Paleohydrology of the upper Laurentian Great Lakes from the late glacial to early Holocene
Paleohydrology of the upper Laurentian Great Lakes from the late glacial to early Holocene
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晚冰期至全新世早期上劳伦森五大湖的古水文学
DOI：
10.1016/j.yqres.2009.01.003
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发表时间：
2009
影响因子：
2.3
通讯作者：
T. Johnson
中科院分区：
文献类型：
--
作者：
A. Breckenridge;T. Johnson
苏必利尔湖冰湖湖盆底栖介形虫的δ18O值在10,500~9,000卡/年之间，范围为−18~−22‰。相比之下，休伦湖和密歇根湖盆地的同时代介形虫和双壳类记录具有极端的δ18O变化，从反映主要是冰川来源的值(∼−20‰PDB)到区域陨石源的高得多的值(∼−5‰PDB)。重新评估休伦和密歇根记录的年龄模型，得出了更一致的δ18O地层学。这些记录的显著特点是δ18O值在9400至9000卡/年BP之间急剧下降。在休伦盆地，这种低δ18O漂移归因于赤柱低水位晚期，而在密歇根湖盆地，归因于阿加西湖洪水。来自阿加西斯湖的灾难性洪水很可能发生，但第二种可能性是，低δ18O漂移记录了从苏必利尔湖盆地溢出的水从一个未经记录的北部出口返回五大湖盆地。由于苏必利尔湖和阿加西斯湖冰川湖水系中的底栖介形虫可能没有记录到地表水的平均δ18O值，因此对这一系统的淡水通量进行量化仍然是困难的。
Between 10,500 and 9000 cal yr BP, δ18O values of benthic ostracodes within glaciolacustrine varves from Lake Superior range from − 18 to − 22‰ PDB. In contrast, coeval ostracode and bivalve records from the Lake Huron and Lake Michigan basins are characterized by extreme δ18O variations, ranging from values that reflect a source that is primarily glacial (∼ − 20‰ PDB) to much higher values characteristic of a regional meteoric source (∼ − 5‰ PDB). Re-evaluated age models for the Huron and Michigan records yield a more consistent δ18O stratigraphy. The striking feature of these records is a sharp drop in δ18O values between 9400 and 9000 cal yr BP. In the Huron basin, this low δ18O excursion was ascribed to the late Stanley lowstand, and in the Lake Michigan basin to Lake Agassiz flooding. Catastrophic flooding from Lake Agassiz is likely, but a second possibility is that the low δ18O excursion records the switching of overflow from the Lake Superior basin from an undocumented northern outlet back into the Great Lakes basin. Quantifying freshwater fluxes for this system remains difficult because the benthic ostracodes in the glaciolacustrine varves of Lake Superior and Lake Agassiz may not record the average δ18O value of surface water.