Permian-Triassic Metalliferous Provinces of North-Central Siberia: ABSTRACT

Abstract

In the Arctic part of the Yenisey-Lena River region of Siberia, a large area is present which was stabilized during the late Paleozoic. This area shows evidence of tectonic reactivization accompanied by the emplacement of a mafic igneous complex and related endogenic mineralization. 1. Tholeiitic basalt is the predominant rock type of the mafic complex; associated trachybasalt, olivine basalt, and basic to ultrabasic units are subordinate. Tholeiitic basalt is both effusive and intrusive. The effusive facies consists of saturated and undersaturated rocks; the intrusive facies consists of oversaturated material. The olivine basalt formation has the most complex and variable composition. Nepheline basalt-trachyte lavas and nepheline picrite-mugerite intrusive series are typical. Basic to ultrabasic rocks are represented by flows of picrite basalts and by their intrusive equivalents that have isotropic and anisotropic structures (massifs of Norilsk-Talnakh type). The alkaline ultrabasic rocks are composed of volcanic rocks of the central type (Gulin massif). 2. Spatial distribution of the basic complexes is determined by structures formed as a result of tectonic reactivization, with faulting taking the leading role. There exists a genetic range of structures of block-fold origin, from linear synforms (grabens) through sublinear troughs to flat synclines. The relations between the structural features and the outcrops of definite types of basic formations permits the delineation of a Taimyr tholeiitic trachybasalt province, a Norilsk-Olenek basic-hyperbasic province with trachybasalts, and a Kotuy-Maymecha alkaline ultrabasic province. 3. These magmatic provinces correspond to the concept of a metalliferous province because there is a close spatial and genetic connection between the endogenic mineralization of the Permian-Triassic metallogenic stage and the specialized rock suites. The increase in metal content toward later magmatic phases is clearly recognized. The Taimyr province is characterized by non-economic copper and zinc sulfide ore occurrences; in northern Tunguska, there are noneconomic ore and sulfide deposits. In the Norilsk-Olenek and Kotuy-Maymecha provinces, large economic copper, nickel, rare metals, apatite, and other deposits have been found. End_of_Article - Last_Page 2482------------