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利用华北地震科学台阵和首都圈地震台网记录的4511次近震和625次远震的P波到时数据,采用纬度和经度方向分别为0.5°×0.5°的网格划分,反演得到了华北北部地区(111°E—120°E,37°N—42°N)深至400km的地壳上地幔三维P波速度结构.层析成像结果表明,研究区的速度存在明显的横向不均匀性,随着深度增加横向不均匀性总体呈现减弱趋势.燕山隆起带在60—120km深度内存在明显的高速异常,这与较大的岩石圈厚度有关;山西裂陷盆地、华北平原下方60km深度存在明显低速异常,与软流圈的出现有关.燕山隆起带岩石圈厚度在120km以上,明显比太行山隆起的岩石圈厚度大,与稳定大陆地区的岩石圈厚度一致.太行山山前断裂已切穿莫霍面,贯入岩石圈.研究区上地幔顶部大范围的低速异常反映了软流圈上隆的特点.在华北平原及燕山隆起下方200—300km存在高速异常可能与太古代大陆板块岩石圈的残留体有关.
Using 4511 near earthquakes and 625 teleseismic P-wave arrival data recorded by the North China Seismic Science Array and the Capital Circle Seismic Network, P-wave arrival data of the latitude and longitude directions are respectively 0.5 ° × 0.5 °. The inversion results The three-dimensional P-wave velocity structure of the crust and upper mantle in the northern part of North China (111 ° E-120 ° E, 37 ° N-42 ° N) is up to 400 km.The tomographic imaging results show that there is obvious lateral heterogeneity With the increase of depth, the lateral inhomogeneity generally shows a weakening trend.The Yanshan uplift has obvious high-speed anomalies within the depth of 60-120km, which is related to the larger lithosphere thickness. In the Shanxi rift basin, the depth of 60km below the North China Plain There is a clear low-velocity anomaly, which is related to the appearance of asthenosphere.The lithosphere of the Yanshan uplift is over 120 km thick, which is obviously thicker than the lithospheric uplift of the Taihang Mountains and consistent with the lithosphere thickness of the stable continent. Moho surface, penetrating into the lithosphere.The large-scale low-velocity anomaly at the top of the upper mantle in the study area reflects the characteristics of asthenosphere uplift.The high velocity anomaly 200-300 km below the North China Plain and Yanshan uplift may be related to the Archean continental plate Block lithosphere residual body related.