Research on Metallogenic System and Deposit Genesis: With Zhacun Goldmine in Weishan County of Yunnan as an Example

Abstract

This paper mainly takes Zhacun goldmine as the research object and carries out research on the metallogenic system and genesis of the deposit in the area. The research methods are as follows: according to the geological characteristics of the metallogenic mining area in the Zhacun goldmine, combined with the comparative analysis of the metallogenic age, alteration characteristics and lithology between the Zhacun goldmine and the Lianhuashan alkali rich rock mass, and the analysis of the isotopic data in the Zhacun goldmine, this paper demonstrates that the magmatic activity of the Lianhuashan quartz monzonite porphyry plays an important role in the mineralization of this area, which is both an important ore source and fluid source. It is also the main heat source driving the circulation of ore-forming fluid. On this basis, through the analysis of the metallogenic elements in the area, the metallogenic system model of Zhacun goldmine is constructed. It is considered that under the action of long-term horizontal compressive stress, the atmospheric precipitation infiltrated into the formation continued to penetrate along the fractures and fissures to deep crust and finally mixed with the magmatic water sealed in the thick formation. During this period, a series of shallow and ultrashallow porphyry mass intruded, providing heat source and part of the ore-forming materials and resulting in incomplete homogenization under high temperature and high pressure, which formed highly mineralized mixed water. Under the combined action of long-term compressive stress and various deep thermal dynamics, these mineral fluids migrated along the buried deep faults near the core of the duplex anticline to the upper part of the crust. When the metal elements in these ore fluids migrated over long distances to the nappe fault zone of the gold-bearing fracture zone, the gold began to precipitate, and the native gold and the coarse-grained pyrite and quartz formed at the same time or earlier started to fill the fracture zone along the fissures and accumulate into minerals. Then, through the analysis of metallogenic conditions, gold mineralization process, and genetic mechanism of the deposit, it is proposed that the genetic type of the ore deposit in this area is magmatic mesothermal-epithermal gold deposit. The establishment of metallogenic system model in Zhacun goldmine will provide theoretical and practical guidance for deep and peripheral prospecting prediction in the area, carry out targeted and reasonable prediction, and improve prospecting effectiveness.

Thermophysical Dynamics of Ore-forming Fluids in Heat Ore Deposits: Implications for Ore-formation Processes

“…Extensive explorations, spearheaded by institutions such as the Yunnan Provincial Geological Bureau, Dali Prefecture Geological Bureau, and the Third Geological Brigade, have been conducted since 1960. Between 1960 and 1971, the Shanghuangshan gold-heavy concentrate anomaly area was demarcated, laying the groundwork for gold prospecting in the Yanzijiao-Shanghuangshan vicinity [21]. Subsequent investigations, spanning from 1984 to 1990, illuminated the ore-controlling structure within the Deposit, elucidating aspects such as distribution range, scale, and morphology of the gold-bearing fracture zone.…”

“…Such insights have unequivocally influenced subsequent exploration strategies. Nevertheless, a more intricate understanding remains to be pursued, especially concerning the interplay between ore-forming effects and intrusive rocks, potential concealed rock masses in deeper strata, and the oreforming system at large [21].…”

“…Therefore, this group of faults is the main ore guiding and hosting structure in the Deposit, and provides a good channel and storage space for ore-containing hydrothermal solutions in the Deposit. Figure 1 shows the remote sensing mineral geological characteristics and near-ore and prospecting indicators in the Zhacun Gold Deposit [22]. Construction of a solute diffusion equation aimed to accurately describe how solutes in ore-forming fluids in heat ore deposits were distributed over time and space, which is crucial for better understanding and predicting deposit formation.…”