Mutiple proxy approach to Terrestrial Paleoclimate - The Late Triassic Ischigualasto Basin, NW Argentina

基于古土壤的陆地古气候代用指标在过去的二十年里激增。这项研究的结果提供了一个急需的测试，众多的古气候代理的交叉检查的结果提供的矿物在一个单一的盆地，在某些情况下，一个单一的古土壤剖面。此外，这项研究的结果应提供信息，帮助确定哪些地球化学代理最不可能生存到地质记录。为此，本研究记录了古土壤中所含矿物的成土和成土后历史，确定了哪些古气候的地球化学指标最有可能在埋藏后保留下来，以及哪些指标提供了盘古大陆南部Iberggualasto盆地晚三叠世古气候的可靠和定量记录。本研究有两个主要目标：（1）记录古土壤中矿物的矿物组成、稳定同位素组成和40 Ar-39 Ar年龄，以描绘矿物结晶的时间框架和特定矿物作为古环境代表的效用。感兴趣的矿物包括层状硅酸盐、羟基氧化物和碳酸盐，因为这些是常见的成土矿物，在地质记录中含量丰富。(2)从多种矿物学指标重建晚三叠世大气PCO 2的演化，阐明大气绿色气体浓度变化与古气候参数（如古温度和古降水量）之间的任何强劲趋势。“深时”地质记录的古气候研究为全球变暖或变冷的重复、突然间隔以及极端气候状态之间的转变提供了令人信服的证据。许多这些气候事件引发了重大的生物周转，并导致大规模的变化，在地球化学循环。此外，最近的发展引发了一场关于过去5亿年pCO 2-气候范式有效性的辩论。这些问题与目前令人关切的气候变化辩论并行不悖，因此突出表明需要充分了解地球气候系统及其可变性。以相同的空间和时间分辨率建立海洋和陆地古气候档案，对于记录这种大规模环境扰动的全球性质和描述地球气候系统动态的全部特征至关重要。总的来说，这项研究的重要性超越了任何一个地方或时间（即，阿根廷晚三叠世），因为这项研究提供了一个更好的理解，只是如何有用的古土壤可能是古气候重建一般。

Terrestrial paleoclimate proxies based on paleosols have proliferated over the past two decades. The results of this study provide a much-needed test of the numerous paleoclimate proxies by crosschecking of the results provided by minerals within a single basin and, in some instances, a single paleosol profile. In addition, the results of this study should provide information that help to determine which geochemical proxies are least likely to survive into the geological record. To that end, this research documents the pedogenic and post-pedogenic history of the minerals contained within paleosols, determines which geochemical proxies of paleoclimate are most likely to be retained in spite of burial, and which of these provide a robust and quantitative record of Late Triassic paleoclimate in the Ischigualasto basin of southern Pangea.This research is directed by two main objectives: (1)Documentation of the mineralogical composition, stable isotopic composition, and 40Ar-39Ar ages of minerals contained within paleosols in order to delineate the temporal framework of mineral crystallization and the utility of a particular mineral as a proxy of paleoenvironment. The minerals of interest include phyllosilicates, oxyhydroxides and carbonates, as these are common pedogenic minerals and are abundant within the geological record. (2) To reconstruct the evolution of Late Triassic atmospheric PCO2 from multiple mineralogical proxies and elucidate any robust trends between changing atmospheric green house gas concentrations and other paleoclimate parameters such as paleotemperature and paleoprecipitation.Paleoclimate studies of 'deep-time' geologic records provide compelling evidence for repeated, abrupt intervals of global warming or cooling, and transitions between extreme climate states. Many of these climate events triggered significant biotic turnover and led to wholesale changes in biogeochemical cycling. Moreover, recent developments have fueled a debate over the validity of the pCO2-climate paradigm over the past half billion years. These issues parallel the climate change debate of concern at present, thus highlighting the need to fully understand Earth's climate system and its variability. The development of marine and terrestrial paleoclimate archives at equal spatial and temporal resolution is critical to documenting the global nature of such large-scale environmental perturbations, and to characterizing the full range of Earth climate-system dynamics. In total, the importance of this research transcends any one place or time (i.e., Late Triassic of Argentina), because this study provides a better understanding of just how useful paleosols may be for paleoclimate reconstructions in general.