US-Brazil Planning Visit: An Integrated Approach to Resolving the late Paleozoic Ice Age in the Parana Basin, Brazil

美国-巴西计划访问：重建巴西巴拉那盆地最后一个冰库气候的合作努力第1部分：这项国际合作研究将彻底改变我们将整个南美洲的地质、古气候和生物事件联系起来的能力，并将能够评估晚古生代气候系统中事件的全球同步性程度和遥相关的性质。我们将开发的地质年代学框架也有可能有助于解开安第斯山脉的构造演化，并揭示南美洲经济金属和石油资源的来源。长期的国际合作将促进研究人员交流科学和教育信息和资源，并为美国和巴西的本科生和研究生提供更多样化的培训。第二部分：地球上最后一座冰库(3.4亿至2.6亿年前)，在我们现在的冰川世界之前，是过去5亿年中寿命最长、地理范围最广的冰期。尽管与今天的地理位置有很大的不同，但晚古生代冰期(LPIA)提供了对冰室气候过程和生物圈对主要扰动的反应的洞察，包括气候的二氧化碳强迫。这座冰库的消亡记录了植被和后生动物世界从冰川状态到完全温室条件的唯一转变。过去二十年的研究提出了一些基本问题，并界定了这一时期气候系统和气候-生命联系的悖论。解决这些科学问题需要对包含丰富的LPIA记录的高纬度沉积盆地进行更好的时间限制。巴拉那盆地是一个理想的天然实验室，因为它包含了晚古生代冰川和冰后地层最厚的系列之一，长期以来一直被认为是冈瓦那冰川作用性质和时间之谜的关键地理部分。广泛分布的火山灰提供了形成高时间分辨率和连续性的高纬度U-Pb年代记录的可能性。沉积沉积富含古气候指标，表征了冰川沉积之上和之间的序列，为通过化石土壤、地球化学和化石树叶分析评估区域气候条件和古大气二氧化碳在冰川最大和最小冰期之间的变化提供了机会。我们正在进行一次计划访问和侦察实地考察，以便与南里奥格兰德州联邦大学(Roberto Iannuzzi)和巴拉那联邦大学(Fernando Farias Vesely)的巴西调查人员开展国际研究和教育合作。这个较长期的合作项目整合了S小组的科学兴趣和专业知识，重点关注三个研究目标，这些目标将在这最后一个冰库中提高我们对气候系统和气候与生命之间的联系的理解。这些工作包括：(1)开发巴拉那盆地石炭-二叠纪序列内灰烬的高精度U-Pb年龄；(2)将冰盖地理分布的现场证据与冰川沉积中碎屑锆石的U-Pb和Hf同位素组成相结合，以重建冈瓦那中西部的冰盖历史；(3)开发巴拉那盆地的高分辨率气候记录，并评估它们与冰川史、冈德瓦南古植物学记录和现有低纬(古热带)替代记录的联系。

US-Brazil Planning Visit: A Collaborative Effort to Reconstruct the Climate of the Last Icehouse in the Paraná Basin, BrazilPart1: This international collaborative research will revolutionize our ability to correlate geologic, paleoclimate, and biotic events throughout South America and will permit assessment of the degree of global synchroneity of events and the nature of teleconnections in the late Paleozoic climate system. The geochronologic framework we will develop has the potential to also contribute to unraveling the tectonic evolution of the Andes and shedding light on the origin of economic metals and petroleum resources in South America. The long-term international collaboration will facilitate the exchange of scientific and education information and resources by the investigators and provide more diverse training of US and Brazilian undergraduate and graduate students.Part2:The last icehouse on Earth (340 to 260 million years ago), prior to our current glacial world, was the longest lived and most geographically extensive ice age of the past half billion years. Despite substantially different geography than today, the late Paleozoic Ice Age (LPIA) provides insight into the response of icehouse climate processes and the biosphere to major perturbation, including CO2-forcing of climate. The demise of this icehouse records the only transition of a vegetated and metazoan world from a glacial state to fully greenhouse conditions. Studies of the past two decades have raised fundamental questions and defined paradoxes regarding the climate system and climate-life linkages during this time. Resolving these scientific issues requires better time constraints for high-latitude depositional basins that contain a rich record of the LPIA. The Paraná Basin is an ideal natural laboratory as it contains one of the thickest successions of late Paleozoic glacial and post-glacial strata and has long been considered a key geographic piece of the puzzle regarding the nature and timing of glaciation in Gondwana. Widely distributed volcanic ashes offer the potential to develop a U-Pb dated higher latitude record of high temporal resolution and continuity. Sedimentary deposits, which are rich in paleoclimate proxies and characterize the successions above and between glacial deposits provide an opportunity to evaluate, via fossil soil, geochemical and fossil leaf analyses, how the regional climate conditions and paleo-atmospheric CO2 varied between glacial maxima and glacial minima. We are carrying out a planning visit and reconnaissance fieldtrip to initiate an international research and education collaboration with Brazilian investigators at the Universidade Federal do Rio Grande Do Sul (Roberto Iannuzzi) and the Universidade Federal do Paraná (Fernando Farias Vesely). The longer-term collaborative project, which integrates the group?s complimentary scientific interests and expertise, focuses on three research objectives that will improve our understanding of the climate system and climate-life linkages during this last icehouse. These include (1) developing high-precision U-Pb ages for ashes within the Permo-Carboniferous succession of the Paraná Basin, (2) integrating field evidence of the geographic distribution of ice sheets with the U-Pb and Hf isotopic compositions of detrital zircons from glacial deposits in order to reconstruct the ice sheet history in west-central Gondwana, and (3) developing high-resolution climate records for the Paraná Basin & assess their linkages to the glaciation history, Gondwanan paleobotanical records, and existing lower-latitude (paleotropical) proxy records.