At the time that Pentti Eskola published descriptions of these metamorphic facies in the 1920s, the plate tectonics model had not yet been developed. Geologists now realize that volcanic arcs develop at convergent plate boundaries where the oceanic edge of one plate subducts beneath the continental edge of another plate.In the block diagram of a subduction zone (Fig. A7.5.5), place letters in the white circles that are linked to the starred locations on this illustration to show where Eskola’s facies are most likely to occur: A = amphibolite, G = greenschist, E = eclogite, B = blueschist. Subductingsedimentsare metamorphoseddue to increase inpressure andtemperature.300°C600°C900°C1200°CIdealizedgeothermalgradientShallow crustalrocks aremetamorphosed byheat emanatingfrom a nearbymagma body.Subducting oceanic lithosphereLow geothermal gradients are observedin subduction zones because coldoceanic crust and overlying sedimentsare descending into the mantle.IgneousintrusionsRocks buried in alarge sedimentarybasin may encounterlow-grademetamorphicconditions near thebottom of the pile.Rising magma transports heat toEarth's upper crust causing anincrease in the geothermalgradient.Subsidingbasin-300°C600°C---900°C1200°C

Metamorphic facies are the mineral assemblages which are formed at a definite temperature and…

Answered: At the time that Pentti Eskola…

Applications and Investigations in Earth Science (9th Edition)

9th Edition

ISBN:9780134746241

Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Chapter1: The Study Of Minerals

Section: Chapter Questions

Problem 1LR

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At the time that Pentti Eskola published descriptions of these metamorphic facies in the 1920s, the plate tectonics model had not yet been developed. Geologists now realize that volcanic arcs develop at convergent plate boundaries where the oceanic edge of one plate subducts beneath the continental edge of another plate.

In the block diagram of a subduction zone (Fig. A7.5.5), place letters in the white circles that are linked to the starred locations on this illustration to show where Eskola’s facies are most likely to occur: A = amphibolite, G = greenschist, E = eclogite, B = blueschist.