Growth and differentiation of continental crust in the accretionary orogen : a case study of the Chinese Altai, Central Asian Orogenic Belt

2017 ◽  
Author(s):  
Yang Yu
Keyword(s):  
Continental Crust ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
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.

A mid-Palaeozoic ocean–continent transition in the Mazongshan subduction–accretion complex, Beishan, NW China: new structural, chemical and age data constrain the petrogenesis and tectonic evolution

2020 ◽  
Vol 157 (11) ◽  
pp. 1877-1897 ◽  
Author(s):  
J.-X. Wang ◽  
K.-X. Zhang ◽  
Brian F. Windley ◽  
B.-W. Song ◽  
X.-H. Kou ◽  
...  
Keyword(s):  
Continental Crust ◽  
Early Carboniferous ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Published Data ◽  
Zircon Age ◽  
The North ◽  
Tectonic History ◽  
Central Asian ◽  
Tectonic Mélange

AbstractAccretionary orogens contain key evidence for the conversion of oceanic to continental crust. The late tectonic history and closure time of the Palaeo-Asian Ocean are recorded in the Mazongshan subduction–accretion complex in the southern Beishan margin of the Central Asian Orogenic Belt. We present new data on the structure, petrology, geochemistry and zircon U–Pb isotope ages of the Mazongshan subduction–accretion complex, which is a tectonic mélange with a block-in-matrix structure. The blocks are of serpentinized peridotite, basalt, gabbro, basaltic andesite, chert and seamount sediments within a matrix that is mainly composed of fore-arc-trench turbidites. U–Pb zircon ages of two gabbros are 454.6 ± 2.5 Ma and 434.1 ± 3.6 Ma, an andesite has a U–Pb zircon age of 451.3 ± 3.5 Ma and a tuffaceous slate has the youngest U–Pb zircon age of 353.6 ± 5.1 Ma. These new isotopic ages, combined with published data on ophiolitic mélanges from central Beishan, indicate that the subduction–accretion of Beishan in the southernmost Central Asian Orogenic Belt lasted until Late Ordovician – Early Carboniferous time. Structure and age data demonstrate that the younging direction of accretion was southwards and that the subduction zone dipped continuously to the north. Accordingly, these results record the conversion of oceanic to continental crust in the southern Beishan accretionary collage.

scholarly journals Crustal growth and reworking: A case study from the Erguna Massif, eastern Central Asian Orogenic Belt

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chenyang Sun ◽  
Wenliang Xu ◽  
Peter A. Cawood ◽  
Jie Tang ◽  
Shuo Zhao ◽  
...  
Keyword(s):  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Growth ◽  
Central Asian ◽  
Mesozoic Granitoids ◽  
Tectonic Settings ◽  
Crustal Heterogeneity ◽  
Erguna Massif ◽  
T Values

AbstractDespite being the largest accretionary orogen on Earth, the record of crustal growth and reworking of individual microcontinental massifs within the Central Asian Orogenic Belt (CAOB) remain poorly constrained. Here, we focus on zircon records from granitoids in the Erguna Massif to discuss its crustal evolution through time. Proterozoic–Mesozoic granitoids are widespread in the Erguna Massif, and spatiotemporal variations in their zircon εHf(t) values and TDM2(Hf) ages reveal the crustal heterogeneity of the massif. Crustal growth curve demonstrates that the initial crust formed in the Mesoarchean, and shows a step-like pattern with three growth periods: 2.9–2.7, 2.1–1.9, and 1.7–0.5 Ga. This suggests that microcontinental massifs in the eastern CAOB have Precambrian basement, contradicting the hypothesis of significant crustal growth during the Phanerozoic. Phases of growth are constrained by multiple tectonic settings related to supercontinent development. Calculated reworked crustal proportions and the reworking curve indicate four reworking periods at 1.86–1.78 Ga, 860–720 Ma, 500–440 Ma, and 300–120 Ma, which limited the growth rate. These periods of reworking account for the crustal heterogeneity of the Erguna Massif.

Magma volume and timescales in the formation of porphyry molybdenum deposits: A case study from the Central Asian Orogenic Belt

Lithos ◽  
2021 ◽  
Vol 382-383 ◽  
pp. 105951
Author(s):  
Qiang Zhang ◽  
Zhaochong Zhang ◽  
Zhiguo Cheng ◽  
M. Santosh ◽  
Zhenchao Wang ◽  
...  
Keyword(s):  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Central Asian
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