Response of magmatic activity to the closure of Changning-Menglian Palaeothys in western Yunnan: Evidence from geo-geochemical study on granite in southern section of Lincang pluton

Lincang intrusive, as the largest exposed compound batholith of southern Lancangjiang in western Yunnan, and an important component of tethys tectonic domain, is mainly biotite monzogranite in lithology.The zircon sample collected frome granite was dated to 225.1±6.1 Ma, suggesting that these intrusives were emplaced during the Late Triassic.The K₂O/Na₂O value of Lincang granite is greater than 1, and the aluminum saturation index A/CNK ranges from1.05 to 1.95, indicating that Lancang intursives are derived from S-type granite with high potassium calcium basic peraluminum-super peraluminum.Intursives are remarkably characterized by enriched LREE and depleted HREE with (La/Yb)_N=6.06~21.01 and δEu of 0.20~0.38.The petro-geochemistry of intusives indicates that the Lincang granite should be the product of the Changning-Menglian Palaeothys closure process, and the original rock of Lincang granite is lithologically clay-poor metamorphic sandstone and metamorphic mudstone in the middle and lower crust.The syncollision represented in its Pearce structure discrimination diagram is a response to the Palaeothys ocean closure and the Baoshan-Simao block collision.