Mingda Huang , Xiaozhuang Cui , Guangming Ren , Qi Deng , Fenglin Chen , Junwei Yang , Tao Li , Zhiming Sun
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引用次数: 0
Abstract
The geodynamic setting of the southwestern Yangtze Block in the latest Mesoproterozoic has been a controversial issue for decades, which confuses the relationship between the Yangtze Block and the assembly of Rodinia supercontinent. We here report an integrated dataset of petrology, whole-rock geochemistry, zircon U-Pb ages and Hf isotopes for the newly identified latest Mesoproterozoic granitoids from the Yonglang area, southwestern Yangtze Block. SHRIMP and LA-ICP-MS zircon U-Pb dating results suggest that these granitoids were mainly crystallized at ca. 1.02 Ga. These samples show typical geochemical signatures of I-type granite, such as negative correlation between P2O5 and SiO2 contents, positive correlation between A/CNK ratios and SiO2 contents, and zirconium saturation temperature (Tzr) of 748–818 °C. Their zircon εHf(t) values range from −3.0 to 0.8, with two-stage model ages of 2.0–1.8 Ga. These ca. 1.02 Ga granitoids were likely generated by the partial melting of amphibolites under H2O-rich conditions originated from hydrous fluids of the subduction components, reinforced a latest Mesoproterozoic arc-back-arc system in the southwestern Yangtze Block. Based on the spatial–temporal variations of the late Mesoproterozoic subduction-related magmatic records around the periphery of the Yangtze Block, it is suggested that this block may have started to drift towards the Rodinia supercontinent at least at ca. 1.02 Ga.
期刊介绍:
Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as:
(1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology;
(2) Geochronology and isotope and elemental geochemistry;
(3) Precambrian mineral deposits;
(4) Geophysical aspects of the early Earth and Precambrian terrains;
(5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes.
In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes.
Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.