大同火山群
2014-03-05 00:00:00 阅读数:
<p> <span style="line-height:2;font-family:SimSun;font-size:14px;"> 大同火山群主要分布于山西省大同盆地东部,海拔约1000米,</span><span style="line-height:2;font-family:SimSun;font-size:14px;">延伸至山西省阳高县和河北省阳原县的交界处附近。盆地的南部和</span><span style="line-height:2;font-family:SimSun;font-size:14px;">北部为山脉,南陡北缓,平均海拔高度2000米左右,桑干河从西至</span><span style="line-height:2;font-family:SimSun;font-size:14px;">东流经本区南部。野外可见30余座大小不等、形态各异、保存状况</span><span style="line-height:2;font-family:SimSun;font-size:14px;">不相同的火山锥,形态完好的有昊天寺、金山、黑山、狼窝山、阁</span><span style="line-height:2;font-family:SimSun;font-size:14px;">老山和马蹄山。</span> </p> <p> <span style="line-height:2;font-family:SimSun;font-size:14px;"> 大同火山群火山形态多样,有圆锥形、马蹄形、盾形、垄岗形</span><span style="line-height:2;font-family:SimSun;font-size:14px;">和火山小鼓包等。这些火山散布于大同盆地的湖积—冲积平原上,</span><span style="line-height:2;font-family:SimSun;font-size:14px;">构成桑干河两岸独特的有火山、垄岗起伏的平原地貌。在一般的火</span><span style="line-height:2;font-family:SimSun;font-size:14px;">山分类中,大同火山属中心式喷发的复合型火山锥,总体属锥形火</span><span style="line-height:2;font-family:SimSun;font-size:14px;">山。自火山口向外由近而远依次分布的火山碎屑是:火山渣、火山</span><span style="line-height:2;font-family:SimSun;font-size:14px;">集块岩、火山角砾、火山砾、火山豆、火山砂、火山灰等。其中,</span><span style="line-height:2;font-family:SimSun;font-size:14px;">火山集块岩、火山角砾、火山砾环绕火山口分布,组成圈拢火山口</span><span style="line-height:2;font-family:SimSun;font-size:14px;">的墙垣,其间混有颜色不同、大小不等的火山弹、火山绳,常见的</span><span style="line-height:2;font-family:SimSun;font-size:14px;">形状有椭球形、旋扭形、纺锤形、扁圆形、角形、铁饼形和矛形</span><span style="line-height:2;font-family:SimSun;font-size:14px;">等。除了火山碎屑,大同火山区有玄武岩质的熔岩流广泛分布。</span> </p> <p align="center"> <img width="300" height="203" alt="" src="/public/html_images/20140306/20140306000038_468.png" /><img width="300" height="246" style="width:281px;height:203px;" alt="" src="/public/html_images/20140306/20140306000111_791.png" /> </p> <p align="center"> <span style="line-height:2;font-family:SimSun;font-size:14px;"> </span><span style="line-height:2;font-family:SimSun;font-size:14px;">大同火山群 </span><span style="line-height:2;font-family:SimSun;font-size:14px;"> </span><span style="line-height:2;font-family:SimSun;font-size:14px;"> </span><span style="line-height:2;font-family:SimSun;font-size:14px;">大同火山列屏</span><span id="__kindeditor_bookmark_end_52__"></span> </p> <p align="center"> <img width="371" height="260" alt="" src="/public/html_images/20140306/20140306000340_145.png" /> </p> <p align="center"> <span style="line-height:2;font-family:SimSun;font-size:14px;">大同火山群主要火山</span><br /> <span style="line-height:2;font-family:SimSun;font-size:14px;">分布图</span><br /> <span style="line-height:2;font-family:SimSun;font-size:14px;">(据邓晋福,1987)</span><span style="line-height:2;font-family:SimSun;font-size:14px;"> </span> </p> <p> </p>