Transcript Lithospherex

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EIGHT ELEMENTS MAKE UP MOST OF ALL
MINERALS ON THE EARTH
› Elements combine to form Minerals
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LISTED IN ORDER OF ABUNDANCE
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OXYGEN (O)
SILICON (Si)
ALUMINIUM (Al)
IRON (Fe)
CALCIUM (Ca)
POTASSIUM (K)
SODIUM (Na)
MAGNESIUM (Mg)
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BUILDING BLOCKS FOR ROCKS
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DEFINITION:
› naturally occurring, inorganic solids,
consisting of specific chemical elements,
and a definite atomic array
 CRYSTALLINE STRUCTURE – ‘CRYSTAL’
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MINERALS: TWO CATEGORIES
› SILICATES – CONTAIN SILICON & OXYGEN
MOLECULES (SiO)
› NON-SILICATES (NO SiO)
Make up 5% of Earth’s crust
 Native metals: gold, silver, copper
 Carbonates: calcite (used in cement)
 Oxides: hematite (iron ores)
 Sulfides: galena (lead ores)
 Sulfates: gypsum (used in plaster)
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Make up 90-95% of the Earth’s Crust
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Dominant component of most rocks,
include:
› QUARTZ (SiO2)
› FELDSPARS
› MICAS
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AGGREGATIONS OF 2 OR MORE
MINERALS
› Same or different minerals combine together
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THREE CATEGORIES
› IGNEOUS
› SEDIMENTARY
› METAMORPHIC
FORMED FROM COOLED, SOLIDIFIED
MOLTEN MATERIAL, AT OR BELOW THE
SURFACE
 PLUTONIC – INTRUSIVE: COOLED BELOW
SURFACE AT GREAT DEPTHS
 VOLCANIC – EXTRUSIVE: COOLED AT OR
NEAR THE SURFACE THROUGH VOLCANIC
ERUPTIONS
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IDENTIFICATION PROCESSES:
› TEXTURE:
 Size, shape and manner of growth of
individual crystals
› MINERAL COMPOSITION
 Based on SiO content
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GRANITE:
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RHYOLITE: VOLCANIC-EXTRUSIVE; APHANETIC TEXTURE; FELSIC
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DIORITE:
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ANDESITE:
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GABBRO: PLUTONIC-INTRUSIVE; PHANERITIC TEXTURE; MAFIC
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BASALT: VOLCANIC-EXTRUSIVE; APHANETIC TEXTURE; MAFIC
PLUTONIC-INTRUSIVE; PHANERITIC TEXTURE; FELSIC
MINERAL COMPOSITION
MINERAL COMPOSITION
PLUTONIC-INTRUSIVE; PHANERITIC TEXTURE; INTERMEDIATE
MINERAL COMPOSITION
VOLCANIC-EXTRUSIVE; APHANETIC TEXTURE;
INTERMEDIATE MINERAL COMPOSITION
MINERAL COMPSITION
MINERAL COMPOSITION
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VOLCANIC GLASS:
› OBSIDIAN: VOLCANIC-EXTRUSIVE; NO
CRYSTALS FORM; SILICA-RICH, COOLED
INSTANEOUSLY
› PUMICE: VOLCANIC-EXTRUSIVE; NO
CRYSTALS FORM; SILICA-RICH; SOLIDIFIED
FROM ‘GASSY’ LAVA
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PYROCLASTIC ROCKS
› TUFF: VOLCANIC-EXTRUSIVE; SOLIDIFIED
‘WELDED’ ASH
 Weathering
processes break
rock into pieces, sediment,
ready for transportation
deposition burial lithification
into new rocks.
THREE SOURCES
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Detrital (or clastic) sediment is composed of
transported solid fragments (or detritus) of preexisting igneous, sedimentary or metamorphic
rocks
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Chemical sediment forms from previously dissolved
minerals that either precipitated from solution in
water , or were extracted from water by living
organisms
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Organic sedimentary rock consisting mainly of
plant remains
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Lakes
Lagoons
Rivers
Ocean bottoms
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Estuaries
Salt Flats
Playas
Glacial
environments
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LITHIFICATION:
As sediment is buried several kilometers beneath the surface,
heated from below, pressure from overlying layers and chemicallyactive water converts the loose sediment into solid sedimentary rock
Compaction - volume of a sediment is reduced by
application of pressure
Cementation - sediment grains are bound to each
other by materials originally dissolved during
chemical weathering of preexisting rocks
› typical chemicals include silica and calcium carbonate.
METAMORPHISM : process by which
conditions within the Earth alter the
mineral content and structure of any
rock, igneous, sedimentary or
metamorphic, without melting it.
 Metamorphism occurs when heat and
pressure exceed certain levels,
destabilizing the minerals in rocks...but
not enough to cause melting
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Four basic principles
› Principle of Original Horizontality
 Beds of sediment deposited in water formed as horizontal or
nearly horizontal layers.
› Principle of Superposition
 Within a sequence of undisturbed sedimentary or volcanic
rocks, the layers get younger going from bottom to top.
› Lateral Continuity
 An original sedimentary layer extends laterally until it tapers
or thins at its edges
› Cross-cutting Relationships
 A disrupted pattern is older than the cause of the
disruption.
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Physical Continuity
Physically tracing the course of a rock unit to correlate rocks between
two different places
Similarity of Rock Types
Correlation of two regions by assumption that similar rock types in two
regions formed at same time, under same circumstances
Correlation by Fossils
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Plants and animals that lived at the time rock formed were
buried by sediment
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fossil remains preserved in the layers of sedimentary rock -fossils
nearer the bottom (in older rock) are more unlike -those near
the top
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Observations formalized into Principle of Faunal Succession –
fossil species succeed one another in a definite and
recognizable order.
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Index Fossil – a fossil from a short-lived, geographically
widespread species known to exist during a specific period of
geologic time.
Using annual growth rings of trees
 Dates for trees now extending back
more than 9,000 years.
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 Bristlecone Pine, White Mountains, CA (pinus
longaeva) provides a continuous time scale
for last 9,000 years (to 7000 B.C)
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Provides calibration of radiocarbon
dates over most of the last 10,000 years
(Holocene epoch)
Varves are parallel strata deposited in deep
ocean floors or lake floors
 A pair of sedimentary layers are deposited
during seasonal cycle of a single year
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› Laminae (similar to annual growth rings in trees)
record climatic conditions in a lake or large
water body from year to year
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Cores extracted from sea floor or lake floor
are used to date back several million years
to 200 million years
Radiometric dating – based on
radioactive decay of ‘isotopes’
 Decay rate can be quantified because
it occurs at a constant rate for each
known isotope – “half-life” from parent
isotope to stable ‘daughter’ isotope
 Measuring ratio of parent to daughter
isotopes determines absolute ages of
some rocks.
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URANIUM–LEAD (U238–Pb206)
› Half-life: 4.5 billion years
› Dating range: 10 million – 4.6 billion years
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URANIUM–LEAD (U235-Pb207)
› Half-life: 713 million years
› Dating Range: 10 million – 4.6 billion years
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POTASSIUM-ARGON (K40-Ar40)
› Half-life: 1.3 billion years
› Dating Range: 100,000 – 4.6 billion years
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CARBON-14 (C14-N14)
› Half-life: 5730 years
› Dating Range: 100 – 100,000 years
Climate
 Vegetation
 Drainage
 Time
 Parent Material
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› Residual - Transported
› Least Important Factor for Mature Soils
Leaching from Surface
› K, Mg, Na
› Ca
› Si
› Al, Fe
Accumulation beneath Surface
› Al, Fe in Humid Climates
› Ca in Arid Climates
Soil Horizons
 Layers in Soil
 Not Deposited, but Zones of Chemical
Action
Soil Profile
 Suite of Layers at a Given Locality
O - Organic (Humus) Often Absent
 A – Leaching (Clay Removed)
 E - Bleached Zone - Only in Certain Soils
 B – Accumulation
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› Absent in Young Soils
› Distinct in Old Soils
› Al, Fe, Clay (Moist)
› Si, Ca (Arid)
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C - Parent Material (bedrock)
This may be the most
difficult classification
problem in science
because of the many
factors involved.
Varied Bases for
Classification
 Parent Material
 Special Constituent
Materials
 Maturity
 Structure
 Climate & Vegetation
Multiple Objectives
 Scientific
› Genesis &
Evolution
 Agricultural
› Fertility
› Most Effective Use
 Engineering
› Slope Stability
› Expansion and
Shrinkage
› Stability of
Excavations
 U.S.
Soil Conservation
Service
 12 Soil Orders
Degree of Weathering and B Horizon Development
Little
Slight
Moderate Large
Extreme
Entisols
Aridisols
Inceptisols Alfisols
Spodosols Ultisols
Mollisols
Oxisols
Soils Defined by Special Constituent Materials
Andisols
Volcanic Ash
Histosols
Peat, Organic Matter
Vertisols
“Self-Mixing” Clay Soils
Gelisols
Soils on Permafrost
Image: T. Loynachan
Soils-2-1
Images: Martin Miller, NRCS
Soils-2-2
Images: National Cooperative Soil Survey, University of Nebraska
Soils-2-3
Images: NRCS, Soil Classifiers of Michigan
Soils-2-4
Image: T. Loynachan
Soils-2-5
Image: National Cooperative Soil Survey
Soils-2-6
Image: T. Loynachan
Image: T. Loynachan
Soils-4-1
Images: NRCS
Soils-4-2
Image: Soil Classifiers of Michigan
Image: Bruce Molnia
Soils-4-3
Images: National Cooperative Soil Survey, University of Nebraska
Soils-4-4
Images: Bruce Molnia, Soil Classifiers of Michigan
Soils-4-5
Images: Martin Miller, NRCS
Soils-4-6
Images: Travis Hudson, Alaska/Yukon Society of Professional Soil Scientists
Soils-4-7
Image: Image: T. Loynachan
Soils-4-8