大别-苏鲁造山带榴辉岩及其中磷灰石的碳同位素地球化学  

Carbon Isotopes Geochemistry of Eclogite and Enclosed Apatite Separate from the Dabie-Sulu Orogen

作　　者：郑永飞[1] 李一良[1] 龚冰[1] 

机构地区：[1]中国科学技术大学地球和空间科学系化学地球动力学研究实验室,安徽合肥230026

出　　处：《矿物岩石地球化学通报》2001年第4期312-316,共5页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家重点基础研究发展规划项目 (G19990 75 5 0 3);中国科学院知识创新项目 (KZCX2 10 7)资助成果

摘　　要：应用EA MS连线技术 ,对大别山东部和苏鲁地体南部超高压变质榴辉岩及其中的磷灰石进行了碳的含量和同位素分析。结果得到 ,榴辉岩全岩的δ1 3 C值变化较大 (- 30 .7‰～ +2 .5‰ ) ,而所含磷灰石中结构碳酸根的δ1 3 C值变化较小并显著亏损1 3 C(- 2 8.1‰～ - 2 0 .8‰ )。部分榴辉岩具有高的全岩δ1 3 C值 ,指示其形成后受到过含CO2 流体的退化蚀变。低的磷灰石δ1 3 C值指示 ,榴辉岩中含有地表有机碳 ,因此证明这些榴辉岩的原岩曾出露过地表 ,在超高压变质阶段存在以亏损1 3 C为特征的含CO2 流体。The carbon concentration and isotope composition of ultrahigh pressure eclogite and apatite separate from the Dabie-Sulu orogen were analyzed by the EA-MS online technique. The results show a large variation in δ 13C values from -30.7‰ to +2.5‰ for eclogite whole-rock, but a small δ 13C range of -28.1‰ to -20.8‰ for structural carbonate in apatite. Some of the eclogites with the high δ 13C values suffered retrograde alteration by CO 2-bearing fluids. The low δ 13C values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of eclogites was exposed to the surface of the Earth, and that the CO 2-bearing fluid was depleted in 13C during the eclogite-facies metamorphism.

关 键 词：地表碳 碳同位素 磷灰石 榴辉岩 造山带 大别-苏鲁 

分 类 号：P597[天文地球—地球化学]