Sediments deposited by glacial meltwaters (for example, ice-contact delta deposits) form permeable packages in the subsurface that can act as reservoirs for both water and hydrocarbons. They are also an important source of aggregate for the construction industry. As reservoirs they are challenging to characterize in terms of their structure, flow and storage properties due to their complex depositional history. In this study, ice-contact deltas of Salpausselkä I and II end moraines in Southern Finland are studied using a combination of geomorphological mapping, sedimentological studies and near surface geophysical methods. Sedimentary logs from isolated outcrops were correlated to ground penetrating radar (GPR) profiles to unravel the internal structure and depositional history of these ice-contact deltas. Subsequently, electrical resistivity tomography (ERT) and gravity data were analysed to estimate the depth to bedrock and to model porosity distribution within the sediments. Results of the study suggest that the delta deposits have a broad range of porosities (10 to 42%) with lowest values found in the bottomset beds. The most variable porosities are in the subaqueous ice-contact–fan zone, and consistently high porosities occur in delta foreset/topset facies. Detailed sedimentary logging linked to the GPR data shows heterogeneities such as mud drapes on foresets and kettle holes which are below the resolution of ERT and gravity methods but significantly affect reservoir properties of the deltas. Moreover, oscillation of the ice-margin may have introduced larger heterogeneities (for example, buried ice marginal ridges, or eskers) into the sedimentary sequence which are atypical for other Gilbert-type deltas. Finally, subglacially sculpted, highly variable bedrock topography exerts a major control on sediment distribution within the delta making reservoir volume and quality less predictable. This work has implications for present-day freshwater aquifers and low enthalpy geothermal energy in southern Finland and other deglaciated regions, as well as hydrocarbon exploration of analogous deposits in the subsurface from Pleistocene and pre-Pleistocene glaciogenic sequences.

中文翻译：

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冷三角洲：冰接触三角洲的沉积学、地貌学和地球物理特征及其对储层特性的影响（Salpausselkä，芬兰）

冰川融水沉积的沉积物（例如，冰接触三角洲沉积物）在地下形成可渗透的包裹，可作为水和碳氢化合物的储层。它们也是建筑行业的重要骨料来源。作为储层，由于其复杂的沉积历史，很难在结构、流动和储存特性方面进行表征。在这项研究中，结合地貌测绘、沉积学研究和近地表地球物理方法，研究了芬兰南部 Salpausselkä I 和 II 端冰碛的冰接触三角洲。来自孤立露头的沉积测井与探地雷达 (GPR) 剖面相关联，以揭示这些冰接触三角洲的内部结构和沉积历史。随后，对电阻率层析成像 (ERT) 和重力数据进行了分析，以估计到基岩的深度并模拟沉积物中的孔隙度分布。研究结果表明，三角洲矿床具有广泛的孔隙度（10% 至 42%），在底部沉积层中发现的孔隙度最低。变化最大的孔隙度位于水下冰接触扇区，并且始终高孔隙度出现在三角洲前积/顶积相中。与 GPR 数据相关的详细沉积测井显示了非均质性，例如前缘和壶洞上的泥浆覆盖低于 ERT 和重力方法的分辨率，但显着影响了三角洲的储层性质。此外，冰缘的振荡可能引入了更大的异质性（例如，埋藏的冰缘脊、或 eskers）进入其他吉尔伯特型三角洲的非典型沉积层序。最后，冰下雕刻的、高度可变的基岩地形对三角洲内的沉积物分布施加了主要控制，从而使储层体积和质量难以预测。这项工作对芬兰南部和其他冰川消融地区的当今淡水含水层和低焓地热能，以及更新世和更新世前冰川成因序列地下类似沉积物的碳氢化合物勘探具有重要意义。