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

为改进用于古气候样品定年的碳-14校准曲线提供了资金。一般来说，地球化学模拟方法将用于研究气候对洞穴地球化学的控制，而统计分析将用于构建新的校准曲线。具体而言，研究人员将使用中国河上洞的洞穴标本来测试死碳分数（DCF）对样品定年的影响。研究目标包括：(1)通过扩大目前的环境监测计划，调查现代环境对洞穴碳14的控制，包括土壤碳14和碳13的测量，土壤二氧化碳，每月的现代方解石样品，每月的滴水溶解无机碳样品；洞穴空气二氧化碳与现有的校准数据进行比较，以约束喀斯特系统碳循环的环境控制，并研究与其他代理的联系；(2)研究2.5 m年层合HS4石笋内放射性碳弹峰的位置和结构，确定土壤-岩石层碳转移动态；(3)建立HS4的百年分辨率全新世碳-14记录，与现有的铀-钍（U-Th）日期相联系，以研究这一时期气候对DCF的可能控制；(4)通过对长2.0米的石笋HS7（形成于35,800至11,800年前）的配对u - th -碳-14定年，构建了一个新的、经过充分测试的基于洞穴的放射性碳校准曲线。这项研究将支持一名新的女性研究者和学生，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）资助的。

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).