摘要
In the eastern Nanling Range there exists the early Yanshanian syenite-granite assemblage. A representative example is the Pitou-Tabei complex composed of the Tabei syenite pluton and the Pitou syenogranite pluton in southern Jiangxi Province. U-Pb zircon dating yields ages of 188.6±2.2 Ma for the Tabei pluton and 186.3±1.1 Ma for the Pitou pluton. The Tabei syenite is characterized by relatively low SiO2 content (62.40% - 68.75%), high alkalis (K2O+Na2O = 10.56%-11.96%), low percent K2O/Na2O ratios (0.56-0.93), metaluminous fea- ture (A/CNK = 0.80-1.00), enrichment in LILE (Rb, Ba, K) and HFSE (Th, U, Nb, Ta, Zr, and so on), weakly negative to positive Eu anomalies (δ Eu = 0.63-1.82), relatively low (87Sr/86Sr)i (0.70412-0.70543), and relatively high ε Nd(t) (3.14-3.52). The Pitou syenogranite is charac- terized by high silicon content (SiO2 = 71.06%-76.28%), relatively low alkalis (K2O+Na2O = 8.10%-9.80%), high percent K2O/Na2O ratios (1.22-1.94), metaluminous feature (A/CNK = 0.94-1.07), enrichment in Rb, Th (U), K, depletion in Ba, Nb, Ta, Sr, P , Zr, Ti, high ΣREE (av- eraging 451.03 μg/g), strong negative Eu anomalies (δ Eu = 0.27-0.33), relatively high (87Sr/86Sr)i (0.70805-0.70912), and relatively low ε Nd( t ) (?5.35-?6.29). The Tabei syenite and Pitou syenogranite both have the characteristics of A-type granites. The former is considered to be from the asthenosphere mantle, and the latter was the product of the crust-mantle mixture. They both were probably formed in a rifting setting.
In the eastern Nanling Range there exists the early Yanshanian syenite-granite assemblage. A representative example is the Pitou-Tabei complex composed of the Tabei syenite pluton and the Pitou syenogranite pluton in southern Jiangxi Province. U-Pb zircon dating yields ages of 188.6±2.2 Ma for the Tabei pluton and 186.3±1.1 Ma for the Pitou pluton. The Tabei syenite is characterized by relatively low SiO2 content (62.40% - 68.75%), high alkalis (K2O+Na2O = 10.56%-11.96%), low percent K2O/Na2O ratios (0.56-0.93), metaluminous fea- ture (A/CNK = 0.80-1.00), enrichment in LILE (Rb, Ba, K) and HFSE (Th, U, Nb, Ta, Zr, and so on), weakly negative to positive Eu anomalies (δ Eu = 0.63-1.82), relatively low (87Sr/86Sr)i (0.70412-0.70543), and relatively high ε Nd(t) (3.14-3.52). The Pitou syenogranite is charac- terized by high silicon content (SiO2 = 71.06%-76.28%), relatively low alkalis (K2O+Na2O = 8.10%-9.80%), high percent K2O/Na2O ratios (1.22-1.94), metaluminous feature (A/CNK = 0.94-1.07), enrichment in Rb, Th (U), K, depletion in Ba, Nb, Ta, Sr, P , Zr, Ti, high ΣREE (av- eraging 451.03 μg/g), strong negative Eu anomalies (δ Eu = 0.27-0.33), relatively high (87Sr/86Sr)i (0.70805-0.70912), and relatively low ε Nd( t ) (?5.35-?6.29). The Tabei syenite and Pitou syenogranite both have the characteristics of A-type granites. The former is considered to be from the asthenosphere mantle, and the latter was the product of the crust-mantle mixture. They both were probably formed in a rifting setting.
作者
CHEN Peirong1, ZHOU Xinmin1, ZHANG Wenlan1, LI Huimin2, FAN Chunfang1, SUN Tao1, CHEN Weifeng1 & ZHANG Min1 1. State Key Laboratory of Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China
2. Tianjin Institute of Geology and Mineral Resources, China Geological Survey, Tianjin 300170, China
基金
the NationalNatural Science Foundation of China(Grant Nos.40132010 ,40125007)
the State Key Fundamental Research Project(Grant No.1999043209).
