Geology Ch 7
Terms
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- formation and distribution of many metallic mineral deposits are associated with
- divergent and convergent
- Wegener could not explain
- how the continents moved
- generally credited with developing the concept of continental drift
- Alfred Wegener
- where on plate is subducted under another plate
- convergent
- magnetic anomolies in rocks indicates that
- the Earth's magnetic field had reversed itself in the past
- around ocean ridges, anomalies are
- parallel and symmetrical
- driving mechanism of plate movement
- thermal convection cells
- parallel and symmetrical anomalies around ocean ridges means that
- new oceanic lithosphere was forming and the seafloor has been spreading
- concept of continental drift was revived when
- in the1950's, paleomagnetic studies of rocks of different ages on the same continent indicated that in the past there apparently had been multiple magnetic north poles
- the oceanic crust is youngest
- adjacent to mid-oceanic ridges
- oldest continental crust is
- 3.96 billion years old
- absolute motion of plates can be determined by
- the movement of plates over mantle plumes
- credited with developing the continental drift hypothesis
- Wegener
- include rift valleys with thick sedimentary sequences and numerous dikes and sills
- divergent boundaries
- two plates slide past each other
- transform
- evidence for continental drift
- 1) continental fit, 2) similarity of fossil plants and animals, 3) similarity of rock sequences, 4) paleomagnetism
- most geologists (blank) Wegener's ideas
- ignored
- supercontinent that formed at the end of the Paleozoic Era
- Pangaea
- Wegener gathered infor from any sources to show that
- continents were once connected as one supercontinent
- concept of continental movement is
- old
- ocean basins are
- recent geological features
- tree types of plate boundaries
- divergent boundaries, convergent boundaries, and transform boundaries
- first evidence that continents may once have been united and then drifted apart
- earliest maps showing the similarity between the east coast of South America and the west coast of Africa
- example of divergent plate boundary
- East African rift valleys
- relationship between mountain building and the opening and closing of ocean basins is called
- Wilson cycle
- geologists believe this is responsible for plate movement
- convection heat system
- example of oceanic-oceanic plate boundary
- Aleutian Islands
- generally do not leave any characteristic or diagnostic features in the rock record
- transform faults
- formation and distribution of the Earth's natural resources are related to
- plate movements
- ancient plate boundaries can be recognized by their
- associated rock assemblages and geoloic structures
- a close relationshipe exists between the formation of some
- mineral deposits and plate boundaries
- most common biotic province boundaries
- geographic and climatic barriers
- where plates more away from each other
- divergent
- mantle plume
- upwelling of abnormally hot rock within the Earth's mantle
- plate tectonic became accepted in the 70's because of
- overwhelming evidence supporting it and because it provides geologists with a powerful theory for explaining such things as mountian building, global climatic changes, the distribustion of biota and some mineral resources
- small accreted lithospheric blocks that are different from the surrounding rocks are
- microplates
- oldest oceanic crust is
- less than 180 million years old
- ophiolites and andesitic rocks are two characteristic features
- convergent boundaries
- deviations from the average strength of the Earth's magnetic field
- magnetic anomalies
- locations of continents could be rearranged such that
- the magnetic minerals in the rocks pointed to the same location for the magnetic north pole
- magnetic surveys of the oceanic crust revealed
- magnetic anomolies in the rocks
- Wegener called the supercontinent
- Pangaea
- allows geologists to determine absolute plate motion
- hot spots
- episode of intense rock deformation or mountain building
- orogeny
- temperature at which iron-bearing minerals gain magnetization
- curie point