摘要
阿勒泰地区石英角斑岩呈北西—南东向沿阿勒泰复向斜北翼呈线状长距离分布,其寄主层位是下泥盆统康布铁堡组地层。火山活动形成于海相环境。火山岩主要由灰白色石英角斑质熔岩和火山碎屑岩组成,属钙碱性系列。在西部的阿勒泰一带以钾质为主,向东到蒙库一带过渡为钠型占绝对优势。酸性岩浆起源于上地壳底部,岩浆喷出地表固结,后期受强烈钠交代蚀变而改造成钠质石英角斑岩;钾质岩石是流纹岩类受钠交代蚀变微弱等化学变质的产物。
Quartz-Keratophyres in the Aletai area are linearly along the NW—SE direction distributed over the north side of the Aletai composite syncline,and their host stratum is of the Lower Devonian Kangbutiebao formation. The volcanic rocks, formed in the marine environment mainly by explosion aad effusion and the eruption index being 60, Consist largely of greyish quartz-keratophyrec lavas and volcanoclastic rocks. They belong to the calc-akaline series bocause their SiO_2 contents are mostly higher than 75δ_(ωH)％ and almost all their Rittmann indexes smaller than 2. The rocks in the west Aletai area are mainly of potash and transitionally change into dominent sodie type in the east, the Mengku area. The study suggests that tha sodic keratophyres were possibly formed through the extensive soda metasomatic alteration of the solidified lavas of the acidic magmas derived from the 17km deep upper crust, and the potash recks are the isochemically metamorphic products of rheolites, which underwent a weak soda metasomatic alteration.
出处
《矿物岩石》
CAS
CSCD
1991年第4期1-11,共11页
Mineralogy and Petrology
关键词
石英角斑岩
岩石学
成因
新疆
Aletai, Mengku, quartz keratophyre, soda metasomatic alteration
