大兴安岭呼中火山岩区中生代古构造应力场初探

大兴安岭火山岩带北段呼中火山岩区,在中-晚侏罗世时期,最大主压应力轴方向为NW266°～316°,早白垩世最大主压应力轴为NE12°～50°,显示侏罗纪与白垩纪应力场的应力状态是截然不同的,但都处于拉张环境下.中-晚侏罗世由于NNE-SSW向的拉伸应力场的作用,在本区北部发生构造岩浆活动,形成了上黑龙江断陷盆地如NWW向展布的劲涛-蒙克山中基性火山喷发带,派生的NEE向张扭性应力使前中生代基底构造重新活动,形成大面积火山喷发.而早白垩世在NE-SW向拉伸应力场作用下,“额尔古纳地块“东部形成拗陷带,火山基底构造为NE-NNE向.

STUDY OF MESOZOIC PALAEOTECTONIC STRESS FIELD IN THE VOLCAMIC ROCK AREA OF HUZHONG,THE NORTHERN PART OF DAHINGANLING VOLCANIC ZONE

In the volcanic rock area of Huzzhong in the northern part of Dahiinganling volcanic Zone, the maximum principal compressive strress of Middle-Late Juraassic were mainly oriented the direction of NW266°~316°;but one of Early Cretaceous of the direction NE12°~50°.It shows that Mesozoic stress fields were different in Jurassic and Cretaceous, but these fields are all in tensile environment. In Middle-Late Jurassic, the tectonic magma activity resulting from NNE-SSW tensile stress field in the northern part of this area formed upper Heilongjiang fault basin and NWW trending Jintao-Mengkeshan intermediate-basic volcanic belt, its induced NEE trending tenso-shear stress field made the Premesozoic basement tectonics rejuvenate and formed volcanic eruption of big area. But under the control of NE-SW tensile stress field of Early Cretaceous, in the eastern part of "Ergun Block" sag belt was formed and the basement tectonics is NE-NNE direction.