Buried-valley aquifers in the Canadian Prairies: geology, hydrogeology, and origin1Earth Science Sector (ESS) Contribution 20120131.
Buried-valley aquifers in the Canadian Prairies: geology, hydrogeology, and origin1Earth Science Sector (ESS) Contribution 20120131.
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加拿大大草原的埋谷含水层：地质学、水文地质学和起源1地球科学部门 (ESS) 贡献 20120131。
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
D. Sharpe
中科院分区：
文献类型：
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作者：
D. Cummings;H. Russell;D. Sharpe
我们回顾了100多年来关于草原隐谷的文献，为未来的研究和政策制定提供了一个平台。草原隐谷填充物通常起蓄水层的作用，产生丰富的地下水。它们具有独特的地质和独特的地层环境，这赋予了它们独特的水文地质特性，并为它们如何形成和填充提供了线索。草原隐谷含水层通常包裹在低渗透地层中：白垩纪页岩通常位于其下，而厚的（10-300 m）低渗透第四纪土层往往覆盖在其上。这减少了补给，在极少数情况下几乎完全减少，同时保护地下水资源免受污染和干旱。它还会导致地下水化学物质高度矿化。草原隐谷的地层位置也说明了它们的起源：那些从基岩不整合面上垂下（“垂下”）的可能是落基山脉晚第三纪隆升期间被冰期前河流系统侵蚀的，而那些从till包内表面垂下的可能是在冰期前溢洪道或隧道-山谷环境中被侵蚀的冰川-河流山谷。草原隐谷的另一个关键特征是它们的填充物往往是异质的，结构复杂。沙子、砾石、泥浆和砾石是常见的；任何一个都可以在给定的位置控制填充。这种非均质性，再加上暗谷基岩底板常见的不规则性，通常会导致含水层分区化，使得在钻探前难以预测含水层潜力。它还表明，随着时间的推移，在多种沉积环境中，大多数草原埋藏的山谷可能经历了多次冰川作用。
We review over 100 years of literature on Prairie buried valleys to provide a platform for future research and policy development. Prairie buried-valley fills commonly function as aquifers that yield abundant groundwater. They have distinct geologies and a distinct stratigraphic setting, which imparts them with distinct hydrogeological properties and gives clues as to how they formed and filled. Prairie buried-valley aquifers are commonly encased in low-permeability strata: Cretaceous shale commonly underlies them, and thick (10–300 m) low-permeability Quaternary till tends to overlie them. This reduces recharge, in rare cases nearly completely, while protecting groundwater resources from contamination and drought. It also tends to lead to highly mineralized groundwater chemistries. The stratigraphic position of Prairie buried valleys also speaks to their origin: those that subtend (“hang”) from the bedrock unconformity were likely eroded by preglacial fluvial systems during late Tertiary uplift of the Rocky Mountains, whereas those that subtend from surfaces within the till package are likely glaciofluvial valleys eroded in proglacial spillway or tunnel-valley settings. Another key trait of Prairie buried valleys is that their fills tend to be heterogeneous and architecturally complex. Sand, gravel, mud, and diamicton are common; any one can dominate the fill at a given location. This heterogeneity, in conjunction with irregularity common to buried-valley bedrock floors, commonly causes aquifer compartmentalization and makes prediction of aquifer potential difficult prior to drilling. It also suggests that most Prairie buried valleys filled over time, and likely over multiple glaciations, in multiple depositional environments.