太行山南段中生代杂岩体成因及其演化分析  

Petrogenesis and Evolution of Mesozoic Complexes from Southern Taihang Orogen

作　　者：尹明[1,2] 郭敏[2] 张海东[1] 

机构地区：[1]长安大学资源学院,陕西西安710054 [2]河南省国土资源研究院,河南郑州450002

出　　处：《西北地质》2014年第3期43-53,共11页Northwestern Geology

基　　金：中国地质调查局"太行山地区中生代岩浆活动与成矿作用研究"(1212011121076)

摘　　要：平顺-符山-武安-洪山杂岩体主要由橄榄辉长辉绿岩、角闪闪长岩,经闪长岩、二长闪长岩、正长岩、花岗岩一系列岩石组成,其地球化学性质相似,CaO、FeO、MgO和TiO与SiO2呈线性正相关,富集大离子亲石元素(如Sr、Ba、K)和LREE,亏损高场强元素(如Nb、Ta、Ti)和HREE,具有微弱的正Eu异常。符山杂岩体的εNd=-12.3^-16.9,ISr=0.705 6~0.707 1,武安杂岩体εNd=-13.8^-18,ISr=0.705 9~0.707 6,相比之下,洪山杂岩体具有比符山-武安杂岩体明显高但相对均一的εNd值(-8.2^-11)和变化较大的ISr(0.705 2~0.710 2)。平顺杂岩体Pb同位素比值较高,(206Pb/204Pb)i=17.859~18.474,(207Pb/204Pb)i=15.429~15.612,(208 Pb/204 Pb)i=37.374~38.641。而符山杂岩体(16.92~17.3,15.32~15.42,37.16~37.63)、武安岩体(16.63~17.4,15.28~15.44,36.78~37.3)和洪山杂岩体(17.28~17.74,15.40~15.48,37.01~38.12)变化连续。平顺-符山-武安杂岩体可能是同一期岩浆演化的产物,起源于EMI型富集地幔的部分熔融,但在上升过程中受到不同程度的下地壳物质混染。洪山岩体也来源于EMI型富集地幔的部分熔融,但属于不同岩浆热事件,仅受轻微下地壳混染。太行山南段中生代广泛的岩浆活动可能与邯邢地幔柱上涌有关。Pingshun-FuShan-WuAn-HongShan complex mainly consists of olivine-gabbro-diabase, hornblende diorite, diorite, monzodiorite, syenite and granite, which have similar geochemical properties. The content of CaO, FeO, MgO, TiO and SiO~ are in linear positive correlation. The composite pluton is enriched in lithophylic elements （such as Sr, Ba, K） and LREE, but is depleted in high field strength elements （such as Nb, Ta, Ti） and HREE, and there is a weak positive Eu anomaly. The value of epsilon Nd（t） varies from --12.3 to --16.9 in FuShan complex, with that of I Sr ranges from 0. 7056 to 0. 7071; the value of epsilon Nd（t） varies from --13.8 to --18 in WuAn complex, and the value of I Sr is between 0. 7059~0. 7076. By contrast, the values of end （--8. 2 ^- 11） in HongShan complex is obviously higher and relatively more homogeneous than that in FuShan-WuAn complex, and the value of ISr（0. 705 2~0. 710 2） has a greater varie- ty. Pb isotope ratio of PingShui complex is relatively higher, the values of （206 pb/204 Pb）l,（207Pb/204Pb）i and （208Pb/204Pb）i are respectively 17. 859~18. 474, 15. 429~15. 612, 37. 374~ 38. 641, while those of FuShan complex （16.92~17.3, 15.32~15.42, 37.16~37.63）, WuAn complex （16.63--17.4, 15.28--15.44, 36.78~37.3）, and HongShan complex （17.28~17.74, 15.40--15. 48, 37. 01 ~ 38. 12） change continuously. Pingshun-Fushan-Wuan complexes are probably the products of contemporaneous magma evolution, originated from the partial melting of EMI-enriched mantle, but experienced different degrees of hybridization of crust materials in the rising process. Hongshan complex also originated from the partial melting of EMI-enriched mantle, but belonged to different magmatic thermal event, and merely experienced slight hybrid- ization of crust materials. The extensive Mesozoic Magmatic Activity of southern Taihang Mountain is probably related to the plume upwelling of Hanxing.

关 键 词：杂岩体 EMI型富集地幔 部分熔融 太行山南段 

分 类 号：P588.12[天文地球—岩石学]