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以陕西镇安西口石炭-二叠系界线剖面为具体实例,探讨了冰川型海平面变化控制下的台地碳酸盐岩成岩作用规律.描述了陕西镇安西口石炭-二叠系界线剖面碳酸盐岩的各种成岩作用类型.根据成岩组构将研究区碳酸盐岩的成岩环境分为海水、大气淡水和埋藏环境.综合分析了各种成岩作用及其成岩环境的纵向分布特征.研究表明,剖面上碳酸盐岩成岩作用和成岩环境的特征与岩石在高频旋回中的相对位置存在明显的对应关系,受大振幅、高频率的冰川型海平面变化控制.早期海平面相对上升,形成旋回的下部单元,岩石首先经历海底成岩作用,随着上覆沉积物的增加,逐渐进入浅埋藏环境,成岩作用表现为以压溶、重结晶作用发育为主要特征.晚期形成旋回的上部单元,由于海平面相对下降,沉积物逐渐抬升,早期海底成岩作用尚未充分发育就脱离海水环境,进入大气淡水成岩环境,以强烈的大气淡水成岩作用为特征.
Taking the Carboniferous-Permian boundary line in the west of Zhen’an, Shaanxi as an example, the paper discusses the diagenesis of platform carbonate rocks under the control of glacier-like sea level variation.The paper describes the carbonate-permian boundary section of Zhen’an west exit, According to diagenetic structure, the diagenetic environment of carbonate rocks is divided into seawater, atmospheric freshwater and burial environment, and the diagenesis and longitudinal distribution characteristics of diagenetic environment are comprehensively analyzed. The results show that there is a clear correspondence between the characteristics of carbonate diagenesis and diagenetic environment and the relative position of rocks in high-frequency cycles, and controlled by the glacier-like sea level with large amplitude and high frequency. , Forming the lower unit of the cycle. The rock first underwent seabed diagenesis and gradually entered the shallow burial environment with the increase of overlying sediments. Diagenesis was mainly characterized by depressurization and recrystallization, and the upper part of the later cycle Unit, due to the relative decline in sea level, sediment gradually uplifted, the early submarine diagenesis has not yet fully developed from the seawater environment, into the atmosphere light Diagenetic environment, with a strong feature meteoric diagenesis.