Please answer as many you can 12) a) To convert the orthopyroxene to a clinopyro

Question

Please answer as many you can

12) a) To convert the orthopyroxene to a clinopyroxene what percentage of the M-sites must be filled by Ca? (1 mark)
b) The basic struture of pyroxenes contains single silicate chains. How do the chains react, what do they do, and what is the effect on the M-sites, to enable the orthopyroxene structure to accomodate the relatively large Ca2+ cations? (3 marks)

13) Two of the most voluminous magma series on Earth develop at mid-ocean spreading ridges or subduction zones. Of these two magmas, which is expected to be compositionally simple, and which is expected to be most complex? Explain your answer, using diagrams if necessary (6 marks).

14) Different rocks that crystallise from a single magma may have different compositional properties. Describe, using examples and sketches if necessary, how you would present data for compositionally different rocks, and prove that they were genetically related to one another (6 marks).

15) The development of textures in magmatic rocks is controlled by the environment of formation.
a) What is a phaneritic texture, and in which type of igneous rocks would you expect it to develop? (3 marks)(Remember to define "phaneritic" and to use sketches and illustrations if required).
b) Construct a graph showing a temperature versus time diagram for a rock that cools and crystallizes with a phaneritic texture. (2 marks).

11) Amphiboles may be classified on the basis of the cations that occupy the B-site in the generalised formula Aro B2csTsom oH): The four general subsets are alkali, and sodic calcic. Assign each of the following amphiboles to one of these groups (1 mark each: 4 marks total) nopyroxene what percentage of the M-sites must be filled by 12) To convert the orthopyroxene to a Ca (1 mark) b) The basic struture pyroxenes contains si silicate chains. How do the chains react, what do of they do, and what is the effect on the M-sites, to enable the orthopyroxene structure to accomodate the relatively large Ca cations? (3 marks) 13) Two of the most voluminous magma series on Earth develop at mid-ocean spreading ridges or which two magmas, which is expected to be compositionally simple, and subduction zones ected to be most complex? Explain your answer, using diagrams if necessary (6 marks). Different rock that crystallise from a single magma may have different compositional properties. Descri using examples and sketches if necessary, how you would present data for compositionally rocks. and prove that they were genetically related to one another (6 marks) t 15) The development of textures in magmatic rocks is by the environment of formation. controlled a) What is a pha texture, and in which type of igneous rocks would you expect it to develop? and to use hes and illustrations if required) (3 mark b Construct a graph showing a temperature versus time diagram for a rock that cools and crystallizes with a phaneritic texture. marks)

Explanation / Answer

Q-14:

Different types of rocks

There are 3 main types of rocks according to their way of formation from their original magma. They are:

1. Sedimentary rocks

Examples: conglomerate and limestone.

2. Metamorphic rocks

Examples: gneiss and marble.

3. Igneous rocks:

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