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New Zircon U‐Pb Dating of the Tuanliangzi Formation in South Lancangjiang Zone, Western Yunnan: Implications for the Tethyan Evolution of the Simao Block
Author(s) -
ZHAO Han,
XIAO Qianru,
YU Xiaoxuan,
XIONG Fuhao,
GONG Tingting,
WANG Qiang
Publication year - 2019
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13846
Subject(s) - christian ministry , zircon , mineralization (soil science) , geochemistry , china , tectonics , chinese academy of sciences , geology , geography , archaeology , political science , paleontology , soil science , law , soil water
The Lincang area has witnessed complex history of the Proto-Paleo Tethyan evolution. Much attention has been paid on the Lincang granite batholith and Changning– Menglian suture, but the properties of the Lancangjiang tectonic belt and the boundary of the Simao block still remain highly controversial. The Tuanliangzi Formation widely distributed in the southern Lancangjiang tectonic belt was previously considered to be the Proterozoic basement rock of the western margin of the Simao Basin. The Tuanliangzi Formation is mainly composed of metasedimentary rocks. As is known, zircons in metasedimentary rocks have a variety of origins, including detrital zircons of protoliths and later metamorphic zircons, which may be its disadvantage on dating for stratum when compared with coeval interbedded volcanic rocks. Unfortunately, previous studies have focused on the metasedimentary rocks, ignored the determination of meta -volcanic rocks, which has restricted the accurate understanding of its formation time and tectonic affinity. Recently, a suit of andesitic tuffs in the Upper Tuanliangzi Formation were discovered for the first time, which provides an excellent way for determining its upper depositional time and exploring its tectonic significance. This study carried out systematic studies on its field geology, petrography and geochronology, with the purpose to date the time of the Tuanliangzi Formation. This new discovery is of great significance for understanding the tectonic evolution of the Sanjiang Tethyan tectonic zone, especially the Simao block.