U-Pb Zircon Age, Geochemical and Sr-Nd Isotopic Constraints on the Age and Origin of the Granodiorites in Guilong, Southeastern Yunnan Province, Southern China

• 作者: Caixia Feng Chaogui Yang Guangying Feng Ian M. Coulson Ruizhong Hu Shan Gao Shen Liu Tao Wang Youqiang Qi Yuhong Yang
• 来源期刊: 地质学期刊(英文)
• 学科: 地球科学
• 关键词: Granodiorites Age ORIGIN Southeastern YUNNAN Province Southern China
• 年，卷（期）: 2012,（4）
• 页码范围: 229-240
• 页数: 12页
• 分类号: P5

摘要

Post-collision felsic rocks in Southeastern Yunnan province contain granodiorites. U-Pb zircon ages, geochemical data and Sr-Nd isotopic data for these rocks are reported in the present paper. Laser ablation inductively coupled plasma mass spectrometry U-Pb zircon analyses yielded consistent age 252.5 ± 1.0 Ma for one sample of the felsic rocks. The granodiorites were characterized by variational and high (87Sr/86Sr)i, ranging from 0.7223 to 0.7236 and very low εNd (t) values from –29.1 to –30.4. In addition, these rocks are characterized by slight Eu negative anomalies, Nb, Ta, Ti and Sr negative anomalies on primitive mantle normalization spider. Geochemical and isotopic characteristics suggest that these rocks were derived from an enriched crust source. The granodiorites resulted from the fractionation of potassium feldspar, plagioclase and ilmenite or rutile. However, the granodiorites were unaffected by visible crustal contamination during ascent. As a result, the granodiorites may have been formed due to partial melting of crust-derived sedimentary rocks beneath southeastern Yunnan province, southern China.