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华南连县─博罗─港口地带地壳结构及速度分布的爆炸地震探测结果
CRUSTAL STRUCTURE AND VELOCITY DISTRIBUTION FROM DEEP SEISMIC SOUNDING ALONG THE PROFILE OF LIANXIAN-BOLUO-GANGKOU IN SOUTH CHINA
【摘要】 在华南连县-博罗-港口地区200多个观测点上取得700多道地震记录,并绘制成6张地震记录剖面图.经过分析处理,识别出下列波组:来自地壳浅层的P波组,地壳中各界面的反射组有:P1,P2,P3和P4,莫霍面的反射波组Pm,以及上地幔顶部的折射波组Pn.经分析解释得出初步结果:①通过P震相的处理,构制了测线下方浅层地壳结构和速度分布图,它与测线穿过的断裂构造带有较好的相关性。②该地区莫霍面的反射波组Pm清晰,求得地壳平均速度为6.25km/s左右.在清远至连县之间,地壳厚度为32-34km.博罗、惠东一带地壳厚度为30km,惠东至港口之间为29.5km,说明该地区莫霍面起伏不大.地壳厚度由北向南和由西向东有逐步变薄的趋势。③观测距离较长的地震剖面图上清晰地记录到上地幔顶部的Pn民震相,该震相从140km处开始以初动出现,能量强,可追踪到200km,求得的Pn速度分别为:港口-惠东-博罗一带为8.05km/s,博罗-从化-清远一带为8.06km/s,由西向南的大湾-清远-从化-博罗一带为8.13km/s,考虑到莫霍面的起伏因素,该区Pn速度值以取8.06km/s为宜。④得到该区地壳5层结构和速度分布模型,并结合该测区的地质、地震、地热和矿产分布等资料进行了初步讨论.
【Abstract】 The Profile is located in South China, 400km long, running from Lianxian toGangkou. There are 200 recording stations being Placed along the profile to record theseismic signal from explosive sources. Six seismic bine sections are Plotted by about700 seismic recording channels, from which tWo refraction phases (P0 and Pn and fivereflection Phases (P1, P2, P3, P4. and Pm) are traced. The P0 travels through the shllowearth’s crust and Pn is refraCted from the top of uppermantle. P1, P2, P3 and P4 arecaused by various interfaces in the crust respechtiely and Pm comes from Mohodiscontinuity. By analyzing, some Primary resultS are obtained. The shallow crustalstructure and velocity distribution having a close relationship with the faults are imagedby travel bine of P0 wave phase. The crustal average velocity of Pm wave is 6.25 kin/s,which calculated by Pm phase with stronger energy. The thickness of the crust becomethen gradually from northWest to southeast part, but the variation of thickness is slightly.The depth of Moho is 32-34 km from Qingyuan tO Lianxian, about 30 fan at theregion of Boluo to Huldong, and 29.5 km betWeen Huidong and Gangkou. The PnPhase can be traced beyond 140 km to 200 km from the section with longer recordingdistance. The velocity of Pn is about 8.06 km/s. A 2D model with five-layered was obtained and discussed in thes paper integrating the model with data of geologicalhistory, earthquake, geothermal survey and mineral resources.
【Key words】 South China; Moho disconhninty; Deep seismic scuding; Crustalstructure.;
- 【文献出处】 地球物理学报 ,Chinese Journal of Geophysics , 编辑部邮箱 ,1999年03期
- 【分类号】P631.4
- 【被引频次】84
- 【下载频次】281