沉积记录中的古气候周期及其在高频层序形成中的意义

目前认为,构造升降、气候所控制的湖平面变化以及沉积物的供给对陆相湖盆层序发育的范围、厚度、演化阶段及层序边界的形成起着主要控制作用,而对于同一湖盆演化的不同阶段,则是不同因素对各级层序的形成起着主要的控制作用.某一时期,构造因素决定着较大级别层序边界的形成;而在构造活动相对稳定期,基于天文旋回的气候周期是高频层序形成的主要控制因素.在以往的研究中,对气候周期的深入分析一直较薄弱.加强气候因素的研究,从而更精确地解析高频层序的成因,进行高频层序的划分、对比,预测优质储层和烃源岩的特征及分布是今后能源和盆地研究中必不可少的一个工作重心.另外,随着"天文年代表"概念的提出,天文轨道旋回的方法已成为确定地层年代的一个重要手段.

Paleoclimatic Cycles of Depositional Record and Their Control over the Formation of High-Frequency Sequences

The stratigraphic cyclicity has been an interest for geologists for over 20 years.Since its application,the sequence stratigraphy has been a significant theory for basin filling study and an important method for resources estimation.It is supposed that tectonic uplift and subsidence,climate and changes of sediment supply rate are the controlling factors of sequence development in lacustrine basins.They are responsible for the formation of different sequences in different periods or stages.The major unconformities mainly resulted from tectonic factors,while climate is the major controlling factor for high-frequency sequence.However,the controlling mechanisms are poorly understood. It should also be noted that the astronomical climatic cycles in stratigraphic record have been becoming a significant method to determine geologic ages with the presence of "Astronomical Time Scale".Therefore,the research should be focused on climate factors,the forming mechanism of high-frequency sequences,and the distribution,quality and characteristics of the reservoir and source rocks in resources exploration.