Geological features and Re-Os isotopic dating of the Lalingzaohuo molybdenum polymetallic deposit in East Kunlun

Abstract：The Lalingzaohuo molybdenum polymetallic deposit in the Qimantag metallogenic belt of Qinghai Province is a newly discovered skarn –porphyry type deposit. Eleven samples and four repetition samples for Re-Os isotopic dating were analyzed, and the model ages show two segments： 214.1~223.9 Ma and 235.7~240.8 Ma with 187Re-187Os isochron ages of ( 214.5±4.9 ) Ma and (240.8±4.0) Ma and the weighted average model ages of (217.6±3.5) Ma and ( 238.4±1.2 ) Ma , respectively. The age dating indicates that there are two metallogenic epochs： Middle Triassic and Late Triassic. The rhenium content of the molybdenite ranges from 17.40×10-6 to 149.52×10-6, with the great majority concentrated in a dozen micrograms to tens of micrograms, indicating a crust-mantle mixed mineral source. Combined with previous studies, the authors hold that the two ore-forming events in Triassic were associated with the breakoff of the subducting slab in Middle Triassic and lithospheric delamination in Late Triassic.