Time Averaging in the Formation of Fossil Assemblages

PI将调查死亡所需的时间跨度 组合的形成和时间的程度， 在其形成的事件，因此，时间的历史， 社区，都被单独保存了下来。 这样做需要 一种廉价的测定贝壳死亡时间的方法。 正在开发的方法是基于观察 双壳类贝壳中的蛋白质基质 逐渐分解，释放蛋白质结合的氨基酸 然后积累起来，观察到这些免费的 氨基酸逐渐扩散出壳。 因此，剩余的蛋白质基质的程度 和存在的游离氨基酸的量（由所述方法测定）。 生产平衡和扩散损失）都是时间 壳的相关属性。 为了让这项技术 有用，它是必不可少的，它是可用的货架上 集会。 大陆架的典型特征是 小物种和一个重要的跨大陆架热 梯度，其中每一个都将征税的能力， 法 因此，本提案的目的是 证明氨基酸定年法的能力， 回答以下关于死亡的重要问题 装配形成：（1）需要什么时间跨度 碎屑沉积体制中的死亡组合形成？ (2)社区中的哪些时间事件是离散的 在死亡组合形成过程中保存下来（不是如何 它们被地层压缩了，但它们 在地层序列中谨慎保存）？ (3)可以 确定埋藏改变的速率，或者至少 埋藏蚀变的相关程度 与贝壳年龄（死亡后的时间）进行测量？

PI will investigate the time span required for death assemblage formation and the extent to which the temporal events in its formation, and hence the temporal history of the community, are discretely preserved. To do so requires an inexpensive method for dating time-since-death of shells. The method under development is based on the observation that the proteinaceous matrix in the shells of bivalves gradually decomposes, freeing protein-bound amino acids which then accumulate, and the observation that these free amino acids gradually diffuse out of the shell. Accordingly, the degree of proteinaceous matrix remaining and the amount of free amino acid present (determined by the balance of production and diffusional loss) are both time dependent properties of the shell. For the technique to be useful, it is essential that it be usable on shelf assemblages. The shelf is typified by a preponderance of small species and a significant cross-shelf thermal gradient, each of which would tax the capabilities of the technique. Accordingly, the purpose of this proposal is to demonstrate the ability of the amino acid dating method to answer the following important questions about death assemblage formation: (1) What time span is required for death assemblage formation in clastic depositional regimes? (2) Which temporal events in the community are discretely preserved during death assemblage formation (not how stratigraphically compressed they are, but are they discreetly preserved in stratigraphic sequence)? (3) Can the rates of taphonomic alteration be determined or at least can the extent to which taphonomic alteration is correlation with shell age (time-since-death) be measured?