摘要
根据《内蒙古1∶5万辉音敖包、达勒廷查干、固腊卜赛罕敖包、乌兰哈德农场幅区域地质调查》项目工作成果,认为出露于内蒙古东乌旗乌兰哈德一带的晚侏罗世满克头鄂博组火山机构类型为破火山,由早到晚依次发育初始爆发、大规模爆发、破火口塌陷沉积和破火山复活(为潜流纹岩)4个演化阶段,与典型破火山的演化模式基本一致。同一演化阶段的岩石组合具有整体一致的爆发强度。据此将属于地层范畴的前3个演化阶段依次划分为一、二、三段:一段为凝灰质砾岩夹沉凝灰岩;二段以流纹质熔结凝灰岩、流纹质熔结角砾凝灰岩为主,夹流纹质凝灰岩,局部夹少量流纹岩;三段为沉角砾凝灰岩夹沉凝灰岩。本划分方案标准较统一,野外易于操作,可填性强。各岩性段反映的是破火山活动的强弱特征,记录的是破火山演化阶段。岩性段的划分与火山演化历史研究等有机地结合在一起,有利于该组正确地层层序的建立和较大区域内的地层对比。
According to the achievement of the project named ＂1∶50000 Areal Geology Survey in Huiyin Obo,Daletingchagan,Gulabosaihan Obo,Wulanhade Farm＂,it is suggested that the volcanic apparatus type for Late Jurassic Manketou′ebo Formation in the Wlanhade,Dongwuqi,Inner Mongolia is caldera ,from the early stage to late,There are four evolution stages： initial eruption stage,large-scale eruption stage,collapse deposition stage of caldera and regrowth of caldera （subvocanic rhyolite）,as same as the typical caldera evolution model,basically.In the same stage,the rock associations have the same eruptive strength.So,the former three stages which belongs to volcanic stratum can be devided into three members,respectively.The first Member is tuffaceous conglomerate with tuffite; the second Member with the main rhyolitic ignimbrite,welded rhyolitic breccia tuff and rhyolitic tuff,with local have little rhyolite; the third Member is breccia tuffite and tuffite.This division has a uniform standard,and it is easy for operable mapping in the field.Each lithologic member expresses the strong or weak features of the caldera activity,recording the evolution stage of the caldera.Thus,the divison integrate the lithologic member division with the study of the volcanic evolvement organically,and it is good for building correct stratigraphic sequence and stratigraphic correlation in the large area.
出处
《地质通报》
CAS
CSCD
北大核心
2010年第11期1649-1654,共6页
Geological Bulletin of China
基金
中国地质调查局项目<内蒙古1:5万辉音敖包
达勒廷查干
固腊卜赛罕敖包
乌兰哈德农场幅区域地质调查>(编号:1212010781032)资助
关键词
内蒙古东乌珠穆沁旗
满克头鄂博组
火山演化阶段
岩石组合
岩性段
Dongwuzhumuqinqi
Inner Mongolia
Manketou′ebo Formation
volcanic evolution stages
rock association
lithologic member
