Lamprophyres of the Southern Coast of Novaya Zemlya: Composition, Tectonomagmatic Position, and New Age Data

Abstract

—The Novaya Zemlya Archipelago is an early Cimmerian folded structure located on the northern periphery of the Ural–Mongolian fold belt. The geologic development of the archipelago is well-studied and serves as a benchmark for interpolating its features to the shelf of the surrounding water areas, whose sedimentary cover contains large accumulations of hydrocarbon raw materials. In addition to the stratified section of essentially sedimentary rocks, it is of interest to study igneous formations, which clearly mark tectonic events in the geologic history of the archipelago. In the light of this, the age of these formations remains important. The age of some magmatic complexes of the archipelago is still debatable. This paper focuses upon a lamprophyre complex in the extreme south of Novaya Zemlya, which has been dated at the Late Proterozoic or Late Proterozoic–early Paleozoic(?) until recently. The results obtained for the U–Pb age of apatites contained in the rocks of this complex confirm the Devonian age of the lamprophyres, and it is suggested by estimates based on the presented data that the emplacement time lies in a range from 360 to 398 Ma. This means that they might be associated with riftogenic processes on Novaya Zemlya since the second half of the Early Devonian, when the stage of short-term stable carbonate sedimentation (in the first half of the Devonian Period) was replaced by the initiation of a new structural–formational zonal sequence.