油区构造解析课件 9底辟构造：Diapirs+structure

盐滑脱
The primary salt weld recognized in the central part of the the line emphasizes the tectonic disharmony associated with the bottom of the salt layer. The overburden and sub-salt strata show quite different deformations. Salt roller
撒哈拉穹窿——理查德构造
理查德构造——相当于非洲之眼的眼球
非洲之眼是晚白垩纪碱性岩浆热液上 侵，沿灰质白云岩陆架的环状同生断 裂上侵，引发地表穹隆侵蚀和热液卡 斯特作用，由此而形成一个直径40公 里的眼珠状构造。
岩浆上侵穹窿？
含岩盐盆地的盐丘是是最常见的一类底劈构造，与油气关系密切。 世界含盐盆地分布
压扭性盐构造
Fig. 13- Compressive strike-slip structures (faulted conical-folds) induced by reactivation of fracture zones are frequent in South Atlantic margins. Loeme salt (Kwanza and South Congo basins) forms often the core of anticline structures. Similarly, the Oligocene unconformity is uplifted and locally eroded before being fossilised by Tertiary deepwater deposits.
挤入底劈
Ridge push forces seem to be responsible of the shortening of the cover in deep water, where salt diapirs have been squeezed and backthrusted, as well as the mini-basins between them. The geometrical relationships between the seismic reflectors (seismic surfaces) and the morphology of the seafloor strongly suggest that shortening still is going on.
第八节 垂直构造
底辟构造 Diapirs structure
地下较深处的密度相对小的高塑性岩层或岩体在差异重 力等机制作用下向上拱起或刺穿上覆岩层形成的一种构造。 是垂直构造类型的一种。
一、底辟构造结构要素及基本特征：
（1）.底辟核 （2）.核上构造 （3）.核下构造
1.底辟构造的结构要素
1－底辟核；2－核上构造；3－核下构造
伸展断层
Stretching faults strike in all directions. They are induced by local extension tectonic regimes, in which 2 and 3 are equal. As they elongate the sediments to accommodate them to new volume conditions, On seismic lines they have opposite vergences. Theoretically, the sum of throws with opposite vergence must be zero.
小型底劈构造
小型底劈构造
盆地中的底劈构造
？？
2.底劈构造核部岩性类型
泥底劈
盐底劈（硫酸盐、碳酸盐、石盐）
岩浆底劈
盐底劈
Releasing Bend 释放弯曲 Reatrainning Bend 约束弯曲
泥底劈
Top Taglu Structure map showing the relationship between the present-day compressional
盐丘的几种剖面形态
盐丘的几种剖面形态
构造位置与盐构造类型
二、盐底劈构造类型及特征
1.挤压盐构造
盐背斜
As illustrated on this seismic line, it is quite obvious the salt and overburden have been shortened (compression still is going on) by a compressional tectonic regime that some associate with ridge pushing forces. The faults in the top of the antiforms are strike-slip and not normal faults. Time slices between 3.0 and 3.2 seconds, strongly suggest that such a faults elongate the anticline axis along the s2
no so evident, an Oxfordian salt layer (Auquilco formation) was inverted (inverted rift-type basin in lower middle part of the line) with development of “en echelon folds” in the up-thrown faulted block. Notice, that two different compressional tectonic regimes, one with the basement involved and a younger without involvement of the basement can also explained the deformation recognized on this line.
盐排出盆地
该测线上，有微型盆地在外来岩层上，只能用原生盐抽真空作用来解释。在测线的中部，沿着陡 冲断层，盐向上移动。右下角可见盐下地层和裂缝型盆地）
Salt Weld-盐连接；盐颈 盐盖
This interpretation takes into account the Rayleigh-Taylor instability. During longtime, in this area, erroneously large diapiric structures (>30 km wide) were proposed. With such large salt structures explorationists give up the area due to absence of significant traps (in depth, such structures were 3-4 times thicker than the basin itself). It is obvious that interpretations with salt canopy structures strongly change the petroleum potential, at least the trapping parameter.
2.伸展盐构造
断坪
外来盐
In spite of the stretched horizontal scale, the salt flats, at the bottom of the allochthonous salt sheet, are quite well recognized on this line.
Fig. 25- The salt weld in the central part of the line suggests that before deformation the salt layer was continuous between the yellow and brown interval. Then, the infra-salt strata were lengthened by normal-faults creating potential voids that were filled by salt (“salt grabens”) due to a lateral salt flowage, which created a window in the salt layer. Finally, a compressional tectonic regime shortened the cover inverting the salt grabens.
推覆体
外来盐
It is interesting to notice that in depth, the distal thrust fault corresponds to the seaward limit of a salt basin. Seaward, the salt is allochthonous and forms a salt nappe, which has been reactivated and shortened probably by ridge push forces. It is quite obvious that the thickness of the salt is apparent and due to thrusting. Some argued that the salt being thicker in the ultra deep offshore was the proof of an unique pristine salt basin that was later split in two. Recently, such a erroneously hypothesis has been systematically falsified.