This paper argues that the presence of external control of fluid composition during metamorphism of iron-formation should be indicated by the occurrence of high-grade rocks which either lack the bufering assemblages such as olivine-magnetite-quartz or by the presence of such assemblages in which the silicates show a very restricted range in composition. A review of high-grade iron-formations fr...

High-precision dating of the metamorphic sole ophiolites can provide insight into tectonic evolution and subduction zone processes. To understand initiation beneath a young, well-preserved, well-characterized ophiolite, we performed coupled zircon laser-ablation inductively mass spectrometry (LA-ICP-MS) trace element analyses high-precision isotope dilution-thermal ionization (ID-TIMS) U-Pb on ...

Where plates converge, one-sided subduction generates two contrasting thermal environments in the subduction zone (low dT/dP) and in the arc and subduction zone backarc or orogenic hinterland (high dT/dP). This duality of thermal regimes is the hallmark of modern plate tectonics, which is imprinted in the ancient rock record as penecontemporaneous metamorphic belts of two contrasting types, one...

Microdiamonds from the Akluilâk minette dykes (Nunavut, Canada) are similar to diamonds formed in subducted metamorphic rocks. High concentrations of unaggregated nitrogen and positive delta(15)N suggest that the microdiamonds formed within rocks subducted to ultrahigh pressures before being sampled by the minette magma 1.8 billion years ago. This ultrahigh pressure metamorphism in North Americ...

The grossular–andradite garnet is an ideal mineral for indicating the formation age of skarn, which also pretends to constrain skarn processes because its higher REE (rare earth elements) content. Tongshanling deposit a medium-sized reduced Cu–W–Pb–Zn associated with highly evolved I-type granodiorite intrusion in Nanling metallogenic belt, South China. Different assemblages, microscopic charac...

ABSTRACT We report the discovery and characterization of high-speed (>100 km s−1) horizontal flows in solar active regions, making use Sun-as-a-star spectroscopy range 5–105 nm provided by EVE (Extreme Ultraviolet Variability Experiment) spectrometers on Solar Dynamics Observatory. These apparent are persistent time-scales days, well observed lines Mg x, Si xii, Fe xvi for example. They ...