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...

[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...

Wherry discussed the origin of this material and on the basis of mineralogical and structural evidence suggested its derivation from aan original sedimentary type. He concluded that the presence of sillimanite indicated a noteworthy alumina content of the original sediment and thought that very likely the material w’as originally an argillaceous sandstone. The present writer” has discussed the ...

Metamorphic index mineral zones, pressure– temperature (P–T) conditions, and CO2–H2O fluid compositions were determined for metacarbonate layers within the Wepawaug Schist, Connecticut, USA. Peak metamorphic conditions were attained in the Acadian orogeny and increase from 420 C and 6.5 kb in the low-grade greenschist facies to 610 C and 9.5 kb in the amphibolite facies. The index minerals olig...

soursat metamorphic complex (smc) in west of takab city is one of the polyphase metamorphic terrenes in northern sanandaj-sirjan metamorphic belt of iran. the smc composed mainly of metasedimentary rocks associated with granitic intrusions. based on metamorphic rocks, two metamorphic phases could be separate in the complex. m1 is representative of regional metamorphisms which varies from greens...

Abstract. Permeability of crystalline rocks depends on parameters such as density and interconnectivity fractures pores. While in pristine porosity is usually considered to be low, low-grade solution phenomena the formation episyenites occur occasionally may cause a local dramatic increase permeability. These can effective otherwise unaltered result preferential removal certain mineral phases, ...

The Hellefjord Schist, a volcaniclastic psammite-pelite formation in the Caledonides of Arctic Norway contains discoidal impressions and apparent tube casts that share morphological and taphonomic similarities to Neoproterozoic stem-holdfast forms. U-Pb zircon geochronology on the host metasediment indicates it was deposited between 437 ± 2 and 439 ± 3 Ma, but also indicates that an inferred ba...