Nd isotopic characteristics of Proterozoic metasedimentary rocks and constraints on their provenance in the eastern segment of Central Tianshan Belt, Xinjiang*

Abstract

Abstract Sm-Nd isotopic characteristics, ϵNd(t) values and Nd modelages (T DM) of Proterozoic metasedimentary rocks in the eastern segment of Central Tianshan Belt (ESCTB), Xinjiang, are used to constrain the sedimentary provenance as well as to evaluate their tectonic implications. ϵNd(t) and T DM values of these samples range from −4.00 to +6. 36 and from 1.29 to 2. 29 Ga, respectively. These feature values are distinguished from those of Archean Tarim Craton. Their average ϵNd(t) values of the Weiya, the Kumishi and the south to the Dikar samples are −2.46, +2.06 and +1.37, respectively, Nd model ages of the Weiya samples vary between 1.86 and 2.29 Ga, but those of the Kumishi and the south to the Dikar samples show a significant concentration at 1.6 ∼ 1.9 Ga and the youngest Nd model age is 1.29 Ga. Those Nd isotopic characteristics suggest that these metasedimentary rocks could be derived from a significant proportion of Paleoproterozoic crustal source and a participation of young arc materials, rath...