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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

What is calssed as ''vulcanian'' activicty?

Explosive- bombs up to 1 m