All Questions
3
questions
11
votes
2
answers
2k
views
Why are alkali basalts found at rifting centres and on top of 'plumes', whereas MORBs are generally tholeiitic?
So I was essentially wondering why it was that the basalts on top of 'plumes' at 'hotspots' (sometimes called OIBs, ocean island basalts) and at continental rifting centres are enriched in alkaline ...
- 1,715
5
votes
0
answers
103
views
What causes a change in composition from basanite to nephelinite?
Can the change in composition from basanite to nephelinite (i.e. increasing alkalis with decreasing SiO2) be explained in terms of fractional crystallisation, or only by a decreasing degree of partial ...
- 51
1
vote
0
answers
313
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What is solidus and liquidus temperature of granite?
My understanding is that because a rock is composed of variety of minerals, so it does not have fix melting point, rather there is a range below which whole rock is solid and above which whole rock is ...
- 779