Abstract
Geology of the southern part of Sikhote-Alin is reviewed with reference to our field experience in the Kavalerovo region, where we visited as participants of the Scientific Tour II of the XIVth Pacific Science Congress (Khavarovsk) in September, 1979. Geology of the main anticlinorium zone, main synclinorium zone and coastal anticlinal zone, from west to east, of the Mesozoic Sikhote-Alin geosynclinal region, tin deposits of the main synclinorium and the fracture system of the Sikhote-Alin region are the main subject of this paper. Late Mesozoic-Cenozoic igneous activity in Primorie and Japan is summarized in Table 2. The tin ore deposits occur in folded sedimentary rocks associated with weakly magnetic magnetite-series granitoids and are subvolcanic reduced type veins characterized by much chlorite and sulfide minerals, an exact analogue of which is not known in the Japanese islands. Concerning the fracture system, a satellite image (ERTS) of the Central Sikhote-Alin fault (Plate II) and geologic lineaments on satellite images of the Sikhote-Alin region are given. In view of the major successive feature of the Jurassic eugeosynclinal facies, early Cretaceous flysch-like clastic facies and late Cretaceous-Paleogene acid magmatism combined with the ore genesis, it is emphasized that Sikhote-Alin was more closely allied to the inner side of Southwest Japan than to Northeast Japan during the Mesozoic-Paleogene time. However, the age and nature of the successive events are somewhat different between Southwest Japan and Sikhote-Alin. During that time, Sikhote-Alin and Southwest Japan formed two neighbouring but relatively distinct tectonic units within the major framework of the Late Mesozoic East Asian tectono-magmatic belt. With the opening of the Sea of Japan, the Japanese islands became the site of an active island arc during late Cenozoic, while Sikhote-Alin remained fixed to the continental side until the Recent and any Neogene marine volcanic basin, such as the Green Tuff region of Japan, is not developed in Sikhote-Alin.
