Recent progress in the use of geophysical exploration techniques for unconformity-related uranium deposits within permafrost terrain in the northeastern part of the Thelon basin, Northwest Territories, Canada, is summarized using exploration case histories. These exploration techniques have attempted to use the unique physical and petrological propertiesof altered rocks that accompany uranium mineralization.
Altered rocks are detectable as low resistivity anomalies by airborne resistivity and ground VLF-resistivity surveying, and the influence of thin surficial thawed zones on the responses are minimal except for the ground underneath large lakes. Gravity surveys are very effective for detecting low density zones associated with alteration and mineralization provided that the overburden is uniform in thickness (or the actual thickness is known), and a low density alteration zone is relatively shallow and/or large enough to produce a recognizable anomaly.
A geophysical model can be established to link the physical properties of various alteration zones. Resistivity can be significantly decreased in the early stages of alteration (or relatively weak alteration) by hydrolysis of feldspar (sericitization). However, it is not the hydrolysis of feldspar that is responsible for the significant change of density that is typical of inner part of alteration zones, but rather the dissolution of quartz followed by replacement by water. This suggests that an influx of a considerable volume of hydrothermal solutions has contributed to promote desilication, and that the mineralization must be related to this influx of solution, which can be inferred by the close spatial relationship between desilication and uranium mineralization.

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The Hishikari gold deposits are of an epithermal quartz-adularia vein type, in which two major mineralized areas have so far been confirmed: the Honko and the newly discovered Yamada areas.
The wall rocks in the Honko area are composed of sediments of pre-Neogene Shimanto supergroup and volcanic rocks of Quaternary age, whereas these in the Yamada consist of the latter.
These wall rocks are more or less suffered from hydrothermal alteration in the vicinity of the vein systems. In this paper, four alteration zones are established, based on the mineral assemblage of clay minerals in volcanic rocks and relationship between formation of hydrothermal clay minerals and temperature in active geothermal systems. These are from the center to marginal zone of the mining area: IV quartz-chlorite; III quartz-chlorite (or sericite)/interstratified clay minerals; II quartz-smectite; and I Cristobalite-smectite.
In general, the zone IV occurs at the deepest and central parts and forms the principal alteration zone with which most of the productive veins of the Honko area and the lower half of the Yamada vein system are directly associated.
The zone III and II envelop the mineralized center in the Honko area, while the former is associated with the upper half of the Yamada deposit.
The zone I and least-altered rocks surround these three zones in turn.
In addition to the above, sporadic acidic alteration (quartz-kaolinite and quartz-alunite) is superimposed on them at the higher levels.

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The final product of the Cape Ashizuri A-type granitic activities of Miocene age in the Outer Zone of Southwest Japan is a few N-S trending dikes of rhyolitic composition. This rock is pale bluish green in color composed mainly of alkali feldspar and alkali amphibole, and some accessory minerals. Its (Na₂O+K₂O)/AL₂O₃ (mole) exceeds 1, thus peralkaline in the chemistry. The rock is anomalously rich in the following valuable rare metal elements; Nb 633 ppm (50 times of JG-1 granodiorite reference sample), Ta 52 ppm (31 times), Zr 1567 ppm (15 times), Hf 38 ppm (11 times), Th 104 ppm (8 times), U 25 ppm (7.6 times), total rare earth elements (REE) 751 ppm (6.5 times) and Y 161 ppm (5.4 times). These elements appear to be contained at least four independent accessory minerals. The rock can therefore be a new type of rare metal mineral resources.

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Diving surveys were performed in the North Fiji Basin, Southwest Pacific, using deep-sea submersible Nautile and her mothership Nadir under the framework of the Japan-France Joint Research Project STARMER. Three diving sites were selected based on the results of previous cruises; two along the N15E central spreading axis of the basin and one at the triple junction of three rift axes. In the first diving site (16°59'S;173°55'E), an active white smoker which is called "White Lady" was found. It expels clear, low salinity, hydrothermal solution (T=285°C). We believe that the solution is the vapor condensate of boiled solution. The chimney mostly consists of anhydrite and is built on top of extinct sulfide chimneys which are composed of pyrite, marcasite, wurtzite, chalcopyrite, and covelline. Seepage of low temperature hydrothermal solution was also observed along the fault scarps of the central graben.
In the second site (16°58'S; 173°55'E), which locates about 1 km north of the previous one, huge hydrothermal area, more than 1 km long, of "dead" sulfide chimney forest was observed. This hydrothermal site could be the largest one in western Pacific area. Those chimneys are about 15 m in height, 5 m in bottom diameter and are composed mainly of dendritic aggregate of marcasite. The northeast rift system in the third site (16°45'S; 174°05'E) is suggested to be tectonically active. A cross section of oceanic crust was observed on a cliff face 1000 m in height.

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