Abstract
The Huayangchuan ore belt is located in the western segment of Xiaoqinling Orogen in the southern margin of the North China Craton (NCC), and hosts voluminous magmatism and significant U−REE−Mo−Cu−Fe polymetallic mineralization. However, geochronological framework of the various mineralization phases in this region is poorly understood. Here, we present new Re−Os isochron ages on magnetite from the Caotan Fe deposit (2 675 ± 410 Ma, MSWD = 0.55), and on pyrite from the Jialu REE deposit (2 127 ± 280 Ma, MSWD = 1.9) and Yuejiawa Cu deposit (418 ± 23 Ma, MSWD = 11.5), and Re−Os weighted average model age on pyrite from the Taoyuan Mo−U deposit (235 ± 14 Ma, MSWD = 0.17). These ages, combined with regional geology and mineralization ages from other deposits, suggest that mineralization in the Huayangchuan ore belt lasted from the Neoarchean to the Late Mesozoic. The mineralization corresponds to regional tectono-magmatic events, including the Neoar-chean alkali magmatism (REE mineralization), Paleoproterozoic plagioclase-amphibolite emplacement (Fe mineralization), Paleoproterozoic pegmatite magmatism (U mineralization), Paleozoic Shangdan oceanic slab subduction-related arc magmatism (Cu mineralization), Early Mesozoic Paleo-Tethys Ocean subduction-related arc magmatism (Mo−U mineralization), and Late Mesozoic Paleo-Pacific oceanic plate subduction direction change-related Mo(-Pb) mineralization. We proposed that the Huayang-chuan ore belt has undergone prolonged metallogenic evolution, and the magmatism and associated mineralization were controlled by regional geodynamic events.
Highlights
We summarize the geological informa‐ tion of various deposits in the Huayangchuan ore belt, most of which being firstly documented in this study, and present new Re-Os isotopic ages of pyrite and magnetite in these deposits
REE deposits, we infer that the Jialu REE mineralization occurred at ca. 2 675 Model age (Ma)
This Neoarchean ore-forming age at Jialu is broadly co‐ eval with the widespread TTG magmatism in the Xiaoqinling District (Jia, 2016), which were mainly derived from the juvenile crust source and represent the MesoNeoarchean North China Craton (NCC) crustal growth (Jia et al, 2020; Diwu et al, 2018)
Summary
The Caotan Fe deposit is hosted in the Taihua Group (up‐ per part) hornblende plagiogneiss, and the orebodies are often lenticular-shaped (Fig. 2b). Major metallic minerals in‐ clude magnetite with accessory chalcopyrite and pyrite, whilst non-metallic minerals include mainly calcite, tremolite, musco‐ vite, chlorite Calcite + pyrite + chalcopyrite veins crosscut the magnetite (Fig. 3e) and ilmenite crystalized from magnetite (Fig. 3f). Mineralization at Yuejiawa occurred mainly in quartzsulfide veins and minor in granitic veinlets and cataclastic gneiss, which is strictly controlled by the NW-/NE-trending faults (Fig. 2c). Extensive hydrothermal alterations around the orebodies in‐ clude quartz, calcite, pyrite, epidote, sericite, and chlorite (Fig. 3g), with the former three being mineralization-related (Fig. 3h). Ore minerals comprise dominantly chalcopyrite (Fig. 3i) and minor bornite, with textures being anhedralsubhedral and poikilitic Euhedralsubhedral pyrite shows straight boundary with chalcopyrite (Fig. 3i), indicating that they were co-precipitated
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