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53 Cards in this Set
- Front
- Back
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What is a mineral? (6 characteristics)
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Naturally occurring
Solid Formed by geologic processes Definable chemical composition Orderly arrangement of atoms Inorganic |
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What is a polymorph?
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Two different minerals that have the same composition but different crystal structure.
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5 Ways that Crystals can form
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Solidification of a melt
precipitation from a solution Solid-state diffusion Biomineralization from a vapor |
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What is a geode?
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A mineral-lined cavity in a rock
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Euhedral crystl
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Well-formed crystal faces
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Anhedral
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Do not have well-formed crystal faces
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How can you tell one mineral from another?
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Color, streak, luster, hardness, specific gravity, crystal habit, cleavage, fracture, special properties
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Streak
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the color of a powder produced by scraping the mineral
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Luster
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the way a mineral surface scatters light (metallic vs nonmetallic, silky, satiny, resinous, pearly, earthy)
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Hardness
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the measure of the relative ability of a mineral to resist scratching
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Specific gravity
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Density of a mineral
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Crystal habit
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The shape of a single crystal with well-formed crystal faces
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Fracture
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Some minerals lack planes of weakness
Due to equal molecular bonds in all directions These minerals fracture and hence don't have cleavage |
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Cleavage
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Tendency to break along planes of weakness
Cleavage produces flat surfaces Described by number of planes and their angles 1, 2, 3, 4, and 6 cleavage planes possible |
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Calcite dilutes with...
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dilute hydrochloric acid
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Conchoidal fracture
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smoothly curving, clamshell-shaped surfaces. typically form in quartz
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Mineral classes (most important)
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Silicates
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Silicates
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Earth's crust is silicone-oxygen tetrahedron
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Silicate minerals compose over...what percent of the continental crust
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95%
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Theory of Plate Tectonics
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The outer layer of the earth (the lithosphere) consists of separate pieces or plates, that move with respect to each other.
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Lithosphere
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consists of crust plus the uppermost (coolest) part of the upper mantle
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Asthenosphere
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the lithosphere floats on this relatively soft or "plastic" layer which can undergo convection
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Does the continental lithosphere lie at a higher or lower elevation than that of the oceanic lithosphere?
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Higher.
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Thick crust, low-density
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Continental lithosphere
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Thin crust, dense rock
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Oceanic lithosphere
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Pieces of the lithosphere
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plates
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Breaks in these
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Plate boundaries
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How many major plates?
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12
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Active margin
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Plate boundaries
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rate at which plate movement occurs
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1 to 15 cm per year
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because of plate tectonics
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the Earth's surface constantly changes
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divergent boundary
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a boundary at which two plates move apart from one another
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convergent boundary
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a boundary at which two plates move toward one another so that one plate sinks beneath the other
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where does sea-floor spreading occur
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mid-ocean ridge
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what else is a divergent boundary called?
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mid-ocean ridge or just a ridge
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ocean crust forms layers of what blobs?
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basalt blobs aka pillow basalt
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true or false, the lithospheric mantle and oceanic lithosphere grow progressively thicker away from the ridge
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true
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subduction
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sinking process, convergent boundaries known as subduction zones
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margins also called...?
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trenches
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amount of oceanic plate consumption world wide equals what?
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amount of sea-floor spreading worldwide so the surface area of the Earth remains constant throughout time
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at what rate does oceanic lithosphere sink?
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less than 10 to 15 cm per year
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what happens to the downgoing plate at convergent boundaries?
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it grinds along the base of the overriding plate which generates large earthquake
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the belt of earthquakes in a downgoing plate is called what?
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Wadati-Benioff zone
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a chain of volcanoes known as a what develops behind the accretionary prism
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volcanic arc
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Transform fault
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the actively slipping segment of a fracture zone between two ridge segments
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what happens at a transform boundary?
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one plate slides sideways past another but no new plates are formed and no old one is consumed
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what is a triple junction
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where three plate boundaries intersect at a point
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hot spots
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volcanoes that exist as isolate points and appear to be independent of movement at a plate boundary
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what is rifting
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when most new divergent boundaries form when a continent splits and separates into two continents
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What is collision?
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A convergent boundary ceases to exist when a piece of buoyant lithosphere such as a continent or an island arc moves into the subduction zone.
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Ridge-push force
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develops because mid-ocean ridges lie at a higher elevation than the adjacent abyssal plains of the ocean
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Slap-pull force
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the force that subducting plates (also called downgoing slabs) apply to oceanic lithosphere at a convergent margin arises simply because lithosphere that was formed more than 10 million years ago is denser than the asthenosphere so it can sink into the asthenosphere
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Why does sea-floor spreading occur?
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in response to the ridge-pull force. subducting lithosphere generates a slap-pull force that tows the rest of the plate along with it.
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