Deciphering of the tectonic elements and internal structure of the Paleoproterozoic Losevo terrane (Volga-Don orogen) using density modeling data

Abstract

Introduction: a lot of aspects of terranes geology that make up the orogens remain controversial. This article focuses on the widest part of the Losevo terrane from the Paleoproterozoic Volga-Don Orogen in the southeastern part of the East European Craton. In this region, the following are the subjects of discussion: the terrane tectonic nature, its relationship with neighboring blocks, kinematics and depth of the limiting faults, shape and occurence depth of plutons and paleovolcanoes, thickness and subdivision of stratified formations.

Methodology: a three-dimensional model of the distribution of absolute values ​​of density of the earth crust to a depth of 10 km was obtained as a result of the inversion of local anomalies of the gravity field.

Results and discussion: the interpretation of the results of density modeling was realized in three ways: (1) identification of lineaments as a reflection of major faults, (2) tracing the structural features of stratified or similar geological units, (3) characteristics of local, contrasting objects, mainly plutons and paleovolcanoes of different compositions.

Conclusion: The study area is a large paleosynform, the base of which is composed of undifferentiated gneisses and terrigenous (lower) strata of the Losevo Series. The kinematics of major faults limiting the Losevo terrane has been established. Greenstone structures of the Strelitsa and Podgornoe Formations of the Losevo Series have been identified and traced to depth. The Voronezh Suite contours, the thickness of which is about 4 km, have been clarified. The vertical dip of the Usman complex batholiths and stocks, the Olkhovka pluton and other intrusions indicates their emplacement in a post-collisional setting.