华北北部晚寒武世沉积旋回分析

LATE CAMBRIAN SEDIMENTARY CYCLES IN THE NORTH PART OF THE NORTH CHINA PLATFORM

华北北部晚寒武世沉积一套多旋回碳酸盐岩建造,在稳定的构造背景和无陆源物质大量供给条件下,这些旋回主要受海平面变化和气候影响控制。由于控制因素在全区一致,因此反映这种变化和影响的沉积旋回是可比的,相对应的沉积旋回具有等时性意义。利用这些等时性关系,编制出一系列高精度岩相古地理图。

Based on a detailed petrologic and sedimentological study, five 3 rd-order sedimentary cycles have been distinguished in the Late Cambrian strata in the study area, and the basic characteristics of the sedimentary cycles have been analysed and the main factors which control the cycles have been assessed. Sea-level change and climates (storm action) were the major factors controlling the cycles in this region. Under the relatively stable tectonic conditions, the sea-level change trend was consistent in the whole platform, the cycles reflecting this change trend are comparable one another and the corresponding cycles were synchronic.Finally, using this kind of synchronic relationship, the author compiled a series of high-precision lithofacies and paleogeographic maps of the sediments which respectively correspond to the culminations of the maximum trangression and regression periods of the lower semicycle and the whole lower semicycle of cycle Ⅲ in the study area.