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TitlePetrochemical and geochronological data of Permian-Lower Triassic clastic sedimentary rocks in the northwestern Junggar basin, NW China: Implications for provenance, tectonism and paleoclimate
AuthorTang, W B; Song, Y; He, W; Tang, Y; Guo, X; Pe-Piper, G; Piper, D J WORCID logo; Guo, Z; Zhang, Y Y; Li, W; Chen, A
SourceMarine and Petroleum Geology vol. 148, 106027, 2022 p. 1-14,
Alt SeriesNatural Resources Canada, Contribution Series 20220194
Mediapaper; digital; on-line
File formatpdf
AreaJunggar; China
Lat/Long WENS 83.0000 86.0000 47.0000 45.0000
Subjectsgeochemistry; Science and Technology; igneous and metamorphic petrology; rifts; basins; weathering; provenance; tectonic environments; Permian
Illustrationslocation maps; stratigraphic columns; photographs; photomicrographs; tables; ternary diagrams; plots
Released2022 11 19
AbstractThe Permian clastic sediments in the Mahu sag offer outstanding conditions to test the control of tectonism and paleoclimate on sedimentation in a rift basin. A synthesis of petrological and geochemical analyses of sandstones, zircon U-Pb geochronology of granitic conglomerates, and principal component analysis have been used to investigate the source composition and chemical weathering indices. The rare earth and trace element compositions of 16 sandstone samples are consistent with first cycle sources from the Carboniferous-Lower Permian mafic and felsic igneous rocks in West Junggar. Lower Permian sandstones contain abundant volcanic lithic clasts and plagioclase grains, and have high Na2O, CaO, Sr and V, suggesting a coeval proximal volcanic source in Central West Junggar during the syn-rift stage. Middle Permian sandstones consist of trachyte and rhyolite clasts, and quartz and albite grains, and show a gradual increase of Th, U and SiO2, indicating an expansion of source areas to more distant Southern and Northern West Junggar during the post-rift stage. In the Lower Triassic, an abrupt increase in the percentages of quartz and K-feldspar, as well as the zircon U-Pb geochronology of granite-clast conglomerates (290-330 Ma), all indicate regional uplift and unroofing of Carboniferous-Permian granitic plutons in West Junggar during the tectonic inversion stage at the Permian-Triassic boundary. Various chemical weathering indices indicate cold and arid climate conditions during the early Permian, followed by a transition to warm and humid climatic conditions. Comprehensive analysis of petrography and geochemistry sheds a new light for studying the source-to-sink evolution of a rift basin, and has further implication for paleoclimate fluctuation and change.
Summary(Plain Language Summary, not published)
This study identifies changing sediment sources in an evolving rift basin and uses chemical composition of sandstones to identify changes in climate.

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