| Citation: |
FAN Bingliang, WANG Xinran, BAI Tao, YU Jiashu, FENG Dexin, XU Changhao. LA-ICP-MS zircon U-Pb age of Late Cambrian Cuoduo-qin quartz diorite in Kargangarea and its significance[J]. Geological Bulletin of China, 2020, 39(4): 471-479.
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LA-ICP-MS zircon U-Pb age of Late Cambrian Cuoduo-qin quartz diorite in Kargangarea and its significance
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Abstract
LA-ICP-MS zircon U-Pb age test was carried out on the Cuoduo-qin quartz diorite in Kargang area, and the result shows that the 206Pb/238U age weighted average value of the rock mass is 495.9±3.2 Ma (MSWD=1.8, n=24), suggesting a product of Late Cambrian.The geochemical characteristics of the rocks show that the rocks have the characteristics of low potassium, rich sodium (Na2O/K2O=4.16~5.47), low alkali (K2O+Na2O=6.41%~6.67%), and low aluminum (Al2O3=14.64%~14.98%, A/CNK≈0.9), implying low potassium calcium alkaline quasi-aluminum type Ⅰ granite.The overall performance of the rare earth elements is the right-inclined type of the relative enrichment exhibiting steep shape on the left and smooth shape on the right for the light rare earth elements, the relative loss of Nb, Sr, P, Ti and other high field strength elements, and enrichment of Rb, Th, U and other large ionic pro-stone elements, with the characteristics of island arc granite.Combined with the analysis of regional geological data, the authors hold that there is a genetic connection between the rock mass and the subduction of the original Tethys Ocean in this area, and the discovery of the Cuoduo-qin quartz diorite is helpful to further exploration of the original Tethys Ocean evolution process.
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References
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FAN Bingliang, WANG Xinran, BAI Tao, YU Jiashu, FENG Dexin, XU Changhao. LA-ICP-MS zircon U-Pb age of Late Cambrian Cuoduo-qin quartz diorite in Kargangarea and its significance[J]. Geological Bulletin of China, 2020, 39(4): 471-479.
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Figure 1.
Tectonic loacation and geological sketch map (b) of the Cuoduo-qin diorite
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Figure 2.
Geological map (a)and field photograph(b)and microphotograph(c)of the Cuoduo-qin quartz diorite
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Figure 3.
SiO2-K2O(a)and A/CNK-A/NK(b)plots of the Cuoduo-qin quartz diorite
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Figure 4.
Chondrite-normalized REE patterns (a) and primitive mantle-normalized trace element patterns(b) of the Cuoduo-qin quartz diorite
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Figure 5.
Cathodoluminescence images and U-Pb age of the Cuoduo-qin quartz diorite
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Figure 6.
Zircon U-Pb concordia diagram of the Cuoduo-qin quartz diorite
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Figure 7.
The genetic discriminant diagrams of the Cuoduo-qin quartz diorite
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Figure 8.
The Illustration of tectonic environment discrimination of the Cuoduo-qin quartz diorite