Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U-Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where io...

The trace element compositions of igneous augite preserved in metamorphosed komatiite samples from the lower Komati Formation, Barberton Mountainland, South Africa (3.49 Ga), were analyzed in order to estimate the pre-metamorphic bulk composition of the samples. The chemical effects of metamorphism are evaluated by calculating the trace element (TE) composition of a hypothetical augite in equil...

Metamorphic malware apply semantics-preserving transformations to their own code in order to foil detection systems based on signature matching. In this paper we consider the problem of automatically extract metamorphic signatures from these malware. We introduce a semantics for self-modifying code, later called phase semantics, and prove its correctness by showing that it is an abstract interp...

Regional metamorphism occurs in plate boundary zones. Accretionary orogenic systems form at subduction boundaries in the absence of continent collision, whereas collisional orogenic systems form where ocean basins close and subduction steps back and flips (arc collisions), simply steps back and continues with the same polarity (block and terrane collisions) or ultimately ceases (continental col...

The garnet amphibolite schist is associated with the gabbroic unit of Mawat ophiolite, Kurdistan region, Northeast Iraq, in imbricated zone Zagros orogenic belt. Field observation, petrographic study, mineral chemistry, geochemical data, and thermodynamic modeling were used to demonstrate identification, predict observed stable assemblages, validate protolith. assemblages prograde are (pyrope-a...

The 18-km-diameter El’gygytgyn crater is located on the Chukotka peninsula, northeastern Russia. It represents the only currently known impact structure formed in siliceous volcanics, including tuffs. The impact melt rocks and target rocks provide an excellent opportunity to study shock metamorphism of volcanic rocks. The shockinduced changes observed in porphyritic volcanic rocks from El’gygyt...