沉积学报2001，Vol.19Issue(1)：7-12,6.
事件层的保存潜力探讨
Discusses on Preservational Potential of Event Bed
摘要
Abstract
The increasing awareness of tempestites in the ancient record has correspondingly led to much consideration of their preservability. The main factors influencing the preservability are the net sedimentation rate, the biogenic mixing rate, and the magnitude of physical reworking. Wheatcroft has put forward the concept of time scales to attempt to solve this problem. The terms of transit time and dissipation time are introduced. Transit time is related to the thickness of the biogenic reworking zone , the thickness of event beds and sedimentation rate. The biogenic reworking zone is also controlled by the animal size and the behavior engaged in during its generation. The determination of transit time is diffi cult because of the unsteady and unpredictable sedimentation rate. The determination of dissipation time is even more complicated than that of transit time. The dissipation time is controlled by many factors such as the size of infauna, the behavior engaged in by the organisms, the dynamic interplay between the benthic community and the depositional event itself, the desirability of the event bed as a site for colonization and as a repository of food resources and the absolute time available for burrowing etc. Unfortunately, the preceding factors appear to resist quantification and therefore severely limit the effectiveness of ex isting mathematical models to explain tempestites preservation in the rock record. Physical reworking of the substrate has a profound effect on the preservation of both the event bed and the fair-weather deposits. On the basis of comprehen sive analyses of all factors influencing preservational potential of event beds and empirical observations, both proximal upper-shoreface and middle-shoreface and distal shelf and lower offshore favor preservation of tempestites but for markedly different reasons. The lowest preservational potential for tempestites appears to occur somewhere between the proximal and distal extremes. Such zones appear to correspond to proximal Cruziana ichnofacies suite of the upper offshore and distal portion of the lower shoreface.关键词
事件层保存潜力过渡时间消除时间机械改造分类
天文与地球科学引用本文复制引用
Pemberton,SG,周志澄..事件层的保存潜力探讨[J].沉积学报,2001,19(1):7-12,6.基金项目
国家自然科学基金 （）
