Abstract The slab–mantle interface in subduction zones is one of the geological boundaries with most significant chemical potential gradients, which leads to fluid-mediated metasomatic reactions and transport. As subducting sediment basaltic crust often contain silica various forms, Si-metasomatism mantle rocks thought occur along zone interface. However, growing evidence from geochemistry alte...

A variety of established and experimental geophysical techniques was used to measure the vertical distribution of fracture permeability in a 229-meter deep borehole penetrating schist and quartz monzonite near Mirror Lake, New Hampshire. The distribution of fractures in the borehole was determined by acoustic borehole televiewer and other geophysical logs. Fracture permeability was estimated by...

Whether or not coarse detrital sedimentary rocks occur within the \3.7 Ga Isua Greenstone Belt (IGB), southern west Greenland, has been debated for some time. Repeated, regional metamorphic, deformational, and metasomatic events have obscured most protolith lithologies leading to misunderstandings about the stratigraphy and environments of deposition. Rocks here interpreted as meta-conglomerate...

Silica scaling is probably the principal factor limiting the extraction of energy from high temperature geothermal systems. Silica exists in a number of polymorphs from quartz through to opal A (or amorphous silica). The thermodynamics of the solubility of quartz and amorphous silica with variations in temperature, salt content, pH and pressure are discussed. However, in silica saturated geothe...

Both highand medium-pressure granulites have been found as because of the absence of modal minerals. The combination of petrographic textures, mineral compositions, metamorphic reaction enclaves and boudins in tonalitic–trondhjemitic–granodioritic gneisses in the Hengshan Complex. Petrological evidence from these history, petrogenetic grids and thermobarometric data defines a nearrocks indicate...

[1] The Rand and Sierra de Salinas schists of southern California were underplated beneath the southern Sierra Nevada batholith and adjacent Mojave‐Salinia region along a shallow segment of the subducting Farallon plate in Late Cretaceous time. Various mechanisms, including return flow, isostatically driven uplift, upper plate normal faulting, erosion, or some combination thereof, have been pro...