Geochronology, petrogenesis, and tectonic implications of Permian felsic rocks of the Central Great Xing’an Range, NE China

摘要

The Hegenshan-Heihe Suture (HHS) is an important suture zone between the Xing'an and Songliao-Xilinhot blocks in the eastern Central Asian Orogenic Belt (CAOB). Many studies have examined the northern and southern parts of this suture zone, but the middle segment remains under-researched and controversial. This paper presents new research into Permian felsic rocks along the middle segment of the HHS, including alkaline granites, rhyolites, and granodiorites. Zircon U-Pb dating of these rocks yielded precise Permian ages of 300.4 +/- 2.5, 292.8 +/- 2.7, and 293.1 +/- 2.2Ma. The alkaline granites and the rhyolites are A-type rocks that were derived from lower crustal protoliths, with the melting of these protoliths caused by asthenospheric upwelling associated with lithospheric delamination. In comparison, the granodiorites are I-type granites were generated from a mantle-derived magmatic source. The petrogenesis of these granites also involved the assimilation of sedimentary rocks and fractional crystallization. This Permian magmatism occurred during post-collisional extension following the amalgamation of the Xing'an and Songliao-Xilinhot blocks.