碟形侵入体的地震信息及解释

Seismic Information and Interpretation of Saucer-Shaped Intrusions

近年来利用高分辨率三维地震在世界众多盆地发现了碟形侵入体,其研究已进入一个新的高度。地震剖面上的碟形侵入体除传统的岩浆侵入成因外,还有砂岩侵入成因。结合国内外众多研究实例,通过详细比对砂岩岩床与火成岩床的地震反射特征以及与它们相关的地质构造,发现两者的异同点主要表现在:1砂岩侵入体多见于具多边形断层的泥岩地层中,呈V形或翼状强振幅,翘倾的翼部与平坦岩席交接处为尖棱转折端,面积上限为数十平方千米;火成岩床的产出背景较为广泛,呈碟形强振幅,其交接处为弧形转折端,面积上限达数百平方千米。2同砂岩岩床相比,碟形火成岩床的侵位会降低其周缘早期成岩成因的多边形断层密度。这两点成为区别砂岩岩床和火成岩床的关键因素,并在此基础上探讨了两者对石油地质的影响。目前碟形侵入体的解释主要集中在火成岩床,以后还应考虑侵入型砂岩岩床的可能性。

In recent years,many saucer-shaped intrusions have been found in the word-wide basins by the use of high resolution 3Dseismic,and their researches have reached a new level.The saucer-shaped intrusions on seismic profile are not only attributed to the traditional magma intrusion but also origin from sand injections.Based on the numerous research examples home and abroad,this study elaborates the seismic reflection characters of igneous sills and sandstone sills,and compares in detail the respectively related structures.The study found that their similarities and differences are evidenced by two aspects.1Sandstone intrusions are common in shale formations with polygonal faults,showing V-shaped or wing-like high amplitude,sharp-edged hinge zone between tilted limbs and even sills,covering an area of over 10 square kilometers in the upper limit of the sill.While igneous sills are more extensive,showing saucershaped of high amplitude,arc-like hinge zone and the toplimit of its area is hundreds of square kilometers.2Saucer-shaped igneous sills will reduce the density of polygonal faults.These two points become the efficient key to distinguish igneous sills and sandstone sills,and on this basis,the impact of both on the petroleum geology is discussed.Currently the explanation of saucer-shaped intrusions mainly focuses on igneous sills,and may later consider the possibility of intrusive sandstone sills.