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由于缺乏准确的时间尺度，目前对中生代古海洋学、古生物学和构造学中一些最热门的问题的调查受到限制。有关的例子包括估计化石生物的演化速度和控制它们的因素、有机质的积累速度及其与海洋缺氧的关系、海底扩张和大洋地壳生产速度及其古气候意义。我们建议通过对北加州大谷群下白垩统凝灰岩和膨润土的锆石U-Pb年代学研究，显著提高晚中生代时间尺度的精度。因为在生物地层学上具有钙质超微化石、翼足类、布希亚和时间尺度，间接形成了整个晚中生代(晚侏罗世至晚白垩世)的年代地层学。此外，更严格的绝对年龄控制将允许对沉积旋回的周期性施加更窄的限制，从而加强旋回地层学作为地层学工具的适用性。

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.