Age, duration of formation, and geotectonic position of the Zavitaya lithium granite-pegmatite system, Eastern Transbaikalia

摘要

The Zavitaya granite-pegmatite system with a lithium deposit is localized in the northern marginal part of the Onon terrane (Aginskii massif) and ajoins to the Ingoda-Shilka branch of the Mongol-Okhotsk suture in the south. This paper presents the first U-Pb (SHRIMP) age of granites and barren and spodumene pegmatites of the Zavitaya field. The Zavitaya polychronous granite-pegmatite system evolved through 40 million years: porphyritic biotite granites (169.0 +/- 3 Ma), two mica granites-leucogranites (147.5 +/- 3.1 Ma), muscovite leucogranites (140.0 +/- 3.0 Ma), barren pegmatites (139.6 +/- 3.1 Ma), and lithium spodumem pegmatites (129.6 +/- 2.7 Ma). The formation of the system coincides with the change in geodynamic regimes of the region at the Middle Jurassic-Early Cretaceous boundary: the age of the early granites of the system and spodumene pegmatites corresponds to the termination of collision and to the beginning of the Early Cretaceous rifting, respectively.