Heterogeneous aquitard properties in sedimentary successions in the Apennine chain: case studies in southern Italy

Abstract

Abstract:The aim of this study was to analyse the hydrogeologic role of siliciclastic deposits and marly-clayey-calcareous successions within the carbonate Apennine chain (southern Italy). The study was carried out along the northern part of the Matese carbonate massif through (1) the hydraulic characterization of siliciclastic rocks in a test site, by means of Lugeon tests, and (2) the identification of the groundwater flow system discharging at an important spring located within a marly-clayey-calcareous succession in a second test site, by means of isotopic investigations.The results showed that the investigated siliciclastic deposits and marly-clayey-calcareous successions may allow significant groundwater discharge from carbonate aquifers. Thus, they do not everywhere behave as aquitard, contrary to the previous model. Instead, groundwater flows through the upper part of these successions, where stress release fracturing enhanced rock permeability in the near-surface bedrock. Thus, these successions may locally be a new groundwater source within the southern Apennine chain.

Complex hydraulic interactions between compartmentalized carbonate aquifers and heterogeneous siliciclastic successions: a case study in southern Italy

“…In agreement with previous suggestions in similar environments (Petrella and Celico, ), these results clearly depict a heterogeneous siliciclastic medium, where an upper part of the sequence, weathered and undetensioned, is characterized by higher permeability with respect to the underlying bedrock. The higher permeability of the shallower portion of the siliciclastic sequence is confirmed by the results of the slug tests carried out in the wells P3 and P4, abutted at depths ranging from 23 to 45 m from the ground surface, respectively.…”

“…However, both the shallower and the deeper groundwaters are fed by the upgradient carbonate aquifer. In fact, (i) the isotopic content of springs S2 and S4 is in the range of those detected in S1 and in P1 (Figure ), and (ii) previous investigations (Petrella and Celico, ) demonstrated that both S1‐water and P1‐water come from the nearby carbonate aquifer, through the surficial horizon of the siliciclastic sequence.…”

“…The Monte Celara massif is a portion of an important aquifer, in which the regional groundwater flow is westward (Figure ; Celico et al ., ). The results of δ 18 O and δ 2 H analyses, performed by Petrella and Celico (), suggest that the groundwater flowing through the studied siliciclastic sequence comes from the carbonate massif, but as the distance from it increases, so does the influence of the local infiltration.…”

“…A copious amount of these rocks is represented by siliciclastic sequences found in the Apennines. Some studies carried out in Italy have demonstrated that these sequences could also behave like aquifers (Gargini et al ., ; Petrella and Celico, ; Vincenzi et al ., ), allowing the discharge of high flow rates of groundwater, contrary to what was assumed before then. Therefore, an adequate understanding of the role that aquitards play in flow dynamics is crucial in order to improve the management of groundwater supply.…”

Recharge processes of Matese karst massif (southern Italy)

“…2) are three main groups of springs (Civita 1969): the Maiella group west of Boiano, the Pietrecadute group located in the village, and Riofreddo group east side of the Boiano. These springs are fed by the karst system of the north-central sector of Matese massif and are located along debris deposits that cover the fault between limestone and flysch sequences (Petrella and Celico 2009). Altogether these springs have an annual discharge of about 2.80 m 3 /s.…”