Physicochemical conditions governing the formation of gold deposits along the southern margin of the North China Craton: A case study from the Chen'er deposit

Abstract

The Chen'er gold deposit hosted in the Precambrian Taihua Supergroup metamorphic rocks is one of the typical gold deposits in the Xiaoqinling region along the southern margin of the North China Craton. The metallic mineral assemblage in this deposit includes sulfides, tellurides, native gold, electrum, and native bismuth. The telluride minerals are composed of calaverite, petzite, hessite, altaite, joseite; except for hessite and matildite, the other tellurides and native bismuth are first reported in this study. Fluid inclusion studies in the auriferous quartz reveal three types: aqueous, aqueous–carbonic, and carbonic inclusions. The homogenization temperatures range from 184 to 364°C, and salinities are in the range of 1.74‐ to 11.47‐wt.% NaCl equiv. At temperatures of 275°C, the logfTe2 and logfS2 of the fluid are estimated as −16.13 to −8.19 and −12.74 to −4.80, respectively, and at temperatures of 305°C, the pH and logfO2 of the fluid are estimated as 3.61 to 5.69 and −34.31 to −27.81, respectively. It is inferred that Au(HS)2− and Au(HS)0 are the predominant gold‐bearing complexes, and tellurium was transported as Te22−. Based on thermodynamic models of logfO2(g) versus pH, we suggest that the precipitations of native gold and electrum in the early and main mineralization stages are different, with the oxygen and hydrogen isotope values of auriferous quartz suggesting mixing of magmatic water with meteoric water.

Geochronology and fluid source constraints of the Songligou gold‐telluride deposit, western Henan Province, China: Analysis of genetic implications

“…Late Jurassic to Early Cretaceous granitoids, including the Huashani complex (132.0–127.6 Ma, Mao et al, ; Xiao et al, ), Wuzhangshan (157 ± 1 Ma, Mao et al, ), Banzhusi (129 ± 1 Ma, Liang et al, ) pluton, and many granitic dikes (Deng et al, ), intruded into the Taihua Supergroup and the Xiong'er Group. Among these granitoids, the Haoping intrusion (135.4–134.0 Ma, Mao et al, ; Li, ) is related to Pb–Zn mineralization (134.9 ± 0.8 Ma, Ye, ), while the Leimengou (131.0 ± 0.6 Ma, Cao et al, ) and Shiyaogou (134.3–132.8 Ma, Han et al, ) granitic rocks coincide with porphyry Mo mineralization (132.4 ± 1.9 Ma, Li et al, ; 135.2 ± 1.8 Ma, Gao et al, ).…”