利用接收函数研究河南及邻区的地壳深部构造特征

本文利用接收函数反演了河南及邻区26个宽频带地震台站下方的地壳厚度和波速比。研究结表明:河南省地壳厚度及泊松比分布与地质构造密切相关。主要表现为:(1)太行山断块,地壳厚度由东向西逐渐递增,地壳深度范围为31.8~40.2km,区域东北部永年台及附近台站泊松比为0.23~0.25,与较大范围的花岗岩分布有关,主要是石英、长石含量高,焦作台、涉县台、浚县台泊松比为0.26~0.27,表明铁镁质和长英质成分含量相当。(2)东部黄淮海平原块地,地壳厚度为28~34km,其中驻马店台、尖山台和浚县台,地壳厚度分别为30.5km、34.9km和31.8km,该地区泊松比变化范围比较稳定,数值在0.24~0.25之间。(3)在秦岭地块断裂活动强烈,卢氏台下方的地壳厚度为38.4km、泊松比为0.23,反映出燕山运动使该地区地壳盖层产生了褶皱台隆和地幔酸性岩浆的侵入活动。南阳盆地北部地壳厚度反演结果为28.8km,泊松比为0.29,泊松比升高,表明以中性、基性岩石为主,地壳岩石中铁镁质成分明显增加,是由于地幔物质深度侵入改变了部分地区的岩石性质。(4)大别山地块位于苏鲁-大别超高压变质带,由大别山北部的商城台向南至大别山地块内的金寨台存在地壳厚度梯度带,地壳厚度从31.8km增加至35.8km,而泊松比由0.27下降到0.24,反映出陆相褶皱带内的逆冲推覆构造的显著特征。

Study on the structural characteristics of the deep crust in Henan Province and its adjacent areas by using the receiver function

This paper uses the method of receiving function to inverse crustal thickness and wave velocity ratio of 26 wide frequency seismic stations in Henan and its adjacent areas. The research results show that:The distribution of crust thickness and Poisson''s ratio in Henan Province is closely related to the geological structure,which demonstrates itself in:(1)In the Taihang Mountains fault block,the crustal depths range from 31.8km to 40.2km and crustal thickness is gradually increasing from east to west. At Yongnian station and the majority of the stations in the northeast,the Poisson ratio is from 0.23 to 0.25 for a larger range of granite distribution here,mainly high content of quartz and feldspar. At Jiaozuo station,Shexian station and Xunxian station,the Poisson''s ratio is from 0.26 to 0.27,which shows that the felsic and Iron,mafic composition contents are equal in amount. (2)In the eastern block of Huanghuaihai Plain,the crustal thickness is from 28km to 34km. At Zhumadian station,Jianshan station and Xunxian station,the crustal thickness is 30.5km,34.9km and 31.8km respectively,The Poisson''s ratio in the region is relatively stable,and the data is between 0.24 and 0.25. (3)Qinling Mountains block has strong fault activities,the thickness of the crust beneath Lushi station is 38.4km and the poisson''s ratio is 0.23. This reflects that the Yanshan movement helps the crust in the area produce uplift folds and mantle acid magma intrusion activities. The crustal thickness in northern part of the Nanyang Basin is 28.8km,and Poisson''s ratio is 0.29. It indicates that the crustal lithology is mostly neutral and basic rock. In crustal rocks iron and magnesium composition increases significantly,because the mantle material deep intrusion changes the rock properties in some areas. (4)Dabie Mountain''s block is located in the Su-Lu(Jiangsu-Shandong)-Dabie ultrahigh pressure metamorphic belt. There is a crustal thickness gradient belt between Shangcheng station in the northern part of the Dabie Mountain and Jinzai station in the Dabie Mountain. The crustal thickness is from 31.8km to 35.8km,but Poisson''s ratios show negative growth and fall from 0.27 to 0.24. This reflects the prominent features of thrust nappe structure in the continental fold belts.