A 30,000 yr Continental Paleotemperature Record Derived from Noble Gases Dissolved in Groundwater from the San Juan Basin, New Mexico
A 30,000 yr Continental Paleotemperature Record Derived from Noble Gases Dissolved in Groundwater from the San Juan Basin, New Mexico
复制标题
来自新墨西哥州圣胡安盆地地下水中溶解的稀有气体的 30,000 年大陆古温度记录
作者：
M. Stute;J. Clark;P. Schlosser;W. Broecker;G. Bonani
摘要利用溶解在新墨西哥州西北部圣胡安盆地Ojo Alamo和纳西米恩托地层14 C测年地下水中的惰性气体，获得了末次盛冰期（LGM）的古温度。全新世和末次冰期之间的年平均（地面）温度差被确定为5.5 ± 0.7°C。以前从得克萨斯州南部的卡里佐含水层中得到了几乎相同的结果，即5.2 ± 0.7°C。这表明美国西南部在末次盛冰期时温度均匀降低，而从墨西哥湾到新墨西哥州西北部的一条横断面的年平均温度梯度自末次盛冰期以来一直保持不变。该地区的古生态证据支持了稀有气体古温度。全新世/末次冰期的温差为5.4°C，这表明可以应用简单的直减率计算将科罗拉多前缘山脉1000米的雪线冰川凹陷转换为温度下降。5.4 ± 0.7°C的大陆温度变化与墨西哥湾表面沃茨确定的约2°C的温度变化不一致。
Abstract Paleotemperatures for the last glacial maximum (LGM) have been derived from noble gases dissolved in 14C-dated groundwater of the Ojo Alamo and the Nacimiento formations in the San Juan Basin, northwestern New Mexico. The difference in mean annual (ground) temperature between the Holocene and the LGM was determined to be 5.5 ± 0.7°C. A practically identical result, 5.2 ± 0.7°C, has been obtained previously from the Carrizo aquifer in southern Texas. This suggests that the southwestern United States was uniformly cooler during the LGM and that the mean annual temperature gradient along a transect from the Gulf of Mexico to northwestern New Mexico has been unchanged since the LGM. The noble gas paleotemperatures are supported by paleoecological evidence in the region. The Holocene/LGM temperature difference of 5.4°C indicates that a simple lapse rate calculation may be applied to convert the 1000-m glacial depression of snowlines in the Colorado Front Range into a temperature decrease. A continental temperature change of 5.4 ± 0.7°C is inconsistent with a temperature change of about 2°C determined for the surface waters of the Gulf of Mexico.