Sedimentary Geochronology: Coupled Studies of Re-Os and U-Pb

本研究将把Re-Os和U-Pb体系发展为有机- 丰富的沉积物地质年代计。这些元素的富集 富含有机质的沉积物在早期成岩作用期间有效地 这些放射性时钟 初步 结果表明，这些衰变方案可以成功地 用于获得独立和一致的年龄测定 新奥尔巴尼页岩，密西西比-泥盆纪边界黑色 伊利诺伊盆地的页岩 该研究计划将扩大 Re-Os系统测定白垩纪沉积物和 元古代碳质页岩。 通过将Re-Os系统应用于 测年黑色页岩和相关的陆架碳酸盐 Cenomanian-Turonian边界，我们将研究潜在的变化 并确定Re-Os是否 系统可以获得年轻沉积物的高精度年龄。 我们 研究的元古宙沉积物从带盆地在 美国西部的重点是展示耦合的效用， 利用U-Pb、Pb-Pb和Re-Os体系研究前寒武纪 沉积物 在变质的东西梯度上取样 带盆地内的等级将使我们能够评估 这些精密计时器在各种条件下的耐用性。

This study will develop the Re-Os and U-Pb systems as organic- rich sediment geochronometers. Enrichment of these elements in organic-rich sediments during early diagenesis effectively set these radiometric clocks soon after deposition. Preliminary results demonstrate that these decay schemes can be successfully employed to obtain independent and concordant age determinations for the New Albany Shale, a Mississippian-Devonian boundary black shale from the Illinois Basin. The proposed research will extend the Re-Os system to dating both Cretaceous sediments and Proterozoic carbonaceous shales. By applying the Re-Os system to dating black shales and associated shelf carbonates at the Cenomanian-Turonian Boundary, we will examine potential variations in initial Os isotopic composition and determine whether the Re-Os system can yield high precision ages for young sediments. Our investigation of Proterozoic sediments from the Belt basin in the western U.S. focuses on demonstrating the utility of coupled studies using the U-Pb, Pb-Pb and Re-Os systems to date Precambrian sediments. Sampling across the east-west gradient in metamorphic grade within the Belt basin will enable us to evaluate the robustness of these chronometers under a variety of conditions.