Harnessing stratigraphic bias at the section scale: conodont diversity in the Homerian (Silurian) of the Midland Platform, England
Harnessing stratigraphic bias at the section scale: conodont diversity in the Homerian (Silurian) of the Midland Platform, England
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DOI：
10.1111/pala.12326
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发表时间：
2018-01-01
期刊：
影响因子：
2.6
通讯作者：
Munnecke, Axel
中科院分区：
文献类型：
--
作者：
Jarochowska, Emilia;Ray, David C.;Munnecke, Axel
由于沉积和成岩环境的变化，地质序列中的化石丰度和多样性容易产生偏差，导致化石积累和保存的速度不同。在模拟中，这种偏差可以根据层序-地层架构进行限制。然而，缺乏一种实用的量化方法，将层序地层结构在群落古生态学中的贡献和从个体演替中得出的多样性分析结合起来。作为一个受地层偏差影响的动物群更替模型，我们使用了穆尔德事件，这是一个假设的中志留世牙形刺更替时间间隔，与全球海平面变化相吻合，并基于区域限制的观测。我们测试牙形刺周转率是否在与事件和事件后间隔相对应的边界处最高，而不是牙形刺周转率反映生境跟踪和峰位相变化的替代方案。基于米德兰地台北部和中部的准层序级地层格架，利用置换多元方差分析方法，评价了层序地层结构、时间和沉积环境对牙形刺分布的相对控制作用。沉积环境控制着牙形刺组合组成的最大变异性，而无法检测到假想的莫德事件，即牙形刺多样性的真正时间变化。根据地层层序的划分，可以产生对比的多样性和更替模式。这里提出的简单方法，模拟将多样性划分为空间和时间部分，可能有助于限制地层偏见，即使是在单个剖面的规模上也是如此。
Fossil abundance and diversity in geological successions are subject to bias arising from shifting depositional and diagenetic environments, resulting in variable rates of fossil accumulation and preservation. In simulations, this bias can be constrained based on sequence-stratigraphic architecture. Nonetheless, a practical quantitative method of incorporating the contribution of sequence-stratigraphic architecture in community palaeoecology and diversity analyses derived from individual successions is missing. As a model of faunal turnover affected by the stratigraphic bias, we use the Mulde event', a postulated mid-Silurian interval of elevated conodont turnover, which coincides with global eustatic sea-level changes and which has been based on regionally constrained observations. We test whether conodont turnover is highest at the boundary corresponding to the event' and post-event' interval against the alternative that conodont turnover reflects habitat tracking and peaks atfacies shifts. Based on the previously documented, parasequence-level stratigraphic framework of sections in the northern and central part of the Midland Platform, the relative controls of sequence-stratigraphic architecture, time and depositional environment over conodont distribution are evaluated using permutational multivariate analysis of variance. The depositional environment controls the largest part of variability in conodont assemblage composition, whereas the postulated Mulde event', or genuine temporal change in conodont diversity, cannot be detected. Depending on the binning of the stratigraphic succession, contrasting diversity and turnover patterns can be produced. The simple approach proposed here, emulating partitioning of diversity into spatial and temporal components, may help to constrain the stratigraphic bias, even at the scale of an individual section.