The Molasse Basin in Southern Germany is part of the North Alpine Foreland Basin and hosts the largest accumulation of deep geothermal production fields in Central Europe. Despite the vast development of geothermal energy utilization projects especially in the Munich metropolitan region, the evolution of and control factors on the natural geothermal field, more specifically the time-varying recharge and discharge governing groundwater and heat flow, are still debated. Within the Upper Jurassic (Malm) carbonate aquifer as the main geothermal reservoir in the Molasse Basin, temperature anomalies such as the Wasserburg Trough anomaly to the east of Munich and their underlying fluid and heat transport processes are yet poorly understood. We delineate the two end members of thermal–hydraulic regimes in the Molasse Basin by calculating two contrasting permeability scenarios of the heterogeneously karstified Malm carbonate aquifer along a model section through the Wasserburg Trough anomaly by means of two-dimensional numerical thermal-hydraulic modelling. We test the sensitivity of the thermal-hydraulic regime with regard to paleoclimate by computing the two Malm permeability scenarios both with a constant surface temperature of 9 °C and with the impact of paleo-temperature changes during the last 130 ka including the Würm Glaciation. Accordingly, we consider the hydraulic and thermal effects of periglacial conditions like permafrost formation and the impact of the numerous glacial advances onto the Molasse Basin. Thermal-hydraulic modelling reveals the effect of recurrent glacial periods on the subsurface targets of geothermal interest, which is minor compared to the effect of permeability-related, continuous gravity-driven groundwater flow as a major heat transport mechanism.

中文翻译：

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Malm 碳酸盐岩渗透率、重力驱动的地下水流和古气候的相互作用——对前陆盆地区 Molasse 盆地（德国南部）地热场和潜力的影响

德国南部的莫拉塞盆地是北高山前陆盆地的一部分，拥有中欧最大的深层地热生产田。尽管地热能利用项目，特别是在慕尼黑大都市区，地热能利用项目取得了巨大的发展，但自然地热场的演变和控制因素，更具体地说是控制地下水和热流的时变补给和排放，仍然存在争议。在作为 Molasse 盆地主要地热储层的上侏罗统（马尔姆）碳酸盐岩含水层内，诸如慕尼黑以东的 Wasserburg 海槽异常及其潜在的流体和热传输过程等温度异常仍知之甚少。我们通过二维数值热工水力建模，沿着穿过 Wasserburg 海槽异常的模型剖面计算非均质岩溶马尔姆碳酸盐含水层的两个对比渗透率情景，描绘了莫拉塞盆地热工水力体系的两个末端成员。我们通过计算两个 Malm 渗透率情景来测试热力水力状况对古气候的敏感性，这两种情况均具有 9 °C 的恒定表面温度和过去 130 ka 期间古温度变化的影响，包括 Würm 冰川。因此，我们考虑了冰缘条件的水力和热效应，如永久冻土层的形成以及大量冰川推进对莫拉塞盆地的影响。