P2C2: Testing Speleothem-Based Radiocarbon Calibrations Through A Process-Based Cave Study and a New 35 Kyr Calibration Curve

提供资金以改进用于测定古气候样本年代的碳-14校准曲线。 一般来说，地球化学模拟方法将被用来研究气候控制的洞穴沉积物地球化学，而统计分析将被用来构建一个新的校准曲线。具体来说，研究人员将使用中国和尚洞的洞穴沉积物来测试死碳分数（DCF）对样品测年的影响。 研究目标包括：（1）通过扩大现有的环境监测计划，包括土壤碳、土壤二氧化碳、每月现代方解石样品、每月滴水溶解无机碳样品的碳-14和碳-13测量，调查洞穴沉积物碳-14的现代环境控制，和洞穴空气中的二氧化碳与现有的校准数据进行比较，以限制岩溶系统中碳循环的环境控制，其他代理人;（2）研究2.5m的HS 4石笋中放射性碳弹峰值的位置和结构，以确定土壤-洞穴石笋的碳转移动力学：（3）建立百年分辨率的HS 4全新世碳-14记录，并与现有的铀-钍（U-Th）年龄相联系，以研究这一时期DCF可能的气候控制;（4）对一个2.0米长的石笋HS 7（形成于35，800 - 11，800年前）进行U-Th-C-14配对定年，建立了一个新的、经过良好检验的基于洞穴沉积物的放射性碳校准曲线。这项研究将支持一个新的女研究员和学生，同时加强国际科学合作。该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助。

Funding is provided to improve the carbon-14 calibration curve that is used for dating paleoclimate samples. In general, geochemical modeling approaches will be used to study climatic controls on speleothem geochemistry while statistical analyses will be used to construct a new calibration curve. Specifically, the researcher will use speleothems from Heshang Cave, China to test the dead carbon fraction (DCF) effect on sample dating. The research goals include: (1) investigating the modern environmental controls on speleothem carbon-14 through expansion of the current environmental monitoring program to include carbon-14 and carbon-13 measurements of soil carbon, soil carbon dioxide, monthly modern calcite samples, monthly dripwater dissolved inorganic carbon samples, and cave air carbon dioxide for comparison with existing calibration data to constrain environmental controls on carbon cycling in the karst system and investigate links with other proxies; (2) investigating the location and structure of the radiocarbon bomb peak within the 2.5 meter annually-laminated HS4 stalagmite to determine soil-to-speleothem carbon transfer dynamics; (3) constructing a centennial-resolution Holocene carbon-14 record from HS4, tied to existing uranium-thorium (U-Th) dates, to investigate possible climatic controls on DCF over this time period; and (4) constructing a new, well-tested speleothem-based radiocarbon calibration curve from paired U-Th-carbon-14 dating of a 2.0 meter long stalagmite, HS7, which formed from 35,800 to 11,800 years ago. This research will support a new female investigator and students while strengthening international science collaborations.This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).