Question

1.How are volcanic activity and plate tectonics related?

2.Describe the 5 characteristics (definitional) of minerals and the principal physical properties. What physical properties would you use to identify quartz, feldspar and mica in the field.

3.There are three major types of volcanoes. What are they? What are their characteristics and their dangers?

Answer 1

1) Generally volcanism and plate tectonics are related because at the plate boundaries either the crust thins or the subduction occurs to cause the volcanism. At divergent plate boundary decompressional melting occurs by which we find eruption of magma. At convergent boundary flux melting (melting due to the addition of volatiles) occurs of the subducted oceanic block, that causes the volcanism. That's why major volcanism and earthquakes are related to the plate boundaries. But still we have some intraplate volcanic activity also like hot-spot type setting.

2) Properties to characterise s mineral is, colour, Streak, hardness, cleavage, fracture, luster etc.

Quartz is harder than feldspar and mica and don't have cleavage. Mica has 1 sets of perfect cleavage that's why it breaks in sheets. This property of mica makes it unique. Quartz shows vitreous Lustre. Feldspar has 2 sets of perfect cleavage which are perpendicular to each other.

3) Volcanoes can be active, dormant or extinct. This is based on their eruption history.

Active volcano means it is erupting now. So obviously is is the most dangerous.

Dormant means now it is not erupting but it will erupt in the coming future. So this a very dangerous type volcano.

Extinct means during the geologic past eruption was there but now it is not there and also in future there is no possibility for eruption. So this type of volcano has no risk.