摘要
本文重新厘定了云县三叠纪火山岩的组合和系列,识别了4个层位中的酸性熔结凝灰岩,重新划分了火山喷发旋回和韵律。中三叠统忙怀组(T_(2m))为富硅富铝高钾流纹质火山岩组合,该旋回由5个喷发韵律层组成;上三叠统小定西组(T_(3x))为高钾玄武岩-钾玄岩-安粗岩及火山碎屑岩组合,该旋回由6个喷发韵律层组成。芒汇河组(T_(3mh))为钾质粗面玄武岩-高钾流纹质火山岩组合,该旋回由6个喷发韵律层组成。T_(2m)火山岩属碰撞型弧火山岩,T_(3x)和T_(3mh)火山岩属钾玄岩系列火山岩,具有滞后型弧火山岩之属性。
The authors not only stipulate again the Triassic volcanic rocks association and series
in Yunxian, but also recognize acid welded tuffs in four layers and divide volcanic eruption
cycle and rhythm. The rhyolitic volcanic rocks association in Manghuai Formation(T,m) is
riched in SiO,, Al,O, and K:O, and the first cycle is made up of five rhythm units. There
is the association of high--K,O basalt--shoshonite--latite and the volcanic fragment rocks in
Xlaodingxi Formation (T,x), and the second cycle is made up of six rhythm units. There is
the association of potassic trachy basaIt--high--K,O rhyolitic volcanic rocks in Manghuaihe
Forrnation(T,mh),and the third cycle is composed of six rhythm units. The volcanic rocks
in Manghuai Formation belong to colIision type arc--volcanic rocks. The voIcanic rocks in
Xiaodingxi and Manghuaihe Formation belong to shoshonite series and lag type arc--vol-
canic rocks.
出处
《现代地质》
CAS
CSCD
1993年第2期151-159,T001,共10页
Geoscience
关键词
三叠纪
火山岩
钾玄岩
构造意义
South Lancangjiang belt, Triassic volcanicrocks, shoshonite series, arc-volcanic rocks
