(ESH) Paleoenvironmental Change in the Atacama Desert During the Late Quaternary: Evidence from Middens and Paleosprings

（ESH）阿塔卡马沙漠第四纪晚期的古环境变化：来自米甸和古泉的证据

• 批准号: 9904838
• 负责人: Jay Quade
• 金额: $ 25.86万
• 依托单位: University of Arizona
• 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: 1999-09-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904838&HistoricalAwards=false
• 关键词: ESH; Paleoenvironmental; Change; Atacama; Desert

Fossil rodent middens and paleospring deposits at key sites along a 1500-km transect in northem Chile/southern Peru will be used to reconstruct late Quaternary vegetation and climate histories in the Atacama Desert. There are several advantages to studying these deposits in the Atacama Desert: 1) unlike lake records, middens and spring deposits contain abundant vascular plants that suffer no "hard water" effects in 14 C dating; 2) rainfall seasonality can be inferred from midden occurrences of plant taxa tethered to either summer or winter precipitation; 3) the lower elevational limits of most Atacama plants reflect local precipitation (and not growing-season temperature), whereas water levels in springs reflect regional snowpack in the high Andes; 4) both middens and spring deposits are ubiquitous and preserve a regional history of vegetation and water levels along the upper margins of the Absolute Desert. Carbon isotopes in soil carbonates also will be analyzed and relict drainage networks in parts of the Absolute Desert that might have experienced periods of sustained rainfall and vegetation expansion will be mapped.Three key areas affected by different synoptic climatologies will be sampled, and asynchronous climate histories are expected. Middens and spring deposits near Arequipa, Peru (16.5 S) will allow the proponents to track changes in summer precipitation just 200 km west of Lake Titicaca. Sites near Copiapo, Chile (27 S), 600 km north of Santiago, should isolate variations in the strength of extratropical winter precipitation. The central sites near Calaina, Chile, straddle the Tropic of Capricorn (23.5 S) and will reveal the interplay between tropical and extratropical rainfall belts. The proposed research will help refine current understanding of the nature and timing of late Quaternary climate change, and its hydrological and ecological effects, in subtropical South America.

智利北部/秘鲁南部沿 1500 公里横断面关键地点的啮齿动物化石化石和古泉沉积物将用于重建阿塔卡马沙漠的晚第四纪植被和气候历史。研究阿塔卡马沙漠中的这些沉积物有几个优点：1）与湖泊记录不同，丘陵和泉水沉积物含有丰富的维管束植物，在 14 C 测年中不会受到“硬水”影响； 2）降雨季节性可以根据与夏季或冬季降水相关的植物类群的中出现次数来推断； 3) 大多数阿塔卡马植物的海拔下限反映了当地降水量（而不是生长季节温度），而泉水水位反映了安第斯山脉高地的区域积雪； 4) 沙坑和泉水沉积物无处不在，保留了绝对沙漠上缘植被和水位的区域历史。还将分析土壤碳酸盐中的碳同位素，并绘制绝对沙漠部分地区可能经历持续降雨和植被扩张时期的残余排水网络。将对受不同天气气候影响的三个关键区域进行采样，并绘制异步气候历史预计。 秘鲁阿雷基帕（南纬 16.5 度）附近的丘陵和春季沉积物将使支持者能够追踪的喀喀湖以西仅 200 公里处夏季降水的变化。 圣地亚哥以北 600 公里处的智利科皮亚波 (南纬 27 度) 附近的站点应能隔离温带冬季降水强度的变化。 智利加莱纳附近的中心地点横跨南回归线（南纬 23.5 度），将揭示热带和温带降雨带之间的相互作用。拟议的研究将有助于完善目前对南美洲亚热带晚第四纪气候变化的性质和时间及其水文和生态影响的理解。