山东省灵山岛负载构造和球-枕构造研究

本文运用野外露头考察、沉积岩石学、地质统计等方法,对灵山岛的负载构造和球-枕构造进行研究。这些负载构造和球-枕构造侧向延伸好,在整个剖面上连续分布,具有多尺度、多形态、多组合等特点。形成负载构造和球-枕构造的前提条件是地层密度的倒置(上大下小),变形的根本驱动力是沉积物自身的重力。球-枕构造和负载构造的形成机制相同,只是变形程度和阶段不同。根据不对称负载构造受横向剪切力分析,证明早白垩世时该盆地存在古斜坡,并且SE高、NW低。综合考虑地震触发形成震积岩的标志特征和灵山岛的构造地质背景,认为本研究区的负载构造和球-枕构造系古地震触发形成。

Load structures and ball-and-pillow structures on the Lingshan Island, Shandong

The load structures and ball-and-pillow structures on the Lingshan Island, Shandong are examined in the light of outcrop observation, sedimentary petrology and geostatistical analysis. These load structures and ball-and-pillow structures are laterally extensive in the studied sections, and have the features of multiple scales, multiple morphologies and multiple associations. They are interpreted to be originated from the stratigraphic density inversion (bigger in the upper part and smaller in the lower part). In other words, the gravity-induced overlying deposits with greater densities and earthquake-induced liquification penetrated into the underlying strata, resulting in the formation of the load structures and ball-and-pillow structures. The asymmetrical morphology of the load structures strongly support the existence of the Lingshan palaeoslope during the Early Cretaceous. The statistics of the sizes of the load structures and ball-and-pillow structures may be used to deduce those of earthquake magnitudes. The presence of abundant load structures on the Lingshan Island indicates that frequent structural activities, especially the seismic activities may be responsible for the formation of the load structures and ball-and-pillow structures in the study area.