The Late Permian-Early Triassic cyclostratigraphy in Shangsi section of Guangyuan area，Sichuan Province: Implications for P-T geological event based on wavelet analysis
Qiao Yanguo1, Shi Zhiqiang1, Wang Yanyan2, Zhang Biao1
1 Institute of Sedimentary Geology，Chengdu University of Technology，Chengdu 610059，Sichuan 2 College of Materials and Chemistry & Chemical Engineering，Chengdu University of Technology，Chengdu 610059，Sichuan
Abstract：Based on the analysis of the GR energy spectrum collected from the Upper Permian to Lower Triassic carbonate rocks in Shangsi section at Guangyuan area，Sichuan Province，it was indicated that the sedimentary layers are controlled by Milankovitch cycles，whose scale ratio was 410：102.5：42.6：21.5.During the Late Permian，the Shangsi area was in a deep-water environment of the paleo-Tethys and the deposition rate was low to 5 cm/ka.During the P-T transitional period the tectonic movement was strong and terrestrial and marine fauna experienced mass extinction.At the same time，weathering rate increased sharply because of the acid rain and lack of terrestrial vegetation and mass terrigenous material fluxed into shallow sea in turn，which resulted in a rapid deposition rate of 25cm/ka in Shangsi section.The rapid rate of deposition displayed a strong influence on marine ecosystems，that is，it restrained the diversity of marine fauna and delayed the resuscitating of marine ecosystems.The cyclicity of the latest Permian sedimentary record was more obvious and stable in Shangsi section.However，the periodicity turned to be labile when it came to the Early Triassic.We concluded that the accelerated deposition rate and deteriorated sedimentary cyclicity were triggered by the turbulent paleoclimate and mussy marine environment.The perturbation of the terrestrial realm contributed to the change of marine conditions，which might be one of the major reasons for the marine ecosystem recovering relatively slowly in the Early Triassic.
Qiao Yanguo,Shi Zhiqiang,Wang Yanyan et al. The Late Permian-Early Triassic cyclostratigraphy in Shangsi section of Guangyuan area，Sichuan Province: Implications for P-T geological event based on wavelet analysis[J]. JOPC, 2012, 14(3): 403-410.
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