Formation of the Miaoan Au-Polymetallic Deposit in the Northern Taihang Mountain, North China Craton: Ore Geology, Geochronological and Geochemical Perspectives

Abstract

Several gold ore-concentrated areas have been recognized in the destruction zone of the North China Craton (NCC). However, the deposits in the western part of the destruction zone have received less attention. Miaoan, a typical Au-polymetallic deposit in the northern Taihang Mountain, provides a good sample for deepening our understanding of the genesis of gold deposits in the western destruction zone. In this study, detailed ore geology, pyrite Rb-Sr age, trace element and S-C-O isotopes of Au-bearing ores were conducted to constrain the source of ore-forming materials and their tectonic setting. The pyrites obtain an Rb-Sr isochron age of 129.5 ± 2.5 Ma, consistent with those of magmatic rocks in this deposit, suggesting their genetic relationship. The δ34S values ranging from −5.5‰ to 1.6‰ and the high Co/Ni and Y/Ho ratios of pyrites indicate the mantle-crust mixing characteristics of ore-forming fluids. The δ13C (−6.3‰ to −2.0‰) and δ18O (9.3‰ to 17.6‰) values of Au-bearing ores and calcites suggest mixing characteristics as well. Geochronologically, the Miaoan Au-polymetallic deposit was formed during the destruction of the NCC. We propose that the Miaoan Au-polymetallic deposit is a decratonic gold deposit and that its ore-forming materials have a mixed source of mantle and crust.

Geology and Geochronology of Magmatic–Hydrothermal Breccia Pipes in the Yixingzhai Gold Deposit: Implications for Ore Genesis and Regional Exploration

“…Many porphyry Cu-Mo deposits, skarn Fe-Au deposits, and lode Au deposits formed within or around these early Cretaceous intrusions (Figure 1b). Previous molybdenite Re-Os, garnet U-Pb, titanite U-Pb, and phlogopite 40 Ar/ 39 Ar geochronological studies revealed that the mineralization formed in the period of 140-130 Ma, concurrent with the early Cretaceous intrusions [17,18,21,[30][31][32]. Numerous breccia pipes have been identified in the CTD [15].…”