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HYPERBASITES – PICROBASITES AND CHROMITE MINERALIZATION

V. L. Khomichev

Siberian Research Institute of Geology, Geophysics and Mineral Resources, Novosibirsk, Russia

In the Urals (in particular, on sheet O-41-XIII), the heterogeneity of serpentinites (ultrabasites) that directly determines the prospects for chromite mineralization is established. In the west, in the narrow Tagil faulting megazone, large extended bodies of serpentinites (ultrabasites) of the alpine-type dunite-harzburgite formation, with which the chromite deposits are associated, are widely developed. And in the wide Eastern-Urals megazone of brahiform structure adjacent from the east, granitoid massifs (protrusions of the Salda pluton at depths) and accompanying small bodies of gabbros and serpentinites prevail. The latter are also mistakenly related to the alpine-type complex and predict a chromite mineralization in them. However, these are completely different ultrabasites which represent the early phases of the formation (crystallizates) of a gabbro-granitoid formation, unpromising for chromites. Unfortunately, in the vast territory east of the Urals, such picrobasites are indiscriminately attributed to alpine-type hyperbasites, which has led to errors in prospecting planning.

Keywords: alpine-type hyperbasites, gabbro-granite picrobasites, chromite mineralization.

DOI 10.20403/2078–0575–2019–3–94-105