COLLABORATIVE RESEARCH: The Biostratigraphic Effects of Facies Control, Depositional Sequences, and Sampling Intensity: An Interactive Modeling and Field Approach

所有生物地层对比方法面临的主要问题是，在局部剖面上首次和最后出现的地层并不总是反映真实的起源和灭绝时间。采样、相控制和层序地层构型都对局部地层范围造成了偏差。许多方法声称可以解释这些偏差，但这种说法很少得到检验，而且人们对不同方法的相对准确性知之甚少。本文拟对三种杨树生物地层学方法（传统的地层学、双重生物地层学和图解对比）进行测试，以确定哪种方法最能有效地处理有偏差的化石记录，并找出对生物地层对比准确性影响最大的因素。我们将通过建模和实地研究相结合的方法来解决这个问题。建模将用于测试这三种方法在各种采样密度、相控制水平和层序地层结构下的相对准确性。建模的好处是我们最终会知道正确的相关性，因此我们可以客观定量地衡量各种方法在不同条件下的准确性。我们在这里开发的技术将允许在未来测试许多其他类型的生物地层学方法。利用从建模研究中获得的知识，我们将评估田纳西州东部和弗吉尼亚州西南部中奥陶世腕足类动物的经典相关性问题。我们将把这三种生物地层学方法应用于野外数据，并将结果与现有的基于牙形刺的地层格架进行比较。本研究不仅将对采样、相控制和层序地层构型对三种常用生物地层学方法的影响进行一般性评价，而且还将应用这些结果建立一个腕足类生物带和层序地层对比框架，以补充阿巴拉契亚南部中奥陶统以牙形刺为基础的对比。由于生物地层学是在大部分地层记录中对事件进行排序的主要手段，因此这项研究的结果对如何重建地球历史具有广泛的意义。

9705732 Holland The principal problem facing all biostratigraphic correlation methods is that first and last occurrences in local sections do not always reflect the true times of origination and extinction. Sampling, facies control, and sequence stratigraphic architecture all impose biases on local stratigraphic ranges. Many methods claim to account for these biases, but this claim has rarely been tested and the relative accuracy of different methods is poorly known. We propose to test three poplar biostratigraphic methods (traditional zonal biostratigraphy, dual biostratigraphy, and graphic correlation) to determine which is the most effective at dealing with the biased fossil record and to identify those factors that exert the strongest control on the accuracy of biostratigraphic correlation. We will approach this problem through a combined modeling and field study. Modeling will be used to test the relative accuracy of these three methods under a variety of sampling densities, levels of facies control, and sequence stratigraphic architectures. The advantage of modeling is that we will ultimately know the correct correlation, so we can objectively and quantitatively measure the accuracy of the various methods under different conditions. The techniques we develop here will allow many other types of biostratigraphic methods to be tested in the future. Armed with the knowledge gained from the modeling studies, we will evaluate a classic correlation problem with brachiopods in the Middle Ordovician of eastern Tennessee and southwestern Virginia. We will apply these same three biostratigraphic methods to the field data and compare the resulting correlations to the existing conodont-based stratigraphic framework. This study will lead not only to a general evaluation of the effects of sampling, facies control, and sequence stratigraphic architecture on three common biostratigraphic methods, but will also apply these results to develop a combined brachiopod-biozone and sequence stratigra phic correlation framework to supplement existing conodont-based correlations in the Middle Ordovician of the Southern Appalachians. Because biostratigraphy is the principal means by which events are ordered throughout much of the stratigraphic record, the results of this study have broad implications for how Earth's history is reconstructed.