布达特群热流体活动及其对火山碎屑岩的改造作用--以海拉尔盆地贝尔凹陷为例

海拉尔盆地贝尔凹陷布达特群热流体活动频繁,主要特征如下:多种类型、多期次脉体的发育;受局部热流体作用,不同地区镜质体反射率随深度的变化明显;热流体在形成过程中具有较高的温度场。同时,受热流体活动的影响,热流体对火山碎屑岩具有一定改造作用,如在安山质岩屑凝灰岩中,斜长石绢云母化、火山岩岩屑绿泥石化明显;在凝灰质泥岩中,热流体对围岩中有机碳具有明显的"催熟"加热作用,微量元素则出现异常现象。这些变化从微观角度进一步证实了热流体活动存在的证据。

The Thermal Fluid Activities and Their Modification on Volcaniclastic Rock in Budate Group -An Example from the Beier Sag of Hailaer Basin

The thermal fluid acted frequently in the Budate Group of the Beier sag,Hailaer Basin.The main characters of the thermal fluid activity are recognized as follow: many types and stages of veins are widely developed;vitrinite reflectivity of different areas varies apparently with the depth;there was a high temperature field during the formation of the thermal fluid.meanwhile,the volcaniclastic rocks were modificated by the thermal fluid activity,for example,sericitization of plagioclase,chloritization of volcanic detritus in andesitic detris tuff;in the tufaceous mud,the thermal fluid activity accelerates "maturating" of the organic carbon by heating;and the trace elements show an anomaly in the wall rocks.These changes prove further the existence of the thermal fluid activity in micro-scale.