chapter 4 rocks & igneous rocks. rock definition a naturally occurring, solid composed of one or...
TRANSCRIPT
![Page 1: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/1.jpg)
Chapter 4Rocks & Igneous Rocks
![Page 2: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/2.jpg)
Rock DefinitionA naturally occurring, solid
Composed of one or more minerals
![Page 3: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/3.jpg)
Exceptions to the Definition
Some rocks are not formed of minerals
Noncrystalline, glassy volcanic rocks such as obsidian and pumice
Coal which is formed from compacted plant remains
![Page 4: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/4.jpg)
Appearance of a Rock
The appearance of a rock is determined by two major factors
Mineralogy
Texture
![Page 5: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/5.jpg)
Appearance of a RockMineralogy refers to the relative proportions of the constituent minerals
Texture is determined by the size, shape and arrangement of the mineral crystals
![Page 6: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/6.jpg)
Appearance of a Rock
Mineralogy and texture are related to how and where a rock was formed and what has happened to the rock since it was created
![Page 7: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/7.jpg)
Three Families of Rocks
Igneous- from magma/lava
Sedimentary-compaction/cementing of sediments
Metamorphic- changed by heat and pressure
![Page 8: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/8.jpg)
Three Types of Rocks
![Page 9: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/9.jpg)
Igneous Rocks
Rocks formed by the solidification of magma (molten rock)
Granite
![Page 10: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/10.jpg)
Two Types of Igneous Rocks
Extrusive igneous rocks form when magma erupts at the surface (i.e., above ground) and rapidly cools
Intrusive igneous rocks form when magma intrudes into bedrock and slowly cools (i.e., below ground)
![Page 11: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/11.jpg)
Igneous RocksIgneous Rocks
![Page 12: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/12.jpg)
Most Igneous Rock are Silicates
QuartzFeldspar
MicaPyroxene Amphibole
OlivineBasalt
![Page 13: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/13.jpg)
Granite
![Page 14: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/14.jpg)
Sedimentary Rocks
Rocks formed by consolidation of sediments
Classified by the type of sediments
![Page 15: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/15.jpg)
Three Major Types of Sediments
Clastic Sediments are physically deposited particles derived from weathered rocks
Chemical Sediments include minerals carried in solution such as calcite and halite
Organic Sediments are composed of living materials (plant/animal material and fossils/shells)
![Page 16: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/16.jpg)
From Sediments to Solid RocksLithification is the process of converting sediments into solid rocks
(will cover in detail in another lecture)
![Page 17: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/17.jpg)
The Two Types of Lithification
Compaction – sediments are squeezed together by the weight of overlying sediments into a solid mass
Cementation – minerals precipitate around the sediments and bind them into a solid rock
![Page 18: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/18.jpg)
Sedimentary Rocks
![Page 19: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/19.jpg)
Sedimentary Rocks
5 % by volume of the upper crust
75 % by exposed surface area of continents
![Page 20: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/20.jpg)
Sedimentary RocksSedimentary rocks commonly contain fossils
In fact, some sedimentary rocks are almost entirely composed of fossils
Can exhibit extensive horizontal layers called bedding
![Page 21: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/21.jpg)
Composition
Sedimentary rocks can be composed of sediments created from any of three great families of rock (igneous, sedimentary, metamorphic)
Chemical cementation commonly includes calcite, gypsum and halite
![Page 22: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/22.jpg)
Metamorphic Rocks
Metamorphic rocks are formed by the transformation of previously-existing rocks in the solid state due to increased temperature and pressure
![Page 23: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/23.jpg)
Metamorphic RocksMetamorphism can change the mineralogy, texture and/or the chemical composition of a “parent rock” while maintaining its solid form
Note that the rock does not melt (temperature range 250 to 700 C)
![Page 24: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/24.jpg)
Regional and ContactMetamorphism
Regional metamorphism occurs where high temperature and pressures occur over large region (plate tectonics)
Contact metamorphism is limited to smaller areas such as around a magma intrusion into bedrock
![Page 25: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/25.jpg)
Regional Metamorphism
![Page 26: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/26.jpg)
Contact Metamorphism
![Page 27: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/27.jpg)
Other Forms of MetamorphismUltra-high pressure metamorphism occurs deep in the continental and oceanic crust
High-pressure, low-temperature metamorphism occurs where oceanic crust subducts under a continental plate
Shock metamorphism at impact sites
![Page 28: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/28.jpg)
Metamorphic MineralizationSilicates are the most common mineral in metamorphic rocks
Minerals can tell you the “grade”of metamorphism
Certain minerals are uniquely characteristic of metamorphic rocks (kyanite, staurolite, some garnets)
![Page 29: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/29.jpg)
Contact Ultra-high pressure Regional High-press, low-temp
Metamorphic Mineralization
![Page 30: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/30.jpg)
Proportions of the Rock Types
![Page 31: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/31.jpg)
A Few More Facts…Igneous processes create new rock
Metamorphic and sedimentary processes re-work old rock into a new form
Silicate mineral are the most common minerals found in all types of rocks
![Page 32: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/32.jpg)
Common Minerals Found in Rocks
![Page 33: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/33.jpg)
Five Very Different Locations
![Page 34: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/34.jpg)
![Page 35: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/35.jpg)
![Page 36: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/36.jpg)
![Page 37: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/37.jpg)
![Page 38: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/38.jpg)
![Page 39: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/39.jpg)
Rock Cycle
![Page 40: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/40.jpg)
Rock Cycle
![Page 41: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/41.jpg)
Subduction of an oceanic plate beneath a continental plate uplifts a volcanic mountain range
Magma rises from melting plate and intrudes or extrudes in the crust
Rock Cycle
![Page 42: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/42.jpg)
Magmas cool to make igneous rock
Basalt versus granite
Rock Cycle
![Page 43: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/43.jpg)
Weathering and erosion creates sediments
Rock Cycle
![Page 44: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/44.jpg)
Sediments are carried to the oceans and lakes
Lithification
Rock Cycle
![Page 45: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/45.jpg)
Tectonic plates interact
Metamorphism of subducted rock
Rock Cycle
![Page 46: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/46.jpg)
Entire process starts over as plates interact
Rock Cycle
![Page 47: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/47.jpg)
Igneous Rocks
![Page 48: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/48.jpg)
Igneous Rocks
How do igneous rocks differ from one another?
Where do they form?
How do rocks solidify from a melt (magma)?
Where do rock melt?
![Page 49: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/49.jpg)
We Classify Igneous Rocksby Appearance
Mineralogy (Chemistry)
Texture
![Page 50: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/50.jpg)
Igneous Rocks
![Page 51: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/51.jpg)
We Classify Igneous Rocks by Genetics (Origin)
There are two classes of igneous rocks
Intrusive
Extrusive
![Page 52: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/52.jpg)
Genetic Classification of Igneous Rocks
Intrusive igneous rocks crystallized from slowly cooling magma intruded within the Earth’s crust, such as granite and gabbro
![Page 53: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/53.jpg)
Granite Intrusions
![Page 54: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/54.jpg)
Genetic Classification of Igneous Rocks
Extrusive igneous rocks crystallized from rapidly cooling magma extruded on the surface of the Earth as lava or erupted as pyroclastic material, such as basalt
![Page 55: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/55.jpg)
Extrusive Igneous RocksRocks formed from the cooling of lavas extruded onto the Earth’s surface or onto ocean floors
Rocks formed by the cooling of pyroclastic material, such as fragmented pieces of magma and material erupted into the air
![Page 56: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/56.jpg)
We Can Also Classify Igneous Rocks by Composition
Chemistry
Mineralogy
![Page 57: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/57.jpg)
Chemistry
Modern classification of igneous rock is based upon the silica (SiO2) content
The silica content is determined by the silicate minerals that occur in the rock (i.e., the minerals contain SiO2)
The percentage of silica ranges from about 40% to about 70%
Rocks are referred to as “silica rich” or “silica poor”
![Page 58: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/58.jpg)
Mineralogy
There are four major divisions of igneous rocks based upon the content of elements in the minerals:
Felsic
Intermediate
Mafic
Ultramafic
![Page 59: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/59.jpg)
Rich (high) in minerals containing silica
Poor (low) in iron and magnesium
They include: Granite Rhyolite
Felsic Igneous Rocks
![Page 60: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/60.jpg)
Intermediate Igneous Rocks
Intermediate in composition between felsic and mafic igneous rocks
Less silica, more Fe & Mg than felsic
More silica, less Fe & Mg than mafic
They include: Granodiorite DaciteDioriteAndesite
![Page 61: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/61.jpg)
Mafic Igneous Rocks
Poor (low) in minerals containing silica
Rich (high) in iron and magnesium
They include: Gabbro Basalt
![Page 62: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/62.jpg)
Ultramafic Igneous Rocks
Very uncommon on the Earth’s surface
Very poor (lower) in minerals containing silica
Consist primarily of mafic minerals (olivine, pyroxene)
The most common ultramafic rock is: Peridotite
![Page 63: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/63.jpg)
![Page 64: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/64.jpg)
Felsic Intermediate Mafic
Granite Granodiorite Diorite Gabbro
BasaltAndesiteDaciteRhyolite
![Page 65: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/65.jpg)
![Page 66: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/66.jpg)
Common Minerals of Igneous Rocks
![Page 67: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/67.jpg)
When Do Rocks Melt?Melting starts at ~700o C
When the temperature exceeds the melting point of the rock or some minerals within the rock
Minerals melt at different temperatures
![Page 68: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/68.jpg)
Three Factors Affecting Melting of Rocks
Pressure: Increased pressures raises melting points
Water Content: Increased water content lowers melting points
Composition: Felsic minerals melt at lower temperatures than mafic minerals
When Do Rocks Melt?
![Page 69: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/69.jpg)
Magma Differentiation
The process by which rocks of various compositions can arise from a
uniform parent magma
![Page 70: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/70.jpg)
The Formation of
Magma Chambers
Partial meltingPartial melting
![Page 71: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/71.jpg)
Partial meltingPartial melting
Less dense magmaLess dense magma
The Formation of
Magma Chambers
![Page 72: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/72.jpg)
Partial meltingPartial melting
Less dense magmaLess dense magma
Magma risesMagma risesThe
Formation of Magma
Chambers
![Page 73: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/73.jpg)
Partial meltingPartial melting
Less dense magmaLess dense magma
Magma risesMagma rises
Magma pools in Magma pools in magma chambermagma chamber
The Formation of
Magma Chambers
![Page 74: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/74.jpg)
Magma DifferentiationOccurs because different minerals crystallize (solidify) at different temperatures
In other words, as the magma cools some minerals form first, some form last
![Page 75: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/75.jpg)
The process by which crystals forming in a cooling magma are segregated from the remaining liquid
In a simple scenario, the crystal settle to the floor or adhere to the walls of the magma chamber
Fractional Crystallization
![Page 76: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/76.jpg)
Fractional Crystallization
The elements (such as Fe and Mg) used to create the newly formed crystals are now no longer available for creating new minerals
Therefore the chemical composition of the magma slowly changes as new minerals are continually formed and the available matter is selectively used up
![Page 77: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/77.jpg)
Bowen’s Reaction Series
Experiments that determined the sequence of crystallization of minerals from a gradually cooling mafic (basaltic) magma
Conducted by Norman L. Bowen prior to 1916
These experiments totally rewrote our understanding of igneous rock formation
![Page 78: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/78.jpg)
Bowen’s Reaction Series
![Page 79: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/79.jpg)
Evidence of Fractional Crystallization in the Palisades Sill
![Page 80: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/80.jpg)
Evidence of Fractional Crystallization in the Palisades Sill
first olivine next pyroxene pyroxene finally plagioclase & plag. Feldpar finishes
![Page 81: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/81.jpg)
Partial melting of upper mantle: e.g. at divergent spreading centers
Partial melting of continental crustal rocks
Mafic
Magmas
Felsic Magmas
Partial Melting and the Origin of Magmas
![Page 82: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/82.jpg)
Magmatic Stoping: Making Room for the Intrusion of Magma
Wedging open overlying rock
Breaking off large blocks of rock (remnants of which are called xenoliths)
Melting of surrounding country rock
![Page 83: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/83.jpg)
Rising Magma Wedges Open and Fractures Overlying Country Rock
![Page 84: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/84.jpg)
Overlying rocks may bow up
![Page 85: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/85.jpg)
Magma melts surrounding rock
![Page 86: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/86.jpg)
…changing the composition of the magma
![Page 87: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/87.jpg)
Blocks of the Overlying Country Rocks (Xenoliths) May Break Off and
Sink into the Magma
![Page 88: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/88.jpg)
PlutonsLarge igneous bodies formed at depth in the
Earth’s crust
![Page 89: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/89.jpg)
Types of Plutons
Batholith: Massive, discordant intrusive body covering at least 100 km2
Stock: Massive, discordant intrusive body covering less than 100 km2
Dike: Tabular, discordant intrusive body
Sill: Tabular, concordant intrusive body
![Page 90: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/90.jpg)
Types of intrusive and extrusive igneous structures
![Page 91: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/91.jpg)
Sill
![Page 92: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/92.jpg)
DikeDike
![Page 93: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/93.jpg)
Where Do Most Magmas Occur?Divergent Plate Margins
Convergent Plate Margins
Mantle Plumes/Hot Spots
![Page 94: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/94.jpg)
Island Arc Plate Subduction
(Japanese Islands)
![Page 95: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/95.jpg)
ContinentalPlate Subduction
(Mount St. Helens)
![Page 96: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/96.jpg)
Hot SpotVolcanism
(Hawaii)
![Page 97: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/97.jpg)
Generation of Magmas at Convergent Plate Margins
Subduction drags oceanic lithosphere (including a veneer of “wet” sediments) beneath the adjacent plate
![Page 98: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/98.jpg)
Generation of Magmas at Convergent Plate Margins
The release of volatiles lowers the melting point of the adjacent mantle, causing fluid-induced melting to form a mafic magma, which becomes more intermediate in composition as it rises through the overlying crust
![Page 99: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/99.jpg)
![Page 100: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/100.jpg)
xx
![Page 101: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/101.jpg)
Ophiolite Suites
Unusual assemblages of rocks found on land that had characteristics of seafloor
Composed of deep-sea sediments, basaltic lavas and mafic igneous intrusions
Fragments of ocean crust moved onto land by plate tectonics
![Page 102: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/102.jpg)
?
Idealized Section of an Ophiolite
Suite
![Page 103: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/103.jpg)
Generation of Igneous Rocks at Divergent Plate Margins
Some of the mafic magma cools in massive magma chambers to form massive gabbros
Some of the magma is intruded as sheeted dikes
These dikes are feeder for basaltic lava flows which form pillows as they extrude beneath the ocean
![Page 104: Chapter 4 Rocks & Igneous Rocks. Rock Definition A naturally occurring, solid Composed of one or more minerals](https://reader034.vdocuments.net/reader034/viewer/2022051216/56649e375503460f94b27844/html5/thumbnails/104.jpg)