Ostracode-Shell Luminescence Dating for Quaternary Deposits

第四纪沉积物的介形虫壳发光测年在初步可行性试验的基础上，开发一种新的发光时钟，用于第四纪重要的古环境代表指标——介形虫壳的直接测年。非海相介形虫壳可作为湖泊、池塘、泉水和溪流古环境条件的代用指标。目前，这些贝壳可以用放射性碳方法直接测定年代，但如果能在35-40 ka之间直接测定年代，将为全世界从大陆沉积记录中重建古环境历史细节的努力提供新发现的机会。PI的初步工作表明介形虫壳具有一些理想的发光特性。然而，需要开发适合发光测年的精细样品制备方案，并且几乎不知道它们可能的有用年龄范围。介形虫壳的自然样本将分别从Bonneville湖盆地（犹他州西北部）和Mono湖（加利福尼亚州东部）的湖床（更新世晚期）中收集。建立可靠的发光测年方案的基础。然后将这些方案应用于一两个年龄超过100岁的样本，以便从发育试验中进行推断。这项研究将构成研究生论文项目的基础。

ABSTRACTOSTRACODE-SHELL LUMINESCENCE DATING FOR QUATERNARY DEPOSITSThis proposal intends to build on preliminary feasibility tests, to develop a new luminescence clock for the direct dating of an important Quatemary paleoenvironmental proxy indicator: ostracode shells. Non-marine ostracode shells serve as proxy indicators of paleoenvironmental conditions in lakes, ponds, springs and streams. Presently these shells can be dated directly by radiocarbon methods, but a means to date them directly when older than 35-40 ka would provide opportunities for new discoveries in the worldwide effort to reconstruct details of paleoenvironmental histories from continental sedimentary records.Preliminary work by the PI indicates that ostracode shells have some desired luminescence properties. However, refined sample preparation protocols suitable for luminescence dating need to be developed, and almost nothing is known of their likely useful age range. Natural samples of ostracode shells will be collected from independently well-dated (by 14C) lacustrine beds (late Pleistocene age) from the lake Bonneville Basin (northwestern Utah) and from Mono Lake (eastem Califomia). The foundations for reliable luminescence dating protocols will be established. These protocols will then be applied to one or two samples older than ca. I00 ka, to extrapolate from the developmental tests. This research will form the basis of a graduate student's thesis project.