A sample of granulite-facies metamorphic rock of felsic composition, with garnet porphyroblasts. Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism.They are medium to coarse–grained and mainly composed of feldspars sometimes associated with quartz and anhydrous ferromagnesian minerals, with ...

2023年11月24日 · The classification of granulites is based on the mineral assemblage and composition. Some common types of granulites include: Orthopyroxene Granulite: Dominated by orthopyroxene, with other minerals like garnet and biotite. Pyroxene Granulite: Contains pyroxene as a dominant mineral, along with other minerals like plagioclase and garnet.

Granulite is a high-grade metamorphic rock in which the presence of feldspar and absence of primary muscovite are critical. Fe-Mg-silicates (generally clinopyroxene and orthopyroxene) are dominantly hydroxyl-free; quartz, garnet, biotite, kyanite, hornblende and cordierite may also be present. The mineral composition is to be indicated by prefixing the major constituents.

garnet composition as a petrogenetic indicator: an example from a marble – calc-silicate granulite interface at kondapalle, eastern ghats belt, india pulak sengupta* and michael m. raith** abstract.

Download scientific diagram | Garnet compositions of garnet-bearing charnockitic granulite and Al – Mg granulite in the pyrope – (grossular + andradite) – (almandine + spessartite) diagram.

Mafic, iron-rich garnet-pyroxene granulite from the Guaxupk Massif has symplectite that formed by nearisothermal decompression, as a consequence of uplift of the granulite facies terrane. ... Garnet composition and the construed petrogenetic grid will thus provide independent constraints on the P-T-Xfluid evolution of high-grade rocks of ...

2021年8月1日 · In addition, the estimated P-T conditions of high-pressure granulite-facies stages are not in equilibrium using the garnet core composition, as shown by the dotted line segment in Fig. 10 (path ②). Subsequently, the mafic granulites suffered intense decompression and garnet breakdown into plagioclase, orthopyroxene, hornblende, and ilmenite.

Garnet occurs widely as a secondary mineral in the granulite-facies rocks of the Lofoten-Vesteraalen islands of North Norway. The garnet-forming reactions may be inferred from the resulting textures and are interpreted as being retrograde reactions. Microprobe analyses show that garnets with high proportions of CaO and MgO occur in coronas around olivine grains in anorthosites, whereas the ...

2002年10月1日 · PULAK SENGUPTA* and MICHAEL M. RAITH** The P-T-fluid histories of aluminous garnet+clinopyroxene-bearing calc-silicate granulites are commonly constrained through interpretation of sequential reaction textures based on activity-corrected petrogenetic grids for model systems, for example the widely used GAS(CO 2 -H 2 O) topologies. Application of these topologies to calc-silicates of diverse ...

As a result, the P-T slope of a garnet-forming reaction changes with the garnet composition, with sharp changes at "singular points" across which one or more phases change their sides with respect to garnet in a given reaction. ... An example from a marble - calc-silicate granulite interface at Kondapalle, Eastern Ghats Belt, India American ...