Introduction to the special issue on SFB 574 “Volatiles and fluids in subduction zones: climate feedback and trigger mechanisms for natural disasters”

Abstract

combine field work on land with marine cruises probing the seafloor. During the course of the SFB 574, many different aspects of subduction zone processes were investigated. Geophysical investigations identified and quantified the input of water through hydration of the bend-faulted subducting plate as far as mantle depths. This process and water release from the subducting slab deeper in the subduction zone was investigated by numerical modeling. These studies highlighted the important role of hydration and dehydration of mantle rocks for the global water cycle. Subducted oceanic fracture zones are another conduit for water transported deep into the subduction zone. Compactional and thermal dehydration of the subducted sediment layer affects the strength of interplate coupling and the depth and lateral extension of the seismogenic zone where disastrous earthquakes are generated. The fluids, largely generated by clay mineral transformation, are expelled through the forearc by splay faults. At the seafloor, the sites of cold seeps, often associated with mud volcanoes, are populated by biota that control the carbon transfer to the ocean. The most prominent manifestations of cold seeps are authigenic carbonates that form from anaerobic oxidation of methane and which serve as archives of forearc processes. The largest cold seep emissions occur at faults generated by the subduction of volcanic seamounts. Petrological analyses of ancient, exhumed subduction zone metamorphic rocks revealed the important role of pervasive, typically channelized fluids in high-pressure metamorphic reactions of dewatering subducted igneous crust and mantle. Slab-derived fluids hydrate the mantle wedge along the slab–wedge interface and form a subduction channel in which mixing of different fluids and fluid–rock interaction causes metasomatic overprinting. The element redistributions associated with the liberation of fluids from Sonderforschungsbereiche (SFBs) are a successful funding model in use by the German Science Foundation (DFG) for over 30 years to strengthen basic research first locally at universities and later also supra-regionally by including academic institutions at different cities and states. Literally translated, SFB means “special research area” that comprises research that complements but does not duplicate research at participating institutions and departments. The English terminology used by the DFG is “Collaborative Research Centre,” which better describes the expected approach by emphasizing collaboration and interdisciplinary efforts in such a way that the overall result is better than the sum of individual results. The SFB 574 had united more than 70 scientists with expertise in structural geology, geophysics, sedimentology, geochemistry, empirical and experimental petrology, volcanology, and biology for 11 years (2001–2012). The overarching theme addressed the role of volatiles in subduction zone tectonic, hydrological, metamorphic and magmatic processes, and resulting hazards. The main areas of research were the subduction zones of Central America and southern Chile. Both extend across shorelines from deepsea trenches to arc-volcano summits and thus required to