南米高地における湖古環境変動解析

来自拉古纳-Hedionda的凝灰岩样品的~(14)C测年结果表明，该矿床的年龄为10,036-9,642年。乌云尼凝灰岩的稳定同位素分析与前人对同一地区凝灰岩的研究结果(δ18O+0.73±0.0 5~-2.5 9±0.0 5‰，δ13C+4.78±0.0 2~+2.94±0.0 2‰)重叠。利佩兹湖的凝灰岩分析结果内部一致，去除次生碳酸盐值后，说明了在拉古纳海迪昂达和恰尔科塔附近发现的盖层凝灰岩(δ18O+2.55至-0.12‰和δ13C+6.23至+1.29‰)与本田拉古纳和斋月周围的海滩凝灰岩(δ18O+2.93至+1.29‰和δ13C+5.23至+1.60‰)之间的差异。对于这项研究，覆盖凝灰岩是最适合进行更详细检查的，因为它不太可能被地下水污染。数据显示了所有凝灰岩样品的总体干旱信号，以及快速形成的层状凝灰岩的年或季节变化的高分辨率证据。结合这些沉积物的年龄数据，可以认为这些凝灰岩以及今天深度以上的Lipez湖的形成与南部智利北部盆地的湿润阶段有关，而不是与北部阿尔蒂普诺中部和北部的大型湖泊有关。需要在高原上的偏远地区开展进一步的工作，以寻找更高分辨率的气候指标，以便更好地了解区域气候系统。

The 14C dating of tufa samples from Laguna Hedionda suggests that the age of this deposit is 10,036 to 9,642 cal yrs BP. Stable isotope analysis of tufa from Uyuni overlap with previous studies of tufa from the same area (δ18O +0.73 ± 0.05 to －2.59 ± 0.05‰ and δ13C +4.78 ± 0.02 to +2.94 ± 0.02‰) that formed during the last major lake phases. Analysis of tufa from the Lipez Lakes are internally consistent and, after secondary carbonate values are removed, illustrate a difference between the capping tufa found around Laguna Hedionda and Chiar Khota (δ18O +2.55 to －0.12‰ and δ13C +6.23 to +1.29‰) and the beach tufa found around Laguna Honda and Ramaditas (δ18O +2.93 to +1.29‰ and δ13C +5.23 to +1.60‰). For this study the capping tufa is the most appropriate to examine in more detail as it is less likely to have been contaminated by groundwater.The data show a general signal of aridity across all tufa samples, as well as high-resolution evidence for annual or seasonal variations in rapidly formed laminated tufa. Combined with the age data from these deposits it can be suggested that the formation of these tufa, as well as Lipez Lakes above present day depths, is associated with the wet phase in the northern Chile basins to the south rather than the large lakes on the central and northern Altiplano to the north. Further work needs to be carried out in the remote regions on the Altiplano to find further high-resolution climate proxies to better understand regional climate systems.