论文部分内容阅读
20世纪80年代起,辽宁省岫岩县境内的一个环形构造由中国科学家从地质、地球化学推断为陨石撞击坑,后经地质钻探进行了证实.但该环形构造的深部整体特征仍有待用地震勘探方法来确认.为了对该环形构造的深部有个整体认识,利用三维地震成像方法首次对岫岩坑的地震波折射数据进行了研究,获得了该坑的三维速度结构.结果表明:该撞击坑从地表到深度100 m的速度层对应坑内上部107 m厚的湖泊相沉积物,深度100 m到300 m的速度层对应坑内下部厚度为188 m的角砾岩堆积透镜体.大约250 m深处的波阻抗界面与地质钻孔的260 m深处的陨石冲击分界面相对应.深度300 m到650 m的低速度层可能对应角砾岩堆积透镜体下面的下元古界变质岩系的程度较低的撞击裂隙层.坑中心深度约700 m周围以及向下出现的7.0 km/s以上的高波速可能是陨石撞击时所产生的高温高压使表层岩石达到熔融状态,改变了围岩的性质,致使围岩速度升高.
Since the 1980s, a ring structure in Xiuyan County of Liaoning Province has been inferred by Chinese scientists from geology and geochemistry as a meteorite impact crater, which has been confirmed by geological drilling, but the overall characteristics of this ring structure remain to be quasi- Exploration method to confirm.In order to have a holistic understanding of the deep part of the ring structure, the seismic reflection data of Xiuyan pit was first studied by 3D seismic imaging method, and the three-dimensional velocity structure of the pit was obtained.The results show that the impact pit The velocity layer from the surface to the depth of 100 m corresponds to lacustrine sediments with a thickness of 107 m in the upper part of the pit and the velocity layer with a depth of 100 m to 300 m corresponds to a breccia accumulation lens body with a thickness of 188 m in the lower part of the pit. Corresponds to the meteorite impact interface at a depth of 260 m of the geological borehole.The low velocities between 300 m and 650 m in depth may correspond to the extent of the Lower Proterozoic metamorphic rocks beneath the breccia conglomerate lens Lower impact crack layer.The high wave velocity of 7.0 km / s around and down about 700 m deep in the center of the pit may be the high temperature and high pressure caused by the impact of the meteorite, A molten state changed the nature of the surrounding rock, resulting in increased speed of the surrounding rock.