Geochemistry, Zircon U-Pb Age and Hf Isotopic Constraints on the Petrogenesis of the Silurian Rhyolites in the Loei Fold Belt and Their Tectonic Implications
Zircon U-Pb dating, Lu-Hf isotopic and geochemical data for the Silurian rhyolites from the Loei fold belt are presented to constrain their petrogenesis and tectonic settings.The rhyolites give a weighted mean 206pb/238U age of 423.7±2.7 Ma, and are characterized by high SiO2, Al2O3, K2O and low MnO, MgO and P2O5.All samples are enriched in LILEs (e.g., Ba, K, Pb) and LREEs and depleted in HFSEs (e.g., Nb, Ta, Ti) with obvious negative Eu-anomalies (δEu=0.56-0.63).The calc-alkaline rhyolites are typical arc-related rocks.The Loei rhyolites have high A/CNK ratios (1.19-1.34) and positive εHf(t) (4.03-5.38), which can be interpreted as partial melting of juvenile crustal materials followed by multistage melting and differentiation, similar to highly fractional Ⅰ-type rocks.Combined with regional geological surveys, the Loei rhyolites should be formed in a volcanic arc environment and may be in contact with the Truong Son fold belt during the Early Paleozoic.Moreover, the Simao Block might be in contiguity with the Indochina Block during Silurian.
Ⅰ-type rhyolite zircon U-Pb dating Hf isotopic composition geochemical characteristics Loci fold belt Indochina Block
Tianyu Zhao Xin Qian Qinglai Feng
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
国际会议
武汉
英文
391-402
2015-10-16（万方平台首次上网日期，不代表论文的发表时间）