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Application of the geochemical block method to the assessment of copper resources in Ethiopia |
XIANG Wen-Shuai1( ), BAI Yang2( ), JIANG Jun-Sheng1, LEI Yi-Jun1, HUNDIE Melka3, SISAY Degu3, ZHANG Yuan-Pei2, WU Ying2, ZHENG Xiong-Wei2 |
1. Wuhan Center, China Geological Survey,Central South China Innovation Center for Geosciences, Wuhan 430205, China 2. Geophysical Exploration Brigade, Hubei Geological Bureau, Wuhan 430056, China 3. Ethiopian Geological Survey, Addis Ababa 999047, Ethiopia |
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Abstract Low-density geochemical mapping is characterized by high order streams to be sampled and a large coverage area and can be used to effectively trace geochemical blocks with high metal contents. Based on the 1:1,000,000 low-density geochemical mapping data of Ethiopia and the processing of the testing data of Cu in the original stream sediments, this study calculated the anomaly threshold of Cu at 37×10-6 through iterative deletion. Then, this study delineated three geochemical blocks and two regional anomalies with 37×10-6, 42×10-6, 47×10-6, 52×10-6, 59×10-6, and 66×10-6 as grading intervals. It calculated the mineralization coefficient of Cu ore bodies in the study area at 0.055% by referencing the known reserves of Cu deposits in geochemical blocks with a high level of copper exploration in the same metallogenic belt. Moreover, this study estimated the Cu resources in the study area at 2,600,000 t based on a rock mass thickness of 1,000 m. By combining the analysis of metallogenic geological conditions, this study determined that the zones where geochemical blocks nos. 2, 3, and 4 are located can be considered key metallogenic prospect areas for further detailed exploration.
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Received: 19 April 2022
Published: 11 October 2023
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15]) ">
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Brief geologyand sample point map of Ethiopia-Eritrea(revised according to reference [15])
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Brief geology and mineral map of Eritrea-North Ethiopia(revised according to reference [20])
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元素 | 数据量 | 最小值/10-6 | 最大值/10-6 | 四分位值/10-6 | 平均值/10-6 | 标准差/10-6 | 25% | 50% | 75% | Cu | 839 | 1.9 | 137.4 | 12.7 | 20.5 | 31.4 | 25.1 | 17.7 | 元素 | 剔除3倍离差后 | 浓度分带/10-6 | 平均值/10-6 | 标准差/10-6 | 1级 | 2级 | 3级 | 4级 | 5级 | 6级 | Cu | 22.9 | 14.1 | 37 | 42 | 47 | 52 | 59 | 66 |
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Processed geochemical statistic characteristics of copper and content level of the geochemical blocks
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Distribution of copper geochemical blocks and regional anomalies in study area
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Internal structure of No.2 copper geochemical block (a~f is first to sixth level content, including 1,1,4,4,4,4 child geochemical blocks respectively)
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Internal structure and Family tree diagram of No.1 copper geochemical block (a~d is first to fourth level content,includig 1,4,1,1 child geochemical blocks respectively)
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No.2 geochemical block and brief regional geology and mineral map
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编号 | 面积/ km2 | Cu最大 值/10-6 | Cu最小 值/10-6 | Cu平均 值/10-6 | Cu供应 量/万t | 1 | 3424 | 89.4 | 18.3 | 51.8(n=20) | 47711 | 2 | 19009 | 137.4 | 23.6 | 55(n=53) | 281238 | 3 | 9529 | 88.4 | 18.4 | 47.3(n=19) | 121244 | 4 | 2592 | 78.2 | 40.8 | 63.5(n=7) | 44275 |
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Statistic characteristic of copper geochemical blocks
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编号 | Cu面积/ km2 | Cu最大 值/10-6 | Cu最小 值/10-6 | 平均值/ 10-6 | Cu供应 量/万t | I | 458 | 76.7 | 48.7 | 62.7(n=2) | 7725 | II | 359 | 66.9 | 43.1 | 53.9(n=4) | 5205 |
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Statistic characteristic of copper regional geochemical anomalies
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编号 | 面积/ km2 | 矿床 | Cu供应 量/万t | 探明 Cu资源 量/万t | 预测 Cu资源 量/万t | 1 | 3424 | Emba Derho铜矿、Debarwa铜矿、Adi Nefas铜矿 | 47711 | 52 | 52 | 2 | 19009 | Adyabo铜矿、Harves铜矿、Shire铜矿、North Ethiopia铜矿、Shehagne铜矿 | 281238 | | 155 | 3 | 9529 | Tigray-Afar铜矿 | 121244 | | 67 | 4 | 2592 | | 44275 | | 24 | I | 458 | | 7725 | | 8 | II | 359 | | 5205 | | 6 | 总计 | 35371 | | 507398 | | 312 |
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Estimated potential copper resources of copper geochemical blocks and regional anomalies
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No.3 geochemical block and brief regional geology and mineral map
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