通过沉积速率判断沉积地层连续性方法简介

A method to estimate the completeness of stratigraphic sections by using sedimentation rates

沉积地层的连续性判断对于定义生物灭绝等大的生物演化事件具有重要意义、对近25000个不同沉积环境下的沉积速率数据的综合分析发现，沉积速率随着时间尺度的增大呈现减小的趋势，且减小的程度与沉积环境有关。依据该相关性Sadler提出利用长期沉积速率与短期沉积速率的比值来估算地层在不同时间尺度上的连续性，然而随后的研究发现平均短期沉积速率的计算存在很大弊端，需要对数据进行校正才能用于评价地层的连续性。

A quantitative understanding of the completeness of the geologic record is necessary for a proper understanding of organic evolution like extinctions. A compilation of nearly 25000 rates of sediment accumulation shows a systematic trend of falling mean rate with increasing time span. The gradients of such trends vary with environment of deposition. Basing on this principle, Sadler suggested a ratio of median long- to short-term accumulation rates to estimate the completeness of sedimentary stratigraphic sections, at the time scale of the short- term rate. However, the followed study found that the median short-term sedimentation rates calculated in this method are erroneous. A new method for recalculating median sedimentation rate has been applied to measure the completeness of sedimentary section.