Lithogeochemistry of Intrusive Rocks in the Halo Porphyry Copper-Molybdenum Prospect, Northeast Cambodia  

作　　者：Seang Sirisokha Kotaro Yonezu Thomas Tindell Tetsuya Nakanishi Koichiro Watanabe Jocelyn Pelletier 

机构地区：[1]Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan [2]Department of Geo-Resources and Geotechnical Engineering, Institute of Technology of Cambodia, Phnom Penh, Cambodia [3]Kyushu University Museum, Kyushu University, Fukuoka, Japan [4]Geology Resources Department, Geoccop, Montreal, Canada

出　　处：《Open Journal of Geology》2019年第7期342-363,共22页地质学期刊（英文）

摘　　要：The Halo copper-molybdenum prospect is a porphyry system in Ratanakiri province, northeastern part of Cambodia. There is only one research was carried out on this prospect about geological mapping and short wave infrared (SWIR) spectroscopy on alteration mineral identification. The purpose of this research is to confirm the deposit type from previous Angkor Gold’s report and find the centre of porphyry deposit based on characteristic of intrusive rocks at surface and subsurface, characteristics of the intrusive rocks and alteration lithogeochemistry of intrusive and volcanic rocks by using Pearce Element Ratio (PER) analysis. PER analysis was used to examine the nature and extend of the alteration halos in the porphyry Halo copper-molybdenum prospect. The intrusive rocks and volcanic rocks in Halo, range from diorite to granite (quartz feldspar porphyry) in composition as well as dacite to trachyandesite (andesite porphyry) in composition, respectively. They were formed in a subduction-related tectonic setting, likely a volcanic arc. Trace elements spider diagrams were normalized to primitive mantle display strong enrichment in large-ion lithophile elements such as Rb, Ba and K and depletion in some high-field strength elements such as Nb and Ti, suggesting magmas generated in a subduction-related tectonic setting. PER analysis indicates a moderate to high degree of sericite alteration of dacites, quartz feldspar porphyries, andesite porphyries and granodiorite porphyries. Moreover, three alterations in the Halo prospect such as potassic (secondary K-feldspar and biotite), phyllic (sericite) and propylitic (epidote) alteration were identified, which are consistent with petrography analysis. The potassic alteration zone is vectoring center of the hydrothermal system which may represent the locus of mineralization. Therefore the geochemical signature of potassic alteration within the quartz feldspar porphyry, andesite porphyry and granodiorite porphyry with high grad of copper ranges up to 2670 ppm and molybdenumThe Halo copper-molybdenum prospect is a porphyry system in Ratanakiri province, northeastern part of Cambodia. There is only one research was carried out on this prospect about geological mapping and short wave infrared (SWIR) spectroscopy on alteration mineral identification. The purpose of this research is to confirm the deposit type from previous Angkor Gold’s report and find the centre of porphyry deposit based on characteristic of intrusive rocks at surface and subsurface, characteristics of the intrusive rocks and alteration lithogeochemistry of intrusive and volcanic rocks by using Pearce Element Ratio (PER) analysis. PER analysis was used to examine the nature and extend of the alteration halos in the porphyry Halo copper-molybdenum prospect. The intrusive rocks and volcanic rocks in Halo, range from diorite to granite (quartz feldspar porphyry) in composition as well as dacite to trachyandesite (andesite porphyry) in composition, respectively. They were formed in a subduction-related tectonic setting, likely a volcanic arc. Trace elements spider diagrams were normalized to primitive mantle display strong enrichment in large-ion lithophile elements such as Rb, Ba and K and depletion in some high-field strength elements such as Nb and Ti, suggesting magmas generated in a subduction-related tectonic setting. PER analysis indicates a moderate to high degree of sericite alteration of dacites, quartz feldspar porphyries, andesite porphyries and granodiorite porphyries. Moreover, three alterations in the Halo prospect such as potassic (secondary K-feldspar and biotite), phyllic (sericite) and propylitic (epidote) alteration were identified, which are consistent with petrography analysis. The potassic alteration zone is vectoring center of the hydrothermal system which may represent the locus of mineralization. Therefore the geochemical signature of potassic alteration within the quartz feldspar porphyry, andesite porphyry and granodiorite porphyry with high grad of copper ranges up to 2670 ppm and molybdenum

关 键 词：Cambodia Hydrothermal Alteration HALO PORPHYRY Copper-Molybdenite Deposit Pearce Element Ratio Analysis 

分 类 号：P5[天文地球—地质学]