​​​​​Orogenic Architecture and Crustal Growth 

from Accretion to Collision

IGCP 662
Deep juvenile and old composition, architecture and genesis of
the largest juvenile crustal region in the Central Asian Orogenic Belt

Abstract: The relationship between orogeny and crustal growth is a fundamental and widely discussed scientific problem in the solid earth sciences. How large and extensive is juvenile crust in Phanerozoic orogens? What are the characteristics of such juvenile crust? How can we semi-quantitatively estimate crustal growth and relate it to different types of orogeny? These problems currently attract worldwide attention. The Central Asian Orogenic Belt (CAOB) is the most typical and largest Phanerozoic accretionary orogenic belt on Earth and is also the most prominent domain of crustal growth. This study will investigate the Junggar-South Mongolia region, the largest area of juvenile crust so far recognized in the CAOB. We shall conduct regional granitoid Nd-Hf isotopic mapping and thus characterize the deep sources and constrain the isotopic provinces of these rocks. We shall then evaluate the proportion of crustal growth by estimating the ratios of juvenile versus old crustal material and identify areas of juvenile and old crustalcomponents. The major aims of this project are: (1) to establish criteria to 
(semi-) quantitatively describe a typical accretionary orogen through evaluation of the relative proportions of juvenile vs. reworked crust; (2) to understand horizontal and vertical crustal growth mechanisms according to the source evolution of syn- and post-orogenic granitoids; (3) to reconstruct the architecture and tectonic evolution of the largest juvenile crustal region in the CAOB. This study may help significantly to understand the relationship between orogeny and continental growth.
Key words:Granitoid pluton; Iotopic mapping; Juvenile crust; Accretionary orogen; Central Asia


Map and Data
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