Collaborative Research: Development of a New Late Mesozoic Time Scale on U-Pb Geochronology of Volcanic Horizons from the Great Valley Group, Northern California

9406114鲍林中生代古海洋学、古生物学和构造学中一些最热门问题的研究目前由于缺乏准确和精确的时间尺度而受到限制。相关的例子包括化石生物的演化速率及其控制因素的估计，有机质的积累速率及其与海洋缺氧的关系，海底扩张和海洋地壳的产生速率及其古气候意义。我们建议通过对北加州大峡谷群下白垩统凝灰岩和膨润土的U-Pb锆石年代学研究，显著提高晚中生代时间尺度的精度。由于生物地层学上以钙质纳米化石、准足类、布甲类等为时间尺度，间接地以一个年代地层学为整个晚中生代（晚侏罗世至晚白垩世）区间。此外，更严格的绝对年龄控制将使沉积旋回的周期性受到更窄的约束，从而增强旋回地层学作为地层工具的适用性。

9406114 Bowring Investigation of some of the most topical problems in Mesozoic paleoceanography, paleobiology and tectonics are currently limited by the lack of an accurate and precise time scale. Pertinent examples include estimating rates of evolution of fossil organisms and the factors that control them, accumulation rates of organic matter and their relationship with oceanic anoxia, and sea floor spreading and oceanic crustal production rates and their paleoclimatic significance. We propose to significantly improve the precision of the Late mesozoic time scale by investigating the U-Pb zircon geochronology of Lower Cretaceous tuffs and bentonites from the Great Valley Group, Northern California. Because the biostratigraphically with calcareous nannofossils, the pelecypod, Buchia and time scale, and indirectly to a chronostratigraphy for the entire Late mesozoic (Late Jurassic to Late Cretaceous) interval. In addition, tighter absolute age control will allow narrower constraints to be placed on the periodicities of sedimentary cycles, thus enhancing the applicability of cyclostratigraphy as a stratigraphic tool.