A new geochemical technique for gold exploration; alkali element mobility associated with gold mineralization in the west Australian goldfields

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doi: 10.2113/gsecongeo.99.2.313
Authors:Heath, Christopher J.; Campbell, Ian H.
Author Affiliations:Primary:
Australian National University, Research School of Earth Sciences, Canberra, Australia
Volume Title:Economic Geology and the Bulletin of the Society of Economic Geologists
Source:Economic Geology and the Bulletin of the Society of Economic Geologists, 99(2), p.313-324. Publisher: Economic Geology Publishing Company, Lancaster, PA, United States. ISSN: 0361-0128
Publication Date:2004
Note:In English. 36 refs.; illus., incl. 2 tables, geol. sketch map
Summary:The hypothesis that alkali element mobility can be used as a tool to monitor fluid flow associated with gold-bearing hydrothermal systems and as a geochemical vector for locating new gold deposits is tested. This was achieved by analysing 114 samples of two mafic rock types from four localities in the Archaean Yilgarn craton of W Australia; the giant Golden Mile deposit at Kalgoorlie, the smaller Victory mine at Kambalda, two drill holes that intersected subeconomic mineralization 8 km S of Kalgoorlie, and two drill holes well away from gold mineralization. The results show that Cs, Rb, and Ba are enriched in areas that are prospective for gold-bearing mineralization and depleted in areas that are not. The primitive mantle normalized ratio ((Cs + Rb)/Th)N is used as an alteration index to quantify and discriminate potentially mineralized from unmineralized areas. The Golden Mile deposit is surrounded by a zone of ((Cs+Rb)/Th)N >5 that is 10 to 100 times larger than the visible alteration halo. The alkali enrichment halos around the smaller Victory deposit and subeconomic mineralization S of Kalgoorlie are narrower but are still over 10 times larger than the visible alteration halos adjacent to veins. These zones of high ((Cs + Rb)/Th)N around the mineralization show that the hydrothermal fluids penetrated tens of metres, and in the case of the Golden Mile, hundreds of metres into the wall rocks. Within this zone, ((Cs + Rb)/Th)N increases toward ore and provides a vector to mineralization. [G.L.B.]
Sections:Geochemistry
Subsections:Exploration geochemistry
Subjects:Alkalic composition; Boreholes; Chemical composition; Chemical ratios; Enrichment; Faults; Fluid phase; Geochemical methods; Geochemistry; Geophysical methods; Gold ores; Haloes; Hydrothermal alteration; Igneous rocks; Infrared methods; Lithostratigraphy; Metal ores; Metasomatism; Migration of elements; Mineral assemblages; Mineral exploration; Mines; Mobility; Models; Movement; Sedimentary rocks; Stratigraphic units; Sulfides; Techniques; Trace elements; Volcanic rocks; Australasia; Australia; Kalgoorlie Australia; Kambalda Australia; Western Australia; Golden Mile; Victory Mine
Coordinates:S314500 S310000 E1220000 E1213000
Abstract Numbers:04M/3142
Record ID:2005010393
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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