Formation age and petrological geochemical characteristics of intermediate-acid intrusive rocks in Dashuigou of East Kunlun organic belt

The authors investigated zircon U-Pb dating and petrological geochemical characteristics in the east of East Kunlun orogenic belt. The results show that the U-Pb age of zircons in tonalite is (402±2) Ma, belonging to Early Devonian of Variscan. The petrological geochemical characteristics show that the aluminium saturation A/CNK index ranges from 0.946 to 1.077, and the ratio of light rare earth elements and heavy rare earth elements (LREE/HREE) is from 2.94 to 18.93, which indicates the enrichment of light rare earth elements. And the δEu parameter is between 0.01 and 0.85, belonging to europium depletion type. The δCe parameter is between 0.95 and 1.23, reflecting normal-slightly enrichment. Overall, the rocks are mainly by I-type granite. Combined with the tectonic discrimination diagrams, the authors concluded that intermediate-acid intrusive rocks in Dashuigou are orogenic granite formed after Early Devonian.