Deposits of calcite coating the lower passages of Wind Cave in the southern Black Hills of South Dakota were precipitated under phreatic conditions. Data from samples associated with a new cave survey and hydrologic studies indicate that past water tables within Wind Cave reached a maximum height of 45 m above modern levels but were mostly confined to 25 m or less. Uranium-series ages for basal layers deposited on weathered wall rock indicate subaerial conditions in this part of the cave persisted between 1000 and 300 ka. Ages and elevations of wall coatings and cave rafts establish a 300,000 yr paleohydrograph indicating that water-table highstands occurred during interglacial or interstadial-to-early glacial periods and lowstands occurred during full-glacial and stadial episodes.Isotopes of Sr, U, C, and O from dated calcite samples were obtained to evaluate potential shifts in paleo-groundwater composition. For comparison, Sr and U isotopic compositions were determined for modern groundwater from 18 sites previously classified into five hydrogeologic domains. Isotope data for different domains tend to cluster in separate fields, although several fields overlap. Compositions of Calcite Lake (informal name) water reflect modern recharge to shallow aquifers. In contrast, speleothem data indicate that paleo-groundwater highstands were not supported by increased infiltration associated with local recharge, or by upwelling from deeper Proterozoic sources. Instead, cave water was similar to deeper, warmer groundwater from the Madison Aquifer discharging at modern artesian springs flanking the southern Black Hills. Highstands were likely influenced by large-scale hydraulic processes associated with recharge to the Madison Aquifer under the Laurentide ice sheet on the northeast side of the Williston Basin, causing increased hydrostatic pressures in confined aquifers on the south side of the basin.

中文翻译：

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美国南达科他州风洞30万年的地下水位波动历史—麦迪逊含水层中的规模，时间和地下水混合

在南达科他州南部布莱克希尔斯（Black Hills）南部风洞下部通道的方解石沉积物是在潜水条件下沉淀的。来自与新的洞穴调查和水文研究相关的样本数据表明，风洞内过去的地下水位达到了比现代水准高出45 m的最大高度，但主要限于25 m或更小。沉积在风化的围岩上的基底层的铀系列年龄表明该部分洞穴的地下条件持续了1000至300 ka。壁层和洞穴筏的年龄和海拔高度建立了300,000年的古水文图，表明水位高位发生在冰间期或间期至早冰期，低位发生在全冰期和地静止期.Sr，U，C，并从过时的方解石样品中获得O，以评估古地下水组成的潜在变化。为了进行比较，确定了现代地下水中Sr和U同位素的组成，这些同位素以前被划分为五个水文地质领域，共有18个站点。尽管多个字段重叠，但不同域的同位素数据倾向于聚集在单独的字段中。方解石湖（非正式名称）的水成分反映了浅层含水层的现代补给。相比之下，sp虫病数据表明，与局部补给相关的入渗增加，或来自较深的元古代来源的上升，并没有支持古地下水高位。取而代之的是，山洞水类似于来自麦迪逊含水层的更深，更温暖的地下水，这些水在南部黑山两侧的现代自流泉中排放。