My question is
"Select the rock type most likely to form in each situation"
Andesite, Granite, Diorite, Basalt, Peridotite, Gabbro, Rhyolite
A. Silicic magma cooling slowly in a batholith
B. Mafic magma cooling rapidly in a dike
C. Intermediate magma cooling slowly in a stock
D.Low-silica magma cooling slowly in the mantle
E. Silicic magma cooling quickly near the surface.
I give up, Ive come up with several answers because I always pick 1 rock that I think can fit in 2 of those...so can someone answer this for me?|||Andesite and Rhyolite are extrusives and can be excluded in this question. Basalt is generally an extrusive but can also be applied to shallow intrusives as well.
A. Granite: silica bearing, large-grained=slow cooling in batholith/pluton
B. Diorite: fine-grained=rapid cooling
C. Gabbro: intermediate grained larger than diorite
D. Peridotite: a classic felsic, deep crust/upper mantle and low in silica)
E. Basalt|||use your Earth Science Reference Tables|||A- Granite, It has a high silica content and the large crystals are characteristic of slow cooling.
B- Basalt, there is nothing else in that list which is mafic and contains sufficiently small crystals. Someone mentioned diorite which is coarse grained and therefore the wrong answer.
C- Diorite, Coarse grained (slow cooled) and of intermediate composition. Gabbro is most certainly not the correct answer as it is basic not intermediate.
D- Peridotite, It's the only one on the list which forms in the mantle.
E- Rhyolite, I will show why by saying why it can't be any of the others:
- Andesite cools relatively quickly but is intermediate.
- Granite is silicic but cools slowly.
- Diorite cools too slowly and is intermediate.
- Basalt cools quickly but is basic, not silicic.
- Peridotite forms too deep.
- Gabbro is a basic composition and it cools too slowly.
The only one it can therefore be is rhyolite which fits both criteria of being silicic and rapidly cooled.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment