Magmatic activities in the Phan Si Pan uplift and red river zone

Trong Hoa Tran, Gleb V. Polyakov, Tuan Anh Tran, Alexander S. Borisenko, Andrey E. Izokh, Pavel A. Balykin, Thi Phuong Ngo, Thi Dung Pham

Research output: Chapter in Book/Report/Conference proceedingChapterResearchpeer-review


Cezonoic magmatic activities in the Phan Si Pan Uplift and Red River Shear Zone, northwest Viet Nam are related with India - Eurasian collision. The Cenozoic biotite granite and porphyric granite in the Phan Si Pan Uplift are exposed in the shape of small blocks and dykes. They have geochemical indications analogous to high-K calc-alkaline magmatics series were occurred between 35 and 32 Ma (U-Pb, zircon, LA-ICP-MS), coincident with the timing of an early strong shear motion along the Red River zone. A primarily crustal source of the magmas is supported by high-Al, -alkaline, relatively low Nb, Ta and Zr, and high initial87Sr/86Sr isotopic ratios. On the other hand, the contemporaneous occurrence of the granite magmatism and start of the major shear motion phase suggests that the magmas can be viewed as syn-kinetic. The syn-kinetic magmatism in the Red River Shear Zone formed an uniform association including small intrusive bodies comprised of lherzolite, websterite and gabbro, which were subsequently turned into shear boudinage in later stages. The magmas occurred in two major stages at 35 and 25 Ma (Ar-Ar). These observations suggest that the formation of mafic - ultramafic magmas in the early stage may be associated with the exhumation process, while the later magmas may be related to post-gneiss exhumation activities along the Red River shear zone. However, the magmas of two stages are geochemically similar, suggesting their common source. The occurrence of high-Al, −alkaline and high-pressure melting granite during 24-22 Ma (Ar-Ar) is a specifi c character of the Red River shear zone. The undeformity or weak deformity feature of the granite indicates that magnitude of shear motion in the Red River zone decreased after the peak time between 35 and 22 Ma. Note that the occurrence of granite aplite and pegmatite in gneiss in the Red River zone is not related to the nature of Tan Huong -type granite generation. This is evident by their spatially separated distribution as well as the large difference in their intitial strontium isotopic ratios as mentioned earlier.

Original languageEnglish
Title of host publicationModern Approaches in Solid Earth Sciences
PublisherSpringer International Publishing AG
Number of pages58
Publication statusPublished - 2016
Externally publishedYes

Publication series

NameModern Approaches in Solid Earth Sciences
ISSN (Print)1876-1682


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