Sediment recycling and crustal growth in the Central Asian Orogenic Belt: Evidence from Sr–Nd–Hf isotopes and trace elements in granitoids of the Chinese Altay

2017 ◽  
Vol 47 ◽  
pp. 142-160 ◽  
Author(s):  
Chen Zhang ◽  
Luofu Liu ◽  
M. Santosh ◽  
Qun Luo ◽  
Xin Zhang
Keyword(s):  
Trace Elements ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Hf Isotopes ◽  
Crustal Growth ◽  
Central Asian

Quantifying the growth of continental crust through crustal thickness and zircon Hf-O isotopic signatures: A case study from the southern Central Asian Orogenic Belt

2021 ◽  
Author(s):  
Yujian Wang ◽  
Dicheng Zhu ◽  
Chengfa Lin ◽  
Fangyang Hu ◽  
Jingao Liu
Keyword(s):  
Continental Crust ◽  
Crustal Thickness ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Thickening ◽  
Crustal Growth ◽  
Isotopic Signatures ◽  
Central Asian ◽  
Southern Central ◽  
Juvenile Crust

Accretionary orogens function as major sites for the generation of continental crust, but the growth model of continental crust remains poorly constrained. The Central Asian Orogenic Belt, as one of the most important Phanerozoic accretionary orogens on Earth, has been the focus of debates regarding the proportion of juvenile crust present. Using published geochemical and zircon Hf-O isotopic data sets for three belts in the Eastern Tianshan terrane of the southern Central Asian Orogenic Belt, we first explore the variations in crustal thickness and isotopic composition in response to tectono-magmatic activity over time. Steady progression to radiogenic zircon Hf isotopic signatures associated with syn-collisional crustal thickening indicates enhanced input of mantle-derived material, which greatly contributes to the growth of the continental crust. Using the surface areas and relative increases in crustal thickness as the proxies for magma volumes, in conjunction with the calculated mantle fraction of the mixing flux, we then are able to determine that a volume of ∼14−22% of juvenile crust formed in the southern Central Asian Orogenic Belt during the Phanerozoic. This study highlights the validity of using crustal thickness and zircon isotopic signatures of magmatic rocks to quantify the volume of juvenile crust in complex accretionary orogens. With reference to the crustal growth pattern in other accretionary orogens and the Nd-Hf isotopic record at the global scale, our work reconciles the rapid crustal growth in the accretionary orogens with its episodic generation pattern in the formation of global continental crust.

Geochemical signature of Paleozoic accretionary complexes of the Central Asian Orogenic Belt in South Mongolia: Constraints on arc environments and crustal growth

2006 ◽  
Vol 227 (3-4) ◽  
pp. 236-257 ◽  
Author(s):  
Christoph Helo ◽  
Ernst Hegner ◽  
Alfred Kröner ◽  
Gombosuren Badarch ◽  
Onongin Tomurtogoo ◽  
...  
Keyword(s):  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Growth ◽  
Geochemical Signature ◽  
Central Asian

Duobagou Permian–Triassic granites from the Dunhuang orogenic belt, NW China: implications for the tectonic evolution of the southernmost Central Asian Orogenic Belt

2020 ◽  
pp. 1-17
Author(s):  
Zhendong Wang ◽  
Yuanyuan Zhang ◽  
Xiangjiang Yu ◽  
Zhaojie Guo
Keyword(s):  
Partial Melting ◽  
Tectonic Evolution ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Growth ◽  
Central Asian ◽  
Granitic Intrusions ◽  
Mantle Component ◽  
Type Granite ◽  
T Values

Abstract The Duobagou Permian–Triassic granites of the Dunhuang orogenic belt are of great importance in understanding the tectonic evolution of the southernmost Central Asian Orogenic Belt. LA-ICP-MS U–Pb zircon ages indicate that Permian–Triassic granitic intrusions from the Duobagou area formed at 276–274 Ma and 246 ± 1 Ma. These granites have high SiO2, Na2O and K2O, but low Al2O3, CaO and MgO contents and belong mainly to the high-K calc-alkaline I-type granite series. Based on whole-rock geochemistry and Sr–Nd and zircon Hf isotopes, the Duobagou Permian–Triassic granites were dominantly derived from the partial melting of lower continental crust formed during late Palaeoproterozoic to Mesoproterozoic times in a post-collisional extensional setting. Permian granites with zircon ϵHf(t) values of −5.4 to +3.1 and Hf model ages of TDM2 = 1.14–1.70 Ga indicate the involvement of a mantle component in their petrogenesis. Triassic granites with higher zircon ϵHf(t) values (+0.5 to +3.8) and TDM2 = 1.08–1.31 Ga suggest more juvenile sources caused by a greater contribution of mantle-derived melts, indicating a significant crustal growth. Regional extension from lithospheric delamination and heating from asthenospheric upwelling were proposed to have triggered the partial melting of lower crust, resulting in the generation of the Permian–Triassic magmatism. This may have been the mechanism for the significant crustal growth during Permian and Triassic times in the southernmost Central Asian Orogenic Belt.

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