赤峰东南部建平群斜长角闪岩黑云母矿物化学特征及地质意义

利用电子探针、激光剥蚀-电感耦合等离子体质谱测试技术,对赤峰东南部建平群斜长角闪岩中黑云母的常量元素、微量(稀土)元素进行了测试分析。研究表明:赤峰东南部建平群斜长角闪岩中的黑云母主量元素以富Fe、Mg为特征,为高铁镁云母;黑云母稀土元素含量低,轻重稀土分馏较强,δEu、δCe均值为正,为选择Ce、Nd的配分型矿物;黑云母中Rb、Ba、Pb和Cs等大离子亲石元素富集,特别是Cs、Ba明显富集,而Sr略有亏损;高场强元素Zr、Hf、Sc等亏损,较富集的元素为U、Th、Nb、Ta元素;亏损的亲铁元素为Cr、Ni,而显著富集的元素为V、Ti;亲硫元素Cu亏损而Zn明显富集;分散元素Ga有明显的富集。

Geochemical characteristics of biotites from amphibolites in Jianping Group,southeastern Chifeng and their geological implications

The major and trace elements for biotites from amphibolites in Jianping Group，located in the southeast of Chifeng City，have been analyzed by electron microprobe and laser ablation inductively coupled plas- ma- mass spectrometry (LA- ICP- MS)． The study shows that the biotite from amphibolites in Jianping Group char- acterized by enrichment in Fe and Mg，belonging to high iron magnesia mica． The biotites are low ＲEE in content， with strong fractionation between LＲEE and HＲEE and positive anomalies of both Eu and Ce，indicating the bio- tites as a Ce + Nd － rich fraction elemental assemblage mineral． The biotites exhibit the enrichment of LILE (e. g． ，Ｒb，Ba，Pb，and Cs，especially in Ba and Cs) except Sr，while significantly nagetive HFSE (e. g.，Zr， Hf and Sc)，and weakly enriched in U，Th，Nb and Ta． It is also characterized by relatively low siderophile ele- ments Cr，Ni，high V，Ti． The elements Cu is low，high Zn． And the dispersed elements Ga is enriched obviously．