εHf(t) values (0.5 to −8.4) and εNd(t) values (−0.79 to −4.82). Besides the Huangbaikeng porphyry, all the Jurassic porphyries in the northwest Zhejiang Province have a wide range of SiO2 contents (76.78–60.91 wt.%). They do not contain typical aluminous minerals (e.g. cordierite and garnet), and are mainly metaluminous to weakly peraluminous with high Na2O, low FeOT/MgO, and Zr + Nb + Ce + Y concentrations in composition. They thus fit the I-type granite definition. Some major and trace elements show strong correlations with SiO2, possibly indicating extensive fractional crystallization during their magma evolution. Tectonic discriminations imply that these plutons were likely formed in a volcanic arc regime possibly related to subduction of the Palaeo-Pacific plate. Sr–Nd–Hf isotopic data suggest a mixed source of the Mesoproterozoic crust and 30–50% mantle components. Compared with the adjacent Dexing Cu-bearing porphyies, which have more positive εHf(t) and εNd(t) values with more significant mantle components (55–70%), the Jurassic porphyries in the northwest Zhejiang Province probably lack metallogenic potential to form a giant porphyry copper deposit as Dexing. © 2016 Informa UK Limited, trading as Taylor & Francis Group.


Zou Z.,Chengdu University of Technology | Zhang J.,Chengdu Center | Hu R.,State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry
Resource Geology | Year: 2017

The Jinman Cu polymetallic deposit is located within Middle Jurassic sandstone and slate units in the Lanping Basin of southwestern China. The Cu mineralization occurs mainly as sulfide-bearing quartz-carbonate veins in faults and fractures, controlled by a Cenozoic thrust-nappe system. A detailed study of fluid inclusions from the Jinman deposit distinguishes three types of fluid inclusions in syn-ore quartz and post-ore calcite: aqueous water (type A), CO2-H2O (type B), and CO2-dominated (type C) fluid inclusions. The homogenization temperatures of CO2-H2O inclusions vary from 208°C to 329°C, with corresponding salinities from 0.6 to 4.6 wt.% NaCl equivalent. The homogenization temperatures of the aqueous fluid inclusions mainly range from 164°C to 249°C, with salinities from 7.2 to 20.2 wt.% NaCl equivalent. These characteristics of fluid inclusions are significantly different from those of basinal mineralization systems, but similar to those of orogenic or magmatic mineralization systems. The H and O isotope compositions suggest that the ore-forming fluid is predominantly derived from magmatic water, with the participation of basinal brine. The δ34S values are widely variable between -9.7 ‰ and 9.7 ‰, with a mode distribution around zero, which may be interpreted by the variation in physico-chemical conditions or by compositional variation of the sources. The mixing of a deeply sourced CO2-rich fluid with basinal brine was the key mechanism responsible for the mineralization of the Jinman deposit. © 2017 The Society of Resource Geology.


YE S.,Sinopec | ZHU H.,Sinopec | LI R.,Chengdu Center | YANG Y.,Sinopec | LI Q.,Sinopec
Petroleum Exploration and Development | Year: 2017

Based on the integrated geochemical and isotopic analysis of natural gases, formation waters, authigenic minerals, and fluid inclusions, a set of organic and inorganic geochemical tracing parameters, including methane/ethane ratio (C1/C2), N2 content, arene/alkane ratio, carbon isotope of methane (δ13C1), total dissolved solids (TDS) and chemistry of formation water, oxygen and carbon isotopic composition of authigenic calcite cement (δ18Ocalcite and δ13Ccalcite), and homogenization temperature (Th) and salinity of hydrocarbon-bearing brine inclusions, have been proposed to indicate the phase, direction, and pathway of natural gas migration and to discuss the migration processes and mechanisms of the Jurassic hydrocarbon in western Sichuan. This study results reveal that the Middle Jurassic gases in western Sichuan depression mainly migrated in water-dissolving phase and have the characteristics of increase of arene/alkane ratio and δ13C1 during migration and desolubilization, lower TDS of gas-associated waters, light δ18Ocalcite and δ13Ccalcite in gas-bearing sands, and high Th and low salinity of hydrocarbon-bearing brine inclusions, while the Upper Jurassic gases primarily migrated in free gas phase. Additionally, it is demonstrated that the migration directions and pathways of the Jurassic gases in western Sichuan can be investigated effectively by applying multiple organic and inorganic geochemical tracing parameters, in combination with the study results of geological setting and phase state evolution of water-dissolved gases during desolubilization and accumulation. © 2017 Research Institute of Petroleum Exploration & Development, PetroChina


Liu J.,Hefei University of Technology | Liu J.,Chengdu Center | Liu J.,CAS Nanjing Institute of Geology and Palaeontology | Organ C.L.,Montana State University | And 3 more authors.
Nature Communications | Year: 2017

Live birth has evolved many times independently in vertebrates, such as mammals and diverse groups of lizards and snakes. However, live birth is unknown in the major clade Archosauromorpha, a group that first evolved some 260 million years ago and is represented today by birds and crocodilians. Here we report the discovery of a pregnant long-necked marine reptile (Dinocephalosaurus) from the Middle Triassic (1/4245 million years ago) of southwest China showing live birth in archosauromorphs. Our discovery pushes back evidence of reproductive biology in the clade by roughly 50 million years, and shows that there is no fundamental reason that archosauromorphs could not achieve live birth. Our phylogenetic models indicate that Dinocephalosaurus determined the sex of their offspring by sex chromosomes rather than by environmental temperature like crocodilians. Our results provide crucial evidence for genotypic sex determination facilitating land-water transitions in amniotes. © The Author(s) 2017.


Zhu M.,CAS Institute of Geology and Geophysics | Zhang L.,CAS Institute of Geology and Geophysics | Dai Y.,Chengdu Center | Wang C.,CAS Institute of Geology and Geophysics | Peng Z.,CAS Institute of Geology and Geophysics
Ore Geology Reviews | Year: 2017

The volcanic zircons, inherited pre-magmatic core domains and hydrothermal zircons in felsic meta-volcanic rocks and Cu–Zn orebodies from the Neoarchean Hongtoushan deposit in China were distinguished according to their texture, 207Pb/206Pb ages, Th/U and oxygen isotopic ratios. Their respective element compositional and Lu–Hf isotopic features were studied using LA–(MC)–ICP–MS methods, showing that the compositions of the pre-magmatic core domains are intensely modified by hydrothermal processes, exhibiting no differences with hydrothermal zircons. All zircons show a linearly decreasing trend in the ZrO2 vs SiO2 plot, but similar REE patterns, with steep slopes, Ce and Eu anomalies and enrichments of HREE, indicating their common petrologic origin. Nevertheless, compared with volcanic zircons, pre-magmatic core domains underwent compositional modification in the hydrothermal accretion processes by P and Y substitution mechanisms. Therefore, these core domains are highly enriched in P2O5, Y2O3, REEtotal, and Hf2O as well as some incompatible elements, such as Rb, Sr, Nb, Ta and Pb, similar to the hydrothermal zircons. Moreover, the Lu/Hf ratios are elevated by almost an order of magnitude, which is associated with the addition of Lu rather than changes in Hf, leading to increased 176Lu/177Hf ratios and decoupling of Hf–O isotope systematics. Nevertheless, the hydrothermal influence on the 176Hf/177Hf ratios seems to be undetectable, rising by 0.022% when compared with the ratios of the volcanic zircons. All 176Hf/177Hf ratios plot between depleted mantle and modern known plumes suggest a mantle plume setting corresponding to the ∼2.6 Ga crustal growth in the Qingyuan district. © 2017 Elsevier B.V.


Zhang Y.-C.,Deakin University | Zhang Y.-C.,CAS Nanjing Institute of Geology and Palaeontology | Shen S.-Z.,CAS Nanjing Institute of Geology and Palaeontology | Shi G.R.,Deakin University | And 3 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2012

The tectonic evolution of the Qiangtang Block in the Qinghai-Tibetan Plateau has been a controversial subject for a long time. In this paper, the discovery of new stratigraphic and fusuline fossil evidence from the Permian sequences (Qudi and Lugu formations) of the Qiangtang Block is reported and the palaeogeographical position and tectonic history of this block during the Late Cisuralian (Late Early Permian) are discussed.The Qudi Formation is typified by thick turbidite deposits and contains Artinskian fusulines such as Pseudofusulina and Chalaroschwagerina. The fusulines were deposited as grains involved in debris flow deposits, suggesting a synchronicity with the depositional time of the turbidites. The subsequent Lugu Formation is dominated by seamount-type carbonates with an irregular basalt base. Fusulines Cancellina, Pseudodoliolina and Parafusulina in the base of the carbonates confirm its age as middle Kungurian. The transition from the turbidite Qudi Formation to the seamount Lugu Formation is here interpreted to be a continuous depositional process recording the Qiangtang Block's separation from the Indian Plate. This separation signaled the opening of the Neotethys Ocean between the Qiangtang Block and the Indian Plate. Palaeogeographically, the Qiangtang Block's separation is comparable with the Baoshan Block's separation in the east and Central Pamir's separation in the west. By contrast, the ultimate opening of the Neotethys Ocean by the separation of India-Pakistan and northern Oman is apparently much later than this event recorded in the Qiangtang Block. Consequently, it is interpreted that the opening of the Neotethys Ocean in the whole northern Gondwanan margin is a diachronous series of events. © 2012 Elsevier B.V.


Yin Y.,China Geological Survey | Zheng W.,Chengdu Center | Li X.,China Geological Survey | Sun P.,Key Laboratory of Neotectonic Movement and Geohazard | Li B.,Key Laboratory of Neotectonic Movement and Geohazard
Bulletin of Engineering Geology and the Environment | Year: 2011

Numerous earthquake-induced landslides occurred in the Longmenshan tectonic belt associated with the 12th May 2008 Wenchuan earthquake where the vertical acceleration was greater than the horizontal ground motion. Many of these landslides originated in the steep mountain terrain which amplified the effect of the ground shaking. Three typical landslides are discussed: the Niujuangou sturzstrom, the Chengxi rock slide and the 1,100 million m3 Daguangbao rock slide. Having discussed the individual slides and some previously published models, a mechanism to explain both the very fast velocity of the slides and their long run-out distance is proposed, taking into account aerodynamic principles. The model postulates that air trapped in the steep-sided valley by the collapsing rock mass forms a "cushion-effect" on which the debris moves. © 2010 Springer-Verlag.


Tie Y.,Chengdu Center | Tie Y.,Chengdu University of Technology
Natural Hazards | Year: 2013

Our aim is to determine the run-out distance of the debris flow that is crucial in the assessment, prevention and control of the debris flow hazard. Based on the variation characteristic of debris flow velocity in the alluvial fan, this paper proposes the calculation method of the velocity attenuation coefficient of the debris flow. By defining the velocity attenuation coefficient and deducing its calculating formula, this paper puts forward a new method to determine the run-out distance of the debris flow based on the velocity attenuation coefficient, and Gangou debris flow in Luding County, Sichuan Province is selected as a case for calculation and verification. Having 10 m as its measuring spacing, this paper measured 19 sections at the alluvial fan of the Gangou debris flow (among them, 11 sets of data are valid). And based on the measurement, this paper analyzes the characteristic of the velocity attenuation and calculates its velocity attenuation coefficient after the 2005 debris flow. The study indicates that when the velocity of Gangou debris flow at the alluvial fan is greater than 12 % of the initial velocity (at the mouth of gully), the attenuation is quite remarkable. But when the velocity at the alluvial fan is less than 12 % of the initial velocity, the attenuation is quite slow. Besides, when Gangou debris flow rushes out of the gully mouth (the initial velocity is 10 m/s) and when it attenuates to the 32 time, its velocity is less than 0. 1 m/s, the debris flow is considered to stop flowing, and the run-out distance of Gangou debris flow is calculated to be 320 m. But the present alluvial fan of Gangou debris flow is measured to be 285 m in length, and the calculated run-out distance is 320 m, which is 35 m longer than its present length. This means when the debris flow runs out in 2005, it blocked up the main river (Dadu River) in some extent. And this finding is generally in accordance with that from the field survey. The findings can be of theoretical and practical significance in the debris flow hazard assessment, as well as its prevention and mitigation. © 2012 Springer Science+Business Media Dordrecht.


Wang J.,Chengdu Center | Deng Q.,Chengdu Center | Wang Z.-J.,Chengdu Center | Qiu Y.-S.,Hubei Geological Survey | And 3 more authors.
Precambrian Research | Year: 2013

Recent field geological investigations and sedimentary facies analysis have disclosed that the "Macaoyuan conglomerates" should be assigned to the dolomitized intraclastic lime grainstones rather than the basal conglomerates as previously reported. The conglomerates display depositionally-erosional conformable contacts with their underlying stratigraphic succession. There is no so-called "angular unconformity" or associated "Shennong movement" between the Macaoyuan Group and Shennongjia Group. The Macaoyuan Group consists primarily of carbonate platform facies association and mixed clastic and carbonate shelf facies association, while the "Macaoyuan conglomerates" are mainly made up of carbonate platform slope-channel gravity flow deposits. The sedimentary structures such as basal scouring structures, slump-convolute structures, imbricate structures, inverse grading bedding and lenticular filling deposits are well developed in the slope-channel gravity flow sedimentary succession, whereas cross bedding, wavy bedding, parallel bedding, ripple bedding, and normal grading bedding are common in the mixed inner shelf and platform-margin shoal sedimentary succession. The SHRIMP and LA-ICP-MS zircon age dating techniques are employed for the synsedimentary tuff sample collected from the upper part and sedimentary detrital zircons from the topmost part of the Baliya Formation in the lower part of the Macaoyuan Group. The synsedimentary tuff sample gives a SHRIMP zircon U-Pb age of 1157. ±. 19. Ma, which agrees well with the maximum depositional age of 1180 Ma for the sedimentary detrital zircons. It follows that the age of deposition of the Macaoyuan Group should be traced back to the Mesoproterozoic rather than the Neoproterozoic. The ages of the detrital zircons are mainly concentrated in two time intervals: 1.16-1.26. Ga and 2.60-2.95. Ga. The ca. 2.60. Ga as a marked peak age may represent an important period for the crustal accretion and evolution of the Yangtze block. © 2013 Elsevier B.V.

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