Flashcards in Earth Materials Deck (39)
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1
What igneous rock forms ar MOR
Bassalt
2
What is the mantle made of?
Peeridotite
3
What is peridotie?
A coarse grained ultramafic rock
4
How does basaltic magma form from an ultramafic mantle?
heating and decompression melting
5
What is fertile mantle, and what is it called?
the mantle before melting occurs- Lherzolite
6
What does lherzorite contain
40-90% olivene
Ortho + clioropyroxene
7
What does hazburgite contain?
Olivene and chlinopyroxene
8
What is oceanic crust made of?
Bassalt, dolerite, gabbro
9
Where do island arcs occur? give an example
Oceanic crust beneath oveanic crust
Monseerat- Atlantic ocean crust under carrebbian plate
10
Where do continental arcs occur?
Oceanc under continental
Mt St helens, one of chain of volcanoes- carrebien under atlantic
11
How are granitoids produced?
1) melting of continental crusts
2) fractionisation of basaltic crust
12
What compesition is andersite?
INTERMEDIATE
-Plagioclase, pyroxene, amphibole (water bearing)
--hornblende
13
What is an amphibole?
Mafic water bearing minerals
14
Describe an amphibole under the microscope
ppl-colourless, green-brown, prismatic, moderate relief
xpl-
15
What kind of volcanoes does continental subduction create?
EXPLOSIVE
16
Give examples of continental subduction volcanoes
-Andes (south america)
-Parictuin mexixo
-costa rica centeral america
17
What kind of mineralisetion does continental subdicion give rise to?
Porphyry copper- from hydrothermal fluids
18
What is a stratvolcano?
Pyroclastic fragmeented rocks produced by violent erruption
19
Describe a subduction volcano?
Errution of ANDERSITIC lavas and PYROCLASTIC deposits
STEEP SIDED COMPERSITE STRATAVOLCANOES
20
What chain ov volcanoes does mt st helens belong too?
Cascades
21
What is diorite?
Plutonic amdersite
-coarse grained intermediate
-biotite pyroxene and plagioclaise
22
What does a pyroclastic flow consist of?
-Fragments of lava
-Crystals
-Glass shatds
-pummice
-Ignimbrite flows cool and form ash flow tuffs
23
What kind of magmasdo arc volcanoes commonly errrupt?
-More silica rich
-DACITES AND RHYOLITES
-cold and freexe quickly- obsidian
24
What is pummice?
Pummive forms when extreemly viscous magmas become frothy due to gas exolving out
When pressure drops it solididies to form PUMMICE
25
What are the most common inerals in RHYOLITE and DACITE
alkali felspas and quartz
-some micas and hornblende in dacite
26
What minerals are common in granite?
alkali fspa, qts, mica and hornblende
27
What dominares felsic rocks
QTZ and FSPA
28
What plates produce the Italian volcanoes
African under european
29
Describe ETNA
-Feeder dykes STRATAVOLCANO
-Strombolian cones found at lower levels
- volcanic gasses from creaters
30
