Tectonic Evolution of the Tuvinian Trough (Northern Part of Central Asian Orogenic Belt): Synthesis of Geological Data and Results of Feldspar Ar‒Ar Dating

• Published in: Geotectonics 2024-08, Vol.58 (4), p.449-464
• Main Authors: Vetrov, E. V., Vetrova, N. I., Biryukova, T. A., Agatova, A. R., Gavryushkina, O. A., Bulgakova, D. D.
• Format: Article
• Language: English
• Subjects: Age groups; Carboniferous; Chronology; Dating; Developmental stages; Devonian; Earth and Environmental Science; Earth mantle; Earth Sciences; Evolution; Feldspars; Geochronology; Geochronometry; Geological data; Geological history; Geology; Igneous rocks; Information processing; Jurassic; Low temperature; Magma; Mantle plumes; Mesozoic; Oceans; Orogeny; Paleozoic; Permian; Precambrian; Regional development; Rifting; Segments; Structural Geology; Tectonics; Triassic
• ISSN: 0016-8521; 1556-1976
• DOI: 10.1134/S0016852124700328

The Tuvinian rift trough, located in the northern part of the Central Asian orogenic belt (CAOB), arose in the Early Devonian on Late Proterozoic (?)‒Early Paleozoic terranes as a result of Altai–Sayan mantle plume activity. The sedimentary record from the Middle Paleozoic to the Middle Mesozoic, preserved in the Tuvinian trough, and the Middle Paleozoic igneous complexes confined to the trough structures, reflect the evolutionary stages of Earth’s crust in the Tuva segment necessary for understanding the geological history of the CAOB as a whole. Dating of accessory and rock-forming minerals from igneous rocks using low-temperature geochronology methods yields additional information about postmagmatic processes, making it possible to update the regional tectonic evolution model. In this study, we have reconstructed the stages of tectonic development of the Tuvinian trough in the northern part of the CAOB based on analysis of geological and new Ar‒Ar dating data on feldspars from mafic intrusions. As a result, the chronology of the previously known stages of postmagmatic processes manifested in the Tuvinian trough was refined and new stages identified according to the tectonic evolution of the CAOB. Ar‒Ar dating of feldspars from eight samples yielded four age groups: (i) Late Devonian, (ii) Middle Carboniferous, (iii) Early Permian, and (iv) Early Jurassic. Late Devonian (~377 and 375 Ma) ages record an impulse of mafic magmatism, widely manifested in the northern segments of the CAOB (~380‒365 Ma). Middle Carboniferous (~320 and 319 Ma) dates may reflect closure of the Ob–Zaisan branch of the Paleo-Asian ocean as a result of the Kazakhstan–Siberian collision. Early Permian (~290–279 Ma) ages are consistent with the formation of Late Carboniferous–Early Permian (~305–275 Ma) large igneous provinces in connection with rifting processes in the northern segments of the CAOB. Lastly, a single Early Jurassic (~188 Ma) age marks tectonic reorganization of the CAOB in the Late Triassic‒Early Jurassic in response to (i) closure of the Paleotethys Ocean with subsequent collision of Cimmerian blocks and the southern margin of the Eurasian continent and/or (ii) Mongolian mantle plume activity.