【摘要】 富城杂岩体出露于赣东南,与闽西南的红山岩体共同构成富城-红山花岗质杂岩。富城杂岩主要由富城黑云母巨斑粗粒二长花岗岩、粗石坝中粒二云母花岗岩和珠长洞含红柱石细粒花岗岩三个单元组成。富城花岗岩含较低的 SiO₂、Rb、Nb 和较高的 Al₂O₃、Ba、Sr、Zr、REE 含量,岩石的 ACNK>1.10,K₂O/Na₂O>1.60。粗石坝花岗岩以高 SiO₂、K₂O,低 CaO、P₂O₅和富 Al（ACNK=1.13～1.20）为特征;岩石含较高的 Rb、Nb 和低的 Ba、Sr、Zr、REE 含量,并具有相对低的 K/Rb 和δ（Eu）比值。珠长洞含红柱石花岗岩的地球化学特征相似于富城花岗岩,除了更高的 ACNK 值（1.22～1.36）和 Rb、Nb 含量以及稍低的 Sr、Ba、Zr、REE 含量。富城单元的⁸⁴Sr/⁸⁶Sr 初始比值是0.7135～0.7196,ε_Nd（t）是-9.4～-10.2,Nd 模式年龄是1.78Ga 到1.84Ga,其中的锆石 Hf 模式年龄是1.70～1.89Ga,与 Nd 同位素一致;粗石坝单元具有与之相似的 Nd-Hf 同位素组成;珠长洞单元的⁸⁷Sr/⁸⁶Sr 初始比值更高（0.7214）,ε_Nd（t）更低（-16.9）,而 Nd 模式年龄达2.37Ga。这些地球化学特征表明富城杂岩体的源岩都是由古老物质组成的沉积岩,其中富城和粗石坝单元起源于具晚古元古代模式年龄的基底,而珠长洞单元的源区物质具有早古元古代平均地壳存留年龄。富城杂岩体的各单元之间没有显示一致的变化规律,表明它们不是单一岩浆演化的结果,它们成分的差异主要受源区成分影响。LA-ICPMS 的锆石 U-Pb 定年显示富城黑云母花岗岩形成较早（239±17Ma）,而粗石坝和珠长洞花岗岩形成稍晚（231±16 Ma 和229±6.8 Ma）。它们的形成时代与华南印支期早期构造-岩浆活动的峰期一致。结合地球化学和岩石组合特征,可以认为富城-红山杂岩形成于同构造背景。更多还原

【Abstract】 The Fucheng granitic complex is located in the southeastern Jiangxi province,which is combined with the Hongshan granite in the southwestern Fujian province to be the Fucheng-Hongshan Complex.The Fucheng Complex may be divided to three units,the Fucheng megacrystic porphyrotic biotite monzogranite,the Cushiha middle-grained two-mica granite and the Zhuchangdong andalusite-bearing fine-grained granite.The Fucheng biotite granites have relatively low SiO₂,Rb and Nb concentrations and high Al₂O₃,Ba,Sr,Zr,REE concentrations.Their ACNK are>1.10 and K₂O/Na₂O>1.60.The Cushiba granites are characterized by high SiO₂,K₂O and Al₂O₃（ACNK=1.13～1.20）,and low CaO and P₂O₅.The rocks are rich in Rb and Nb,and poor in Ba,Sr,Zr and REE.They all have relatively low K/Rb and Eu/Eu^* ratios.The Zhuchangdong andalusite-bearing granites are similar to the Fueheng granites in geochemistry,except for higher ACNK（1.22～1.36）,Cs,Rb,Nb,Ta and Sn concentrations and lower Sr,Ba, Zr,Hf and REE contents.The Fucheng granites have initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7135～0.7196 and ε_Nd（t）of -9.4～-10.2 with the Nd model ages ranging from 1.84Ga to 1.78Ga.The zircons in the Fucheng granite have Hf model ages of 1.70～1.89Ga, consistent with bulk Nd model ages.The Cushiba granites have bulk Nd isotope and zircon Hf isotope similar to the Fucheng granites. The Zhuchangdong granite has higher initial ⁸⁷Sr/⁸⁶Sr ratio（0.7214）and lower ε_Nd（t）value（-16.9）with older Nd model age （2.37Ga）.These geochemical data indicate that the protoliths of granites in the Fucheng Complex are sedimentary rocks consisting of ancient crustal materials.The original magma of the Fucheng and Cushiba granites probably originated from late Paleoproterozoic basement,and the source of the Zhuchangdong granites is early Paleoproterozoic basement.A variety of granites from the three units in the complex do not exhibit coherent geochemical change,suggesting they are not the results evolved from an original magma,which also is supported by field observation and geochronological studies.The difference in geochemistry among granites from three units is likely caused by the source compositions.LA ICPMS zircon U-Pb dating indicates that the Fucheng granite formed at ca.239Ma,and the Cushiba and Zhuchangdong granites formed at 231～229 Ma,which are in accordance with peak time of early Indosinian tectonic- magmatic activity in south China.Coupled with the geochemical characteristics and assemblage of Indosinian rocks,it is suggested that the Fucheng-Hongshan granitic complex was probably formed in the syn-orogenic tectonic setting.更多还原