黑龙江五大连池火山群大地电磁探测和研究初步结果

Preliminary Study of Wudalianchi Volcanic Cluster in Heilongjiang Province by MT measurement

对黑龙江五大连池火山群新近观测的7条大地电磁测深剖面资料进行了处理、解释和分析。研究表明,在地下约几百米深度至15～20 km左右,存在一个上宽下窄似铆钉状的高阻异常体,推测为固结过程中的火山岩浆体。该高阻体一直穿过地壳与上地幔连接,有向深处延伸的通道,并随着深度的加大,其电阻率逐渐减小。该火山群属于岩浆直接来自上地幔的火山类型,在地壳内没有明显的低阻岩浆囊存在。火山区的构造走向为近南北方向。

MT measurement are recently carried out at 71 sites along 3 east—west direction profiles and 4 north—south direction profiles in the volcanic cluster and the vicinity to study the magma chamber and deep structure. The preliminary results show that there is a high resistive body rivet -shaped beneath the cluster at the depth between a few hundreds meters and about 15～20 km. It is postulated that the high resistivity body is a cooling magma chamber and it passes through crust and connects to the upper mantle. The tip of the rivet body extends continually down to several tens kilometers and resistivity deceased with increasing depth. The above results can be interpreted by that the magma came up from the upper mantle. There is not magma chamber with low resistivity in the crust. The fracture strike is along N—S direction.