First paleomagnetic and isotope-geochronological data on four basaltic volcanic pipes of the North-Minusinsk depression are reported. It is shown that the volcanic pipes appeared between 82 and 77 Ma ago. All ChRM directions of the pipe basanites are of reverse polarity. This fact is in agreement with the 40Ar-?9Ar ages of the rocks (within the accuracy of the 40Ar-39Ar method). The revealed ChRM corresponds to the end of chron 33R of reverse polarity (according to the geomagnetic-polarity time scale). The paleomagnetic poles of the studied pipes differ from the APWP of Eurasia.

In the North-Minusinsk intermontane depression, volcanic

Geological exploration of Mongolia has been extremely inconsistent. From the frst regional exploration by Russian explorers of Asia to the present, little more than 41% of the country’s territory has been covered by areal geological surveys in combination with prospecting at a scale of 1:50,000. Regional geological surveys at a scale of 1:200,000, 1:500,000, and 1:1,000,000 cover 100% of the country.

A variety of global and regional classifi cation schemes for uranium deposits have been proposed in the past by a number of geoscientists including Heinrich (1958), Roubault (1958), Ruzicka (1971), Ziegler (1974), Mickle and Mathews (1978), Mathews et al. (1979), Nash et al. (1981), Barthel et al. (1986), Dahlkamp (1989, 1993), McKay and Miezitis (2001) mainly for deposits in the western hemisphere and by Kazansky and Laverov (1977), Boitsov (1989, 1996),

Uranium is a widespread commodity throughout the crystalline Bohemian Massif and the basins of its platform cover in the Czech Republic. Most uranium mined occurred in vein- and sandstone-type deposits that cluster in a number of districts within eight uranium regions. Small deposits and occurrences also occur isolated elsewhere in the country. $Figure 3.1 shows the uranium regions with districts and deposits and $Table 3.1 lists reported data of districts and deposits. Since uranium mining was resumed after World War II,74 deposits were mined in 6 districts and at several localities scattered throughout the country.