Genesis of the Late Mesozoic Great Xing'an Range Large Igneous Province in eastern central Asia: A Mongol-Okhotsk slab window model

摘要

The late Mesozoic Great Xing'an Range Large Igneous Province (XRLIP), with an area of >3 x 10s km2, is a prominent, enigmatic feature in eastern central Asia. The province is characterized by extensive within-plate magmatism, including a >4 km-thick sequence of volcanic rocks and voluminous plutons emplaced during an interval of-40 million years from Late Jurassic through Early Cretaceous times (-150-110 Ma). The igneous activities are characterized by widespread adakitic rocks, alkalic basalts, and A-type granitoids with largely intraplate geochemical signatures, emplaced in a normal continental crustal setting. A Mongol-Okhotsk ridge subduction model is proposed for petrogenesis of the igneous rocks. Partial melting of young, hot, subducting oceanic slabs close to the ridge formed the adakitic rocks. A slab window that opened during ridge subduction triggered alkalic basaltic to A-type granitic and minor calc-alkaline magmas, as well as large-scale, metallogenic mineralization and subsequent basin formation.