Early Permian Volcanic Fragment-Bearing Sandstones in Babu of Southeast Yunnan: Indicative of Paleo-Tethyan Ocean Subduction
Yang Jianghai
Du Yuansheng
Yu Xin
Huang Hu
Chai Rong
Abstract：Babu mafic/ultramafic rocks in Southeast Yunnan Province are interpreted as remnant ocean crust,and together with the ophiolite in Song Hien tectonic zone of North Vietnam,constitute significant components of the Babu-Song Hien PaleoTethyan suture,a possible southern extension of the Ailaoshan suture.Around the Babu ophiolite is a widespread siliclastic rocks dominated sequence,with thin-bedded cherts observed in some locations.These clastic rocks have long been considered to be Triassic turbidity current deposits in spite of absence of reliable fossil and isotopic dating.West to Longlin village,there outcrop coarse sandstone and sandy conglomerate beds nearby the Babu mafic/lutramific rocks.These sandstones contain andesite and rhyolite fragments and display detrital zircon age spectra similar to those of the Late Permian sandstones in Song Hien tectonic zone and Permian sandstones in western Ailaoshan belt,but distinguished from those of the Permian-Triassic clastic rocks of Youjiang and Shiwandashan basins in Southwestern South China.The youngest zircon group with ages of 285 Ma,has geochemical affinities of magmatic zircons crystallized from arc/orogenic settings,corresponding to the occurrence of volcanic rock fragments,indicating a maximum depositional age,and showing an adjacent Early Permian volcanic source.The new findings of chert deposits within a clastic rock section to the east of Babu Village,and the comparison of detrital zircon U-Pb age spectra suggest that the analyzed clastic rocks should be Early Permian rather than Middle Triassic in age and their Permian volcanic source might be related to the subduction of Babu Song Hien Paleo Tethyan ocean.
Keywords：Babu clastic rockEarly PermianPaleo-Tethyan ocean subductiondetrital zirconvolcanic rock fragmentpetrology
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 24-34 )