摘要
鲁西金岭闪长岩位于华北克拉通东南部,主要由辉石闪长岩-黑云母闪长岩组成。LA-ICP-MS锆石U-Pb定年测定闪长岩侵位年龄为(129.17±0.96)和(130.15±0.65)Ma,属于早白垩世岩浆活动的产物。闪长岩SiO2和K_2O的质量分数较低,MgO、Na_2O、Fe_2O_3、MgO和Al_2O_3的质量分数较高,Mg#为58.00~70.00。Na_2O/K_2O为1.08~2.96,相对富钠高铝,其里特曼指数为1.95~2.96,具有钙碱性系列的岩浆演化趋势。金岭闪长岩w(Ni)为99.00×10^(-6)~237.00×10^(-6),w(Cr)为270.00×10^(-6)~600.00×10^(-6),w(Co)为19.00×10^(-6)~44.00×10^(-6),表明其具有幔源岩浆的属性。稀土元素球粒陨石标准化曲线表明样品具有富集轻稀土元素(LREE),亏损重稀土元素(HREE)以及弱Eu(δEu为0.91~1.12)异常的特征。所有样品富集大离子亲石元素(Ba、K、Sr)和高场强元素Nd,亏损高场强元素Rb、Nb、Ta、Zr。样品中约2.5Ga古老锆石的存在证明岩浆源区受到古老下地壳物质的混染作用。鲁西金岭地区闪长岩应形成于太平洋板块俯冲后后撤引起的伸展环境,其岩浆源区是富集地幔起源的基性岩浆底侵华北古老下地壳并与下地壳熔融形成的壳源酸性岩浆混合过程的产物。
The Jinling dioritic pluton in west Shandong is mainly composed of pyroxene diorite and biotite diorite.The zircon U-Pb dating results reveal that the dioritic pluton was emplaced in Early Cretaceous(129.17±0.96)Ma and(130.15±0.65)Ma.The major element data show that the diorites contain low contents of SiO2,K2O,and high contents of Na2O,Fe2O3,MgO,Mg#and Al2O3.TheNa2O/K2O ratios range from1.08to2.96.The diorites are enriched relatively in sodium and alumina.The diorites have calcalkaline characteristics according to the Ritttman index(1.95-2.96).The contents of Ni、Cr、Co are99.00×10-6-237.00×10-6,270.00×10-6-600.00×10-6,19.00×10-6-44.00×10-6respectively,similar to the contents of mantle magma.The chondrite standardized REE curves show that they are enriched in light REE,and depleted of heavy REE with weak Eu anomaly(0.91-1.12).The diorites are enriched in large ion lithophile element(LILE)Ba,K,Sr,and high field strength elements(HFSE)Nd,while depleted of high field strength elements(HFSE)Rb,Nb,Ta,and Zr.The residual ancient zircons(～2.5Ga)in the sample(N1)indicate a mix of ancient lower crust occurred in the source area.The Jinling pluton might be formed under a lithospheric extension related to the rollback of the subducted Pacific plate,and the magma was the mixing product of the siliceous crust melted through underplating of basaltic magma,and the mantle enriched basaltic magma.
作者
张超
崔芳华
张照录
耿瑞
宋明春
Zhang Chao;Cui Fanghua;Zhang Zhaolu;Geng Rui;Song Mingchun(School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, Shandong, China;Shandong Gold Group Co. LTD, Jinan 255014, China;Shandong Bureau of Geology and Mineral Resources Exploration and Development,Jinan 255013, China)
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2017年第6期1732-1745,共14页
Journal of Jilin University：Earth Science Edition
基金
山东省中青年科学家科研奖励基金项目(ZR2016DB08)
泰山学者工程专项经费(ts201511076)~~
