MAGMATIC GEOINTERFACES OF THE PACIFIC SUPERREGION

Abstract

Igneous activity is a very accurate indicator linking the surface of the Earth to its crust and mantle. Features indicative of the general heterogeneity of the lithosphere include great magmatic 'seams', many thousands of kilometers long. Their existence in the Pacific superregion allows it to be divided into large highrank segments of independent geologic and metallogenic significance. In the early stage, the magmatic geointerfaces evolved as a system of longitudinal extension faults of lineament type that bound sets of continental, transitional and oceanic blocks of the lithosphere, i.e., geoblocks or other tectonic structures. The significance of the Greater Pacific geointerface is emphasized by differences in age and ore potential of the upper crustal layers of the sedimentary cover on its west east sides. West Pacific drillholes penetrated Late Jurassic-Early Cretaceous and Late Cretaceous-Eocene buried ore mineralization. On Shatskly Rise in the northwestern geoblock their is an Albian-Plaistocene complex of ore-bearing sediments. A characteristic feature of the intergeoblock volcanic Mid-Pacific Mountains is the presence of finely divided sulfides, transformed by products of hydrochemal activity. The significance of the Great Pacific geointerface is emphasized by differences in age and ore potential of the upper crustal layers of the sedimentary cover.