Petrogenesis and geological significance of the Mamu Early Cretaceous magmatic rocks in the western part of Gangdese
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P588.12+1

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    Abstract:

    A large number of magmatic rocks were formed in the Gangdese belt of the Qinghai-Tibet Plateau. To better understand the petrogenesis, magma source region and evolution, we have studied the petrography, geochemistry, zircon trace elements and Hf isotope analysis of the granite porphyry and rhyolitic crystal tuff in Mamu, Gakyi, western of the Central Lhasa Terrane. The granite porphyry and rhyolitic crystal tuff in Mamu were both formed at Early Cretaceous period. They are both shoshonitic rocks, enriched in large ion lithophile elements, and light rare earth elements, and depleted in high field-strength elements(HFSE) and Eu. They have high negative εHf(t) values of -9.57~-3.43 and -8.79~-4.80, and the older Hf isotopic crustal model age tDM2 of 1 774~1 388 Ma and 1 727~1 477 Ma, respectively. The Early Cretaceous magmatic rocks originated from the remelting of ancient lower crustal materials, with the mixing of mantle material. After the magma mixing, the amphibole, feldspar and biotite were first separated and crystallized, finally formed the granite porphyry and rhyolitic crystal tuff. Combined with previous studies and this paper, we infer that the Early Cretaceous magmatism in Mamu is probably due to the southward subduction of the southward subduction of Bangong-Nujiang suture zone.

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刘畅,杨竹森,徐培言,赵晓燕,夏文杰,杨晓旭,2022,冈底斯西段麻木早白垩世岩浆岩岩石成因及地质意义[J].岩石矿物学杂志,41(3):537~554. LIU Chang, YANG Zhu-sen, XU Pei-yan, ZHAO Xiao-yan, XIA Wen-jie, YANG Xiao-xu,2022,Petrogenesis and geological significance of the Mamu Early Cretaceous magmatic rocks in the western part of Gangdese[J]. Acta Petrologica et Mineralogica,41(3):537~554.

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History
  • Received:September 15,2021
  • Revised:March 09,2022
  • Adopted:
  • Online: May 17,2022
  • Published: