Steidle Simon D, Wendt Kathleen A, Dublyansky Yuri, Edwards R Lawrence, Li Xianglei, McClure Gracelyn, Moseley Gina E, Spötl Christoph
Institute of Geology, University of Innsbruck, Innsbruck, Austria.
College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR USA.
Commun Earth Environ. 2024;5(1):376. doi: 10.1038/s43247-024-01550-0. Epub 2024 Jul 14.
Quaternary climate changes are driven in part by variations in the distribution and strength of insolation due to orbital parameters. Continental climate variability is well documented for the most recent glacial-interglacial cycles, yet few records extend further back in time. Such records are critically needed to comprehensively assess the entire spectrum of natural climate variability against the backdrop of anthropogenic warming. Here, we apply uranium isotope geochronology to calcite deposits to date groundwater-table changes in Devils Hole cave, Nevada. The deposits record multi-meter groundwater-table fluctuations over the last 750,000 years, reflecting the long-term evolution of hydroclimate in this presently arid region. During periods between glacial or interglacial extremes, the water table responded sensitively to variations in 65°N summer insolation, likely caused by the increasing extent of North American ice sheets during cold period, which steered moisture-laden trajectories towards the southwestern USA. These orbitally-driven hydroclimatic changes are superimposed on a tectonically-driven long-term decline in the regional groundwater table observed prior to 438,000 ± 14,000 years ago.
第四纪气候变化部分是由轨道参数导致的日照分布和强度变化驱动的。对于最近的冰期-间冰期循环，大陆气候变化已有充分记录，但很少有记录能追溯到更久远的时间。在人为变暖的背景下，迫切需要这样的记录来全面评估自然气候变化的整个范围。在这里，我们应用铀同位素地质年代学来测定内华达州魔鬼洞洞穴中方解石沉积物的地下水位变化年代。这些沉积物记录了过去75万年中地下水位数米的波动，反映了这个目前干旱地区水文气候的长期演变。在冰期或间冰期极端情况之间的时期，地下水位对北纬65°夏季日照的变化敏感响应，这可能是由于寒冷时期北美冰盖范围扩大，引导了携带水汽的气流轨迹向美国西南部移动所致。这些由轨道驱动的水文气候变化叠加在43.8万±1.4万年前之前观察到的由构造驱动的区域地下水位长期下降之上。
