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.