TY - JOUR

T1 - Metal source and ore precipitation mechanism of the Ashawayi orogenic gold deposit, southwestern Tianshan Orogen, western China

T2 - Constraints from textures and trace elements in pyrite

AU - Zhou, Zhenju

AU - Chen, Zhengle

AU - Weyer, Stefan

AU - Horn, Ingo

AU - Huo, Hailong

AU - Zhang, Wengao

AU - Li, Nuo

AU - Zhang, Qing

AU - Han, Fengbin

AU - Feng, Hongye

N1 - Funding Information: We are grateful to Prof. Chao Zhang and Dr. Wei Xi for helping with the laboratory work, as well as Drs. Xiaohu Wang, Tao Zhang, Ji Ma and Bin Yang for helping with the field investigation. We thank Thomas Ulrich and an anonymous reviewer for their insightful comments and detailed reviews, which improved the quality of this manuscript. We acknowledge Editor Huayong Chen for his very helpful suggestions and efficient handling. This work was jointly supported by the National Natural Science Foundation of China (42172093, 42172258, U1803242 and 41772085), and the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (2021YFC2901904, 2018YFC0604005 and 2015BAB05B04). Funding Information: We are grateful to Prof. Chao Zhang and Dr. Wei Xi for helping with the laboratory work, as well as Drs. Xiaohu Wang, Tao Zhang, Ji Ma and Bin Yang for helping with the field investigation. We thank Thomas Ulrich and an anonymous reviewer for their insightful comments and detailed reviews, which improved the quality of this manuscript. We acknowledge Editor Huayong Chen for his very helpful suggestions and efficient handling. This work was jointly supported by the National Natural Science Foundation of China (42172093, 42172258, U1803242 and 41772085), and the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (2021YFC2901904, 2018YFC0604005 and 2015BAB05B04).

PY - 2023/6

Y1 - 2023/6

N2 - The metal source and ore precipitation mechanism of orogenic gold mineralization are not yet well understood, partly because ore metals may be derived from different sources. Pyrite is a dominant Au-hosting mineral in the Ashawayi orogenic gold deposit in the southwestern Tianshan orogen, western China. Petrographic features of pyrite in host rocks and orebodies define four generations: diagenetic preore (Py1), hydrothermal early-ore (Py2), main-ore (Py3), and late-ore (Py4) pyrites. Trace element abundances were analyzed in situ by femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICP-MS) to unravel the pyrite formation history. Preore Py1 contains the lowest Cu, Mo, Se, Au and As contents, consistent with a diagenetic origin. Py2 has higher Au and As contents than Py1 and may have formed by the reaction between hydrothermal fluid and preexisting Py1, as indicated by diagenetic pyrite-like As/Ni and Bi/Au ratios but lower hydrothermal pyrite-like Sb/Au ratios in Py2. Hydrothermal pyrite (Py3) contains more abundant As (1723–65182 ppm) and Au (0.32–107 ppm) but lower Co and Ni contents than Py2, suggesting a greater hydrothermal fluid contribution. Oscillatory zoning and abundant mineral inclusions (e.g., arsenopyrite and chalcopyrite) in porous Py3 indicate that fluid boiling was responsible for gold deposition during the main-ore stage. Py4 is a relict of hydrothermal pyrite (Py3) but not diagenetic pyrite, as supported by Py4 and Py3 clustering into a class based on hierarchical cluster analysis. The application of a machine learning method (i.e., artificial neural network) to the syn-ore pyrite indicates that the Ashawayi gold deposit has affinity to those from orogenic-type gold deposits worldwide. Our study, therefore, highlights that ore metals in orogenic gold deposits may originate from different sources, such as Au and As, which are largely sourced from metamorphic fluids, while Co and Ni are mainly released from preore sedimentary pyrite, fluid boiling and fluid-rock interaction triggered precipitation of Au and other metals.

AB - The metal source and ore precipitation mechanism of orogenic gold mineralization are not yet well understood, partly because ore metals may be derived from different sources. Pyrite is a dominant Au-hosting mineral in the Ashawayi orogenic gold deposit in the southwestern Tianshan orogen, western China. Petrographic features of pyrite in host rocks and orebodies define four generations: diagenetic preore (Py1), hydrothermal early-ore (Py2), main-ore (Py3), and late-ore (Py4) pyrites. Trace element abundances were analyzed in situ by femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICP-MS) to unravel the pyrite formation history. Preore Py1 contains the lowest Cu, Mo, Se, Au and As contents, consistent with a diagenetic origin. Py2 has higher Au and As contents than Py1 and may have formed by the reaction between hydrothermal fluid and preexisting Py1, as indicated by diagenetic pyrite-like As/Ni and Bi/Au ratios but lower hydrothermal pyrite-like Sb/Au ratios in Py2. Hydrothermal pyrite (Py3) contains more abundant As (1723–65182 ppm) and Au (0.32–107 ppm) but lower Co and Ni contents than Py2, suggesting a greater hydrothermal fluid contribution. Oscillatory zoning and abundant mineral inclusions (e.g., arsenopyrite and chalcopyrite) in porous Py3 indicate that fluid boiling was responsible for gold deposition during the main-ore stage. Py4 is a relict of hydrothermal pyrite (Py3) but not diagenetic pyrite, as supported by Py4 and Py3 clustering into a class based on hierarchical cluster analysis. The application of a machine learning method (i.e., artificial neural network) to the syn-ore pyrite indicates that the Ashawayi gold deposit has affinity to those from orogenic-type gold deposits worldwide. Our study, therefore, highlights that ore metals in orogenic gold deposits may originate from different sources, such as Au and As, which are largely sourced from metamorphic fluids, while Co and Ni are mainly released from preore sedimentary pyrite, fluid boiling and fluid-rock interaction triggered precipitation of Au and other metals.

KW - Ashawayi (W China)

KW - Orogenic gold deposit

KW - Pyrite

KW - Southwestern Tianshan

KW - Trace elements

UR - http://www.scopus.com/inward/record.url?scp=85156119702&partnerID=8YFLogxK

U2 - 10.1016/j.oregeorev.2023.105452

DO - 10.1016/j.oregeorev.2023.105452

M3 - Article

AN - SCOPUS:85156119702

VL - 157

JO - Ore geology reviews

JF - Ore geology reviews

SN - 0169-1368

M1 - 105452

ER -