Search results
Results From The WOW.Com Content Network
The zeolite facies is the metamorphic facies with the lowest metamorphic grade. At lower temperature and pressure processes in the rock are called diagenesis. The facies is named for zeolites, strongly hydrated tectosilicates. It can have the following mineral assemblages: In meta-igneous rocks and greywackes:
The sequence of metamorphic zones is called a metamorphic facies series, and the most common of these is Barrovian (called after George Barrow who first mentioned it in 1912). In this series of zones, both pressure and temperature increase gradually along the metamorphic gradient.
However, Buchan facies series plot along line 3 and Barrovian at somewhat higher pressure and with the appearance of kyanite. The facies series have connections to plate tectonics. Facies series 1 is typical of contact metamorphism, but also found in regional metamorphosed rocks. Facies series 2 correlates with volcanic arc environments, and so ...
Metamorphic facies is a classification system first introduced by Pentti Eskola in 1920 to classify particular metamorphic mineral assemblages that are stable under a range of P-T conditions. [ 54 ] [ 55 ] [ 1 ] Before the mid-1970s, geologists utilized the metamorphic facies classification to investigate metamorphic rocks and determined their ...
Based on inspection of extreme metamorphism and post-subduction magmatism at convergent plate margins, paired metamorphic belts are further extended to two contrasting metamorphic facies series: [7] one is blueschist to eclogite facies series that was produced by subducting metamorphism at low thermal gradients of <10 °C/km, and the other is ...
Greenschist facies results from low temperature, moderate pressure metamorphism. Metamorphic conditions which create typical greenschist facies assemblages are called the Barrovian Facies Sequence, and the lower-pressure Abukuma Facies Series. Temperatures of approximately 400 to 500 °C (750 to 930 °F) and depths of about 8 to 50 kilometres ...
The hornfels facies is the metamorphic facies which occupies the lowest pressure portion of the metamorphic pressure-temperature space. [9] The most common hornfels (the biotite hornfels) are dark-brown to black with a somewhat velvety luster owing to the abundance of small crystals of shining black mica. Also, most common hornfels have a black ...
The metamorphic facies is not usually considered when classifying metamorphic rock based on protolith, mineral mode, or texture. However, a few metamorphic facies produce rock of such distinctive character that the facies name is used for the rock when more precise classification is not possible. The chief examples are amphibolite and eclogite ...