Minerals vs. RocksMinerals vs. Rocks

Common silicate minerals:Common silicate minerals:

OlivineOlivine- independent tetrahedra joined by Fe or - independent tetrahedra joined by Fe or MgMg

PyroxenePyroxene- single chains of linked tetrahedra- single chains of linked tetrahedraAmphiboleAmphibole- double chains of linked tetrahedra- double chains of linked tetrahedraMicasMicas and and ClaysClays- 2-D sheets of linked tetrahedra- 2-D sheets of linked tetrahedraQuartzQuartz- 3-D framework of fully polymerized - 3-D framework of fully polymerized

tetrahedratetrahedraFeldsparFeldspar- also a 3-D framework, but Al, Na, Ca, or - also a 3-D framework, but Al, Na, Ca, or

K can substitute K can substitute

Minerals vs. RocksMinerals vs. Rocks

Common non-silicate minerals:Common non-silicate minerals:

CalciteCalcite- CaCO- CaCO33 a carbonate a carbonate

DolomiteDolomite- CaMg(CO- CaMg(CO33))22

ApatiteApatite- Calcium phosphate (PO- Calcium phosphate (PO44))

HaliteHalite- NaCl- NaClGypsumGypsum- hydrated CaSO- hydrated CaSO44

Rock TypesRock Types IgneousIgneous

Volcanic

Plutonic

Mafic(hi Mg-Fe)

Silicic(hi Si-Al)

Intermediate

Basalt

Gabbro

Andesite

Diorite

Rhyolite

GranitePeridotite

Ultramafic(hi Mg-Fe)

Rock TypesRock Types IgneousIgneous

Polished slab of granitePolished slab of granite10 cm across10 cm across

Thin section of basaltThin section of basalt4 mm across4 mm across

Rock TypesRock Types SedimentarySedimentary

MetamorphicMetamorphic

Clastic

Chemical

> 2 mm0.6 -

0.004 mm0.6 - 2 mm

Conglomerate Sandstone

Silt

< 0.004 mm

Clay

Shale

SandCobbles, Pebbles

Limestone Dolostone

SiO2 NaCl, KCl, etc.

Evaporites

CaMg(CO3)2CaCO3

Chert

2) The Earth’s Interior2) The Earth’s Interior

General General Geological Geological Principles: Principles: 1) Geologic 1) Geologic

TimeTime

Geologic TimeGeologic Time RelativeRelative dating by superposition, cross-cutting dating by superposition, cross-cutting

relationships, fossils and evolutionrelationships, fossils and evolution

Geologic TimeGeologic Time RelativeRelative dating by superposition, cross-cutting dating by superposition, cross-cutting

relationships, fossils and evolutionrelationships, fossils and evolution AbsoluteAbsolute dating by radioactive decay (igneous) dating by radioactive decay (igneous)

# pa

rent

ato

ms

# pa

rent

ato

ms

time time

11

½½

¼¼

IsostasyIsostasy

Water density 1.0

Wood density 0.5

2 g 2 g3 g 3 g5 g 5 g

8 g

Water density 1.0

0.5 0.50.3 0.30.2 0.2

density= 0.1

Each block weighs 2 g

IsostasyIsostasy

IsostasyIsostasy

3) Plate Tectonics3) Plate Tectonics

Divergent and Transform Plate BoundariesDivergent and Transform Plate Boundaries

Continental Continental RiftingRifting

Continental Continental RiftingRifting

the East the East African Rift African Rift

Convergent Convergent Plate Plate

BoundariesBoundaries

““Andean-type” Andean-type” orogenesisorogenesis

Crust thickens by Crust thickens by addition of magma addition of magma

Compression due to Compression due to plate convergenceplate convergence

Convergent Plate BoundariesConvergent Plate Boundaries

The Origin of the HimalayasThe Origin of the Himalayas

““Himalayan-type” Himalayan-type” orogenesisorogenesis

Begins as Andean-typeBegins as Andean-type

““Himalayan-type” Himalayan-type” orogenesisorogenesis

How do you locate the “suture zone” today?How do you locate the “suture zone” today?How can you determine the “polarity” of subduction?How can you determine the “polarity” of subduction?

Slivers of oceanic crust and upper mantle (ophiolites) become incorporated into the “mélange” in the accretionary wedge of deformed sediments

The “suture zone” is marked by the mélange and particularly by the occurrence of ultramafic rocks composing the mantle portion of the ocean lithosphere

Chain of ultramafic bodies in Vermont indicating a suture zone of the Ordovician Taconic Orogeny. The ultramafics mark a closed oceanic basin between North American rocks and an accreted island arc terrane. From Chidester, (1968) in Zen et al., Studies in Appalachian Geology, Northern and Maritime. Wiley Interscience.

Appalachian Appalachian HistoryHistory

Can “accrete” Can “accrete” island arc island arc

terranes as well terranes as well as continentsas continents

Accreted Accreted Terranes of Terranes of the Western the Western CordilleraCordillera

Hot Spots Hot Spots

The Plate Tectonic The Plate Tectonic Regime of the Western Regime of the Western

USAUSA

Earthquakes and Plate TectonicsEarthquakes and Plate Tectonics

General General Geological Geological Principles: Principles: 4) The Rock 4) The Rock

CycleCycle

Plate Tectonics and the Rock CyclePlate Tectonics and the Rock Cycle

Examples of Other Examples of Other Cycles: the Cycles: the Hydrologic Hydrologic

CycleCycle

Examples of Other Cycles:Examples of Other Cycles: the the Carbon CycleCarbon Cycle

PopulationPopulation

PopulationPopulation

PopulationPopulation

Impacts:Impacts: ResourcesResources Waste DisposalWaste Disposal PollutionPollution Hazards/DisastersHazards/Disasters Farmland and Food/SoilFarmland and Food/Soil Disruption of Natural SystemsDisruption of Natural Systems