GEOLOGY OF NATIONAL PARKS SC 211 · 2017-11-15 · GEOLOGY OF NATIONAL PARKS SC 211 JOHN BUSH...
Transcript of GEOLOGY OF NATIONAL PARKS SC 211 · 2017-11-15 · GEOLOGY OF NATIONAL PARKS SC 211 JOHN BUSH...
GEOLOGY OF NATIONAL PARKSSC 211
JOHN BUSH
NOVEMBER 15, 2015
Rodinia1.3 BY – 650 MYA • First “confirmed” Supercontinent
• Formed from dispersed remains of Columbia and accretion of smaller land masses
• Formation created new shallow seas• Grenville Orogeny is an important part of
Rodinia formation
1.3 – 1.1 MYA 750 MYA
SuperoceanMirovia
Ur??
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Pangaea335 – 175 MYA
• Latest and best documented Supercontinent• Formed from collision of Laurasia and
Gondwana• Began to break apart ~215 MYA and continues
to do so today
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DVDACADIA’S HIGHLANDS
AND ISLANDS
GEOLOGY (IS ABOUT) ROCKS
• Rocks are solid mixtures (mostly) of minerals • Brittle—break under stress• Ductile—flow under stress
• The properties depend on the rocks’ chemical composition & physical structure and on conditions of temperature and pressure
• The properties of rocks can tell a geologist the rocks’ history• How and when did they form?• What did they form from?• How have they been modified since they were formed?
• The history of a region’s rocks reveal the geologic history of the region.
SOME WAYS TO TALK ABOUT ROCKS
• Conditions of formation• Igneous—plutonic, intrusive, volcanic*• Sedimentary*--clastic, biochemical, chemical (diagenesis)• Metamorphic—foliated, non-foliated
*Form initially on the Earth’s surface
• Composition of dominant minerals• Sodium, potassium, calcium, aluminum silicates (sialic, felsic)• Abundant iron, magnesium silicates
• Mafic--dense• Ultramafic—denser
• Carbonates, oxides, sulfates, chlorides, sulfides, phosphates
• Subcategories are based on physical and optical properties and on texture
SOME ROCKS OF THE SHENANDOAH/GREAT SMOKY/ACADIA NATIONAL PARKS
• Sedimentary• Mudstone/Shale • Sandstone• Conglomerate/ Breccia• Limestone/ Dolostone
• Igneous• Granite (felsic, sialic)• Basalt (mafic)• Peridotite (ultramafic)
• Metamorphic• Gneiss• Slate• Greenstone• Marble
MUDSTONE/SHALESEDIMENTARY/CLASTIC
SANDSTONESEDIMENTARY/CLASTIC
CONGLOMERATE/BRECCIASEDIMENTARY/CLASTIC
BRECCIA
CONGLOMERATE
LIMESTONE/DOLOSTONESEDIMENTARY: BIOLOGICAL, CHEMICAL
LIMESTONE
DOLOSTONE
IGNEOUS ROCKS
•Granite-like (Felsic, Sialic)
•Basalt-like (Mafic)
•Olivine-like (Ultramafic)
FELSIC IGNEOUS ROCKSFORMS OF “GRANITE”
• Volcanic—Rhyolite—lava, ash, tuff, pumice, glass (obsidian)
• Intrusive -- Rhyolite
• Plutonic -- Granite, Granodiorite
PLUTONIC FELSIC IGNEOUS ROCKSGRANITE AND GRANODIORITE
FORMS OF “GRANITE”
PUMICE RHYOLITEOBSIDIAN
FORMS OF BASALT
• Volcanic – Lava, ash, tuff, tachylyte
• Intrusive – Diabase (Dolerite, Microgabbro)
• Plutonic -- Gabbro
MAFIC IGNEOUS ROCKSFORMS OF “BASALT”
LAVA
DIABASE GABBRO
DIABASE ASH
LAVA
METAMORPHIC ROCKS
QUARTZITE MARBLE
METAMORPHIC ROCKS
SLATE GNEISS
METAMORPHIC ROCKS
MUSCOVITE SCHISTNOVACULITE
METAMORPHIC ROCKS
GREENSTONE EKLOGITE
ULTRAMAFIC ROCKS
KIMBERLITELHERZOLITE
QUARTZ
• Macrocrystalline--milky quartz, rock crystal, amethyst
• Microcrystalline—chalcedony (agate, onyx, carnelian)
• Cryptocrystalline—chert, flint, jasper, novaculite
• Amorphous -- radiolarian chert, opal
MASSIVE QUARTZ VEINS
QUARTZ: CHALCEDONY
CRYPTOCRYSTALLINE QUARTZ
CHERT
FLINT
JASPER JASPER
JASPER NOVACULITE
AMORPHOUS QUARTZ
RADIOLARIAN CHERT MEXICAN FIRE OPAL COMMON OPAL
PRECIOUS OPAL