Main Tectonic Features of Northern Part of Pacific Mobile Belt: ABSTRACT

Abstract

The Koryak-Kamchatka-Kuriles and Alaska-Aleutian areas form the northern part of the Pacific mobile belt (Pacifides). The Koryak-Kamchatka-Kuriles area is one of polycyclic migration of a eu- and miogeosynclinal feature, with the southeastward displacement of geosynclinal systems (Mesozoides-Cenozoides-modern Kuriles geosyncline) from the continent toward the ocean. This displacement is emphasized by the reentrant junctions, formed by the intersection of the zones of deep-seated faults which are the outer geosynclinal borderlines. The bisectors of the reentrant angles show the general direction of the migration of the geosynclinal processes which occurred parallel with and normal to the general structural trends. The Alaska-Aleutian area is a polycyclic-inherited type of eu- and miogeosynclinal style of development. The migration of the geosynclinal processes occurred along the Cordilleran belt (early Mesozoides-late Mesozoides-modern Aleutian geosyncline). The fact that Alaska lacks geosynclinal formations synchronous with the Cenozoides of the Olyutorskiy-eastern Kamchatka system testifies to the asymmetric structure of the northern part of the Pacifides. The character of the junction of the Aleutian arc with the Kamchatka Cenozoides (through the Komandor Islands = Commander Islands) in the west and with the Alaska Mesozoides in the east also demonstrates the asymmetry. The development of the geosynclinal systems of the northern part of the eastern Asia Pacific coastal zones is associated mainly with the tectonic movements of tensional type and those of North America with compression-type movements--a conclusion confirmed by the structural form and tectonic-magmatic features of the development of the geosynclinal systems of the northern Pacific belt. The fold systems of the adjoining Arctic mobile belt End_Page 2479------------------------------ (Arctides-northern Alaska-Novosibirsk-Chukotsk) join the Pacifides along the zone of the Mackenzie-Lena deep-seated faults. They are characterized by a monocyclic and miogeosynclinal type of development. Analysis of the available data permits identification of the mineralogenic character of the Pacifides and adjoining Arctides with their diverse late Mesozoic and Cenozoic ore-bearing deposits (gold, mercury, copper and polymetals, tin and tungsten--especially in the Arctides); low-temperature ore deposits prevail. It may be assumed that the possible oil and gas troughs of Arctic Canada, northern Alaska, Chukotsk, Chukotsk Sea, and the East Siberian Sea comprise a single Arctic oil and gas belt related tectonically to the formation of the Arctides. One may also infer the existence of a North Pacific belt of oil and gas accumulations, including oil- and gas-bearing troughs and depressions in the Kamchatka-Koryak and Cordilleran-Alaska areas. End_of_Article - Last_Page 2480------------