Evolution of Pyrite Compositions at the Sizhuang Gold Deposit, Jiaodong Peninsula, Eastern China: Implications for the Genesis of Jiaodong-Type Orogenic Gold Mineralization

Abstract

Gold deposits in the Jiaodong Peninsula represent a primary gold resource in China and mostly exhibit similar ore-forming features related to sericite-quartz-pyrite alteration and other controls from (micro-)structural deformation. This study investigates the pyrite textures and trace elements in the Sizhuang gold deposit (>100 t Au) to document the key factors impacting on the genesis of the Jiaodong-type orogenic deposits. Three main types of pyrite are identified: (1) the first generation of pyrite (Py1) occurs as disseminated euhedral to subhedral grains in K-feldspar-albite-rutile-hematite and sericite alteration (stage 1), (2) Py2 as aggregates in quartz-sericite-pyrite altered rocks or quartz-pyrite veins (stage 2) can be subdivided into Py2a as irregular cores, Py2b as a zoned overgrowth on Py2a, and Py2c as overgrowth on early pyrite, and (3) Py3 as fine-grained crystals in siderite-polymetallic veins (stage 3). Primary gold at the Sizhuang deposit is coevally or slightly later deposited with Py2b, Py2c, and Py3. Laser ablation–inductively coupled plasma mass spectrometry (LA–ICP–MS) analyses show that the highest Co and Ni contents in Py1 and high but variable Co in Py2b favors the involvement of deep high-temperature magmatic waters at stage 1 and middle stage 2. The elevated As contents from Py2a to Py2c and depletion of trace elements (e.g., Co, Ni, As and Te) and high Au/Co, Cu/Ni, and As/Ni values in Py2a and Py3, combined with published H-O isotope data, imply a meteoric water ingress during stage 2–3. Thus, the fluid evolution at Sizhuang is a consequence of pulsed deep magmatic fluid release plus progressive meteoric fluid ingress. The rhythmic Co–As–Ni–Au bands of Py2b additionally suggest episodic changes in the composition of ore-forming fluids. Moreover, the sharp textural features (e.g., pyrite overgrowth on previously cataclastic crystals) of Py2 and As-Cu-rich and Co-poor bands in zoned Py2b probably also reflect rapid metal deposition and self-organization and subsequent mineral crystal growth due to the pressure release during phase separation in the Sizhuang deposit. Considering the significantly concentrated gold (>1300 t) in the regional Jiaojia fault zone and Au-bearing mineral formation related to phase separation (boiling) in the Sizhuang deposit, gold mineralization in the Sizhuang deposit was interpreted to be controlled by the pressure-driver owing to the seismic activities in the Jiaojia fault system.

Three-Dimensional Mineral Prospectivity Modeling with the Integration of Ore-Forming Computational Simulation in the Xiadian Gold Deposit, Eastern China

“…However, we noticed that non-ore units can also undergo similar, high temperature changes (Figure 10e,f). Thus, gold-mineralization is most likely controlled by multiple factors at Xiadian, of which pressure fluctuation and water-rock interaction (i.e., sulfidation) have been recognized as important ore-forming mechanisms [57,63,65,66,101].…”

“…This research aims to provide a new way to uncover more predictor variables for 3D MPM, gain new insights into the controls on gold mineralization, and identify mineral resources responsibly and efficiently. [57,63]).…”

“…(a) Schematic map showing the position of the North China Craton. (b) Geological map of the Northwestern Jiaodong Peninsula (Modified from[57,63]).…”

Computational simulation of the ore-forming processes associated with the Sanshandao-Haiyu gold belt, Jiaodong Peninsula, eastern China: implications for the duration of ore formation

“…The Jiaodong Peninsula in the eastern North China Craton (NCC; Figure 1A) hosts more than 5,000 t gold resources and has been documented as the third largest gold province in the world (Song et al, 2015;Groves et al, 2018;Deng et al, 2020;Liu et al, 2021a). The formation of the deposits happens at a time of 120 ± 5 Ma in a craton reworking setting and is linked to structuralmagmatic-hydrothermal processes that involve moderate temperature gold-bearing fluids ascending, pooling, and reacting with wall rocks (Fan et al, 2003;Song et al, 2015;Zhang et al, 2020;Liu et al, 2021b). Fracture zones due to structural activities are critical to the gold mineralizing processes by increasing permeability and pore-fluid conduits that focus pore-fluids into favorable sites, facilitating the fluid-wall rock interaction for gold deposition at Jiaodong (Chen et al, 2004;Song et al, 2012;Mao et al, 2019;Wang et al, 2019;Liu et al, 2021c).…”

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

“…The margin of the craton is often abnormally rich in gold, molybdenum, and rare earth element (REE) deposits [1][2][3][4]. Several large-scale Au mineralization provinces formed around the NCC destruction zone during the Mesozoic, such as the Jiaodong, Xiaoqinling, Liaodong, and Jidong mineralization provinces [2,[5][6][7][8][9][10][11].…”