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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.
Multiple boreholes in the northern Yellow Sea basin encountered pre-Mesozoic and Mesozoic igneous rocks, confirming that the Mesozoic multisectoral tectonic activity of the basin was accompanied by multi-stage igneous rocks.The petrographic identification of volcanic rocks of wells X1 and X2 in the North Yellow Sea Basin, Magnetic susceptibility and density tests, major elements, trace elements and rare earth elements in ICP-MS were studied. The results show that the Paleozoic basalts and rough basalts of Well X1 are weak magnetic (131.5 ~ 138.5) (4π × 10 -6 )), Medium density rocks, and the Mesozoic dacite (lower level) and brecciated dacite (upper level) in the X2 well are weakly magnetic (27.5 ~ 82.5) (4π × 10 -6) Rock; the well X1 in the well belongs to the high-K calc-alkaline series, the rough basalts belong to the calc-alkaline series, and the two volcanic rocks show the higher ΣREE (108.11 × 10 -6 to 208.02 × 10 -6) ), LREE / HREE = 4.04 ~ 6.91, and δEu with weak anomaly (0.99 ~ 1.18). The volcanic rocks in the second layer of Well X ~ 2 belong to the calcareous alkaline series and all show low ΣREE and light rare earth enrichment , ΔEu has a weak anomaly, and the trace elements have the characteristics of Ba, U, Sr enrichment and depletion of Nb and Ta, and the ratio of (Rb / Sr) _N, (La / Nb) _N and (Ba / Nb) The original mantle Reflecting the molten magma from the earth’s crust. Before and after the North Yellow Mesozoic volcanic structure formed in the inner panel background, may be formed in Mesozoic volcanic arc extensional subduction.