鄂尔多斯南缘中奥陶统中的滑塌构造及其地震成因  

The Slump Structures in the Middle Ordovician on the Southern Margin of Ordos Basin and Their Seismic Origin

作　　者：袁效奇 苏德辰[2] 贺静 孙爱萍[2] 吕洪波[3] 李海兵[2] 乔秀夫[2] 

机构地区：[1]中国石油长庆油田分公司勘探开发研究院,西安710016 [2]中国地质科学院地质研究所大陆构造与动力学国家重点实验室,北京100037 [3]中国石油大学华东地学院,山东青岛266580

出　　处：《地质论评》2014年第3期529-540,共12页Geological Review

摘　　要：奥陶系赵老峪组主要出露于鄂尔多斯盆地南缘的陕西富平地区,该组地层主体为深水相的薄层灰岩和页岩状极薄层灰岩,期间夹有大量的滑塌构造和异常角砾灰岩.作者对属于中奥陶统的赵老峪组1～4段地层中的滑塌构造进行了专题调查,在近30个层位中发现了典型的、规模不等的滑塌褶皱变形和滑塌角砾岩.这些滑塌体主要由强烈褶皱变形的灰岩和角砾灰岩组成,与上下岩层之间界线截然.大部分滑塌（砾岩）层厚度稳定,分布范围较大.根据滑塌构造的形态和成分特征、非滑塌软沉积物变形构造的特点以及前人成果,认为赵老峪组中的滑塌构造和滑塌砾岩的最直接触发因素不是风暴、潮汐等盆地内部的因素,而是构造活动（包括火山活动）引发的地震,每一个滑塌变形层对应一次较大的地震事件.赵老峪组地震成因的滑塌层的大量发育,说明其形成期间,盆地周边的构造活动非常强烈.并进一步推论赵老峪组中的没有明显滑塌变形的异常角砾灰岩很可能也是由地震触发的滑塌形成的颗粒流或浊流的产物.The Middle Ordovician Zhaolaoyu Formation is mainly outcropped in the west and southern margin of the Ordos Basin. After a thorough field investigation in 2013, the writers found nearly 30 slump layers and slump debris layers of different scales in the Middle Ordovician （1 st～4th Member of the Zhaolaoyu Formation）. All the boundaries between the slump layer and overlying/underlying strata are very smooth and distinctive. Most slumping layers have a stable thickness and are widely distributed among the study area. Based on the field observation and the related data of former researchers, the writers conclude that all the slump features in the Zhaolaoyu Formation are the products of ancient seismic slumping caused by tectonic movement （ including the volcanism）. Other factors such as storms or tides can be excluded for the very deep formation depth of the Zhaolaoyu Formation. Each slump layer is the corresponding to one big ancient earthquake event. The abundant slump layers in the Zhaolaoyu Formation indicate the intensive tectonic activities around the sedimentary basin during the Middle Ordovician. The authors further infer that the “abnormal layers” of limestone breccias in the Zhaolaoyu Formation are probably also the products of sliding/slumping movements triggered by independent seismic events, although they may have little or even no evidence of obvious slump structures.

关 键 词：滑塌构造 角砾灰岩 古地震 赵老峪组 鄂尔多斯盆地 

分 类 号：P548[天文地球—构造地质学] P315.2[天文地球—地质学]