The age, geological setting, and types of gold deposits in the Yanbian and adjacent areas, NE China

Abstract

The eastern part of the Xing'an–Mongolian Orogenic Belt (XMOB) in Jilin and Heilongjiang Provinces, NE China, is highly prospective for gold mineralization, and more than ten gold and gold–copper deposits have been found in the Yanbian and Dongning areas in the last decade. These deposits are classified, based on geological characteristics and mineralogical and geochemical information, into orogenic, intrusion-related, gold-rich porphyry, and epithermal deposits; the latter are further divided into high-sulfidation (HS) and low-sulfidation (LS) deposit types.We present the results of zircon laser ablation U–Pb dating of some representative gold deposits and associated magmatic rocks within the eastern XMOB; these are the orogenic Wudaogou deposit, the intrusion-related Naozhi deposit, and the epithermal Jiusangou gold deposit. The weighted mean age of the granodiorite that hosts mineralization at Wudaogou is 253.1±0.3Ma, whereas zircons from a porphyritic dacite dike that was intruded at the same time as the formation of the Naozhi deposit yielded two groups of weighted mean ages (198.9±3.6 and 126.3±1.7Ma). Zircons from a porphyritic quartz diorite within the breccia that hosts the Jiusangou deposit yielded a weighted mean age of 108.1±1.4Ma.These data, combined with data from previous studies, enable the identification of three periods of Phanerozoic gold mineralization within the Yanbian area and adjacent regions; these are ca. 270–240, ca. 130–120, and ca. 115–100Ma. The Late Permian to Early Triassic (270–240Ma) events formed the orogenic gold deposits at Yangjingou and Wudaogou; both are located near the Xar Moron–Changchun Suture Zone between the North China Craton and the XMOB. The Early Cretaceous (130–120Ma) events produced intrusion-related gold mineralization, such as the Naozhi and Miantian deposits, which are associated with Jurassic granodiorite plutons or volcanic rocks. Almost all of the gold-rich porphyry and epithermal gold deposits in this area formed during the late Early Cretaceous (115–110Ma). We propose that the orogenic gold mineralization in the Yanbian area was closely related to the collision between the North China Craton and the eastern XMOB, whereas the other gold deposit types formed at Early Cretaceous lithospheric extensions associated with post-subduction tectonics.