层序级别划分与驱动机制的探索

Reviews on sequence hierarchy and driving mechanism

关键词:  层序地层  层序级别  驱动机制  海平面变化  天文旋回

Key words:  sequence stratigraphy  sequence hierarchy  driving mechanism  sea-level change  astronomic cycle

摘要:

在多年研究的基础之上,地质学家提出了两种层序级别划分途径。第一种划分方案是按层序界面特征和属性进行级别划分,不受时间范围的限制,有利于小型陆相孤立盆地的层序级别划分。第二种划分方案以层序发育时限为基础进行级别划分,把全球海平面振荡作为形成层序的驱动机制,为研究全球变化和地层的大范围对比提供了一个有效途径。海平面变化与构造运动、沉积物供给等因素相互影响形成层序的假设已得到普遍认可,同时将这种旋回性与天文周期结合起来为进一步探索形成层序的最终驱动机制提供了一个更加广阔的思考空间。基于显生宙资料得出的层序地层模式在前寒武纪地层划分对比中还存在许多问题,有待于进一步解决。各种不同的概念和模式都是前辈地质学家对解释复杂而不完整的地层记录的一种尝试,追踪这一具有重要意义的层序地层学基本问题可以为今后的研究提供线索。

Abstract:

Two kinds of classification schemes for sequence hierarchy have been proposed by the previous geologists. The one depends on physical attributes of boundary rather than cycle duration. This kind of classication schemes is much more convenient for the stratigraphic division of small isolated continental facies basins. The other is based on the cycle duration or boundary frequency, and emphasizes global sea-level changes as the main driving force behind stratigraphic cyclicity. This kind of classication schemes has provided an effective way to the study of global changes and large-scale stratigraphic correlation. It is a widely perceived notion that the sequences are the products of interaction among sea-level changes, tectonism and sediment supply. The integration of stratigraphic cyclicity and astronomic orbital cycles will offer some profound thoughts not only on the final driving mechanisms but also on possible future directions and problems. Many problems remain to be resolved for the Precambrian stratigraphic division and correlation due to the limit of the existing sequence stratigraphic models only based on the Phanerozoic data.