Structures of degassing and fluid transport within the modern zones of the lithosphere destruction in the eastern margin of the Central Asian Fold Belt

Abstract

The modern geodynamic transformations of the Amur geoblock are related to the activation of pull-apart–strike-slip and simple strike-slip movements. These movements resulted in the formation of destruction zones along ancient transregional fault systems (Nenjiang–Selemdzha, Lermontovka–Belogorsk, West Turan, Khingan, Tan Lu, and others) and young NW- and WE-trending fractures with distinctly expressed shearing displacements. These processes are fixed by earthquakes, focal magmatism, pulsed degassing of the Earth’s interior, and fluid discharge. High-permeability structures confined to the juncture of the destruction zones and young fractures served as the deep degassing drainage systems. These structures are traced by decompaction fields and anomalies of He and other gases. The most contrasting Varvarovka anomaly is located in the northeastern flank of the Yerkovtsy brown coal deposit. The paleogene coal-bearing rocks studied in the Yuzhny quarry within this deposit are characterized by high contents of noble, rare metals, and rare-earth elements, which frequently exceed their average abundances by ten orders of magnitude. Based on assay analysis, the Au content in the coals varies from trace amounts to 4.6 ppm.