Insolation, Moisture Balance and Climate Change on the South American Altiplano Since the Last Glacial Maximum
Insolation, Moisture Balance and Climate Change on the South American Altiplano Since the Last Glacial Maximum
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自末次盛冰期以来南美高原的日照、水分平衡和气候变化
DOI：
10.1023/a:1013090912424
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发表时间：
2002
期刊：
影响因子：
4.8
通讯作者：
S. Fritz
中科院分区：
文献类型：
--
作者：
H. Rowe;R. Dunbar;D. Mucciarone;Geoffrey O. Seltzer;P. A. Baker;S. Fritz
的的喀喀湖的沉积物岩心包含过去的湖泊水位和南美高原水文变化的代用记录。有机碳的同位素组成（C/N，wt.%）的大的向下岩芯偏移Corg、%CaCO3和% biogenicsilica说明了过去20，000年间湖泊水位的动态变化。第一批取自湖北方次盆地水深超过50米的岩芯被用来发展和延长古湖泊水位记录，追溯到末次盛冰期（LGM）。根据现代湖相有机物源的δ 13 C和现代沉积物的δ 13 C，利用转换函数定量估算了湖泊水位。湖泊水位略高于现代在大部分的后期末次盛冰期（20000 - 13500年BP）和湖水淡水在相关的流出条件。更新世/全新世过渡期（13，500 - 7，500年BP）是一个逐渐回归的时期，偶尔会发生一些小的变化。在大约7250年BP的短暂高位之后，湖平面迅速下降到现代水平以下85米，到6250年BP达到最大低位条件。湖泊水位在5000 - 4000年BP之间迅速上升，而在4000 - 1500年BP之间上升较慢。轨道引起的太阳辐射变化，加上厄尔尼诺-南方涛动变化的长期变化，是湖泊水位千年尺度变化的最可能驱动力，反映了南极-亚马逊-高原水文系统水分平衡的区域尺度变化。
Sediment cores from Lake Titicaca contain proxy records of past lake level and hydrologic change on the South American Altiplano. Large downcore shifts in the isotopic composition of organic carbon, C/N, wt.%Corg, %CaCO3, and % biogenicsilica illustrate the dynamic changes in lake level that occurred during the past 20,000 years. The first cores taken from water depths greater than 50 meters in the northern subbasin of the lake are used to develop and extend the paleolake-level record back to the Last Glacial Maximum (LGM). Quantitative estimates of lake level are developed using transfer functions based on the δ 13C of modern lacustrine organic sources and the δ 13C of modern sedimented organic matter from core-tops. Lake level was slightly higher than modern during much of the post-LGM (20,000–13,500 yr BP) and lake water was freshunder the associated outflow conditions. The Pleistocene/Holocene transition (13,500–7,500 yr BP) was a period of gradual regression, punctuated by minor trangressions. Following a brief highstand at about 7250 yr BP, lake level dropped rapidly to 85 m below the modern level, reaching maximum lowstand conditions by 6250 yr BP. Lake level increased rapidly between 5000yr BP and 4000 yr BP, and less rapidly between 4000 yr BP and 1500 yr BP.Lake level remained relatively high throughout the latest Holocene with only minor fluctuations (<12 meters). Orbitally induced changes in solar insolation, coupled with long-term changes in El Niño-Southern Oscillation variability, are the most likely driving forces behind millennial-scale shifts in lake level that reflect regional-scale changes in the moisture balance of the Atlantic-Amazon-Altiplano hydrologic system.