大同第四纪火山群的活动特点

一、引言大同第四纪火山群位于山西省大同县和阳高县境内(图1),包括近5年来在大峪口,秋林地区首次发现的6个小火山。该火山群大、小火山共计31个。大同火山群南以六棱山北麓断裂为界,分布于大同盆地东部的第四纪沉积区范围。火山群南侧的六棱山和北部的小北山是由前寒武花岗片麻岩组成的山地。

Characteristics of the Datong Quaternary Volcano Group

The Datong Quaternary Volcano Group is located in the eastern part of the Datong basin,Shanxi Graben System.This volcano group was formed by eruptions of basalt magma through the late Cenozoic fault zones in later part of mid-Pleistocene(from 120,000 to 450,000 a.B.P.).The basalt magma was the partial melting product of the mantle peridotite.Inclusions of lherzolite are found in the basalt of Langwushan Volcano. The Datong Quaternary Volcano Group can be subdivided by the Chenzhuang-Xubao fault into two parts:the southern and northern areas.In the southern area volcanos are typical of effusive eruptions in shield or dome forms with no craters.Their volcanic rocks are olivine tholeiite.In the northern area,volcanos are typical of explosive eruptions in cone form with craters.Their volcanic rocks are alkaline olivine basalt.