Neoproterozoic gabbro-granite association from the Micangshan area, northern Yangtze Block: Implication for crustal growth in an active continental margin

2017 ◽  
Vol 53 (6) ◽  
pp. 2471-2486 ◽  
Author(s):  
Shao-Cong Lai ◽  
Jiang-Feng Qin ◽  
Xiao-Ping Long ◽  
Yong-Fei Li ◽  
Yin-Juan Ju ◽  
...  
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Crustal Growth ◽  
Yangtze Block

Provenance of Late Ordovician sedimentary rocks in the SE Yangtze block: Implications for deposition in an active continental margin

2020 ◽  
Vol 127 ◽  
pp. 103862
Author(s):  
Tao Yu ◽  
Zongqi Wang ◽  
Dongsheng Wang ◽  
Changqian Ma ◽  
Yingli Zhang ◽  
...  
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Late Ordovician ◽  
Yangtze Block

Styles of Proterozoic crustal growth on the southeast margin of Laurentia: evidence from the central Grenville Province northwest of Lac St.-Jean, Quebec

2005 ◽  
Vol 42 (10) ◽  
pp. 1643-1652 ◽  
Author(s):  
C Martin ◽  
A P Dickin
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Arc Magmatism ◽  
Crustal Growth ◽  
Grenville Province ◽  
Nd Isotope ◽  
Continental Arc ◽  
Wide Range ◽  
Western Block ◽  
Continental Arc Magmatism

The southeast margin of Laurentia was a very long lived active continental margin, part of whose history is recorded in the Grenville Province of the Canadian Shield. Within this province, Nd-isotope mapping can be used to define the boundaries between terranes with a variety of crustal formation ages and can also distinguish between crustal growth by oceanic and continental-arc magmatism. The former gives rise to large terranes with homogeneous Nd-isotope signatures and well-defined boundaries, whereas the latter leads to areas with heterogeneous Nd-isotope signatures. One of the best examples of continental-arc magmatism in the Grenville Province is provided by the region northwest of Lac St.-Jean, Quebec. Eighty new Nd-isotope analyses are used (along with aeromagnetic data) to divide this area into three blocks, bounded by abrupt changes in Nd model age. The western block consists almost exclusively of tonalitic grey gneisses with Archean model ages. The eastern block is composed almost exclusively of gneisses with Nd model ages of 1.6–1.5 Ga and tonalite–trondhjemite–granodiorite-type chemistry. In contrast, the central block has a wide range of Nd-isotope signatures and more alkaline major element chemistry characteristic of an ensialic arc. The εNd values in this block correlate with distance southeast of the Allochthon Boundary Thrust, suggesting that ensialic arc magmas suffered diminishing contamination in a southeastward direction by old Laurentian crust. A subduction-flip model is proposed, whereby north-dipping subduction under the continental margin followed the accretion of a Mesoproterozoic arc terrane to the Laurentian craton.

Neoproterozoic active continental margin in the southeastern Yangtze Block of South China: Evidence from the ca. 830–810Ma sedimentary strata

2016 ◽  
Vol 342 ◽  
pp. 254-267 ◽  
Author(s):  
Wei Wang ◽  
Mei-Fu Zhou ◽  
Jun-Hong Zhao ◽  
Manoj K. Pandit ◽  
Jian-Ping Zheng ◽  
...  
Keyword(s):  
Continental Margin ◽  
South China ◽  
Active Continental Margin ◽  
Yangtze Block

Nature and origin of the volcanic ash beds near the Permian–Triassic boundary in South China: new data and their geological implications

2019 ◽  
Vol 157 (4) ◽  
pp. 677-689 ◽  
Author(s):  
Binsong Zheng ◽  
Chuanlong Mou ◽  
Renjie Zhou ◽  
Xiuping Wang ◽  
Zhaohui Xiao ◽  
...  
Keyword(s):  
Trace Element ◽  
Continental Margin ◽  
South China ◽  
Volcanic Ash ◽  
Active Continental Margin ◽  
Main Body ◽  
Early Triassic ◽  
Late Permian ◽  
Triassic Boundary ◽  
Permian Triassic Boundary

AbstractPermian–Triassic boundary (PTB) volcanic ash beds are widely distributed in South China and were proposed to have a connection with the PTB mass extinction and the assemblage of Pangea. However, their source and tectonic affinity have been highly debated. We present zircon U–Pb ages, trace-element and Hf isotopic data on three new-found PTB volcanic ash beds in the western Hubei area, South China. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons yields ages of 252.2 ± 3.6 Ma, 251.6 ± 4.9 Ma and 250.4 ± 2.4 Ma for these three volcanic ash beds. Zircons of age c. 240–270 Ma zircons have negative εHf(t) values (–18.17 to –3.91) and Mesoproterozoic–Palaeoproterozoic two-stage Hf model ages (THf2) (1.33–2.23 Ga). Integrated with other PTB ash beds in South China, zircon trace-element signatures and Hf isotopes indicate that they were likely sourced from intermediate to felsic volcanic centres along the Simao–Indochina convergent continental margin. The Qinling convergent continental margin might be another possible source but needs further investigation. Our data support the model that strong convergent margin volcanism took place around South China during late Permian – Early Triassic time, especially in the Simao–Indochina active continental margin and possibly the Qinling active continental margin. These volcanisms overlap temporally with the PTB biocrisis triggered by the Siberian Large Igneous Province. In addition, our data argue that the South China Craton and the Simao–Indochina block had not been amalgamated with the main body of Pangea by late Permian – Early Triassic time.

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