云南个旧煌斑岩脉地球化学特征及其地质意义  

Geochemical characteristics and genesis of lamprophres in Gejiu tin deposit,Yunnan Province,China

作　　者：曹华文[1,2] 张寿庭[1,2] 王长明[1] 宋欣[1] 林进展[1,2] 李冬[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]成都理工大学构造成矿成藏国土资源部重点实验室,四川成都610059

出　　处：《地球化学》2013年第4期340-351,共12页Geochimica

基　　金：国家科技支撑计划(2011BAB04B06);国家地质大调查项目(1212011182388;1212011220925);构造成矿成藏国土资源部重点实验室开放基金(gzck2012006)

摘　　要：云南个旧老厂锡多金属矿区东部地层中发育多条蚀变橄辉云斜煌斑岩脉。在岩石化学组成上,其SiO2含量为51.54%～59.20%,K2O/Na2O比值为2.32～3.56,为碱性-亚碱性、钾质钙碱性煌斑岩。其大离子亲石元素(K、Rb、Ba)、轻稀土元素(LREE)相对富集,Sr相对弱亏损;高场强元素(Ta、Nb、P、Zr、Hf、Ti)亏损,且Ta、Nb和Ti具有"TNT"负异常,深源元素Cr、Co和Ni相对亏损,显示出俯冲带幔源岩石的成分。∑REE为480～1060μg/g,主要集中在500μg/g;LREE/HREE为1.30～7.68,δEu值为0.58～0.78,Eu负异常较明显。岩相学和地球化学特征表明老厂煌斑岩形成于俯冲-碰撞后的拉伸构造环境,可能起源于三叠纪时期古特提斯洋板块俯冲的残留板片对地幔楔的的交代富集作用形成的源区,源区岩石经过低程度部分熔融作用,上升侵位过程中轻微受到地壳物质的混染作用。There are many altered lamprophyre veins, consisting of olive, pyroxene, biotite and plagioclase, in the strata of the east part of the Gejiu-Laochang Sn polymetallic belt. In geochemical composition, the SiO2 content is 51.54%-59.20%, K2O/Na2O value is 2.32-3.56, belonging to alkaline-subalkaline series, and potassic-calc alkaline type. K, Rb, Ba （LILEs） and light rare earth elements （LREEs） are relatively enriched, Sr is relatively weak depleted; Ta, Nb, P, Zr, Hf, Ti （HFSEs） are relatively depleted, with Ta, Nb and Ti negative anomalies; Cr, Co and Ni （transition element） are relatively depleted, indicating the compositions of mantle source in the subduction zone. E REE is 480-1060 μg/g, mostly at 500 μg/g, LREE/HREE values range between 1.30-7.68, whereas εEu between 0.58-0.78, with negative Eu anomaly. The petrographical and geochemical characteristics indicate that the lamprophyres are formed in an extensional post-collision setting, which originate from the source region of residual flake metasomatism with mantle wedge during the Triassic Pleao-tethys plate subduction, followed by partial melting and weak assimilation of crust materials during the magma ascending.

关 键 词：煌斑岩 地球化学 富集地幔 个旧锡矿 

分 类 号：P59[天文地球—地球化学] P595[天文地球—地质学]