晚太古代Sanukite(赞岐岩)与地球早期演化  

Sanukite of late Archaean and early Earth evolution.

作　　者：张旗[1] 王焰[2] 钱青[1] 翟明国[1] 金惟浚[1] 王元龙[1] 简平[3] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]香港大学地球科学系 [3]中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2004年第6期1355-1362,共8页Acta Petrologica Sinica

基　　金：国家自然科学基金(40472047);国家自然科学重点基金项目(40234045);中国科学院知识创新工程基金(KZCX 1-07和KZCX2-SW-119)资助的项目

摘　　要：Shirey and Hanson(1984)将某些太古代的高镁闪长岩套称为sanukite(赞岐岩),类似于日本中新世(11～15 Ma)Setouchi火山岩带的高镁安山岩.Sanukitoids由闪长岩-二长闪长岩-花岗闪长岩组成,不同于TTG岩套(奥长花岗岩-英云闪长岩-花岗闪长岩).Sanukitoids具有下列地球化学特征:富Mg,Mg#＞0.60,Ni和Cr＞100μg/g,Sr和Ba＞500μg/g,LREE富集(大于球粒陨石100倍),无Eu异常.高镁安山岩在太古代很少见,而其相应的侵入岩高镁闪长岩或sanukitoids,虽然数量也很少,但却是各地晚太古代地体中随处可见的.Sannkitoids的原始岩浆是交代的地幔楔部分熔融形成的,随后可能经历了广泛的分离结晶作用.TTG和sanukitoids岩套可以相伴产出,二者均与板片熔融有关,TTG与其直接有关,sanukitoids可能与其间接有关.全球Sanukitoids主要集中在晚太古代时期,可能暗示板块的消减作用在～3.0 Ga以后才起了重要的作用.Some Archean high-Mg diorites suite originally were recognized and termed sanukitoids by Shirey and Hanson (1984), which are similar to those of high-Mg andesites found in the Setouchi Miocene (11 similar to 15 Ma) volcanic belt in Japan. The sanukitoids are composed of diorite-monzodiorites-granodiorite and different from those of TTG suite (trondhjemite-tonalite-granodiorite). Sanukitoids have the following chemical characteristics: Mg numbers > 0.60, Ni and Cr are both > 100 ppm, Sr and Ba both typically > 500 ppm, and light rare earth elements are strongly enriched (> 100 chondritic values) with no Eu anomaly. High-Mg andesite is rare in the Archaean, but the intrusive equivalent, high-Mg diorite or sanukitoid, forms a minor but widespread component of most late Archaean terrains. The source region for sanukitoid parent magmas is thought to be the melting of the metasomatized mantle wedge, followed by extensive fractional crystallization in the crust. TTG and the sanukitoid suite may be continuous with each other, and both the products of slab melting, either directly (TTG) or indirectly (sanukitoid). Sanukitoids appear to concentrate in the Late Archaean, suggesting that subduction may have become an important process only after similar to 3.0 Ga.

关 键 词：Sanukite 赞岐岩 TTG 晚太古代 成因 形成环境 板块构造 

分 类 号：P588.122[天文地球—岩石学]