谷-丘互相对称的地震反射特征与成因及对琼东南盆地北礁凹陷的意义

发布时间：2018-03-26 14:54

本文选题：丘-谷互相对称　切入点：蛋白石-A　出处：《地质科技情报》2017年03期

【摘要】：谷-丘互相对称(下伏地层的谷与丘分别对应上覆地层的丘与谷)的地震反射很少引起关注,但随着地震勘探技术的广泛应用,这类地震反射发现得越来越多,其成因也各不相同。总结了5类谷-丘互相对称的地震反射,其成因类型有蛋白石-A转变成蛋白石-CT、泥岩密度反转、底流侵蚀沉积、在深水环境中以砂岩充填为主的水道(富砂水道)的差异压实、侵入岩岩床。南海琼东南盆地北礁凹陷谷-丘互相对应的地震反射与这5类反射的对比表明,北礁凹陷谷-丘互相对称的地震反射属于这5类中的底流侵蚀沉积成因类型,同时揭示了北礁凹陷中中新统谷-丘为晚中新世早期等深流(底流)剥蚀的结果,之后底流减弱以沉积为主,在中中新统谷-丘的上方形成各自对应的丘-谷,上中新统的谷具有明显的迁移削截现象且伴有浊流沉积,这是与其他4类(无迁移无浊流)谷-丘互相对称地震反射特征的根本区别。
[Abstract]:The seismic reflection of valley and mound symmetry (the valley and mound of underlying strata correspond to overlying strata respectively) is seldom concerned, but with the wide application of seismic exploration technology, more and more of this kind of seismic reflection is found. In this paper, five types of seismic reflection from valley to mound are summarized. The genetic types include opal A transition to opal CTS, mudstone density inversion, bottom flow erosion deposition, and so on. The differential compaction of sandstone-filled waterways (sand rich waterways) in deep water environment and the intrusive rock bed show that the corresponding seismic reflection between valley and mound of Beijiao depression in Qiongdongnan basin of the South China Sea shows that there are five types of seismic reflection. The symmetrical seismic reflection between valley and mound in Beijiao sag belongs to the genetic type of bottom flow erosion in these five types. It is also revealed that the Miocene valley-mound of Beijiao sag is the result of the erosion of isodepth flow (bottom flow) in the early late Miocene. After that, the bottom flow weakened mainly by sedimentation and formed corresponding mound valley above the Miocene valley and mound. The Pliocene valley had obvious migration and truncation phenomenon and was accompanied by turbidite deposition. This is the fundamental difference from the other four classes (no migration and no turbidity current) between the valley and the mound.
【作者单位】：西北大学大陆动力学国家实验室;西北大学地质学系;陕西省一八六煤田地质有限公司;
【基金】：国家科技重大专项(2011ZX05025-006-02) 国家自然科学基金项目(41390451)
【分类号】：P631.4

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