Understanding the anatomy of active magmatic plumbing systems is essential to define the heat source(s) feeding geothermal fields. Mineral-melt thermobarometry and fractional crystallization (FC) models were applied to Quaternary volcanic products of the Los Humeros Caldera (Mexico). Results point to a magmatic system controlled by FC processes and made of magma transport and storage layers within the crust, with significant implications on structure and longevity of the geothermal reservoir.

This paper presents MuLTI-TEM, a Bayesian inversion tool for inverting TEM data with independent depth constraints to provide statistical properties and uncertainty analysis of the resistivity profile with depth. MuLTI-TEM is highly versatile, being compatible with most TEM survey designs, ground-based or airborne, along with the depth constraints being provided from any external source. Here, we present an application of MuLTI-TEM to characterise the subglacial water under a Norwegian glacier.

We present new earthquake focal depths and fault orientations for earthquakes that occurred in 2013 in the vicinity of an underground gas storage off the east coast of Spain. Our focal depths are in the range of 5–10 km, notably deeper than the depth of the gas injection (2 km). The obtained fault orientations also differ from the predominant faults at shallow depths. This suggests that the faults reactivated are deeper, previously unmapped faults occurring beneath the sedimentary layers.

We propose a new exploration of the concept of spontaneous lithospheric collapse at a transform fault (TF) by performing a large study of conditions allowing instability of the thicker plate using 2-D thermomechanical simulations. Spontaneous subduction is modelled only if extreme mechanical conditions are assumed. We conclude that spontaneous collapse of the thick older plate at a TF evolving into mature subduction is an unlikely process of subduction initiation at modern Earth conditions.

We report a peridotite xenolith-bearing basalt dredged from the Seifu Seamount (SSM basalt) in the northeast Tsushima Basin, southwest Sea of Japan, which is one of the western Pacific back-arc basin swarms. An ⁴⁰Ar / ³⁹Ar plateau age of 8.33 ± 0.15 Ma (2 σ) was obtained for the SSM basalt, indicating that it erupted shortly after the termination of back-arc spreading. The SSM basalt was formed in a post-back-arc extension setting by the low-degree partial melting of an upwelling asthenosphere.

We study the petrographical and geochemical occurrence of magmatic sulfide minerals in volcanic rocks for areas characterised by different geodynamic settings, some of which are associated with porphyry (Cu and/or Au) and Au epithermal mineralisation. The aim is to investigate the role of magmatic sulfide saturation processes in depth for ore generation in the surface.

Convection in the deep Earth dynamically changes the elevation of plates. Amplitudes of those vertical motions predicted from numerical models are significantly higher than observations. We find that at small wavelengths (< 1000 km) this misfit can be due to the oversimplification in viscosity of rocks. By a suite of numerical experiments, we show that considering the non–Newtonian rheology of the mantle results in predictions in amplitude of dynamic topography consistent with observations.

This contribution describes a technique to automatically extract digitized fracture patterns from images of fractured rock. Digitizing fracture patterns, accurately and rapidly with minimal human intervention, is a desirable objective in fractured rock characterization. Our method can extract fractures at varying scales of rock discontinuities, and results are presented from three different outcrop settings. The method enables faster processing of copious amounts of fractured outcrop image data.

We use a 4-D numerical sensitivity study to investigate which geological parameters exert a dominant control on the quality of a deep geothermal reservoir. We constrain how the variability of these parameters affects the economic potential of a reservoir. We show that the interplay of high permeability and hydraulic gradient is the dominant control on reservoir lifetime. Fracture anisotropy, typical for faults, leads to fluid channelling and thus restricts the exploitable volume significantly.

In source regions of magmatic systems the temperature is above solidus and melt ascent is assumed to occur predominantly by two-phase flow. This two-phase flow allows for the emergence of solitary porosity waves. By now most solutions of these waves used strongly simplified viscosity laws, while in our laws the viscosity decreases rapidly for small melt fractions. The results show that for higher background porosities the phase velocities and the width of the wave are significantly decreased.