北黄海盆地前中生代-中生代火山岩磁化率、地球化学特征及构造意义

发布时间：2019-02-27 09:38

【摘要】：北黄海盆地内多口钻井钻遇到前中生代和中生代火成岩,证实了盆地中生代经历的多期构造活动伴随着多期次火成岩的发育.对北黄海盆地X1和X2井火山岩进行了岩石学鉴定、磁化率和密度测试、主量元素、ICP-MS微量和稀土元素测试,研究表明:X1井前中生代碱玄岩和粗面玄武岩属于弱磁性((131.5~138.5)(4π×10~(-6)))、中密度岩石,X2井中生代英安岩(下层)和含角砾英安岩(上层)属于微弱磁性((27.5~82.5)(4π×10~(-6)))、中密度岩石;X1井碱玄岩属于高钾钙碱性系列,粗面玄武岩属于钙碱性系列,2种火山岩表现为ΣREE较高(108.11×10~(-6)~208.02×10~(-6))、轻稀土富集(LREE/HREE=4.04~6.91)、δEu有微弱异常(0.99~1.18);X~2井2层火山岩属于钙碱性系列,均表现为ΣREE较低、轻稀土富集、δEu有微弱异常,微量元素具有Ba、U、Sr富集和Nb、Ta亏损的特征,而且(Rb/Sr)_N、(La/Nb)_N和(Ba/Nb)_N的比值均高于原始地幔值,反映岩浆源于地壳熔融.北黄海盆地前中生代火山岩形成于板内构造背景,中生代火山岩可能形成于板块俯冲的弧后伸展环境.
[Abstract]:The multi-port drilling in the North Yellow Sea basin has encountered the pre-Mesozoic and Mesozoic igneous rocks, and it is proved that the multi-period tectonic activity of the Mesozoic experience in the basin is accompanied by the development of the multi-stage igneous rock. The petrology identification, the magnetic susceptibility and the density test, the main element, the ICP-MS trace and the rare earth element test of the volcanic rocks in the X1 and X2 well of the North Yellow Sea basin are carried out. The results show that the Mesozoic basalanite and the coarse-faced basalt in the front of the X1 well belong to the weak magnetism ((131.5 ~ 138.5) (4),10 ~ (-6)), and the medium-density rock. The Mesozoic infanite (lower layer) and the breccia-containing infanite (upper layer) of the X2 well belong to the weak magnetism ((27.5-82.5) (4)-(10-(-6)), medium-density rock, and the X1-well alkali-basalt belongs to the high-potassium-calcium basic series. The coarse-faced basalt belongs to the calcium-alkaline series, and the two volcanic rocks show a high REE (108.11-10-(-6)-208.02-10-(-6)), light rare-earth enrichment (LREE/ HREE = 4.04-6.91), and weak abnormal (0.99-1.18). The 2-layer volcanic rocks of the X-2 well belong to the calcium basic series, all of which are low-REE, light-rare-earth-enriched, and Eu have weak anomalies. The trace elements are characterized by the enrichment of Ba, U, Sr and Nb and Ta, and the ratio of (Rb/ Sr) _ N, (La/ Nb) _ N and (Ba/ Nb) _ N is higher than that of the original earth crust, which reflects the melting of the magma from the earth's crust. The Mesozoic volcanic rocks of the North Yellow Sea basin are formed in the tectonic setting of the plate, and the Mesozoic volcanic rocks may be formed in the arc-backward extension environment of the plate subduction.
【作者单位】：吉林大学地球科学学院;广州海洋地质调查局;
【基金】：国家青年科学基金项目(No.41402087) 中国地质调查局国家专项项目(No.GZH200700405) 中国博士后科学基金面上项目(No.2013M530976)
【分类号】：P588.14;P318.41

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