ESH - Climate Variability and Ecologic Change in Mesoamerica During the Late Holocene: Implications for Maya Cultural Evolution

9709314霍德尔危地马拉北部的佩滕省代表着3000多年前古代玛雅文明兴起的中心地区，在所谓的古典时期蓬勃发展，并在公元800-900年左右神秘崩溃。一个多世纪以来，考古学家一直在争论坍塌的原因。气候变化被认为是一个促成因素，但这一假设尚未得到严格检验。我们之前的工作由NOAA-古气候学资助，试图了解气候变化可能在玛雅文明崩溃中所起的作用。我们在尤卡坦中部和北部的两个湖泊中发现了令人信服的古气候证据，表明在公元800年至1000年之间，与经典玛雅崩塌重合的长期干旱(Hodell等人，1995；Curtis等人，1996)。尤卡坦湖和秘鲁奎尔卡亚冰芯古气候记录中干旱事件的对比表明，过去1500年来，干旱在中美洲和南美洲普遍存在，可能与大气和海洋场的大规模背离有关。在这里，我们打算测试尤卡坦记录的干旱是否影响到危地马拉北电的玛雅低地南部，那里的玛雅人口密度最高，崩溃最严重。我们建议从北辰湖地区采集的沉积物岩芯中收集地球化学、孢粉学和沉积学数据，以重建足够详细的气候和生态变化，以揭示过去5000年来十年至百年的波动。具体地说，我们将测量取自近盆地湖泊岩心的微化石贝壳(介形类和腹足类)中的氧同位素比率，并重建集水区蒸发与降水比率(E/P)的变化。我们还将记录同一岩心的花粉光谱的地层变化，以重建可能受到气候因素和/或人类影响的区域植被变化。这项拟议的研究将阐明玛雅低地全新世晚期E/P和植被变化的空间和时间模式。北坛的古环境记录将有助于我们理解：1)低地新热带地区全新世的自然水文气象变率；与其他区域的气候记录(海洋、湖泊和冰芯记录)建立远程联系；以及3.传统玛雅社会和经济系统对气候和生态变化的反应。

9709314 Hodell The Department of Peten in northern Guatemala represents the central area where ancient Maya civilization arose more than 3000 years ago, flourished during the so-called Classic Period, and mysteriously collapsed around 800 - 900 AD. The cause of the Collapse has been debated by archaeologists for over a century. Climate change has been suggested as a contributing factor, but this hypothesis has not been tested rigorously. Our previous work, funded by NOAA-Paleoclimatology, sought to understand the role that climate change may have played in the collapse of Maya civilization. We discovered compelling paleoclimatic evidence from two lakes in central and northern Yucatan for a protracted drought between ~800 and 1000 AD that coincided with the Classic Maya Collapse (Hodell et al., 1995; Curtis et al., 1996). Correlation of arid events in paleoclimate records between Yucatan lakes and the Peruvian Quelccaya ice core suggests that aridity was widespread in Central and South America over the last 1500 years, and may have been related to large-scale departures in atmospheric and oceanic fields. Here we propose to test if the droughts documented in Yucatan affected the southern Maya lowlands of Peten, Guatemala, where Maya population densities were highest and the Collapse was most profound. We propose to collect geochemical, palynological, and sedimentologic data from sediment cores taken in the Peten Lake District to reconstruct climatic and ecologic changes in sufficient detail to reveal decadal to centennial fluctuations over the past 5,000 years. Specifically, we will measure oxygen isotopic ratios in microfossil shells (ostracods and gastropods) from cores taken in close-basin lakes and reconstruct changes in the ratio of evaporation to precipitation (E/P) over the catchment. We will also document stratigraphic changes in pollen spectra from the same cores to reconstruct regional vegetation changes that may have been influenced by climatic factors and/or human impact. The proposed study will elucidate the spatial and temporal pattern of changes in E/P and vegetation in the Maya lowlands during the late Holocene. Paleoenvironmental records from Peten will contribute to our understanding of: 1.) the full range of natural hydrometeorologic variability during the Holocene in the lowland Neotropics; 2.) teleconnective linkages with climatic records (marine, lacustrine, and ice core records) from other regions; and 3.) the response of Classic Maya social and economic systems to climate and ecologic change.