Quartz Rb-Sr Isochron Ages of Two Type Orebodies from the Nibao Carlin-Type Gold Deposit, Guizhou, China

Abstract

The Nibao gold deposit, which includes both fault-controlled and strata-bound gold orebodies, constitutes an important part of the Yunnan–Guizhou–Guangxi “Golden Triangle” region. Defining the mineralization age of these gold orebodies may provide additional evidence for constraining the formation ages of low-temperature orebodies and their metallogenic distribution in South China. Petrographic studies of gold-bearing pyrites and ore-related quartz veins indicate that these pyrites coexist with quartz or filled in vein-like quartz, which suggests a possible genetic relationship between the two from Nibao gold deposit. Minerals chemistry shows that Rb and Sr are usually hosted in fluid inclusions in quartz ranging from 0.0786 to 2.0760 ppm and 0.1703 to 2.1820 ppm, respectively. The Rb–Sr isotopic composition of gold-bearing quartz-hosted fluid inclusions from the Nibao gold deposit were found to have Rb–Sr isochron ages of 142 ± 3 and 141 ± 2 Ma for both fault-controlled and strata-bound orebodies, respectively, adding more evidence to previous studies and thus revealing a regional gold mineralization age of 148–134 Ma. These results also confirm the Middle-Late Yanshanian mineralizing events of Carlin-type gold deposits in Yunnan, Guizhou, and Guangxi Provinces of Southwest China. In addition, previous studies indicated that antimony deposits in the region which were formed at ca. 148–126 Ma have a close affinity with gold deposits. This illustrates that the regional low-temperature hydrothermal gold mineralization is related in space and time to the Yanshanian (ca. 146–115 Ma) magmatic activity. Specifically, the large-scale gold and antimony mineralization are considered to be inherently related to mantle-derived mafic and ultramafic magmatic rocks associated with an extensional tectonic environment. Based on the initial 87Sr/86Sr ratios of 0.70844 ± 0.00022 (2σ) and 0.70862 ± 0.00020 (2σ) for gold-bearing quartz veins from fault-controlled and strata-bound gold orebodies, respectively, at the Nibao gold deposit, as well as the C, H, O, and S isotopic characteristics of gold deposits located in the Golden Triangle region, we suggest that the mantle-derived material can be involved in the formation of the Nibao gold deposit and that the ore-forming fluid can be derived from a mixed crust–mantle source.

Sm–Nd Isochron Age Constraints of Au and Sb Mineralization in Southwestern Guizhou Province, China

“…Youjiang Basin was then uplifted by the Indosinian orogeny at the end of the Late Tri and, subsequently, folded by the Yanshanian orogeny after the Early Jurassic [35,36] Southwestern Guizhou (Figure 2), situated north of the Youjiang Basin (Figure contains several super-large or large Au (e.g., Shuiyindong, Lannigou, Zimudang Getang) and Sb (e.g., Qinglong and Dachang) deposits. These deposits are thought to formed during a low-temperature hydrothermal metallogenic event [1,5,17,37], wher Au and Sb orebodies were primarily controlled by short-axis anticlines (domes) associated fracture zones (Figure 2). The majority of the exposed strata in this regio Devonian to Triassic, with the Triassic system being distributed most widely, which followed by the Permian, while the Devonian and Carboniferous are sporadically exp at some cores of anticlines or domes.…”

“…Th and Sb mineralization occurs primarily in the SBT and the Upper Permian to L Triassic systems. The Zimudang large Au deposit, with a total Au reserve of over 72 tons [17], is located west of the Huijiabao anticline. The Au orebodies tend to be found in silicified brecciated argillite and limestone of the SBT and in bioclastic limestone, siltstones, and claystone of the Upper Permian and Lower Triassic (Figure 3a,b).…”

Editorial for Special Issue: “Mineralogy of Noble Metals and “Invisible” Speciations of These Elements in Natural Systems”

“…The last part of the issue includes two articles [19,20] devoted to the study of ages of gold deposits in China: Nibao and Chaoyangzhai (Southeast Guizhou). These deposits are an important part of the Yunnan-Guizhou-Guangxi "Golden Triangle" region.…”

“…These deposits are an important part of the Yunnan-Guizhou-Guangxi "Golden Triangle" region. Zheng, Tsang and coauthors [19,20] also discussed possible sources of gold mineralization.…”

“…The Nibao gold deposit includes both fault-controlled and strata-bound gold orebodies. Zheng and coauthors [19] determined the mineralization age of these gold orebodies and provided additional evidence for constraining the formation ages of low-temperature orebodies and their metallogenic distribution in South China. The results confirm the Middle-Late Yanshanian mineralizing events of the Carlin-type gold deposits in Yunnan, Guizhou, and Guangxi Provinces of Southwest China.…”