摘要
对承德三岔口基性岩墙进行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究。定年结果表明岩墙属晚印支期(222.1±1.6)Ma岩浆活动的产物;地球化学特征显示岩墙具有拉斑玄武岩特征,轻稀土(LREE)和大离子亲石元素(LILE)相对富集岩墙,亏损Nb、Ta和Ti等。同位素组成特征显示,岩墙具有正的初始Sr比值和负的εNd(t)值。以上特征都暗示三岔口基性岩墙可能来源于富集的岩石圈地幔。根据年代学、地球化学和前期研究成果认为,与三岔口基性岩墙同期位于华北北缘的东西向侵入岩带,可能是华北克拉通减薄的最初表现。
Zircon LA-ICP-MS U-Pb dating and geochemical analysis have been carried on the mafic dyke from Sanchakou area,Hebei Province.The isotopic dating results indicate mafic dykes,with the age of（222.1 ± 1.6） Ma,were resulted from the Late Indosinian magmatism.Geochemical characteristics indicate they belong to tholeiite basalt,rich in LREE and LILE,as well as obviously depleted in Nb,Ta and Ti.Moreover,Sr-Nd isotopic composition means that the mafic dyke has high initial 87Sr/86Sr ratios and negative εNd（t）（from-9.3 to-6.1）.As it mentioned above,it＇s implied that the studied mafic dyke was derived from enriched lithospheric mantle.The Chronology,geochemisty and previous studies suggest that the Early Mesozoic intrusion zone coexistent with mafic dykes in Sanchakou area,in northern North China block,might be formed in the early period of lithospheric thinning.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2012年第6期1796-1805,共10页
Journal of Jilin University：Earth Science Edition
基金
国家自然科学基金项目(40773020)
西北大学大陆动力学国家重点实验室开放课题基金(08LCD08)
