Geochemical orientation surveys were completed over covered Carlin-type gold deposits in the Cortez mine area with the expressed aim of identifying and evaluating exploration methods to discover Au ore under transported alluvial cover in Nevada. Orientation tests were designed to assess the utility of geochemical applications at various scales of exploration, both drill targets at the deposit scale and “footprints” associated with deposits at the district scale.

Detailed surveys were completed over the covered Gap deposit, located adjacent to the giant Pipeline deposit. Both Carlin-type gold mineralization and earlier, spatially associated, base metal skarn mineralization at Gap were located by soils, soil gas, and vegetation. Loam soils at 6- to 12-cm depth provided a consistent and uniformly available sample medium. Gold ore under 10 m of cover in the northern portion of the Gap deposit was readily detected by analysis of Au by fire assay and ultra trace aqua regia methods in the -80 mesh fraction of these loam soils. Arsenic anomalies occur over the northern end and over the main ore zone at Gap, where there is 25 to 50 m of alluvial cover. Zinc concentrations in soil show the most coherent spatial relationship with underlying Au ore. Tests of MMI-B and Enzyme Leach selective leaches did not result in significant enhancement of the anomalies relative to aqua regia. CO2 and O2 in soil gas indicate faults and underlying mineralized carbonates at Gap, where weathering reactions likely generated CO2 from acid reaction with carbonate. Elevated Au and As in mixed sagebrush and shadscale occur over most ore zones, with the highest Au concentrations over the main ore zone rather than the shallowly buried northern zone. Like soils, elevated Zn in vegetation shows the most coherent spatial relationship with underlying ore.

The geochemical analysis of fades is a special part of geochemistry and geology. The development of this research was initiated by BISCHOF (1847-1851), who was the first to attempt to recognize sediments of different origin by geochemical means. In his now famous book he listed some chemical elements belonging to typical environments, such as boron in marine sediments and metallic sulphides in zones rich in sulphuretted hydrogens. Moreover he was the first author to suppose that all "soluble rocks" of the continents must be present in the oceans. This early concept of facies was supplemented by ROTH (1879-1890) who discovered new elements in the ocean waters and in the ashes of marine organisms. However, the data used by both of these workers were quantitatively unsatisfactory and can only be considered as the qualitative results of inadequate chemical analyses <...>

The gold deposit at La Josefina, in the Deseado Massif of Argentina, is a low-sulfidation epithermal deposit with some features of the intermediate sulfidation style; the Au occurs in quartz veins and hydrothermal breccias hosted by acid pyroclastic rocks produced by Jurassic bimodal volcanism. Exploration for this deposit type uses geochemical data for vectoring to mineralized rocks. Although a general suite of elements with anomalous concentrations around low-sulfidation deposits is known, that suite varies amongst individual deposits, which should be studied individually.

Since most of the elements used by the society come from mineral extrac-tion, mining of mineral resources provide essential raw material for sustain-able development. Mining however leads to severe impact on the environ-ment, including contamination by toxic metals. A recent Europe-wide survey identified wide-spread pollution problems caused by mining, abandoned mines in particular (COM, 2003). Younger et al. (2002) estimated that about 1,000 to 1,500 km of watercourses are polluted by metal mine discharges in the EU. Through mineral extraction and subsequent mineral processing huge amount of wastes are produced. Metals and metal compounds in wastes tend to become chemically more available, which can result in the generation of acid mine drainage (AMD). Due to great volumes and slow chemical proc-esses, mine waste can release toxic compound for a very long time on the scale of centuries and thousands of years (BAT, 2003). Thus, remediation of mine sites, including abandoned mines, has to consider long-term solutions and remediation technologies have to be sustainable for a long time (Sind-ing, 1999). As an alternative, passive in situ remediation methods for AMD treatment using wetlands that provide means of cheap and sustainable reme-diation has been proposed (PIRAMID, 2003). Around the mine site, soils and surface water in the receiving environment are often contaminated with harmful elements or compounds of AMD. These contaminated sites act as secondary sources for pollution, especially for historic sites (Jordan and D‟Alessandro, 2004). <...>