Integrated Sedimentologic/Magnetic Records of Late Paleozoic Climate, Western Pangea

9805130 Soreghan晚古生代气候的历史非常有趣。 极地冰川的特点是宾夕法尼亚州的时间，大陆组装显然是由二叠纪开始的特大季风条件。 这些事件很可能被显著的气候趋势和/或波动记录下来，但这些气候变化的证据和特征仍然缺乏约束。 本研究的目的是（1）证实利用沉积学/岩石磁学综合方法从上古生界黄土中获取古气候数据的可行性，（2）将这些技术应用于阐明西盘古大陆低纬度古气候。 近年来，对许多地区早第三纪-上新世黄土序列的研究表明，岩石磁学分析在古气候研究中是有用的。 这些研究表明，在相对温暖，潮湿（间冰期）时期，成壤生产的超细和细粒磁性材料。 即使成土作用的沉积学证据是模棱两可的，磁性代理信号的气候和时间依赖的土壤形成。 我们的初步分析表明，磁化率的增强与成土形成的磁性物质是保存在非常古老的黄土。 我们建议通过收集详细的沉积学和岩石磁性数据，从上古生代（宾夕法尼亚-二叠纪）黄土剖面暴露在科罗拉多和犹他州这些分析。 在实验室中，我们将进行岩石磁性分析（例如，标准化亚铁磁化率、频率相关磁化率、非滞后剩磁、低温剩磁）来获取磁化率变化的起源，并将这些数据与沉积学/古土壤学和成岩学数据相结合来评估古气候信号。 最终，我们希望将这些数据与改进的年龄分辨率联系起来，以评估目标部分内部和之间的中宾夕法尼亚-早二叠世间隔的短期和长期气候趋势。 据我们所知，我们的努力是首次尝试将岩石磁性技术应用于前新生代古气候分析（上新世-更新世）黄土;我们相信，综合沉积学/岩石磁学方法对上古生界黄土的适用性的证明将代表一个重大的（1）在非常古老的地层中进行古气候研究的技术进步，（2）对我们理解晚古生代西盘古大陆低纬度古气候的贡献。

9805130SoreghanThe history of late Paleozoic climate is of great interest. Polar glaciation characterized Pennsylvanian time, and continental assembly apparently initiated megamonsoonal conditions by Permian time. These events are likely recorded by significant climatic trends and/or fluctuations, but the evidence for and character of these climate changes remain poorly constrained. The objective of the proposed research is to (1) confirm the feasibility of obtaining paleoclimatic data from upper Paleozoic loessite using an integrated sedimentologic/rock-magnetic approach, and (2) apply these techniques to elucidating low-latitude paleoclimate of western Pangea. Recent studies of Quaternary-Pliocene loess sequences in many regions have demonstrated the utility of rock-magnetic analyses for paleoclimate studies. These studies indicate pedogenic production of ultra-fine and fine-grained magnetic material during relatively warm, wet (interglacial) periods. Magnetic proxies signal climatically and temporally dependent soil formation even where sedimentologic evidence for pedogenesis is equivocal. Our preliminary analyses establish that susceptibility enhancement linked to pedogenically formed magnetic material is preserved in very ancient loessite. We propose to extend these analyses by collecting detailed sedimentologic and rock magnetic data from upper Paleozoic (Pennsylvanian-Permian) loessite sections exposed in Colorado and Utah. In the lab, we will perform rock-magnetic analyses (e.g., normalized ferrimagnetic susceptibility, frequency-dependent susceptibility, anhysteretic remanent magnetization, low-temperature remanence) to access the origin of magnetic susceptibility variations, and integrate these data with sedimentologic/paleopedologic and diagenetic data to evaluate the paleoclimatic signal. Ultimately, we hope to link these data to an improved age resolution in order to assess short-and long-term climatic trends across the middle Pennsylvanian-early Permian interval both within and between the target sections. To our knowledge, our effort represents the first attempt to apply rock-magnetic techniques for paleoclimatic analyses in pre-Cenozoic (Plio-Pleistocene) loessite; we believe that demonstration of the applicability of an integrated sedimentologic/rock-magnetic approach to upper Paleozoic loessite will represent a significant (1) technical advance for paleoclimatic studies in very ancient strata, and (2) contribution toward our comprehension of the low-latitude paleoclimate of late Paleozoic western Pangea.