Geology 3 Flashcards
What is Igneous
Formed by the solidfication of magma
What is Sedimentary
Formed from the products of the breakdown of pre existing rocks
What is metamorphic
formed by the transformation of minerals in a preexisting rock under the influence of elevated temperature, pressure, hot fluids or all 3.
What is Magma
Molten rock that originates at the depths as great as 200km within the earth. It consist of Si, O, Fe, Ca, Na, K, Mg, and several gasses.
What is Lava
Magma without the gas that flows on the surface,
Volcanic (Extrusive)
on the surface, fine grained, glassy, vesicular, volcanic fragments.
Plutonic (Intrusive)
magma that crystalizes below the surface, larger crystal grains.
Crystalization of magma
- Ions are arranged in orderly patterns.
- Crystal size of rock is determied by the rate of cooling.
Cooling rate - Slow
Forms large crystals
Cooling rate - Fast
Forms microscopic crystals
Cooling rate- very fast
Forms glass
Igneous rock Classification
- Texture
2.Mineral Combustion
Texture meaning
Size and arrangement of crystals.
Texture types
Aphanitic
Phaneritic
Prphyritic
Glassy
Pegmatic
Vesicular
Pyroclastic
Aphanitic
fine grained, fast rate of cooling, less than 1cm across. Basalt and Andesite
Phaneritic
Coarse grained, slow rate of cooling, intrusive, large mineral grains (1mm to 1km). Granite and Diorite
Porphyritic
2 distinct crystal sizes, 2 rates of cooling, extrusive. Andesite Porphyry.
Glassy
Very fast rate of cooling, extrusive. Obsidian and Perlite.
Pegmatic
Intrusive, crystals larger than 1km across. Pegmatite.
Vesicular.
Extrusive, holes formed by escaping gas. Scoria (Vesicular basalt) and pumice.
Pyroclastic
Extrusive volcanic fragments of crystals, rocks, glass shards, pumice fragments. Ash flow tuff and volcanic Breccia
Mineral Combustion
Magma rich with silica along with Al, Mg, Fe, Ca, Na, and K.
Mineral Combustion Types
Felsic
Intermediate
Mafic
Ultramafic
Felsic
light colored like quartz, feldspars and minor dark materials like horneblende and biotite. Bhyolite and Granite
Intermediate
cotain equal amounds of dark horneblende biotite and lighter feldspars. Andesite and diorite.
Mafic
Cointain mostly dark Mg and Fe rich silicates along with olivine as well as very little light colored feldspars. Basalt and Gabbro.
Ultramafic
Consists of yellowing green olivine and pyrozene Peridotite.
Eruptive Materials
Lava Flows
Gases
Pyroclastics
Lava Flows
Basaltic Lavas are more fluid
Pahoehoe Lava type
loraided lava
Aa Lava Type
Rough, jagged blocks
Gases in magma
gasses are 1 - 5% of magma
H2O and Co2
HCL HF CO SO2 H2S H2 NH3 CH4 SiF4
Pyroclastics Meaning
Fire Fragments
Pyroclastic Types
Ash
Pumice
Lapilla
Cinders
Blocks
Bombs
Pyroclastic Ash
Fine, glassy
Pyroclastic Pumice
Frothy Lava
Pyroclastic Lapilla
Walnut Size
Pyroclastic Cinders
Pea Size
Pyroclastic Blocks
Large hardened lava
Pyroclastic Bombs
Ejected as hot as lava
Factors that determine violence of eruption
Compostion of magma
Temperatrue of magma
dissoved gasses in magma
Viscosity meaning
Ciscosity is a measure of a materials resistance to flow.
Factors affecting viscosity
Temperature
Composition
High SIlica Viscosity
Granite Lava
Low silica Viscosity
Basalitic Lava
Dissolved gasses
H20 Vapor
Co2
gasses expand near surface
Provide fore to extude lava
violence depends on how fast gas escapes
Fluid magma eruption violence
escapes easily - not violent
Viscous magma eruption violence
Violent eruption
Parts of a volcano
Crater
Caldera
Vent
Crater volcano meaning
Steepwalled depression at the summit
Caldera volcano meaning
Summit deppresion greater than 1km in diameter
Vent volcano meaning
Throat of volcano
Types of volcanoes
Sheild
Cinder Cone
Composite (Stratovolcano)
Sheild Volcano
Broad, slightly domed
Balsatic lava
Hawaiian island volcanoes
EX: Kilawea, Mauna Loa
Cinder Cone Volcano
Built from pyrocalstics
steep
>1000ft high
occurin groups
EX: Capulin
Composite (Stratovolcano) Volcano
Alternating layers of lava and pyroclastics
Violent eruptions
large volcanoes
produce clouds of ash and gas that move down the slope at 120mph
pacific coast volcanoes
EX: St helens, Galeros, Fuji, Arenal
Volcanic Landforms
Caldrea
volcanic Neck
Lava Plateau
Pyroclastic Flows
Caldera
A crater that exeeds 1km in diameter
Volcanic neck
resistant vent left after erosion. EX Shiprock NM
Lava Plateau
lava that builds up from fissure eruptions. EX Colombia plateau, Washington and the decon plateau, India.
Pyroclastic Flows
Material is propelled from a vent at a high rate of speed. Consists of ash and pumice fragments.
Fourms ash flow tuff
EX: Yellowstone plateau
Intrusive Igneous Activity
Magma emplaced at depth
Pluton
Pluton
Underground igenous body is called a pluton.
Classifications of Plutons
Shape
Orentation
Shape of Pluton
Tabular or sheet like
Massive
Orentation of Pluton
The surrounding rock
Discordant Pluton
Cuts along sedimentary beds
Concordant Pluton
Cuts parrallel to sedimentary beds
Types of igenous activity
Dike
Sill
Laccolith
Stock
Batholith
Dike
Tabular, discordant pluton
Sill
Tabular concordant pluton. EX PalsidesNY
Laccolith
Lens shaped mass arch like
Stock
less than 100km sized batholith
Batholith
largests intrusive body forms in cores of mountains.
Distrobutions of Igenous Activity
Along Plate Margins
Intraplate volcanism
Along plate margins of Igenous Avtivity
Divergent
Convergent
Divergent
Oceanic ridge spreading center, the lithosphere pulls apart large quantites of basaltic magama is produced.
Convergent
Plates come together and one decends below the other magma rises slowly and forms moutains or islands. EX Andes Mnt. Explosive volcanoes, Ring of Fire
Intra Plate Volcanism
activity within a ridged plate, partial melting of mantle rock, plumes of magma move upward, form hot spots in the ocean. Ex. Hawaiian Island, Carribian Islands.
Deadly Eruptions
Tambora
Krakatau
Mt. Pelle
Nevado Del Ruiz
UnZen
Pinatubo
Tambora Explosion
92,000 from Starvation
Krakatau Explosion
36400 from Tsunami
Mt. Pelle Explosion
29035 from Ash Flows
Nevado Del Ruiz Explosion
25000 Mud Flows
Unzen
14300 Collapse and Tsunami
Pinatubo
800 Collapsed Buildings