论文部分内容阅读
山东沂水地区寒武系张夏组中上部地层的分布，受控于沂沭断裂（Ｆ４和Ｆ３断裂），分为西区、中区和东区。各区岩性、岩相雷同，只是厚度存在明显差异。地层记录旋回性明显，反映高频旋回特点。根据岩性、沉积相序变化及界面特点，将该套地层划分成１个三级、４个四级、１４～１８个五级和６０～８０余个六级旋回层序。各级别旋回层序均由次一级旋回层序向上变浅、变粗、变厚的进积系列组成。其底部均以相应级别的间断－加深面为界。通过高分辨率层序对比，三级、四级旋回层序具有区域对比意义。因受沂沭断裂的影响，区内地层分布并非原始沉积位置所在，由于地方性因素，造成了五级或六级旋回层序数量上的差异。对于三级旋回层序而言，由早期→晚期，随着沉积环境由陆棚盆地→深潮下带→浅潮下带变化，海水由深→浅；沉积速率由小→大；沉积物质由页岩→瘤状灰岩、泥灰岩→鲕粒灰岩→藻灰岩变化。张夏期各地海平面变化趋势相同，均具有高频率振荡特点，为一个复合海平面变化旋回。
The distribution of the upper and middle part of the Cambrian Zhangxia Formation in Yishui area of Shandong is controlled by the Yishu fault (F4 and F3 faults) and divided into the western, central and eastern parts. The lithology and lithofacies are the same in all areas except for the obvious differences in thickness. Stratigraphic records are obviously cyclic, reflecting high-frequency cycle characteristics. According to lithology, sedimentary facies changes and interface characteristics, the set of strata are divided into three stages: one third stage, four fourth stages, 14 ~ 18 fifth stages and 60 ~ 80 sixth-order cycles. The pyramidal sequences at all levels are composed of a sequence of subfractions, which are shallow, thick and thick. The bottom of the corresponding level of discontinuity - deepen the surface as the boundary. By contrasting the high-resolution sequences, the tertiary and quaternary cycles have regional significance. Due to the Yishu fault, the stratigraphic distribution in the area is not the place where the original sediments were deposited. Due to the local factors, the differences in the number of the fifth- or sixth-order cycles are caused. For the third-order gyration sequence, from early stage to late stage, the seawater changes from deep to shallow; the sedimentation rate changes from small to large with the variation of sedimentary environment from the continental shelf basin → deep subtidal zone → shallow subtidal zone; Shale → tumorous limestone, marl → oolitic limestone → algal limestone. The changes of sea level over the same summer have the same characteristics of high frequency oscillation and are a composite sea level change cycle.