Collaborative Research: Late Pleistocene paleoclimatology from soil carbonate pendants in the Colorado Plateau.

这项研究将检查保存在科罗拉多高原首都礁-博尔德山地区土壤中成壤碳酸盐涂层薄层中的同位素和地球化学记录。首先，研究小组将通过显微镜、高分辨率X射线测绘和Th/U年龄测定来检查涂层层片中地层秩序的保存情况。保存完整地层的涂层将进行微量取样，以获得详细的Th/U年龄剖面、稳定同位素分析和微量元素分析。该团队将比较在土壤-空气界面下不同深度收集的涂层的稳定同位素位移的日期分布，以重建在测量的时间间隔内发生的生态和气候变化的时间和幅度。这项研究将评估悬垂记录中的不连续问题，这可能与轨道时间尺度上的气候变化有关。碳酸盐形成的时间和机制将通过现场土壤水分、呼吸和温度测量来评估。现代和化石成土碳酸盐的稳定同位素分析促进了对大陆古气候学的理解，并记录了世界范围内的生态变化。大多数成壤碳酸盐的稳定同位素研究都是以相当粗的分辨率采样土壤碳酸盐；只有少数研究了土层内大型碎屑的土壤碳酸盐涂层的稳定同位素记录。这项工作将测试厚实、层压良好的成壤碳酸盐涂层，以记录其稳定的同位素记录(13C/12C和18O/16O)，以记录有意义的古气候信号，同时涂层保存完整的地层。如果是真的，并且有一些初步的Th/U和稳定的同位素数据支持这一点，那么世界上的沙漠可能包含一个巨大的、尚未开发的关于过去大陆气候和生态变异性的量化档案。该项目是犹他大学和科罗拉多西部州立大学的合作项目。它将增加研究机构和本科机构的教育机会，其成果将被纳入一门国际课程，每年在犹他大学教授，使用稳定同位素作为人类学、生态学、法医学、地质学、水文学、海洋学和动物学的示踪剂。

This study will examine isotopic and geochemical records preserved in the laminae of pedogenic carbonate coatings in soils in the Capitol Reef--Boulder Mountain region of the Colorado Plateau. First, the team will check for preservation of stratigraphic order in the laminae of coatings by microscopy, high-resolution X-ray mapping, and Th/U age dating. Coatings that preserve an intact stratigraphy will be micro-sampled for detailed Th/U age transects, stable isotope analysis, and trace element analysis. The team will compare well-dated profiles of stable isotope shifts from coatings collected at various depths below the soil-air interface to reconstruct the timing and magnitude of ecological and climatological changes that occurred over the measured time interval. This study will evaluate the problem of discontinuities in the pendant record which could be related to climate change on orbital time scales. Timing and mechanisms of carbonate formation will be evaluated with in situ soil moisture, respiration, and temperature measurements. Stable isotope analysis of modern and fossil pedogenic carbonate has advanced the understanding of continental paleoclimatology, as well as documenting worldwide ecological shifts. Most stable isotope studies of pedogenic carbonate have sampled soil carbonate at a fairly coarse resolution; only a few have studied the stable isotope record of soil carbonate coatings of the large clasts within a soil horizon. This work will test thick, well-laminated, pedogenic carbonate coatings for records of a meaningful paleoclimate signal in terms of their stable isotope record (13C/12C and 18O/16O) when coatings preserve an intact stratigraphy. If true, and there is some preliminary Th/U and stable isotope data that supports this, then the world's deserts may contain a vast and untapped quantitative archive of past continental climactic and ecological variability. This project is a collaborative effort between the University of Utah and Western State Colorado University. It will enhance education opportunities for both a research institution and an undergraduate institution, and its results will be incorporated into an international course, taught each year at the University of Utah, using stable isotopes as tracers in anthropology, ecology, forensics, geology, hydrology, oceanography, and zoology.