TUFF-TURBIDITE SERIES OF THE DZHIDA ZONE (CENTRAL ASIAN OROGENIC BELT): MATERIAL COMPOSITION, DETRITAL ZIRCON AGE, AND SOURCE AREA
A.L. Elbaev1, I.V. Gordienko1, V.B. Khubanov2, M.S. Skripnikov1, D.E. Yudin1, A.M. Khubanova2
1Dobretsov Geological Institute SB RAS, Ulan-Ude, Russia
2Schmidt Institute of Physics of the Earth RAS, Moscow, Russia
Keywords: Forearc basin, detrital zircon dating, sedimentary rock sources, Dzhida island-paleoarc system, Southwestern Transbaikalia
Abstract
The composition of volcano-terrigenous formations and age of detrital zircon from the tuff-turbidite series sandstones of the Dzhida zone of the Central Asian Orogenic Belt were studied. The sandstones of this formation, in terms of their mineralogical and petrochemical characteristics, correspond to feldspar graywackes and belong to the rocks of the first sedimentation cycle. The main volume of detrital material is represented by volcanics and, to a lesser extent, plagioclase grains. Relatively low values of chemical index CIA (58-68) indicate moderate or weak chemical weathering of lithic components, that is a low maturity degree of the detrital material formed due to the source rocks mechanical destruction. The distribution curve of U-Pb ages of zircon from sandstones of the tuff-turbidite series has a bimodal character with peaks at 530 Ma and 510 Ma. The studied rocks do not contain zircons of Neoproterozoic age. The greywacke composition of the studied rocks, the low maturity degree and the distribution of zircon grains U-Pb ages suggest the formation of these rocks in the forearc basin conditions due to the removal of material from local sources – Early Cambrian volcanic rocks of the Dzhida ensimatic island arc.
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