Geochronology, Geochemistry and Sr‐Nd‐Hf Isotopes of Early–Middle Triassic Adakitic Plutons in Central‐eastern Jilin Province, NE China: Constraints on the Non‐synchronous Closure of Paleo‐Asian Ocean

Abstract

AbstractThe Changchun–Yanji suture zone (CYSZ) in NE China is considered as the suture between the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB). The geochronology, geochemistry and Sr‐Nd‐Hf isotopes of Early–Middle Triassic adakitic plutions from the CYSZ, are presented in this paper to discuss their petrogenesis and tectonic setting, as well as to constrain the timing and style of the Paleo‐Asian Ocean's final closure. In Early Triassic, the Dayushan pluton (ca. 250 Ma) from western CYSZ has negativeεNd(t) values, bidirectional provenances (NCC and CAOB) ofεHf(t), which are formed in a collision tectonic setting. In contrast, in eastern CYSZ, the early Triassic samples in Liangshan (ca. 242 Ma) were high Mg#values, positiveεNd(t), single provenances (CAOB) ofεHf(t) resulting from a subduction setting. In the Middle Triassic, the A‐type granites in western CYSZ are found in previous studies representing a post‐collisional extensional environment, whereas syn‐collisional Lianyanfeng granites (ca. 237 Ma) in eastern CYSZ with lowISr and large scaleεNd(t) andεHf(t) values from bidirectional provenances (NCC and CAOB), represent a collisional setting. The Paleo‐Asian Ocean's occurred in a scissor‐like fashion along the CYSZ during the Triassic period.