中国中原地区随县—安阳剖面深地震测深资料的解释
ON THE INTERPRETATION OF THE DSS DATA OF SUIXIAN-ANYANG PROFILE IN CENTRAL CHINA
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摘要: 本文描述随县—安阳剖面深地震测深资料分析解释的初步结果。资料处理结果说明,本地区的莫霍界面埋深约28至36km,其上覆盖层(即地壳)的平均速度约6.24km/s,在新郑和淇县一带该界面埋藏较深。在地表附近沉积层速度约3.50km/s左右,在黄河地区该层厚度最大,约5.5km。而在测线南端的大片地区花岗岩出露地表。该沉积层的下侧是结晶基底,其顶面的首波速度为6.00km/s。在它与莫霍面之间还可分出三层,其相应震相为P2,P03和P04,其中P03较为稳定,它是地壳内部的反射波震相,平均速度约5.97km/s,深度为18至23km。本文得出了这几层的深度变化剖面图。并发现在新郑与新乡间黄河流经的地区,地壳内速度的横向变化及梯度层的分布情况有其明显特点。从对其他震相的分析,还获得新乡以南沉积层内的速度分布及舞阳附近的断层位置,并表明在本区上地幔内存在高速夹层的可能性。Abstract: In this paper preliminary results of the interpretation of DSS data of the Suixian—Anyang profile are presented.The results show that the depth oif the Moho interface reaches 28 to 36 km in this region, and the average velocity in the crust here is about 6.24 km/s. The Mohb is deeper near the Qixian and Xinzheng counties. The velocity in the sedimentary layer is about 3.50 km/s, which is much thicker near the Yellow River (5 or 5.5 km). In the southern part of the profile there are granites and metamorphic rocks on the surface. The velocity of head waves near the upper boundary of crystalline basement is about 6.00 km/s. Three interfaces can be traced between this boundary and the Moho. They are P2,P03 and P04; among these the P03 is more stable. It is the reflection from an interface in the crust. The average velocity in it is 5.97 km/s, and its depth varies from 18 to 23 km. Aseismic cross-section is also presented. Distinct features about the inhomogeneity of velocity and the gradient layer in the crust near the Yellow River between Xinzheng and Xinxiang have been noticed.We have also investigated the velocity distribution in the sedimentary layers near Xinxiang and the position of the fault near Wuyang according to the data of the diffracted phases. There is possibility of the existence of intercalary layers with high velocity in the upper mantle of this region.
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