RUI: Taphonomic Character of Plant Fossil Assemblages at the Permian-Triassic Boundary, Karoo Basin, South Africa

RUI：南非卡鲁盆地二叠纪-三叠纪边界植物化石组合的埋藏学特征

• 批准号: 0417317
• 负责人: Robert Gastaldo
• 金额: --
• 依托单位: Colby College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0417317&HistoricalAwards=false
• 关键词: RUI; Taphonomic; Character; Plant; Fossil

PROJECT SUMMARYPage AMany hypotheses have been proposed for the response of the land plants, insects, andvertebrates to the P/Tr boundary extinction event. Many of these hypotheses are based onpoorly unconstrained spatial and/or temporal data. Most lack any contextual constraintof the paleontological data used in the analysis used to support the interpretation.Hence, it is not possible to know if the ?trends? or ?changes? seen to occur from thepreboundary assemblages into the transitional and post-boundary assemblages are a truereflection of the ecosystem or are biased taphonomically.This proposal hypothesizes that an isotaphonomic data set of pre-boundary,trans-boundary, and post-boundary plant-fossil assemblages will allow for the emergence ofa credible characterization of the response within this part of the terrestrial ecosystemat this critical point in Earth history. Will the isotaphonomic plant-fossil recordparallel or be tangential to the well established response in the marine realm? Or, willthere be no change in biodiversity; might the replacement and/or turnover occur earlier orlater in time than directly at the P/Tr boundary?Research conducted, to date, in KwaZulu Natal Province, South Africa, in the northeasternpart of the Karoo Basin indicates that Late Permian megafloral assemblages are preservedin four different sedimentologic and taphonomic conditions. Each megafloral assemblagetype preserves a very different signature of the vegetation contributed to the fossilrecord. These are: (1) parautochthonous assemblages within abandoned fluvial channel fillsequences, similar to modern and other ancient oxbow lakes; (2) dispersed and isolated,allochthonous assemblages preserved on foreset beds and reactivation surfaces withinlarge, fine-grained fluvial regimes; (3) concentrated, mat-like allochthonous assemblageswithin bedload dunes of coarse siltstone channels; and (4) dispersed, sorted assemblagesin turbidites. Data presented in the text concerning two localities ? Bulwer andWagendrift Dam ? demonstrate that previous interpretations of the fossil assemblages inthese sites are incorrect. And if these data are used from the literature as the basisfor interpretation, the resulting suppositions are inappropriate.With an increasing continentalization of the sedimentary package in the Karoo into theTriassic, all but the last taphonomic assemblage type should be encountered in thetransitional and post-boundary sections. Seven cross boundary and post boundary sectionshave been identified in which plant fossils and/or vertebrates are preserved, and willserve as the basis for the 2004 field season. It is anticipated that identification ofisotaphonomic assemblages in this part of the stratigraphy will allow for directcomparison of biodiversity indices with those presently being determined by other membersof an international research team, involving U.S., Dutch, and South African scientists.The present proposal requests funds to support undergraduate student research designed toassist in the acquisition of an isotaphonomic data set in the Karoo Basin, South Africa.Through the next two years of field work and laboratory analysis, P/Tr and early to middleTriassic localities will be assessed to identify and characterize those depositionalsequences as found in the latest Permian.

关于陆地植物、昆虫和脊椎动物对P/Tr边界灭绝事件的反应，已经提出了许多假说。这些假设中的许多都是基于不受约束的空间和/或时间数据。大多数缺乏任何上下文约束的古生物学数据中使用的分析用于支持解释。因此，它是不可能知道，如果？趋势？还是？变更？从边界前组合到过渡和边界后组合的变化是生态系统的真实反映，或者是有偏见的taphonomically.This建议假设，一个边界前，跨边界和边界后的植物化石组合的isophonomic数据集将允许出现ofa可信的表征地球历史上这个关键点的陆地生态系统的这一部分内的响应。植物化石的等声分类记录与海洋领域中已确立的反应是平行的还是相切的？或者，生物多样性不会发生变化;替代和/或周转是否会比直接在P/Tr边界发生得更早或更晚？迄今为止，在卡鲁盆地东北部的南非夸祖鲁纳塔尔省进行的研究表明，晚二叠世的大植物组合存在于四种不同的沉积学和埋藏学条件下。每一个大花群类型都保留了一个非常不同的植被特征，这些特征对化石记录有贡献。这些是：（1）废弃河道充填序列中的准原地组合，类似于现代和其他古牛轭湖;（2）保存在大的细粒河流体系中的前积层和再活化面上的分散和孤立的外来组合;（3）粗粉砂岩河道的推移质沙丘中的集中的席状外来组合;（4）浊积岩中分散的分选组合。文中提出的数据涉及两个地区？布尔沃和瓦根德里夫大坝？表明以前对这些地点化石组合的解释是不正确的。如果这些数据是从文献中作为解释的基础，由此产生的假设是不恰当的。随着越来越大陆化的沉积包在卡鲁到三叠纪，所有的，但最后一个埋藏组合类型应该遇到的过渡和边界后部分。7个跨边界和边界后的部分已被确定，其中植物化石和/或脊椎动物被保存，并将作为2004年实地调查季节的基础。预计这部分地层中的非埋藏组合的识别将允许直接比较生物多样性指数与目前由一个国际研究小组的其他成员确定的生物多样性指数，荷兰和南非的科学家。目前的建议要求资金支持本科生的研究，旨在协助在卡鲁盆地，南非的isophonomic数据集的收购。通过未来两年的野外工作和实验室分析，P/Tr和早中三叠纪的地方将进行评估，以确定和描述这些沉积序列中发现的最新二叠纪。