碳酸盐岩台地三级层序界面的讨论

由于碳酸盐岩沉积作用对海平面变化具特有的敏感性及台地类型存在多样性，碳酸盐岩沉积背景下的三级层序界面应在考虑海平面变化阶段、海平面下降幅度和台地暴露程序基础上扩展为四类。其中沉没性质的ＳＲ４常具台地终止性意义，小幅度海平面下降造成的ＳＢ３是台地演化过程中最常见的，这些层序界面可依沉积、地震及叠加的成岩标志加以识别。

QUANTITATIVE RESEARCH ON SEA LEVEL CHANGE

The law of sea level change is one of sequence stratigraphical research. The global eustasy is of more significance of correlation than relative sea level change. By means of mathematic calculation and the correction of sediments load, compaction, water depth and water load, the method to obtain tectonic subsidence is applied to work out quantatively R 1 curve, which contains only heat effect, global eustasy and subsidence caused by potential local tectonic events after the correction of compaction, water depth and water load. The least square is used to take off tectonic subsidence caused by heat effect, yielding R 2 curve of eustasy. Then best fit polynomial is used to remove effect of long term sea level fluctuation resulting simply R 3 curve, which can identify change of accommodation space. The Fischer's point map (F.P.) and the corrected F.P. for correlation, have further proved that the subsidence analysis yields better effects when applied in Ordos region.