Collaborative Research: Coordinated TIMS U-Series Dating and Paleoenvironmental Interpretation of Pedogenic Carbonate

合作研究：成土碳酸盐的协调 TIMS U 系列测年和古环境解释

• 批准号: 0207490
• 负责人: Ronald Amundson
• 金额: $ 3.88万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-15 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207490&HistoricalAwards=false
• 关键词: Collaborative; Research; Coordinated; TIMS; Series

PROJECT SUMMARY With prior support from NSF, we have shown that TIMS (Thermal Ionization Mass Spectrometry) U-series dating of pedogenic carbonate can provide a precise chronology of pedogenesis and reliable ages for appropriate Quaternary alluvial deposits (Sharp et al., accepted). Though the U/Th ratios of pedogenic carbonate of carbonate-clast dominated alluvium at Kyle Canyon (Nevada) are too low for U-series dating, pedogenic carbonate in granitic-clast dominated gravels of the Wind River Basin (Wyoming) is highly suitable. Precise U-series ages (1-2 percent, 2) may be measured on a few cubic millimeters of pedogenic carbonate and require only very small corrections for detrital 230Th. Suites of ages may be screened for reliability using criteria inherent in the U-series results. The time lag between clast deposition and accumulation of datable carbonate.a critical parameter if U-series dates of innermost clast-rinds are to be used to date host Quaternary deposits.is estimated to be 5+ 5 kyr in the Wind River basin. O- and C-isotope analyses of a trial suite of pedogenic carbonate samples shows that a temporally resolved stable isotope paleoclimatic record can be constructed using pedogenic carbonate dated by U-series. Funds are requested to further develop U-series dating of pedogenic carbonate and its application to the refinement of a Rocky Mountain glacial chronology. Emphasis will be placed on resolving the timing of Bull Lake glacial advances (at their type locality) with respect to other regional and global climate records. Moreover, we propose to characterize the spatial and temporal accumulation of pedogenic carbonate in relict soils of Late-Middle to Late Pleistocene deposits, and measure the O- and C-isotopic compositions of carbonate samples dated by U-series. We will interpret these data to provide a comprehensive history of paleoenvironmental change in the Wind River Basin throughout much of the late Illinoian and Wisconsin glacial cycles. Ultimately, our goal is to correlate the soils-based paleoenvironmental record with the geomorphic expressions of paleoclimatic change.the well-preserved glacial moraines and glacio-fluvial terraces of the Basin.by establishing a common chronological framework based on precise U-series ages. This is a collaborative proposal. Warren Sharp and Ken Ludwig (Berkeley Geochronology Center) will be responsible for U-series analyses and age interpretations; Ron Amundson (U.C. Berkeley) will provide field and laboratory expertise in pedology and stable isotope analysis and interpretation; Oliver Chadwick (U.C. Santa Barbara) will provide expertise in Quaternary geology, geomorphology and soil stratigraphy as well as familiarity with the Wind River area.

在NSF的支持下，我们已经证明，成壤碳酸盐的TIMS（热电离质谱法）U系列测年可以为适当的第四纪冲积矿床提供精确的成壤年代学和可靠的年龄（Sharp等人，接受）。尽管内华达州凯尔峡谷碳酸盐碎屑为主的冲积层中的成土碳酸盐的U/Th比值对于U系测年来说太低，但风河盆地（怀俄明州）花岗岩碎屑为主的砾石中的成土碳酸盐非常适合。 精确的铀系年龄（1- 2%，2）可以在几立方毫米的成土碳酸盐岩上测量，只需要对碎屑230 Th进行很小的校正。 可以使用U系列结果中固有的标准筛选年龄组的可靠性。碎屑沉积和可定年碳酸盐积累之间的时间滞后。如果要使用最内层碎屑的U系列测年来确定第四纪宿主的年龄，则这是一个关键参数deposits.is估计温德河流域的时间为5+ 5 kyr。 O-和C-同位素分析的一套试验成壤碳酸盐岩样品表明，一个时间分辨的稳定同位素古气候记录可以构建成壤碳酸盐的U系列定年。要求提供资金，以进一步发展成土碳酸盐的U系列测年法，并将其应用于改进落基山冰川年代学。 重点将放在解决公牛湖冰川的进展（在其类型的地方）与其他区域和全球气候记录的时间。此外，我们建议的特点的空间和时间积累的成壤碳酸盐在残留土壤中的晚-中-晚更新世的存款，并测量的O-和C-同位素组成的碳酸盐样品的U-系列。我们将解释这些数据，以提供一个全面的历史，在风河流域的古环境变化，在整个晚伊利诺伊州和威斯康星州冰川周期。最终，我们的目标是将基于土壤的古环境记录与古气候变化的地貌表达相关联。Basin.by的保存完好的冰川冰碛和冰川河流阶地建立了一个基于精确U系列年龄的共同年代框架。 这是一个合作提案。沃伦·夏普和肯·路德维希（伯克利地质年代学中心）将负责U系列分析和年龄解释;罗恩·阿蒙森（加州大学）伯克利）将提供土壤学和稳定同位素分析和解释方面的实地和实验室专业知识;奥利弗查德威克（加州大学）圣巴巴拉）将提供第四纪地质学、地貌学和土壤地层学方面的专业知识，并熟悉风河地区。