Multi-element association analysis of stream sediment geochemistry data for predicting gold deposits in Barramiya gold mine, Eastern Desert, Egypt

详细信息	查看全文 | 推荐本文 |

• 作者：Hassan Z. Harraz^a ; ^{hharraz2006@yahoo.com} ; Mohamed M. Hamdy^a ; Mohamed H. El-Mamoney^b
• 关键词：Surficial dispersion of Au ; Stream sediment survey ; R-mode factor analysis ; Principal component analysis ; Multi-element association geochemistry ; Gold
• 刊名：Journal of African Earth Sciences
• 出版年：2012
• 期刊代码：4_1464343X
• 类别：ear
• 出版时间：15 June, 2012
• 卷：68
• 期：Complete
• 页码：1-14
• 文件大小：2336 K

摘要

The use of traditional statistical methods can provide suitable indicators of geochemical element dispersion, and aids in targeting potential areas for mineral exploration. Analyzes of stream sediments from an ophiolite suite of ophiolitic m茅lange matrix and metasediments belt are used for regional geochemical prospecting of gold in the Barramiya mining district, Eastern Desert, Egypt. The principal rocks exposed in the study area are Late-Proterozoic volcano-sedimentary sequences intruded by serpentinite, small bodies of Older and Younger Granitoids, all injected by dykes of various compositions. Gold production derived mainly from shear zone with Au-bearing quartz veins hosted by ultramafic schists and serpentinites at fault intersections or along the basal d茅collement of the major thrusts, especially where granitoid massifs and stocks are common. Orebodies are mainly sulfide-bearing quartz and quartz-carbonate lodes associated with graphite-schist, listvenite and marble exposures, showing signs of structural control expressed in preferable orientation and consistent meso- and microfabrics. The area has two known gold deposits where several chromite mines are present. Auriferous veins are confined along E and ENE fracture systems and zones in a passive tectonic contact between the serpentinites and the metasediments.

Results of 425 stream sediment samples from an area of 鈭?3 km² analyzed for 13 trace elements are presented using simple statistical and R-mode factor methods. The overall sample density achieved by the survey is 鈭? samples/km². Significant variations in background metal contents are recorded near the known mineralized sites. Preliminary visual interpretation of individual spatial distribution patterns of Ag, As, Au, Cu, Mo, Pb, and W show clear-cut relationships with known gold mineralization in the study area. Geochemical patterns of these elements delineate drainage basins with anomalous concentration of elements genetically related to gold mineralization. Gold in analyzed samples ranges from <0.02 to 3.51 ppm with average 0.21 ppm. Most of the high element concentrations in stream sediments are found in the graphite-schist and serpentinized marble rocks.

Application of R-mode factor analysis indicates significant components of the sample composition. These reflect lithological, environmental and mineralization controls. Preparation of factor score map for the association Ag-Au-As-Cu-Zn-Pb-Mo-W enables a more precise delineation of zones of known gold mineralization as well as areas that may contain (on geological grounds) primary gold mineralization. The exploration significance of some anomalies has not been established, but a number of these anomalies may be related to undiscovered mineralization while others may be of no economic significance. Groundwater pH influences the hydromorphic dispersion patterns of Ag, As, and Au in different ways and this requires consideration during data interpretation.