Earth Mat Flashcards - Ch 9
Lava commonly erupts from a _________ located in a crater near the summit of the volcano.
central vent
Low discharge flank eruptions produce smaller _________ along the summit, side or base of larger volcanoes.
parasitic volcanoes
Mauna Kea has _____ parasitic cones
100
are large, generally circular to oval depressions caused by subsidence of Earth’s surface. in the context of volcanism
Calderas
Magma Loss in caldera formation can be caused by two things
subsurface withdrawal of magma from a shallow chamber as magma migrates to another location,
cataclysmic eruptions that empty the shallow magma chamber.
is an intrusive igneous body that is circular, oval or arcuate in plan view and has steep contact
A ring dike or ring dyke
, are the product of massive outpourings of low viscosity basaltic lava that envelop hundreds of thousands of square kilometers.
Flood basalts , also known as large igneous provinces (LIP)
Mantle Hotspot related LIP
Ontong Plateau, W. Pacific
Kerguelen Plateau, Indian Ocean
Continental Flood Plateau
Deccan Traps, India
Siberian Flood Basalts
Karoo, E. Africa
Columbia River/Snake River Plain, N. America
Marine and continental
Records break up of pangea
Central Atlantic Magmatic Province (CAMP)
consist of a 65,000 km long global network of submarine rift mountains
Ocean ridges
Rare examples of surface exposed ocean ridges
Iceland, Galapagos Is., Azores Is.
As hot (1100 – 1300 ° C) basaltic magma rises upward and reacts with cold seawater, spheroidal ____________ develop
pillow lavas
Ocean ridges also contain _________ that emit lower temperature (100 – 300 ° C) solutions that precipitate light - colored minerals such as calcite, gypsum, barite and quartz.
white smokers
are broad, sloping edifices that cover hundreds to thousands of square kilometers with shapes that resemble the defensive shields of ancient warriors.
Shield volcanoes
5 Shield volcanoes of the Big Island of Hawaii
Kilauea
Mauna Loa
Mauna Kea
Hualalai
Kohala
The Hawaiian eruptions that produce shield volcanoes also generate fiery basaltic___________ several hundred feet high
lava fountains
Airborne blobs of liquid lava emitted by fountains are referred to as
spatter
Spatter that solidifies at the base of the lava fountains is referred to as
welded spatter or agglutinate deposits
Lava fountains that erupt via fissures produce linear ridges called ____________ on either side of the fissure
spatter ramparts
are elevated lateral banks that contain the lava flow within stream-like channel.
Lava levees
are shallow subterranean tunnels channelling lava beneath thin, solidifi ed basaltic roofs.
Lava tubes
lava consists of low viscosity, “ runny ” basaltic lava which produces thin flows with a billowing, rippled and/or ropey surface
Pahoehoe lava
More viscous aa lava tends to produce thicker, slower moving lava flows with angular, jagged, fractured surfaces
Aa lava
are steep - sided (~30 – 35° ) conical features composed of tephra.
Pyroclastic cones
Tephra consists
of volcanic rock fragments of various sizes and compositions emitted during explosive eruptions.
Pyroclastic cones composed predominantly of vesicular basaltic material.
Scoria cones
Pyroclastic cones consisting of ash, lapilli and bomb - sized particles of various compositions that accumulate as circular to oval - shaped conical volcanoes
Cinder cones