Collaborative Research: Collaborative Research: Understanding the Late Paleozoic Icehouse from a Southern Hemisphere (Paranaì Basin, Brazil) paleo-perspective

古生代晚期的冰期是过去5亿年中最长的冰期，与人类进化和生活的冰窖有许多相似之处。在古生代冰窖时期（3.4亿至2.9亿年前），大气中的氧和碳含量异常，生命迁移到陆地上，第一批森林遍布地球，大规模的野火出现了。因此，对晚古生代地球及其动力冰川史有更全面的认识是十分重要的。巴西的冰川-海洋巴拉那盆地为这项工作提供了一个理想的机会，该项目将包括通过研讨会、实地和实验室工作以及交换访问对美国和巴西学生进行培训。本研究将涉及三个研究目标。首先，通过对该地区U-Pb锆石年龄的定义，建立可输出、准确、高精度的年代地层格架。这将允许对冈瓦纳冰川的现有假设进行测试，并将限制冰川的同步程度，并确定冈瓦纳中西部冰川最终消退的时间。其次，通过沉积学和碎屑锆石物源研究，建立精细的沉积和冰川模型，并将其与高精度年代地层格架相结合。这将对冰川进入巴拉那盆地的时间、来源和地理范围进行定量限制，并允许重建冰川物质平衡随时间的变化。第三，本研究将开发U-Pb年龄校准的大陆气候变率地球化学代理记录，以验证区域气候的主要变化与冰川进退和冰川消退同步发生的假设。这个项目将使我们对过去从冰窖到温室的转变有更全面的了解。

The late Paleozoic Ice Age is the longest-lived glacial interval of the past half billion years, sharing many parallels with the current icehouse in which humans evolved and live. During the Paleozoic icehouse (340 to 290 million years ago) atmospheric oxygen and carbon levels were anomalous, life moved onto land, the first wooded forests expanded across the Earth, and large-scale wildfires emerged. Thus, it is important that we develop a more complete understanding of the late Paleozoic Earth and its dynamic glaciation history. The glacial-marine Parana Basin, Brazil provides an ideal opportunity for this work and the project will include training for U.S. and Brazilian students through seminars, field and lab work, and exchange visits.This research will address three research objectives. First, an exportable, accurate and high-precision chronostratigraphic framework will be built by defining U-Pb zircon ages of unprecedented precision and accuracy for this region. This will permit testing of existing hypotheses of Gondwanan glaciation and will place constraints on the degree of synchronicity of the glaciations and establish the timing of terminal deglaciation in west-central Gondwana. Second, refined depositional and glaciation models will be developed through sedimentologic and detrital zircon provenance studies, integrated into the high-precision chronostratigraphic framework. This will place quantitative constraints on the timing, source, and geographic extent of glaciers feeding into the Parana Basin and permit reconstruction of changes in their glacial mass balance through time. Third, this research will develop U-Pb age-calibrated geochemical proxy records of continental climate variability that will test the hypothesis that major shifts in regional climate occurred in-step with periods of glacier advance/retreat and terminal deglaciation. This project will lead to a more complete understanding of icehouse to greenhouse transitions of the past.