榴辉岩退变质过程的地球化学研究——以荣成-威海岩段的榴辉岩体为例  

RESEARCH ON GEOCHEMICAL VARIATION DURING THE RETROGRADE METAMORPHIC PROCESSES OF ECLOGITE——From the eclogite bosies in the Rongcheng Weihai rock belt of SU-LU (Jiangsu-Shandong) UHMB

作　　者：孙景贵[1] 胡受奚[1] 

机构地区：[1]南京大学地球科学系金属成岩成矿实验室,南京210093

出　　处：《矿物岩石》2000年第1期17-23,共7页Mineralogy and Petrology

基　　金：国家自然科学基金项目!( 4 913 3 12 0 );南京大学金属成矿实验室开放课题成果

摘　　要：苏鲁超高压 -高压变质岩带为 A型俯冲作用的产物。带内的榴辉岩体多发生退变质作用 ,形成退变榴辉岩、榴闪岩及斜长角闪岩等 ,与榴辉岩一起记录了高压 -超高压进变质峰期经过构造回返减压、降温演化过程所发生物质成分交换的重要信息。本文以荣成-威海岩段具“核 -壳”构造的榴辉岩体为例 ,依据地质、岩相学特征 ,进行了退变质过程元素地球化学变异的深入研究。该过程中主要元素 K,Ba,Rb等大离子亲石元素及 w(K2 O) /w(Na2 O) ,w(Fe2 O3) /w(Fe O) ,w (L REE) /w(HREE)的增加 ,体现壳源物质的加入 ;成矿元素 Zn等明显增加 ,Ni,Co,Cr,Cu降低并均进入围岩或聚集于外壳斜长角闪岩中。这一规律不仅反映伴随构造折返、环境向相对氧化环境变化 ,不仅地壳物质及流体成分加入、发生广泛的物质交换 ,而且揭示了这一过程壳 -幔物质交换的成岩成矿规律。Ultra high pressure metamorphic belt(UHMB) in east Sandong province is the product of A type subduction. Many eclogite bodies in the belt experienced retrograde metamorphism stage and recorded important information that reflects the change from the ultra high pressure advance metamorphism peak phase to retrogressive metamorphism evidenced by variation of eclogite to retrograde eclogite, amphibolite eclogite and amphibolite successively.The study of the geochemical variations of “core shell” structure in eclogite bodies in Rongcheng Weihai rock belt shows that major and trace elements of from eclogite, retrograde eclogite, amphibolite eclogite and amphibolite change with regularity. LILE such as K, Ba, Rb, and K 2O/Na 2O, Fe 2O 3/FeO, LREE/HREE increase gradually, which reflects the introduction of crustal materials. The increased metallogenic element such as Zn and the decreased, Ni, Co, Cr, Cu entered adjacent rock or agglomerate in shell amphibolite. The regularity reveals the diagenetic and mineralizing processes under the condition of exchange of mantle and crust materials.

关 键 词：榴辉岩 退变质过程 地球化学 荣成-威海岩段 

分 类 号：P588.3[天文地球—岩石学]