7 results on '"Yan, Jiaxin"'
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2. Biogeochemical Records at Shangsi Section, Northeast Sichuan in China: The Permian Paleoproductivity Proxies
- Author
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Hu Chaoyong, Ma Zhongwu, Yan Jiaxin, and Xie Xinong
- Subjects
Total organic carbon ,Paleontology ,Biogeochemical cycle ,Water column ,Permian ,Paleoceanography ,Earth and Planetary Sciences (miscellaneous) ,Geochemistry ,Trace element ,General Earth and Planetary Sciences ,Anoxic waters ,Surface water ,Geology - Abstract
The marine primary producers assimilate the atmospheric CO 2 to form the organic carbon in surface water. The organic carbon then settles down through the water column and is removed from the oceans by final preservation in sediments in the form of petroleum or nature gases. The reconstruction of paleoproductivity will thus improve our understanding of the biological processes in the formation of fossil energy resource and help to locate new sites for future exploration. In this study, biorelated elements P, Cd, Al, Ba, as well as redox sensitive element Mo, were analyzed in the 448 rock samples collected from Permian strata at the Shangsi Section, Guangyuan, Northeast Sichuan in China. On the basis of the Ti content, the nondetrital contents of P, Ca, and Al, denoted as P xs , Cd xs , and Al xs , were calculated and found to coincide with the TOC content throughout the whole section, with some enrichment intervals being found in the middle part of Chihsia Formation, topmost Maokou Formation, and Dalong Formation. This suggests that the biorelated elements could be used as proxies for the paleoproductivity here in this section. Ba xs , a paleoproductivity indicator widely used in the paleoceanography, shows insignificant correlation with TOC, P xs , Cd xs , and Al xs , probably arising from the loss of biological barium in anoxic conditions. Compiled with the data of TOC content and P xs , Cd xs , and Al xs , three episodes of enhanced paleoproductivity were identified in Permian strata including the middle part of Chihsia Formation, topmost Maokou Formation, and Dalong Formation.
- Published
- 2008
3. Global oolite deposits across the Permian–Triassic boundary: A synthesis and implications for palaeoceanography immediately after the end-Permian biocrisis.
- Author
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Li, Fei, Yan, Jiaxin, Chen, Zhong-Qiang, Ogg, James G., Tian, Li, Korngreen, Dorit, Liu, Ke, Ma, Zulu, and Woods, Adam D.
- Subjects
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OOLITE , *PERMIAN-Triassic boundary , *PALEOCEANOGRAPHY , *SEDIMENTS , *PHANEROZOIC Eon - Abstract
The Permian–Triassic mass extinction (PTME) is not only a dramatic loss in biodiversity and major change in ecosystem structures, but also coincided with the formation of abundant unusual sedimentary structures. Of these, ooids were widespread in shallow marine carbonate settings during the Permian–Triassic (P–Tr) transition, and giant ooids occurred more frequently at this critical period than any time during the Phanerozoic. Global review of 43 oolite-bearing Permian–Triassic boundary (PTB) sections with reliable biostratigraphic controls indicates that ooids occurred mostly in coincidence with the latest Permian extinction (LPE) and its immediate aftermath. Ooids became widespread over extensive regions just after the LPE during the interval corresponding to the conodont Hindeodus changxingensis Zone. They persisted into the earliest Triassic until the conodont Isarcicella isarcica Zone. In addition, oolites are often found in association with microbialites in low-latitude shallow-marine settings. Proliferation of ooids over the P–Tr transition indicates an extensive range of warm waters with high level of carbonate saturation state that prevailed in the oceans during that time. The latest Permian ooids were usually small (0.3 to 0.7 mm in diameter), aragonitic, poorly preserved and recrystallized, while moderately to well-preserved morphology, bimineralic, and oversized forms usually occurred in the I. isarcica Zone of the earliest Triassic and afterwards. Widespread aragonitic ooids in the end of the Permian reinforce the scenario that an “aragonite sea” period may have resulted in the dramatic losses of skeletal organisms that precipitated low-Mg calcite and hampered their recovery in the aftermath. The anomalous primary mineralogy of Lower Triassic ooids implies that previously assumed stable seawater composition during the Early Triassic needs to be revaluated. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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4. Paleoceanographic conditions following the end-Permian mass extinction recorded by giant ooids (Moyang, South China).
- Author
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Li, Fei, Yan, Jiaxin, Algeo, Thomas, and Wu, Xia
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PALEOCEANOGRAPHY , *PERMIAN Period , *MASS extinctions , *SCIENTIFIC observation , *FLUORAPATITE , *CARBON isotopes - Abstract
Abstract: Early Triassic oceans were characterized by deposition of a number of “anachronistic facies”, including microbialites, seafloor carbonate cement fans, and giant ooids. Giant ooids were particularly prevalent in Lower Triassic sections across South China and exhibit unusual features that may provide insights into marine environmental conditions following the end-Permian mass extinction. The section at Moyang (Guizhou Province) contains abundant giant ooids ranging in size between 2 and 6mm (maximum 12mm) and exhibiting various cortical structures, including regular, deformed, compound, regenerated and “domed”. Preservation of ooid cortical structure is generally good as indicated by petrographic observations, and trace element and carbon isotope analyses suggest that diagenesis occurred in a closed diagenetic system. All ooids exhibit fine concentric laminae, frequently alternating between light-colored coarsely crystalline and dark-colored finely crystalline layers probably reflecting variation in organic content or original mineralogy. Under scanning electron microscope, biomineralized filaments or biofilms and tiny carbonate fluorapatite (CFA) crystals are commonly found in the finely crystalline layers. We infer that the precipitation of CFA was related to adsorption of P via microbial activity on the surfaces of ooids following episodic incursions of deep waters rich in CO2, H2S and phosphate into shallow-marine environments. Giant ooid precipitation may have been promoted in shallow ramp settings during these events by increased watermass agitation and supersaturation with respect to CaCO3, as well as reduced carbonate removal rates through biotic skeletal formation. Spatio-temporal distribution data reveal that giant ooids were widespread in the Tethyan region during the Early Triassic, and that they were most abundant immediately after the end-Permian crisis and disappeared gradually as metazoans repopulated marine environments. [Copyright &y& Elsevier]
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- 2013
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5. Absence of Middle Permian Kamura event in the Paleo-Tethys Ocean.
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Luo, Genming, Huang, Junhua, Bai, Xiao, Wu, Xia, Yan, Jiaxin, and Xie, Shucheng
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MASS extinctions ,PALEOCEANOGRAPHY ,TETHYS (Paleogeography) ,CARBONATES ,CARBON isotopes ,PERMIAN Period - Abstract
The article focuses on a study which examined the mass extinction event in the Paleo-Tethys Ocean or the Kamura event. Samples of fresh carbonate were collected from the Shangsi and Laibin Sections in China. Results of the study showed variations in the carbon isotope composition in the Laibin Section. The study also found that the high positive plateau of carbon isotope during the Capitanian period did not occur in the Tethyan Ocean.
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- 2012
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6. Giant ooids as one kind of anachronistic sediments in Lower Triassic: A case study from Moyang section, Guizhou Province, South China.
- Author
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Li, Fei and Yan, Jiaxin
- Subjects
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SEDIMENTARY structures , *CALCITE , *CRYSTALS , *ARAGONITE , *AUTHIGENESIS , *PALEOCEANOGRAPHY , *TRIASSIC Period - Abstract
The article examines the Lower Triassic giant ooids at the Moyang Section in Guizhou Province, South China. The nuclei of these giant ooids is composed of calcite grains and peloids. Their concentric laminae of tangentially oriented crystals indicate an aragonitic mineral origin. Ooid cortices also exhibited authigenic carbonate fluoropatite (CFA). It notes that the CFA-calcified filament link in the giant ooids indicate the unique paleocenographic condition of this era.
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- 2012
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7. Restoration of reef ecosystems following the Guadalupian–Lopingian boundary mass extinction: Evidence from the Laibin area, South China.
- Author
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Huang, Yuangeng, Chen, Zhong-Qiang, Zhao, Laishi, Stanley, George D., Yan, Jiaxin, Pei, Yu, Yang, Wanrong, and Huang, Junhua
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REEF ecology , *MASS extinctions , *PALEOCEANOGRAPHY , *OCEAN temperature , *MARINE biology - Abstract
Abstract The Guadalupian–Lopingian boundary (GLB), also Middle–Late Permian boundary, mass extinction severely destroyed metazoan reef ecosystems, although some studies argued that both biotic and environmental turnover across the GLB are not so obvious. When compared with prolifically developed reefs in the Capitanian, the Wuchiapingian reef examples appear depauperate and almost 89% of the carbonate production in these bioconstructions was lost. Here, we report a typical sponge reef from the Wuchiapingian stage in the Tieqiao section, central Guangxi Province, South China. The Tieqiao reef might represent the only example of a Wuchiapingian metazoan reef in the eastern Palaeo-Tethys region. It provides insight into ecosystem restoration following the GLB extinction. Major constructors of the Tieqiao reef are sponges (Peronidella , Parauvanella , Sollasia , Tabulozoa, and Amblysiphonella), algae (Anthracoporella , Archaeolithporella , Permocalculus , Gymnocodium) and Tubiphytes. This reef is well constrained as middle–late Wuchiapingian in age by the Clarkina orientalis conodont zone. Carbonate carbon isotope excursions experienced negative spikes near the GLB and multiple perturbations in the early–middle Wuchiapingian, and remained relatively stable during re-establishment of metazoan reefs in middle–late Wuchiapingian. Conodont oxygen isotopes showed that the sea surface temperature (SST) was extremely high, > 30 °C during late Capitanian time, punctuated by a short cooling event and global regression associated with the GLB extinction, and followed by high SST and rapid rise in sea level in the early Wuchiapingian. The reemergence of the Tieqiao reef coincided with the initial cooling in surface oceans and sea-level fall during the middle–late Wuchiapingian. Accordingly, reef ecosystems experienced a long-term depletion worldwide in early–middle Wuchiapingian time and then recovered ~ 2.5 Myr after the GLB extinction based on estimate in integration of both conodont biostratigraphy and radiometric ages. Highlights • A diverse reef dwellers and constructors community proliferated in the Tieqiao reef. • Tieqiao reef may show the final recovery of reef ecosystems after the GLB crisis. • Moderate temperature changes do not have had a strong control on the Tieqiao reef. • The reef began when δ13C finally stabilized following the GLB crisis. • Post-extinction restoration of reef ecosystems was associated with sea-level fall. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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