Before mentioning the characteristics of Kuroko and epithermal vein-type deposits in Japan, it is worthwhile to briefly describe the metallogeny, geology, geophysics, and tectonic situations of the Japanese Islands.

In Chapter 1 we noted that magmas with distinctive major element characteristics are associated with specific tectonic settings. For example, calc-alkaline series magmas are apparently associated uniquely with subduction, while low-K tholeiitic basalts are the typical products of magma generation at constructive plate margins. However, in general, the major element characteristics of primary mantle derived magmas are * not particularly sensitive indicators of tectonic setting.

In a country like India various types of earth science data have been generated for about 170 years by the Geological Survey of India (GSI) and subsequently by its much younger sister organizations like Oil and Natural Gas Corporation, Indian Bureau of Mines, Atomic Minerals Division, Central Ground Water Board etc. and a number of public sector undertakings like Hindustan Copper Limited, Hindustan Zinc Limited etc. In addition to these various earth science related organizations, State Departments of Mines and Geology and a number of academic institutions and Geology Departments under the various universities and Indian Institute of Technologies have come up after the independence of India.

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.