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近年来,随着海区第四纪地质研究的深入,为开展全新世长江水下三角洲沉积模式的研究,我局在西起长江沿岸、东至124°E,北起 32°N、南至30°10′N的四万平方公里测区内进行了3000公里的测深和浅地层剖面测量工作.浅地层剖面调查采用EG＆G公司的地层剖面系统.大量浅地层剖面结合浅钻进行的地质解释,提供了该三角洲研究中重要地质问题的依据和佐证.加强了海区浅部地层划分、厚度变化、区域分布规律,和浅部地层不稳定性的研究.一、地震反射层序的划分及其特征(一)层组的划分:沉积过程中由于岩层的密度、速度差异,沉积物内出现了声学层面和不整合面的两种物性波阻抗界面.浅地层剖面利用声波在海水和海底沉积物中的传播和界面上的反射,根据声波到达海底和各个界面的传播时间及其在地层中的速度来研究海底沉积层.根据这个原理可以按以下原则划分浅地层剖面:
In recent years, with the deepening of quaternary geological research in the sea area, in order to carry out the Holocene depositional model of the Yangtze River Delta, the Bureau starts from the west of the Yangtze River in the west to 124 ° E to the east, 32 ° N to the north and 30 to the south Depth measurement of 3000 km in the 40,000 km 2 test area of ° 10’N.The shallow stratigraphic section survey adopted the stratigraphic profile system of EG & G. A large number of shallow stratigraphic sections combined with the geological interpretation of shallow drills, This paper provides the basis and evidence for the important geological problems in the study of the delta, and strengthens the study on the stratigraphic division, thickness variation, regional distribution law and instability of shallow strata in the sea area.Section 1: Classification and Characteristics of Seismic Reflective Sequence (Ⅰ) Classification of layer groups: Because of the difference in density and velocity of sedimentary layers during deposition, there are two kinds of physical impedance interfaces such as acoustic and unconformities in the sediments.The shallow stratigraphic sections use sound waves in seawater and seafloor sediments According to this principle, we can draw the following principles to draw the following conclusions: Sub-shallow profile: