Geology in the Bayankhongor Region, Mongolia / Геология региона Баянхонгор, Монголия

Mongolia is situated between the Siberian and North China platforms and includes several Precambrian continentalblocks, which are fringed by Paleozoic and Mesozoic magmatic arcs, accretionary complexes and trapped oceanic crusts (Sengör et al., 1993). A number of porphyry, skarn and vein-type hydrothermal deposits have been discovered along these extinct magmatic arcs through regional geological mapping (Jargalsaihan, 1996). Thesedeposits form several metallogenic belts, which are genetically related to regional magmatism and tectonics (Distanov and Obolenskii, 1994; Dejidmaa, 1996). Although geology, alteration and mineralization of these deposits

have been described in explanatory reports of geological maps (e.g., Zabotkin, 1988), only a few geochronological studies have been undertaken for hydrothermal deposits (Sotnikov et al., 1974, 1995; Lamb and Cox, 1998; Muraoet al., 1998). The scarcity of age data for ore deposits makes it difficult to comprehend metallogeny in Mongolia. The Geological Research Center of Mongolia conducted a comprehensive project that re-examined geology (Teraoka et al., 1996), magmatism (Takahashi et al., 1998) and mineral deposits in the Bayankhongor region in central Mongolia (Fig. 1), where many hydrothermal deposits are associated with granitoids. This paper presents geology and K-Ar ages of the South, Huh Bulgiin Hundii, Saran Uul, Taats Gol and Han Uul deposits in the Bayankhongor region, and discusses metallogeny related to Paleozoic magmatism in the region.