黔南大贵州滩早三叠世高频旋回堆积型式及其与地球轨道参数变化周期的关系

RELATIONSHIPS OF THE EARLY TRIASSIC HIGH FREQUENCY CYCLIC DEPOSITION TYPES IN DAGUIZHOUTAN, SOUTHERN GUIZHOU, WITH THE PERIODS OF CHANGE OF THE ORBIT PARAMETERS OF THE EARTH

大贵州滩是右江盆地内的一个三叠纪孤立碳酸盐岩台地。其早三叠世滨潮坪５级小旋回（厚０．５～８ｍ）是由潮下泥粒灰岩和潮间条纹岩及蓝藻细菌粘结岩等组成的。小旋回组合规律为：小旋回按４∶１（个别为３∶１）的比例组成小旋回束，后者又按３∶１的比例组成小旋回组。各小旋回束、小旋回组和海侵—海退旋回下部的小旋回均厚度较大，潮下沉积相对发育；上部的均厚度较小，潮间沉积相对发育。这种特征可作为滨潮坪沉积序列中３、４级旋回（层序）内地层的退积和进积堆积型式的识别标志。大贵州滩早三叠世滨潮坪小旋回同美国科迪勒拉、阿巴拉契亚晚寒武世碳酸盐岩滨潮坪米级旋回的相组合与堆积型式特点非常相似。为了便于研究高频旋回堆积型式和在地表暴露不整合不发育的地层序列内划分３级层序，本文提出３～５级海侵—海退旋回及层序的划分方案：５级为小旋回、复合小旋回，相应层序为小层序、复合小层序；４级为小旋回束、小旋回组，相应层序为小层序束、小层序组；３级为海侵—海退旋回、复合海侵—海退旋回，相应层序为海侵—海退层序、复合海侵—海退层序。大贵州滩早三叠世海侵—海退层序２总时限为２百万年，含５８个小旋回、１５个小旋回束、５个小旋回组，其小旋回和小旋回组的平均年龄分别?

On the basis of the features of high frequency cyclic deposition types and relevant studies,the authors put forward their opinions about the 3rd to 5th order cycles and their corresponding sequence division.According to their suggestion,each order contains two suborders.The 5th order is marked by the minor cycle and composite minor cycle or the essential sequence and composite essential sequence;the 4th order is represented by the minor cycle bundle and minor cycle group or the essential sequence bundle and essential sequence group;the 3rd order cycle is the transgressive regressive cycle and composite transgressive regressive cycle or the transgressive regressive sequence and composite transgressive regressive sequence.The average ages of the minor(meter scale)cycle and cycle group of littoral tidal flat carbonate rocks of the transgressive regressive sequences 2 at Daguizhoutan are 33.3 ka and 400 ka,respectively,which are close to the slope period 34 ka and the long escentricity period 413 ka of the earth orbit prior to the Quaternary,respectively.So it is inferred that the origin of Early Triassic littoral tidal flat high frequency cycles at Daguizhoutan is probably related to that.