Polybaric Fractionation in an Evolving Continental Rift: Evidence from the Keweenawan Mid-Continent Rift

1989 ◽  
Vol 97 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Kenneth W. Klewin
Keyword(s):  
Continental Rift ◽  
Polybaric Fractionation

Petrogenesis and tectonic significance of the middle Neoproterozoic highly fractionated A-type granite in the South Qinling block

2021 ◽  
pp. 1-20
Author(s):  
Xiao-Fei Qiu ◽  
Qiong Xu ◽  
Tuo Jiang ◽  
Shan-Song Lu ◽  
Long Zhao
Keyword(s):  
Tectonic Setting ◽  
Eastern China ◽  
Continental Rift ◽  
The South ◽  
Yangtze Craton ◽  
Dabie Orogen ◽  
Northern Margin ◽  
South Qinling ◽  
Type Granite ◽  
High Alkali

Abstract The South Qinling block, a segment of the Yangtze craton involved in the Qinling–Dabie orogen, is critical for understanding the tectonic evolution of eastern China. However, the tectonic setting of the South Qinling block and the northern margin of the Yangtze block during middle Neoproterozoic time has long been the subject of debate, with two distinctly different models (continental rift or volcanic arc) proposed. Here, a comprehensive study of zircon U–Pb geochronology and geochemistry has been carried out on the Chengwan granitic pluton from the Suizao terrane in the South Qinling block. The granites are monzogranite and syenogranite in lithology, and are mainly composed of potash feldspar, quartz, plagioclase and biotite. This suite has long been regarded as a Palaeozoic magmatic pluton, but zircon U–Pb ages of 809 ± 9 Ma and 816 ± 4 Ma are obtained in this study. The granites are metaluminous to strongly peraluminous with high alkali contents, and exhibit highly fractionated features, including high SiO2, low Zr/Hf ratios, rare earth element tetrad effects and enrichment of K and Rb. They show Hf–Nd isotopic decoupling, which may be genetically related to their petrogenetic process. Based on the geochemical features and the positive εHf(t) values of the zircons, it is indicated that the granites may have been derived from partial melting of juvenile tonalitic rocks by biotite breakdown under fluid-absent conditions. The Chengwan granite geochemically belongs to the A2-subtype granites, suggesting that it might have formed in a post-orogenic tectonic setting. The highly fractionated A-type granite in this study may represent extensional collapse shortly after the collisional events in the South Qinling block, and thus indicate a tectonic regime switch, from compression to extension, as early as middle Neoproterozoic time. Integrating our new data with documented magmatic, metamorphic and sedimentary events during middle Neoproterozoic time in the region may support a continental rift model, and argues against arc models.

Ca. 1050 Ma intra-continental rift-related A-type felsic rocks in the southwestern Yangtze Block, South China

2018 ◽  
Vol 309 ◽  
pp. 22-44 ◽  
Author(s):  
Wei Terry Chen ◽  
Wei-Hua Sun ◽  
Mei-Fu Zhou ◽  
Wei Wang
Keyword(s):  
South China ◽  
Continental Rift ◽  
Yangtze Block ◽  
Felsic Rocks

scholarly journals Insights into the effects of oblique extension on continental rift interaction from 3D analogue and numerical models

2016 ◽  
Vol 693 ◽  
pp. 239-260 ◽  
Author(s):  
Frank Zwaan ◽  
Guido Schreurs ◽  
John Naliboff ◽  
Susanne J.H. Buiter
Keyword(s):  
Numerical Models ◽  
Continental Rift

Evidence for regional metamorphism in a continental rift during the Rodinia breakup

2018 ◽  
Vol 314 ◽  
pp. 414-427 ◽  
Author(s):  
Qiang He ◽  
Shao-Bing Zhang ◽  
Yong-Fei Zheng
Keyword(s):  
Regional Metamorphism ◽  
Continental Rift
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