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

9705732荷兰，所有生物地层对比方法面临的主要问题是，局部剖面中的第一次和最后一次出现并不总是反映起源和灭绝的真实时间。采样、相控制和层序地层结构都对当地地层范围造成了偏差。许多方法声称可以解释这些偏差，但这种说法很少被测试，不同方法的相对准确性也鲜为人知。我们建议测试三种杨树生物地层学方法(传统的带状生物地层学、双重生物地层学和图形对比)，以确定哪种方法在处理有偏差的化石记录方面最有效，并确定对生物地层对比精度起最大控制作用的因素。我们将通过建模和实地研究相结合的方式来解决这个问题。建模将被用来测试在不同的采样密度、相控制水平和层序地层架构下这三种方法的相对精度。建模的好处是我们最终会知道正确的相关性，所以我们可以客观地、定量地衡量不同条件下各种方法的精度。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。有了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的经典相关性问题。我们将把同样的三种生物地层学方法应用于野外数据，并将所得到的相关性与现有的基于牙形刺的地层框架进行比较。这项研究不仅将对采样、相控制和层序地层结构对三种常见生物地层学方法的影响进行总体评估，还将应用这些结果建立腕足类生物带和层序地层对比框架，以补充阿巴拉契亚山脉南部中奥陶统现有的基于牙形刺的对比。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影响。

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.