Geologists are acquainted with the principle of uniformitarianism, which holds that present day processes are the key to those that operated in the past. But the extent this applies to the processes driving the growth and differentiation of the continental crust throughout the Earth history remains a major controversy in earth sciences. An important part of the discussion circles around the pre...

Early Cretaceous alkaline picrites and high-magnesium basalts from the North China craton provide evidence for recycling of continental lithosphere by density foundering. Both the picrites and basalts contain xenocrystic olivines with high Fo92-93 and low CaO (<0.10%), consistent with the lavas’ derivation from, or interaction with Archean mantle lithosphere. Most importantly, both the picritic...

    Introduction Epithermal deposits are usually found in association with near-surface magmatic-hydrothermal environments with volcanic rocks. According to studies, their formation depth is less than 1.5 km and the temperature for their formation is less than 300 ° C. Epithermal deposits are usually rich in gold to gold-silver and rich in silver and include low sulfide, medium sulfide and hig...

Most of our understanding of earthquake rupture comes from interpretation of strongground-motion seismograms; however, near-rupture-tip fields of stress and particle motions are difficult to resolve. In particular, the decay of frictional resistance from a peak value at the leading tip of the rupture to a residual kinetic value and subsequent healing characterizes the earthquake process, yet th...

Cutts et al. (2014) combined thermodynamic modeling of compositional change in metamorphic garnet with metamorphic peak and retrograde pressure-temperature (P-T ) data derived from quantitative P-T pseudosections to determine clockwise P-T paths for several samples from the Tjakastad schist belt. The Tjakastad schist belt is located in the central portion of the Stolzburg domain at the southwes...

introduction the generation and evolution of granitic magmas has been a hot debated subject among petrologists. the diversity of their origin has led different authors to propose that these rocks are not simple in their origin and might be generated in more ways than one. in the past several decades, many petrologists used a variety characteristics to subdivide the granitoid rocks. such proposa...

Simultaneous acquisition of detrital zircon Pb-Pb ages and trace element abundances from grains collected across the Indian craton, spanning ~3 b.y., reveals prominent shifts in Eu/ Eu* and light and middle to heavy rare earth element ratios. These shifts correspond to a ca. 3.0–2.2 Ga interval of crustal thickening during Indian craton formation, followed by a period wherein arc magmatism occu...

introduction the avan cu-fe skarn is located at the southern margin of qaradagh batholith, about 60 km north of tabriz. the skarn-type metasomatic alteration is the result of qaradagh batholith intrusion into the upper cretaceous impure carbonates. the studied area belongs to the central iranian structural zone. in regional scale, the studied area is a part of the zangezour mineralization zone ...

introduction mineral composition is sensitive to variations in the composition of the magma and can be used to characterize the physical conditions of crystallization such as temperature, pressure, oxygen fugacity and water content. the studies have demonstrated that geobarometery by amphibole provides a tool for determining the depth of crystallization and knowledge of the depth of crystalliza...

Empirical tests of oxygen exchange rate in zircon crystals from amphiboliteand granulite-facies metamorphic rocks of the Grenville Province demonstrate preservation of igneous dO through protracted igneous and metamorphic histories, forming the basis of quantitative estimates of diffusion rate. Granitic orthogneisses, which cooled slowly after granulite-facies metamorphism, show no consistent r...