Metamorphic rock - Retrograde Metamorphism: In general, the changes in mineral assemblage and mineral composition that occur during burial and heating are referred to as prograde metamorphism, whereas those that occur during uplift and cooling of a rock
The lattices of the host minerals are generally strong enough to maintain pressure on the inclusions following uplift and retard their inversion to lower-pressure polymorphs (which involves a volume increase). These rocks went unnoticed for decades because virtually all the host rock had re-...
Metamorphism and the mineralogical changes that define it may therefore occur over a wide range of temporal and spatial scales, providing that there is a geological driving force to bury, exhume, heat, or cool a rock over time. While metamorphism may theoretically proceed at the Earth's surface...
This suggests that Himalayan-age metamorphism in the core of the structure was shut-off early during the metamorphic cycle possibly due to erosional exhumation before reaching temperatures high enough to reset hornblende. The 67 and 50 Ma ages suggest that it may be possible to delineate a ...
However, under certain conditions fusion is possible: some of the work of the unfold can be done before all of the work of the fold is complete. This permits streaming metamorphisms, and among other things allows conversion of infinite data representations. We present a theory of metamorphisms...
1. Geological sketch map of the North Qaidam Orogenic Belt (a, modified after Zhang et al., 2017a) and the Yuka–Luofengpo terrane with sampling localities (b, modified after Zhang et al., 2005). CAOB, Central Asian Orogenic Belt; NQSZ, North Qilian Suture Zone; EKLOB, East Kunlun ...
On the contemporary Earth, distinct plate tectonic settings are characterized by differences in heat flow that are recorded in metamorphic rocks as differences in apparent thermal gradients. In this study we compile thermal gradients [defined as temperat
The peak metamorphism of the garnet websterite was after B1.90 Ga when it was subducted to eclogite facies at B2.4 GPa, then exhumed back to granulite facies at B0.9 GPa before B1.82 Ga. The rock associations with their structural relationships and geochemical affinities are comparable to ...
a composite layered pluton of monzodiorite and gabbro that was patchily deformed and recrystallised at ~850 °C and 1.8 GPa21,23. It experienced limited partial melting during metamorphism, as it lacks peritectic phase assemblages and maintains incompatible-element-rich whole-rock compositions21...
Some mineral and fluid inclusions in diopside, titanite, and garnet were also identified by Raman spectroscopy. To precisely determine the band shift of the quartz inclusion, we analyzed standard quartz (surfaced quartz in a rock matrix, therefore not stressed) before and after the inclusion ...