The mesoproterozoic to paleozoic crustal growth and rejuvenation in the Central Asian orogenic belt : constraints from the Nd-Hf Isotopic studies

Abstract

A study of the Nd-Hf isotopic data on the crustal growth of the Central Asian Orogenic Belt has been carried out because it is a relatively new area of study and the orogenic evolution is still controversial. This is a review of the orogenic evolution of the Central Asian Orogenic Belt based on the latest data available in academic research published in recent years. The objective of the study was to analyse the whole rock Sm-Nd dating and the zircon Lu-Hf isotopic dating in the Central Asian Orogenic Belt, to discuss the orogenic evolution of the area and to discuss the discrepancy which may be resulted from the Nd-Hf isotopic analysis. Data has been obtained from a number of published academic research papers through Science Direct. The data is presented in the form plots of εNd and εNd vs. rock ages of the samples. The data has been interpreted in relation to the Nd-Hf isotopic theory and the known geological background of the orogenic belt. It is concluded that the latest isotopic data are generally consistent with the known history of the orogenic evolution of the Central Asian Orogenic Belt. The Central Tianshan Block, the Southern Tianshan Belt and the Erguna Block were formed from reworking of ancient crustal materials. For the Altai Mountains, Mongolia terrane, the Jiamusi Block and the Songliao-Xilinhot Block, there are a change in tectonic setting in the area or simply assemblages of both juvenile and reworked sources for the crustal growth in the orogenic activities. The North Tianshan Belt and Xing’an Block are mainly made up of juvenile source, either from depleted mantle or short-lived crustal materials. The εNd values are less sensitive to the Model age this is probably because the Sm-Nd isotope system is more prone to disturbance comparing with the Lu-Hf isotope system.