扎兰屯地区早白垩世火山岩特征及成因分析

发布时间：2018-12-28 06:45

【摘要】：针对扎兰屯地区中生代早白垩世火山岩的岩石学、地层学、岩相学及年代学等方面存在的问题,在扎兰屯地区实施了火山岩“地层.岩相”双重划分的方法,并对火山岩年龄、典型火山机构详细的解译与分析、早白垩世火山岩地球化学等分析和测定。通过野外和室内的大量研究,将扎兰屯地区早白垩世火山岩地层划分为白音高老组、梅勒图组。白音高老组火山岩以一套年龄在129.3Ma±,岩性为中酸性-酸性的岩石组合,包括流纹岩、石泡流纹岩等；梅勒图组火山岩以一套年龄在120.7Ma±,岩性以中基性-中性为主的岩石组合。按照火山岩“地层-岩相”双层填图的思想理念,将扎兰屯地区白音高老组火山岩划分为3个岩相；梅勒图组火山岩划分为5个岩相。主要以溢流相、爆发相和喷溢相为主。扎兰屯地区火山岩主要以中、酸性火山岩为主,w(SiO_2)%=55.63-74.40,且以亚碱性岩石为主,w(K_2O)%=1.46-5.77,平均=4.05,w(K_2O+Na_2O)%=5.41-9.95,平均=7.8。富集大离子亲石元素(LILE),δEu=0.05-0.96,平均=0.596,δCe=0.88-1.02,平均=1.029。相对亏损高场强元素(HFSE)综合分析扎兰屯地区火山岩特点并结合他人的研究成果,初步认为内蒙古东部中生代火山岩形成于古亚洲洋与蒙古-鄂霍次克洋俯冲闭合有关的双重作用,在整个作用过程中以壳幔混染作用和结晶分异作用为主,可能有平衡分异作用的参与。
[Abstract]:In view of the problems existing in petrology, stratigraphy, petrography and chronology of the Mesozoic early Cretaceous volcanic rocks in the Zalantun area, the volcanic "strata" have been implemented in the area. The method of "double division of lithofacies", and the detailed interpretation and analysis of volcanic age, typical volcanic mechanism and geochemistry of volcanic rocks in early Cretaceous, etc. The volcanic strata of early Cretaceous in Zalantun area are divided into the old group and the Mailetu formation through a lot of field and laboratory studies. The volcanic rocks of the Baiyingao formation are composed of intermediate acidic and acidic rock assemblages of age at 129.3Ma 卤, including rhyolite, etc. The Melertu volcanic rocks are a set of rock assemblages of 120.7Ma 卤, with meso-basic-neutral lithology. According to the idea of double layer mapping of volcanic rocks, the volcanic rocks of Baiyingao formation in Zarantun area are divided into three lithofacies, and volcanic rocks of Mailetu formation are divided into five lithofacies. Main overflow phase, explosive phase and spillage phase. The main volcanic rocks in Zalantun area are intermediate, acidic volcanic rocks (, w (SiO_2)% = 55.63-74.40, and subalkaline rocks dominated by, w (K2O% = 1.46-5.77, with an average of 4.05. W (K2O Na_2O)% = 5.41-9.95, average = 7.8. The average value of (LILE), 未 Eu=0.05-0.96, and 未 Ce=0.88-1.02, are 0.596 and 1.029 respectively. The characteristics of volcanic rocks in Zalantun area are comprehensively analyzed by (HFSE), which is a relatively depleted high field strength element, and combined with the research results of others. It is preliminarily considered that the Mesozoic volcanic rocks in the eastern part of Inner Mongolia were formed in the Paleo-Asian Ocean and related to the subduction closure of the Mongolia-Okhotsk Ocean, and the crust-mantle mixing and crystallization differentiation were dominant in the whole process. There may be balanced differentiation involved.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.14

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