Reworking of the Juvenile Crust in the Late Mesozoic in North Qinling, Central China

• Published in: Journal of earth science (Wuhan, China) Vol. 33; no. 3; pp. 623 - 641
• Main Authors: Xue, Ying-Yu, Liu, Haiyang, Wang, Zhiyi, Sun, Weidong, Chen, Fukun
• Format: Journal Article
• Language: English
• Published: Wuhan China University of Geosciences 01.06.2022; Springer Nature B.V; Center of Deep Sea Research,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China; Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China%Center of Deep Sea Research,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China; Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China%School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China%Center of Deep Sea Research,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China; University of Chinese Academy of Sciences,Beijing 100049,China; Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China; Laboratory for Marine Mineral Resources,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China; School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China
• Subjects: Asthenosphere; Belts; Biogeosciences; Composition; Cretaceous; Dating; Depletion; Earth and Environmental Science; Earth Sciences; Evolution; Field strength; Geochemistry; Geochronometry; Geology; Geotechnical Engineering & Applied Earth Sciences; Granite; Isotopes; Juveniles; Lava; Lead; Magma; Mesozoic; Ocean circulation; Orogeny; Pacific Plate Subduction and the Yanshanian Movement in Eastern China; Plutons; Radiometric dating; Rock; Rocks; Rubidium; Strontium; Strontium 87; Strontium isotopes; Tectonics; Triassic; Upwelling; Zircon; Zirconium; China; Mesozoic; Qinling Orogen; geochemistry; Nd isotope; granite; crustal reworking
• ISSN: 1674-487X; 1867-111X
• DOI: 10.1007/s12583-021-1521-0

The Qinling Orogen resulted from the collision between the North and South China blocks in the Triassic. Mesozoic granitoids, ranging from the Triassic to the Cretaceous, are widely distributed in this orogen, and they provide excellent clues for understanding the crustal evolution and geodynamic evolution of the orogenic belt. The Triassic belt is mostly located in the South Qinling, whereas the Cretaceous belt is located mostly in the North Qinling. The Taibai complex pluton is located at the conjunction of the two belts. Here we present a data set comprising zircon U-Pb dating and elemental and Sr-Nd isotopic geochemistry for Late Mesozoic granite and microgranular enclaves (MME) exposed in the Taibai complex pluton. The granite and MME yield concordant U-Pb zircon ages of 124 to 118 Ma, indicating that they were products of roughly simultaneous magmatism in the Late Mesozoic. The granite rocks are high-K, calc-alkaline, and weakly peraluminous in compositions, and they are characterized by enrichment in large ion lithophile elements (e. g., Rb, Ba), depletion in high field strength elements (e.g., Nb, Ta, Zr, Ti), and variable Sr/Y ratios of 7.64 to 63.6. Low MgO, Cr, and Ni contents imply that the magma(s) were essentially crust-derived. Both the granite and the MME show relative depletion in Sr-Nd isotopic composition (initial 87 Sr/ 86 Sr of 0.704 4 to 0.706 7, initial ε Nd values of −3.4 to −2.6), suggesting that the magma(s) originated from juvenile crustal rocks. These Sr-Nd isotopic characteristics are significantly different from those of other Late Mesozoic granitoids exposed elsewhere in the Qinling orogenic belt, which formed from much older and enriched sources and with negligible contributions from mantle or juvenile crust. We propose a reworking event of the juvenile crust during the Late Mesozoic that was triggered by the tectonic extension and subsequent asthenospheric upwelling that occurred in eastern China.