Abstract Intruding magma can create space by uplift and elastic bending of the overburden, which locally fractures the deforming volume and produces flat-topped or dome-like forced folds. Here, I map such fracture networks and quantify their geometry and connectivity across a range of natural and modelled intrusion-induced forced folds. I show that there is a positive relationship between forced fold length and amplitude, and all fracture networks comprise traces, with variable lengths and orientations, that are more intense and denser where fold curvature is greatest. Fracture length populations are typically best described by power-law distributions, but some fit better to log-normal or exponential distributions. Connectivity of fracture networks is low and generally increases with folding, but resurfacing by eruptive products can disrupt this trend. My work supports previous analyses of forced folds and fractures, suggesting that we can use the fracture characteristics of exposed forced folds to predict that of buried forced folds. Due to their geometry and fracture network, intrusion-induced forced folds make ideal fluid traps. As these forced folds are common in many volcanic settings and sedimentary basins, we should consider their potential as exploration targets for water, magmatic-related mineral and metal deposits, and particularly CO 2 storage.

Abstract Lava flows form important fluid reservoirs and have been extensively exploited for water aquifers, geothermal energy, hydrocarbon production and, more recently, for carbon storage. Effusive subaerial mafic to intermediate lava flows account for vast rock volumes globally, and form reservoirs with properties dictated by well-known lava flow facies ranging from pāhoehoe through several transitional forms to ‘a’ā lava. These variations in flow type lead to critical differences in the pore structure, distribution, connectivity, strength and fracturing of individual lava flows, which, alongside lava flow package architectures, determine primary reservoir potential. Lava flow margins with vesicular, fracture and often autobreccia-hosted pore structures can have porosities commonly exceeding 40% and matrix permeabilities over 10 −11 m 2 (>10 D) separated by much lower porosity and permeability flow interiors. Secondary post-emplacement physicochemical changes related to fracturing, meteoric, diagenetic and hydrothermal alteration can significantly modify reservoir potential through a complex interplay of mineral transformation, pore-clogging secondary minerals and dissolution, which must be carefully characterized and assessed during exploration and appraisal. Within this contribution, a review of selected global lava flow-hosted reservoir occurrences is presented, followed by a discussion of the factors that influence lava flow reservoir potential.