伊犁京希—伊尔曼德金矿床的热液蚀变及成矿流体演化特征

Translated title of the contribution: Hydrothermal alteration and ore-forming fluid evolution of the Jingxi-Yelmend gold deposit, Xinjiang, China

L. Xiao*, F. Wang, M. Fu, G. Begg, N. Hayward

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Spatial zonal features show well in the hydrothermal alteration distribution of the Jingxi-Yelmend gold prospect. The central zone is characterized by intense silicification with a quartz/chalcedony-dickite assemblage. The intermediate zone shows advanced argillic alteration with a dickite-kaolinite-quartz/chalcedony-semectite assemblage. The outer zone is characterized by an argillic alteration assemblage of kaolinite-illite. Such zonation is a reflection of temperature, pressure and chemical gradients, suggesting there is continuous fluid/rock reaction. The fluid inclusions indicate that the fluids related to the alteration and mineralization have temperatures generally between 180∼270°C and relatively low salinity (Max. 5. 3 wt% NaCl equiv.). The evolution of the ore fluids has undergone three stages: (1) Early-stage acidic (pH=2~4) ore fluids were buffered by fluid in neutral limestones while flowing upward along steep faults and the pH values were slightly increased. (2) The pH value was increased to 3~5 when the ore fluids reached highly permeable epiclastic rocks (conglomerate and conglomeratic sandstone) and rapidly reacted with the country rocks, particularly with the assistance of in-charging meteoric water. In this stage, the composition, temperature and pH values were changed and the physicochemical gradients were generated. Highly concentrated residual SiO2 and most acidic (pH<3) fluids were retained in the central part of the fluid-flowing zone, where vuggy quartz (acidic leaching) and dickite occurred while the marginal parts have relatively high pH values and intermediate-argillic alteration was developed. With the decreasing of temperature and pressure (boiling), and increasing of oxidation for the ore fluids, the alteration zonation was formed and gold was deposited.

Translated title of the contributionHydrothermal alteration and ore-forming fluid evolution of the Jingxi-Yelmend gold deposit, Xinjiang, China
Original languageChinese
Pages (from-to)518-526
Number of pages9
JournalActa Geologica Sinica
Volume75
Issue number4
Publication statusPublished - 2001
Externally publishedYes

Keywords

  • Advanced argillization
  • Fluid/rock reaction
  • Gold deposit
  • High sulphidation
  • Hydrothermal alterations
  • Jingxi-Yelmend
  • Ore fluid evolution

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