Basaltic oceanic crust typically exhibits extensive hydrothermal alteration (e.g., Staudigel, 2003). Geochemical and geophysical observations from seafloor drill holes, active hydrothermal vents, ophiolites, and experimental studies have led to a detailed understanding of how this alteration occurs (summarized by e.g.,

Price et al., 2022) to explain observed heat and fluid discharge fluxes at the seafloor. These high values contrast with the 10 −21 -10 −16 m 2 range of measured rock-matrix permeabilities, which only partly overlap with the 10 −18 -10 −10 m 2 results from in situ hydraulic tests (e.g.,

<p>Reactions of seawater and fresh basalts below the seafloor are crucial for the formation of black-smoker type volcanogenic massive sulphide (VMS) deposits. Improved understanding of hydrothermal alteration processes can therefore help to improve the genetic model of VMS deposits, facilitating targeting in mineral exploration. Reactions of downwelling seawater with fresh basalts creates Ca-depleted, Mg- and Na- enriched “spilite” alteration (albite+chlorite+hematite+titanite±augite±epidote±quartz±calcite). The fluid in turn becomes enriched in Ca and depleted in Mg and Na. This chemically evolved, upwelling fluid can create Ca-enriched, Mg- and Na-depleted “epidosite” alteration (epidote+quartz+titanite+hematite). Epidosites have often been proposed as being the source-rocks for metals in VMS deposits. The more rarely described “pumpellyosite” alteration (pumpellyite+quartz+titanite) exhibits a very similar metasomatism to epidosite alteration and is assumed to represent the low-T equivalent of epidosite alteration.</p><p>            We recently discovered large, km<sup>2</sup>-sized areas of pumpellyosite alteration in the Semail ophiolite (Oman), allowing us to study the transition from epidosite to pumpellyosite alteration. We use reactive-transport modelling to investigate the mechanism responsible for the change from epidosite to pumpellyosite alteration. Pumpellyosite alteration was observed up to few meters below the palaeo-seafloor, indicating that evolved fluids discharged directly onto the seafloor. However, no sulphide mineralisation was observed on or below the palaeo-seafloor. This observation makes the involvement of pumpellyosite alteration in the VMS-forming system questionable. The metasomatic fingerprint of pumpellyosite alteration also strongly contrasts with the chlorite-quartz alteration typically found below VMS deposits. Since epidosite and pumpellyosite alteration appear to be genetically linked, epidosites may likewise be unrelated to the genesis of VMS deposits.</p>

Aristocratic Power in the Spanish Monarchy uses the Borromeo family from Milan as a lens through which to study the transformation of aristocratic power in the composite Spanish monarchy of the seventeenth century. It details the Borromeos’ growing entanglement with the Spanish monarchy in the seventeenth century and the ways in which this Milanese family negotiated that transition. In Italy, the Borromeos have long been held up as a rare example of paternalist aristocrats who withstood the temptations of self-enrichment so many of their peers fell for. This monograph challenges this myth and explains how it came about. Based on research in the previously inaccessible Borromeo private papers, the volume charts the family’s increasing involvement with, and dependence on, the patronage of the Spanish crown over the course of the seventeenth century. At the center of the analysis are the ways in which this representative family sought to rationalize and conceal this rapprochement in the face of popular opposition to their pay-to-play. As their self-seeking behavior came under scrutiny, the erstwhile clients of successive minister-favorites reinvented themselves as courtiers committed to delivering good governance for the subject populations who had contested their rule. The book offers new answers to old questions: through a case study of a representative noble family, it explains a major shift in aristocratic power in the seventeenth century, uncovering how dissimulation and subterfuge became central to the preservation of social privilege in an age of unprecedented threats to established power from below.