火山碎屑席
2014-03-05 00:00:00
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<span style="line-height:2;font-family:SimSun;font-size:14px;"> 火山碎屑席主要分布在岩山火山锥周围,属爆破式火山碎</span><span style="line-height:2;font-family:SimSun;font-size:14px;">屑降落堆积物。爆破式火山作用强烈,在火山口之上已形成了</span><span style="line-height:2;font-family:SimSun;font-size:14px;">以浮力上升为主要营力的喷发柱,将高度碎屑化的岩浆碎屑喷</span><span style="line-height:2;font-family:SimSun;font-size:14px;">向高空,再在重力作用下沉降堆积于火山锥体周围的地区,从</span><span style="line-height:2;font-family:SimSun;font-size:14px;">而形成火山碎屑席。在近火山锥体的沟谷低洼处厚度较大,远</span><span style="line-height:2;font-family:SimSun;font-size:14px;">离锥体厚度逐渐变薄,反映了火山喷发时岩浆中挥发成分含量</span><span style="line-height:2;font-family:SimSun;font-size:14px;">较高。</span>
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<span style="line-height:2;font-family:SimSun;font-size:14px;"><img width="600" height="278" alt="" src="/public/html_images/20140305/20140305202747_995.png" /></span>
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<span style="line-height:2;font-size:14px;">火山喷发形成的碎屑席</span>
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