Lithogeochemistry of various hydrothermal alteration types associated with precious and base metal epithermal deposits in the Tarom-Hashtjin metallogenic province, NW Iran: Implications for regional exploration
| Autor: | David R. Lentz, Majid Ghasemi Siani |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
geography
Mineralization (geology) geography.geographical_feature_category 010504 meteorology & atmospheric sciences Geochemistry Propylitic alteration Silicic 010502 geochemistry & geophysics Sericite 01 natural sciences Volcanic rock Petrography chemistry.chemical_compound chemistry Geochemistry and Petrology Economic Geology Mafic Chlorite Geology 0105 earth and related environmental sciences |
| Zdroj: | Journal of Geochemical Exploration. 232:106903 |
| ISSN: | 0375-6742 |
| DOI: | 10.1016/j.gexplo.2021.106903 |
| Popis: | In this study, the styles, types, and degrees of hydrothermal alteration associated with Pb-Zn-Cu-Ag-Au epithermal deposit systems in the Tarom-Hashtjin metallogenic province are evaluated using petrographic studies, as well as mass changes and molar elements ratios (MER), in order to examine regional exploration implications. The MER plots show that the hydrothermally altered rocks were most affected by various types of K-metasomatism, mainly characterized by K gains and Na and Ca losses. The intensity of K-metasomatism is related to precious and base-metal mineralization, showing increasing K trends toward the ore veins. The alteration index (AI) and chlorite-carbonate-pyrite index (CCPI) reveal that argillic, sericitic, and propylitic alteration types are the main zones of alteration surrounding ore veins indicating that AI increases and CCPI decreases toward more proximal to the structures linked to these ore systems. Determination of mass changes in altered rocks surrounding selected epithermal deposits suggest Si, K, and Al gains and Na and Ca losses increasing in intensity toward ore veins, consistent with alteration zoning from the silicic and K-metasomatic (sericite and argillic) inner zones to the propylitic (Fe-rich chlorite alteration) outer zone typical of epithermal ore systems. Data from this study show that the intensity of K-metasomatism in the acidic rocks is greater than in the intermediate and mafic rocks, where it is related to high to intermediate sulfidation epithermal systems. We suggest that exploration can be focused on highly altered volcanic rocks (especially andesite-dacite) with both high intensity of K-metasomatism and higher Pb, Zn, Ag, Au, Ba and Rb and lower Sr. |
| Databáze: | OpenAIRE |
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