逆断层正牵引构造对冲积扇沉积过程与沉积构型的控制作用:水槽沉积模拟实验研究

发布时间：2018-01-23 08:33

  本文关键词： 水槽实验 正牵引构造 冲积扇 沉积过程 沉积构型　出处：《地学前缘》2017年06期 　论文类型：期刊论文

【摘要】：逆断层正牵引构造广泛发育于挤压盆地边缘,伴随逆断层的幕式活动而生成,并影响山前冲积扇沉积过程与沉积构型。为进一步认识这种特殊的凸起构造对冲积扇沉积过程及其内部构型的控制作用,利用水槽实验对正牵引构造发育背景下的冲积扇沉积过程进行模拟与观测。研究表明,携带大量沉积物的碎屑流冲出供水槽后很快受到正牵引构造的阻挡,大量的粗粒沉积物快速卸载在正牵引构造的迎水面,形成一个砂砾坝,同时水流被分成两股分支水流。由于较粗粒的沉积物快速在迎水面卸载,砂砾坝迎着水流逐步向物源方向生长,形成逆向(生长)砂砾坝。分支水流绕过正牵引构造后形成两个新的次级物源,在次级物源持续供给下,形成两个由多期碎屑流朵体复合而成的次级扇。受控于正牵引构造的阻挡,冲积扇表面不同位置的沉积物卸载过程差异较大,相较于正常冲积扇沉积体,砂砾坝沉积物偏粗、分选更差,而次级扇沉积物粒度偏细、分选更好;正牵引构造凸起幅度高低也会影响冲积扇沉积构型,凸起幅度越高,正牵引构造对水流的阻挡作用越强、越持久,逆向砂砾坝和次级扇的规模越大、空间结构也越复杂。正牵引构造完全被沉积物覆盖后,扇面沉积特征与一般冲积扇无异。受控于正牵引构造的冲积扇与一般冲积扇的内部构型存在较大差异,在顺物源剖面上前者依次发育碎屑流朵体、逆向砂砾坝及次级扇,而后者则整体以碎屑流朵体为主;在由近端至远端的切物源剖面上,前者依次以碎屑流朵体主控、逆向砂砾坝主控及次级扇主控,而后者则均以碎屑流朵体主控为主。
[Abstract]:The normal traction structure of the reverse fault is widely developed in the margin of the compressional basin and is formed along with the episodic movement of the thrust fault. It also affects the deposition process and sedimentary configuration of alluvial fan in front of mountains. In order to further understand the control effect of this special uplift structure on the sedimentary process and internal configuration of alluvial fan. The sedimentation process of alluvial fan in the background of positive traction structure is simulated and observed by flume experiment. The results show that the debris flow carrying a large amount of sediment is quickly blocked by the positive traction structure after it is washed out of the supply tank. A large amount of coarse sediment is rapidly unloaded on the front surface of the positive traction structure, forming a gravel dam, and the flow is divided into two streams of water flow. The gravel-gravel dam gradually grows toward the material source and forms the reverse (growth) sand gravel dam. After the branch water flows around the positive traction structure two new secondary material sources are formed under the continuous supply of the secondary material source. Two secondary fans composed of multi-stage clastic flow are formed. Controlled by the blocking of positive traction structure, the process of sediment unloading at different positions on the surface of alluvial fan is quite different, which is different from that of normal alluvial fan. The gravel-dam sediments are coarse and worse, while the secondary fan sediments are finer in size and better in sorting. The higher the uplift amplitude of the positive traction structure is, the greater the sedimentary configuration of alluvial fan is. The higher the uplift amplitude is, the stronger the blocking effect of the positive traction structure is on the flow of water, the longer the duration is, the larger the scale of the reverse gravel dam and secondary fan is. The more complex the spatial structure is, the more the sedimentary characteristics of the fan are similar to those of the general alluvial fan after the positive traction structure is completely covered by the sediment. The internal configuration of the alluvial fan controlled by the normal traction structure is different from that of the general alluvial fan. The former developed debris flow flower body, the reverse sand gravel dam and secondary fan in sequence, while the latter developed debris flow flower body as a whole. In the cutting source profile from the proximal end to the distal end, the former is controlled by the debris flow, the reverse sand dam and the secondary fan, while the latter is dominated by the debris flow.
【作者单位】： 中国石油大学(北京)地球科学学院;油气资源与探测国家重点实验室;长江大学地球科学学院;中国石油勘探开发研究院鄂尔多斯分院;中国石油新疆油田分公司;
【基金】：国家自然科学基金项目(41372116)
【分类号】：P542;P618.13
【正文快照】： 2.长江大学地球科学学院,湖北武汉4301003.中国石油勘探开发研究院鄂尔多斯分院,北京1000834.中国石油新疆油田分公司,新疆克拉玛依834000FENG Wenjie1,2,WU Shenghe1,*,LIU Zhongbao2,XIA Qinyu1,3,ZHANG Ke1,XU Zhenhua1,XIANG Xianpeng41.College of Geosciences,China Uni，

本文编号：1457191