COLLABORATIVE RESEARCH: Integrated Analysis of Permian Terrestrial Sediments & Paleosols: Defining a High-Resolution Proxy for the Evolution of Western Equatorial Pangean Clima

合作研究：二叠纪陆地沉积物的综合分析

• 批准号: 9814639
• 负责人: Emma Rasbury
• 金额: $ 3.71万
• 依托单位: Research Foundation of the City University of New York
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814639&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Integrated; Analysis; Permian

9814639RasburyFew detailed records of the high-resolution variations in climate regimes that likely accompanied the evolution of Pangean monsoonal circulation during the Permian exist. Moreover, geologic climate indicators and numeric models for Pangea suggest that megamonsoon development was accompanied by increased global warming possibly brought on by increased pCO2 levels in Permian atmospheres. Paleosols are a sensitive source of paleoenvironmental and paleoclimate information by offering multiple proxies of paleohydrology, precipitation levels, and seasonality that collectively reflect regional paleoclimatic conditions. In addition, pedogenic carbonates in the same paleosols can provide a direct record of paleo-pCO2 and associated changes in global temperature that is independent from the record provided by other paleosol proxies. Our collaborative research team proposes to define the first detailed paleoclimate reconstruction and paleo-pCO2 record for western equatorial Pangea by carrying out an integrated sedimentologic, petrologic, geochemical, magnetostratigraphic, and geochronologic analysis of Permian paleosols in the terrestrial successions of Texas and Oklahoma.This research is directed by three main objectives: (1) to carry out a comprehensive field and laboratory study of paleosols in order to identify those sedimentologic, mineralogic, geochemical, and biologic proxies that most accurately record temporal changes in regional climate. (2) To reconstruct the evolution of atmospheric pCO2 throughout Permian time by carrying out a stable isotope analysis of pedogenic carbonates and associated vertebrate tooth enamel, as well as compound-specific stable isotope analysis of terrestrial organic matter from the same paleosols. (3) To develop a significantly improved temporal framework for calibration of the detailed paleoclimate and paleo-pCO2 records by applying the following techniques to the Texas and Oklahoma terrestrial successions: a) 40Ar/39Ar dating of volcanic sanidines, pedogenic Fe-sulfates (natrojarosite), and evaporitic minerals (langbeinite), b) U-Pb dating of pedogenic carbonates, c) Rb-Sr dating of Mg-rich authigenic clays encapsulated within evaporites, and d) detailed magnetostratigraphic study of the Late Permian terrestrial successions.The resulting paleoclimate and paleo-pCO2 records should (1) provide significantly enhanced temporal constraints on megamonsoon development and associated evolution of the climate system, (2) contribute toward constraining the timing of deglaciation that would have been brought on by increased atmospheric pCO2 levels, (3) provide detailed and calibrated paleoclimate/paleo-pCO2 records for testing and constraining numeric model results, (4) greatly facilitate the correlation of our terrestrial records to climate records derived from other terrestrial deposits as well as to marine paleoclimate records, and (5) 'set the stage' for better understanding the paleoenvironmental stresses that may have contributed to the massive end-Permian extinction.

9814639拉斯伯里很少有详细记录的高分辨率的气候变化制度，可能伴随着盘古季风环流的演变在二叠纪存在。 此外，盘古大陆的地质气候指标和数值模型表明，巨季风的发展伴随着全球变暖的加剧，这可能是由二叠纪大气中pCO 2水平的增加引起的。 古土壤是古环境和古气候信息的敏感来源，它提供了反映区域古气候条件的多个古水文、降水水平和季节性指标。 此外，在相同的古土壤中的成壤碳酸盐可以提供一个直接的记录古pCO 2和相关的全球温度的变化，是独立于其他古土壤代理提供的记录。 我们的合作研究小组建议通过对德克萨斯州和俄克拉荷马州陆地演替中的二叠纪古土壤进行综合沉积学、岩石学、地球化学、磁性地层学和地质年代学分析，确定西赤道泛大陆的第一个详细的古气候重建和古pCO 2记录。（1）对古土壤进行全面的野外和实验室研究，以确定最准确地记录区域气候时间变化的沉积学、矿物学、地球化学和生物学代用指标。 (2)通过对成壤碳酸盐和相关脊椎动物牙釉质进行稳定同位素分析，以及对来自相同古土壤的陆地有机物进行化合物特异性稳定同位素分析，重建整个二叠纪时期大气pCO 2的演变。 (3)通过将以下技术应用于德克萨斯州和俄克拉荷马州的陆地演替，开发一个显著改进的时间框架，用于校准详细的古气候和古pCO 2记录：a）火山透长石、成土铁硫酸盐的40 Ar/39 Ar定年（钠黄钾铁矾）和钾长石矿物（无水钾长石），B）成土碳酸盐的U-Pb测年，c）包裹在碳酸盐岩中的富镁自生粘土的Rb-Sr测年，（4）对晚二叠世陆地演替进行了详细的磁性地层学研究，由此产生的古气候和古pCO 2记录应（1）提供对大季风发展和气候系统相关演化的显著增强的时间约束，（2）有助于限制由大气pCO 2水平增加引起的冰川消退的时间，（3）提供详细和校准的古气候/古pCO 2记录，用于测试和限制数值模型结果，（4）极大地促进我们的陆地记录与来自其他陆地沉积物的气候记录以及海洋古气候记录的相关性，（5）为更好地理解可能导致二叠纪末大规模灭绝的古环境压力“搭建舞台”。