Petrogenesis of Paleoproterozoic Luyashan charnockitic rocks in Shanxi Province: Constraints from Geochemistry and Nd isotope  

作　　者：LIU Chaohui LIU Shuwen LI Qiugen WANG Yueran DANG Qingning GU Libing YANG Bin ZHAO Fengsan 

机构地区：[1]Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education [2] School of Earth and Space Sciences, Peking University,Beijing 100871, China

出　　处：《Progress in Natural Science:Materials International》2006年第2期183-191,共9页自然科学进展·国际材料（英文版）

基　　金：National Natural Science Foundation of China (Grant No.40420120135)

摘　　要：Luyashan charnockite pluton mainly consists of monzonite, adamellite, charnockite and syenogranite, which are characterized by the enrichment of TiO2, P2O5, K2O, Zr, Nb, Y, Pb, La, Ce, Ba and a higher K2O/Na2O and depletion of MgO, CaO, Mg^#, Th, U and lower Sr/Ba and Rh/Ba. The negative correlations between Zr, Nb, Ce and SiO2 are distinct from I-type granites. Isotopically Luyashan charnoekite plutons are relatively uniform in Nd isotope, displaying initial εNa（ t ） （-5.93 to -6.97） and Nd depleted mantle model ages （2.67 Ga to 2.78Ga）. These features indicate that Luyashan eharnockitie magma derived from pre-existing late Archean crustal sources and the partial melting of mafic granulites probably under exeeptionally high temperature with CO2-rieh fluid. The garnet is a main residual phase during the partial melting. The original dry eharnoekitic magma experienced crystal fraetionation of pyroxene, plagioclase, apatite and ilmenite during early crystallization. The geochemical evidence suggests that the Luyashan charnockitic magma was probably generated in the post-collision thermal relaxation and uplift tectonic setting after the main collision （ - 1850 Ma） between the Eastern and Western continental blocks.Luyashan charnockite pluton 主要由二长岩， adamellite ， charnockite 和 syenogranite 组成，它被 TiO <SUB>2</SUB>, P <SUB>2</SUB 的enrich 描绘> O <SUB>5</SUB>, K <SUB>2</SUB > O ， Zr ， Nb ， Y ， Pb ， La ， Ce ， Ba 和更高的 K <SUB>2</SUB > O/Na <SUB>2</SUB > MgO ， CaO ， Mg <SUP>#</SUP>, Th ， U 和更低的 Sr 的 O 和弄空 Ba 和 Rb Ba 。在 Zr， Nb， Ce 和 SiO <SUB>2</SUB> 之间的否定关联从我类型花岗石是不同的。同位素地 Luyashan charnockite plutons 在 Nd 同位素是相对一致的，显示起始的 <SUB>&#949;Nd</SUB>(t)( 到 -6.97) 和 Nd 的 -5.93 弄空披风模型年龄(到 2.78 Ga 的 2.67 Ga ) 。这些特征显示那 Luyashan charnockitic 岩浆从先存在导出晚太古代的外壳的来源并且与公司 <SUB>2</SUB>-rich 液体的在特别高的温度下面的可能的 mafic granulites 的部分融化。石榴石在部分融化期间是一个主要剩余阶段。原来的干燥 charnockitic 岩浆在早结晶化期间经历了辉石，斜长石，磷灰石，和钛铁矿的水晶分别。geochemical 证据建议 Luyashan charnockitic 岩浆可能在碰撞以后的热松驰被产生并且高举在主要碰撞以后的构造背景(&#8764;1850 妈) 在东方、西方的大陆人块之间。

关 键 词：Luyashan charnockite GEOCHEMISTRY Sm-Nd isotopes PETROGENESIS PALEOPROTEROZOIC 

分 类 号：P588.121[天文地球—岩石学]