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辽河盆地沙三期火山-侵入岩为一套偏碱性的双峰式岩系,其基性端元为碱性玄武岩,中偏碱性端元为粗面质熔岩和侵入岩。碱性玄武岩富集高场强元素(如Nb、Th、Zr、Hf、V等)和轻稀土、Sr、Ba等大离子亲石元素,而亏损Rb和K,具有与板内碱性玄武岩和洋岛玄武岩类似的特征。粗面质岩石显示与基性端元相似的地球化学特征,其不相容元素含量总体上高于碱性玄武岩,但具强烈的Sr和Eu亏损。矿物学、岩石学及地球化学证据表明,玄武质岩石是软流圈地幔低程度部分熔融的产物,并经历了橄榄石和辉石的分离结晶作用,其源区可能有金云母和石榴石残留。玄武质岩浆上升到较浅部位后进一步发生橄榄石、辉石、斜长石和磁铁矿等的分离结晶作用而形成粗面质岩浆,地壳物质混染作用不显著。
The third Eocene volcanic-intrusive rock in the Liaohe Basin is a set of bimodal-type rocks with an over-basality. The basic end-units are alkaline basalts and the mid-alkaline ones are rough lava and intrusive rocks. Basic basalts are enriched in high-field-strength elements (such as Nb, Th, Zr, Hf, V, etc.) and LILEs such as light rare earths, Sr and Ba, while depleted in Rb and K, Island basalt similar features. Rough rocks show geochemical characteristics similar to those of the base end units. The content of incompatible elements is generally higher than that of alkaline basalts, but with strong depletion of Sr and Eu. Mineralogical, petrological and geochemical evidences show that basaltic rocks are the product of low-degree partial melting of the asthenospheric mantle and undergo the crystallization of olivine and pyroxene. The source rocks may have phlogopite and garnet residues. After the basaltic magma rose to a shallower part, further separation and crystallization of olivine, pyroxene, plagioclase and magnetite formed the lithofacies magma, and the crustal material contamination was insignificant.