Question

Question 7 Refer to both diagrams from the previous questions. What minerals would least likely be part of the rock phyllite? O biotite white mica (muscovite) sillimanite O albite Question 8 Refer to both diagrams from the previous questions. If you find the mineral staurolite in a rock, what rock would it likely be? O slate O schist O migmatito O No answer text provided. Question 9 4 pts As parent t progresses from low gradet0 Temperetuser Based on the dlagram above, the metamorphicrock gnelss canform at a depth of about 20km Under standard conalrionsInor shown In this diagram), the temperature al 20 km depth is apprxmely d00 degrees Celius 1. According to the diagroi abovtlel, what teiperature ronse does a greiss require at 20 kmdp 2. Whot is a likely source of the additional heat that crcates gnciss under imnctamorphic conditions? Be specific

Answer 1

Answers:

7. Minerals which would least likely be part of the rock Phyllite, are Sillimanite and to some extent, biotite. Explanation: Sillimanite never occurs in phyllite. It is an aluminosilicate mineral with inosilicate structure. Though biotite is a sheet or phyllo silicate, it also sometimes remain absent in phyllite. The mica which is predominant in phyllite is sericite. Albite may constitute as much as 20% of the total composition.

8. If staurolite is found in a rock, the rock would be schist. Explanation: Staurolite formed from regional metamorphism of shale.

9.1. According to the diagram above, temperature range which a gneiss require at 20 km depth is 700-800^o C.

9.2. The likely additional heat source is the volcanic heat that creates gneiss under metamorphic conditions.