NS 1300 Emergence of Modern Science

Chapter #18Rock Cycle

Rock Cycle

Types of Rocks

IgneousIntrusiveExtrusivePyroclastic

SedimentaryChemical

Precipitates and Evaporites Fossiliferous

Clastic Sorted Unsorted

MetamorphicFoliatedUnfoliated

Distribution of Elements in the Solar System

Elements in the Sun

Carbonaceous Chondrites

Elements in the Earth’s Core

Elements in the Earth’s Mantle

Elements in the Earth’s Crust

Elements in the Earth’s Hydrosphere and Atmosphere

Minerals in Earths’ Crust

Oxygen = 46.6 %Silicon = 27.7 %Aluminum = 8.1 %Iron = 5 %Calcium = 3.6 %Potassium = 2.8 %Magnesium = 2.6 %All Others = 1.5 %

Mineral Identification

Mineral ClassesSilicatesOxidesCarbonatesSulfidesSulphatesHalidesPhosphatesHydroxidesNative Elements

The Earth Scientist’s Periodic Table: most elements in the natural environment exist as ions

Using Mineral Properties to Identify Minerals

Luster

Color and Streak

HardnessMoh’s Scale of Hardness

Cleavage

Specific Gravity

Special Properties

Using Texture and Mineralogic Composition to Identify Rocks

Igneous RocksIntrusiveExtrusivePyroclastic

Sedimentary RocksClasticNonclastic

Metamorphic RocksFoliatedUnfoliated

Igneous Rock Texture

PhaneriticCoarse-GrainedMedium-GrainedFine-Grained

AphaniticGlassyVesicularPyroclastic

Porphyritic

Igneous Mineral Composition

FelsicGraniteRhyolite

MaficBasaltGabbro

IntermediateDioriteAndesite

Bowen’s Reaction Series

Continuous Reaction Series

Discontinuous Reaction Series

Sedimentary Rocks

Sediment FormationMechanical and Chemical Weathering

Sediment TransportWater, Ice, Wind and Gravity

Sediment DepositionEnvironment of Deposition

Environment of Deposition

Non-marineTerrigenousLacustrine

MarineLittoralPelagic

Transitional

Clastic Sedimentary Rocks

SortingGrain Size

Boulders Pebbles Sand Silt Clay

Rounding

Chemical Sedimentary Rocks

PrecipitatesLimestoneDolomiteTravertineChert

EvaporitesGypsumHalite

Other Compositions

Siliceous Sedimentary Rocks

Bioclastic Sedimentary Rocks

Coal

Metamorphic Processes

Recrystallization

Crystallization

Rotation

Conditions of Metamorphism

Contact Metamorphism

Regional Metamorphism

Metamorphic Stories

PeliticShale to Slate to Phylite to Schist to Gneiss

ArenaceousGranite to Schist to Gneiss

MaficAndesite to Schist to Gneiss

CalcareousLimestone to Marble

Classification of Metamorphic Rocks

FoliatedSlatePhylliteSchistGneiss

UnfoliatedMarbleQuartzite

Rock CycleIgneous rocks are formed from magma cooling in the earth’s crust or lava cooling on the surface.

Sedimentary rocks are formed from the weathered pieces of existing rock.

Metamorphic rocks are formed by the recrystallization of existing rocks.

All rocks are susceptible to weathering and erosion.

All rocks are also susceptible to metamorphism.

All rocks can be subducted and re-melted (though the continents preserve rocks formed throughout earth’s history because they float higher in the mantle than do the oceans).

The rock cycle is a continuous process!

Quiz1. T or F: Minerals are naturally occurring elements and compounds in the earth.

2. T or F: Rocks that form from magma, lava or pyroclastic material are metamorphic rocks.

3. T or F: Rocks that form by recrystalization of existing rocks are sedimentary rocks.

4. T or F: Sedimentary rocks formed from pieces of rocks weathered physically are called clastic igneous rocks.

5. T or F: If the metamorphism is extreme the crystals in the metamorphic rocks will migrate and form layers or bands. These are called foliated metamorphic rocks.

Test QuestionsMinerals are naturally occurring elements and compounds in the earth. Rocks are combinations of minerals (or in some cases a single mineral) that form the earth’s crust.

Rocks that form from magma, lava or pyroclastic material are igneous rocks. Rocks that form from sediments produced by chemical and physical weathering are called sedimentary rocks. Rocks that form by recrystalization of existing rocks are metamorphic rocks.

Processes that form and change rocks comprise the rock cycle. The characteristics of rocks tell their stories!

Igneous rocks that form from magma within the earth’s crust are called intrusive igneous rocks. Those that form from lava on the earth’s surface are called extrusive igneous rocks. Those that form from ash and cinder ejected by volcanoes are pyroclastic igneous rocks.

Rocks that form from sediments produced by chemical and physical weathering are called sedimentary rocks. Sedimentary rocks formed from pieces of rocks weathered physically are called clastic sedimentary rocks. Other sedimentary rocks can form from the dissolved pieces of chemically weathered rocks. Oftentimes organisms are involved in removing dissolved chemicals from water and forming shells. When these shells are deposited as fossils they form bioclastic sedimentary rocks.

Rocks that form by recrystalization of existing rocks are metamorphic rocks. If the metamorphism is extreme the crystals in the metamorphic rocks will migrate and form layers or bands. These are called foliated metamorphic rocks.