Geology Lecture Test 1
Terms
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- What rock makes up the mantle?
- Peridotite
- What is the boudary between the crust and the mantle?
- Moho
- How do we know about the upper mantle?
- By studying xenoliths
- What layer does the deepest well drilled in Russia drill into?
- Continental Crust
- What do seismic waves locate?
- Boundaries between rock layers and rock layer depths
- Define mineral
- solid, naturally occuring, inorganic, definite chemical composition, and definite arrangement of atoms
- Solid Solution
- ions of similar size and charge can substitute for each other
- Polymorph
- 2 minterals with the same composition, but different crystal structure
- How are minerals classified?
- By chemical composition and crystalline structure
- Bonds
- Electrical forces of attraction
- Where does bonding take place?
- Outer Shells
- Ionic bond
- Attraction of oppositely charged ions
- Example of Ionic Bond
- NaCl - Halite
- Covalent Bond
- 3,4,or5 electrons tend to share electrons
- Example of covalent bond
- Diamond
- Metallic Bond
- Electrons move freely among atoms
- Example of Metallic Bond
- Copper
- Van der Walls Bond
- Weak and holds layers of atoms togeter in sheets
- Example of Van der Walls Bond
- Mica, Talc
- What does bonding determine?
- Cleavage and fracture
- What is the most common Si mineral?
- Feldspar
- Isolated Tetrahedron
- single units bonded to positively charged ions (metals)
- Single chains
- share 2 corner O ions
- Double Chain
- share 2 cornor O ions in linear chains that are linked by sharing O-
- Sheet Silicates
-
3 oxygen at the base are shared with other tetrahedron
Ex. - Micas - Framework
-
4 oxygen shared by adjacent tetrahedron forming a 3D structure.
Ex. Quartz - Chain Silicates
- form needles, columns, or fibers
- Does Quartz cleave or fracture? Why?
- Fracture, oxygen bonds are equally strong in all directions
- Does feldspar cleave or fracture? Why?
- Cleave, some of the Si is replaced by Al.
- Why does quartz have many colors?
- Open structure allows to trap stray ions (impurities)
- Lithosphere
- Solid outer shell consisting of continental/oceanic and upper mantle
- Continental Drifect
- Idea that continents move freely over earth's surface
- Alfred Wegner
- Proposed continental drift
- Pangea
- supercontinent formed
- Midocean Ridges
- discovery leading to the acceptance of continental drift and plate tectonics
- What mineral records paleomagnetism?
- Magnetite
- What moves in polar wandering?
- Continents
- Seafloor Spreading
- seafloor separates at ocan ridges where upwelling magma creates new crust
- Who proposed seafloor spreading?
-
Harry Hess
Said that continents and oceans move together - What do magnetic anomalies predict?
- age of the seafloor and rate of seafloor spreading
- Wear is the oldest/yougest seafloor located?
-
oldest - near edges of continents
yougest - mid ocean ridges - Age of seafloor
- 180 million
- Which ocean moves fastest?
- Pacific
- What two theories does plate tectonics combine?
- seafloor spreading and continental drift
- Therman convection cells
- driving mechanism for plate tectonics
- What do thermal convection cells determine?
- Where trenches and spreading ridges are located
- Divergent Plate Boundary
-
plates split and move apart
ex. rift and ?new ocean - Transform PB
-
plates slide laterally past each other
ex. fault - oceanic-oceanic pb
-
2 oceanic plates collide and one subducts
ex. deep trenches and volcanic island arc - oceanic-continental pb
-
oceanic plate subducts under cont. plate
ex. trench and volcanoe on land - cont-cont pb
-
2 continents collide
ex. creates nonvolcanic mtns - Hot spots
- plume of hot molten rock
- what do hot spots record?
- plate movement
- What drives the rock cycle?
- plate tectonics
- Sedimentary rocks
- continent edges
- igneous rock
- midocean ridges/rifts
- metamorphic rock
-
transform pb (faults)
ex. San Andreas Fautl - Ophiolites
- fragment of oceanic crust and upper mantle on land
- 4 parts of Ophiolites
- deep sea sedimentary rocks, oceanic crust, gabbro, and upper mantle
- Ocean Crust is composed of
- Gabbro and Basalt
- Cont. Margin Parts
- cont. shelf, cont rise, cont slope
- Cont. Shelf
- between shoreline and cont. slope
- cont. slope
- cont. crust changes to oceanic crust
- cont. rise
- formed by overlapping submarine fans
- Turbidity
- currents transport and deposit muds/silts on continental slopes and submarine canyons
- Parts of passive cont. margin
- broad flat cont. shelf, cont slope, cont rise, and vast abyssal plain
- Sigsbee Abyssal Plain has
- rising salt domes
- Gulf of Mex reefs sit upon
- rising salt domes
- The Atlantic coast slide shows
- deep submarine canyons
- Parts of an active cont. margin
- narrow cont. shelf, cont. slope, ends in a trench
- What is associated with active margins?
- subduction zones and transform faults
- Features found in a rift valley
- hydrothermal vents, black smokers, sulfide chimneys, and pillow basalt
- 2 deep sea sediments
- pelagic clay and calcareous/siliceous ooze