Sinkholes in hypogene versus epigene karst systems, illustrated with the hypogene gypsum karst of the Sant Miquel de Campmajor Valley, NE Spain

Abstract

The Garrotxa-Banyoles artesian aquifer system in NE Spain includes zones with epigene and hypogene evaporite karst and sinkhole development. The sinkhole fields related to hypogene evaporite dissolution are associated with the discharge zones of the aquifer, where groundwater from a confined limestone rises traversing an overlying gypsum formation capped by thick marls. This work analyses the sinkhole field developed in the Sant Miquel de Campmajor Valley (SMCV), a discharge area of the aquifer, where a cartographic inventory including 94 sinkholes has been produced. Sinkholes in this hypogene gypsum karst are mainly large caprock-collapse sinkholes rooted in deep-seated cavities generated by interstratal hypogene karstification, as corroborated by an electrical resistivity imaging (ERI) survey. They show a nonclustered distribution within the sinkhole field and the variations in size and density across the area are mainly controlled by the thickness of the marl caprock. The magnitude and frequency relationships of the sinkholes can be modelled with a high goodness of fit with a log-normal function, like in other regions of the world. However, in this deep-seated hypogene system the depressions show much larger dimensions. ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P TPotential differences between the sinkholes developed in hypogene and epigene karst environments are discussed, including their distribution with respect to the groundwater flow system, their spatial patterns and dimensions.

Closed depressions in Kotido crater, Arabia Terra, Mars. Possible evidence of evaporite dissolution-induced subsidence

“…5). Similarly, regressions generated with the major axis of sinkholes on Earth developed in: (1) a limestone karst mantled by a thin alluvial cover (Val d'Orleans, France;Gombert et al, 2015); (2) a limestone karst mantled by a thick cohesive cover (Hamedan plains, Iran; Taheri et al, 2015); (3) a salt karst with a residual caprock (Gotvand salt pillow, Iran; Gutiérrez and Lizaga, 2016); (4) an epigene evaporite karst with both caprocks and covers (Fluvia valley, NE Spain; ; and (5) a hypogene interstratal evaporite karst (Sant Miquel valley, NE Spain; Gutiérrez et al, 2019), also show a high correlation (R 2 ≥0.92) between the empirical data and logarithmic functions (Fig. 8).…”

“…8). The variable slopes and size distributions of those datasets from different settings are attributed to factors such as the nature, thickness and mechanical strength of the cavity-roof materials (Gutiérrez et al, 2019). Corral and González (2018), using large datasets of karst depressions from the limestone karsts of Kentucky and Florida, and the mantled salt karst of the Dead Sea, obtained better fits with log-normal distributions.…”

The Mixing Regime and Turbidity of Lake Banyoles (NE Spain): Response to Climate Change

“…Lake Banyoles, listed on the Ramsar List of Wetlands of International Importance, is not only the largest fresh-water tectonic-karstic lake in Spain but also its second largest natural lake. Lake Banyoles is also the largest lake on the east coast of the Iberian Peninsula with a surface area of 110 ha, a volume of 10 × 10 6 m 3 , a mean depth of 14 m and a maximum depth of 132 m [17,18]. Located in the pre-Pyrenees (42 • 07 N, 2 • 45 E) of eastern Catalonia (Spain), Lake Banyoles is situated in a region that has a humid Mediterranean climate (Figure 1).…”

“…In this study, the depth of the lutocline (z L ) was obtained from the temperature profiles as the depth at which a sudden increase in temperature of at least 0.5 • C was found. The temporal variations in the piezometric level recorded in the Lake Banyoles aquifer were obtained from the Catalan Water Agency (Agència Catalana de l'Aigua in Catalan) for the period 2008-2019 [17].…”

Natural and human-induced subsidence due to gypsum dissolution: a case study from Inandik, CentralAnatolia, Turkey

“…Sinkholes are closed depressions typical of karst terrain. A significantly-sized cavity is necessary for the formation of bedrock collapse and caprock collapse sinkholes (e.g., Waltham et al, 2005;Gutiérrez et al, 2014Gutiérrez et al, , 2019. Other types of sinkholes, such as the cover-collapse sinkhole, may occur in the presence of limited-size cavities and voids (e.g., Gutiérrez, 2016).…”