Geology, U-Pb geochronology and stable isotope geochemistry of the Heihaibei gold deposit in the southern part of the Eastern Kunlun Orogenic Belt, China: A granitic intrusion-related gold deposit?

Isotope Geochemistry of the Heihaibei Gold Deposit within the Kunlun River Area in the Eastern Kunlun Orogen in Northwest China and Its Metallogenic Implications

“…The MKL, in which the Precambrian metamorphic rocks vary from gneiss to schist to phyllite [3,39], was predominantly emplaced by the widespread Neo-Proterozoic, early Cambrian-Early Devonian, and Late Permian-Early Triassic granitic intrusions [13,[42][43][44][45][46]. The SKL is dominated by Precambrian to Jurassic siliciclastic and carbonate rocks [3,43], and it was locally intruded upon by the Paleozoic and Triassic granites [23,47,48]. The KLRA is tectonically located in the central segment of the SKL within the EKO (Figure 1b).…”

“…20 km NW of the Heihai Lake, is the westernmost of 10 gold deposits in the KLRA (Figure 3). The dominant sedimentary rocks in the Heihaibei area are mainly composed of Silurian-Ordovician Nachitai Group metamorphic feldspathic quartz sandstone and sandy slate in the north, and Triassic Hongshuichuan Formation feldspathic quartz sandstone in the south, with minor Middle-Neo-Proterozoic Wanbaogou Group sandy limestone and basalt, and Triassic Naocangjiangou Formation feldspathic quartz sandstone in the southeast (Figure 3a) [22,23]. An EW-to WNW-striking >15 km long and >100 m wide monzogranite-granodiorite dyke (i.e., the Heihaibei granites) was intruded along the south of the Silurian-Ordovician Nachitai Group.…”

“…An EW-to WNW-striking >15 km long and >100 m wide monzogranite-granodiorite dyke (i.e., the Heihaibei granites) was intruded along the south of the Silurian-Ordovician Nachitai Group. We argued that this monzogranite-granodiorite dyke was classified as A-type granite [50] and was emplaced in the Early Devonian (416 Ma) in a post-collisional setting [50]), rather than in the Ordovician-Silurian (442 Ma [27]), 443 Ma [25], and 453 Ma [23]). The Triassic Hongshuichuan Formation feldspathic quartz sandstone and other minor Triassic sediments were deposited over older sedimentary rocks and the Heihaibei granites [24].…”

“…In recent years, the Kunlun River goldfield (KLRA) in the SKL has gradually become an important gold mineralization belt because more than 10 gold deposits or occurrences were discovered throughout this area (Figure 2), among which the Heihaibei gold deposit is the largest [22][23][24][25]. Thus far, few geologists have carried out geological research on the Heihaibei gold deposit or on other deposits in the KLRA.…”

“…Based on the geological characteristics and a few stable isotope compositions, some other gold deposits in the KLRA such as the Heihainan, Heicigou, and Dazaohuo gold deposits were also considered to belong to orogenic gold deposits [28,29] or altered-rocktype gold deposits [30], and the ore-forming fluids and materials were derived predominantly from metamorphic water and wall rocks, respectively [28,29]. However, Yu et al (2022) argued that the Heihaibei gold deposit was a granitic intrusion-related gold deposit rather than an orogenic gold deposit, and the ore-forming fluids and materials were derived from a magmatic hydrothermal source that was closely related to the Heihaibei granites, according to their three sets of H, O, S, and Pb isotope compositions [23]. In a word, the origins of the ore-forming fluids, sources of metals, and genetic types responsible for the Heihaibei gold deposit or other gold mineralization in the Kunlunhe River area [21]; (b) schematic geological map of the EKO, simplified and modified after [2].…”