Assembly of the Siberian Craton: Constraints from Paleoproterozoic granitoids

Abstract

The paper presents a synthesis of geochronological, geochemical, and isotopic data on Paleoproterozoic granitoids in the Siberian craton and, in some cases, on volcanics related to these granitoids. Different evolution stages of the craton, including its assembly, are recorded in several major events in the history of Paleoproterozoic granitic magmatism. They are 2.52–2.40 Ga and 2.15–2.04 Ga granitoids of different tectonic settings; 2.06–2.00 Ga subduction-related granitoids; 2.00–1.87 Ga collisional granitoids; 1.88–1.84 postcollisional granitoids, and 1.76–1.71 Ga within-plate (anorogenic) varieties. Granitoids with ages of 2.5–2.4 Ga and 2.15–2.04 Ga are distributed locally in separate blocks and terranes which later entered the craton structure. These rocks are of different types and represent different tectonic settings of the respective blocks and terranes, i.e., the Siberian craton did not exist yet as a single unit at that time. The 2.06–2.00 Ga subduction-related granitoids and volcanics are found in the southern and southeastern craton parts. Magmatism of that time interval probably was associated with subduction beneath the Archean Olekma-Aldan and Anabar continental microplates and with the formation of their active margins. Granitoids of the 2.00–1.87 Ga age interval represent a collisional stage of the craton evolution. Collisional granitoids that intruded between 2.00 and 1.95 Ga record the first large-scale stage of craton assembly with collisions of terranes that had built the core of the Anabar, Aldan, and Olenek superterranes. The intrusions of 1.95–1.90 Ga granitoids mark the consolidation of the southeastern craton part. Collisional granitoids with the 1.90–1.87 Ga ages, which are especially abundant in the south and southwest of the craton but almost lack from the north, led to general assembly of the craton. The granitoid and volcanic magmatic activity of 1.88–1.84 Ga in the craton south produced the South Siberian postcollisional magmatic belt that had completed the assembly of the craton which, in its turn, may have been part of the Paleoproterozoic supercontinent of Columbia. Granitic intrusions at 1.76–1.71 Ga are limited to the southwestern and southeastern craton parts and correspond to a setting of continental extension which never led to the breakup of the craton.