NEW DATA ON THE STRUCTURE OF THE KACHKANAR-GUSEVA GABBRO-PYROXENITE PLUTON (URALS)

Abstract

The Kachkanar-Guseva gabbro-clinopyroxenite pluton is a typical representative of the complicated multiphase complexes of the dunite-gabbro-plagiogranite association in folded regions, and contains a large ore deposit of magnetite bearing clinopyroxenites, whose structure at depth has been very little studied. The pluton under study is made up of three rock associations - ultramafics, gabbroids and plagiogranites. The interrelationships and relative positions of the rocks and their associations indicate that the pluton was formed in two intrusive phases - first ultramafics, and then gabbroids. Granitoids, represented by plagioclasite dikes, are of only limited development. Of economic significance is the conclusion that the magnetite clinopyroxenites are confined to the upper parts of the ultramafic massifs below their roofs, their facies being replaced at depth by olivine clinopyroxenite, wehrlite and dunite, and also by gabbroids that are truncated and replaced along the periphery.