基于接收函数方法研究广东地区地壳厚度与泊松比

Study of the Crustal Thickness and Poisson's Ratio in Guangdong with Receiver Function Method

选取广东地区49个固定地震台站记录到的远震资料,采用时间域迭代反褶积法提取P波接收函数,利用Н-к叠加法获得台站下方的地壳厚度与泊松比。结果表明:①广东地区地壳厚度在24.8~31.0 km,平均值为28.3 km,自西北往东南减薄,呈区域性带状分布特征,可能与研究区内山脉隆起、平原和山地相间的地质构造相关。②研究区泊松比为0.220~0.287,平均值为0.244,泊松比北部偏高、南部偏低,沿海地区高于内陆地区,具有区域性块状分布特征,可能与地壳主要深大断裂切割的地质块体有关。③地壳厚度和泊松比分布与断裂的分布有较好的对应关系,并在断裂附近变化明显。④地壳厚度与泊松比呈负相关,可能与古太平洋板块在地壳演化过程中向广东大陆方向推进,幔源物质进入地壳,在地壳深部存在部分熔融,从而导致地壳岩石中镁铁成分含量上升引起的泊松比升高有关。

The teleseismic data recorded at 49 seismic stations in Guangdong were selected,and the P-wave receiver function was extracted using the iterative deconvolution method in the time domain.The crustal thickness and Poisson's ratio below the stations were obtained by theН-кsuperposition method.The results show that:①In Guangdong region,the crustal thickness ranges from 24.8 to 31.0 km,with an average of 28.3 km,and becomes thinner and thinner from northwest to southeast,showing a regional zonal distribution.This may be related to the geological structure of the uplifted mountains,plains and high land in the study area.②In Guangdong region,Poisson's ratio ranges from 0.220 to 0.287,with a mean value of 0.244.Poisson's ratio is higher in the north and lower in the south,and is higher in coastal areas than inland areas;Poisson's ratio distributes in regional blocks.This may be related to the geological blocks cut by deep major faults in the Crust.③The distribution of the Crustal thickness and Poisson's ratio correspond well with the distribution of the faults and they vary significantly near the faults.④The Crustal thickness and Poisson's ratio are negatively correlated,because during the evolution of the Crust,the ancient Pacific plate extruded toward the Guangdong continent,then the mantle-sourced materials got into the Crust,and partially melted in the deep Crust.This led to the increase of the contents of magnesium and iron in the rocks,thus causing the increase of Poisson's ratio.