Week 3 Flashcards
Density of Continental Rocks
2.7 g/cm^3
Density of Oceanic Rocks
3.0 g/cm^3
The volume of mantle in terms of percentage
82.00%
Dominant rock of the upper mantle
Peridotite
Relatively stable areas involced in orogenic episodes much earlier in the geologic time scale
Cratons
expansive flat regions made up of deformed igneous and metamorphic rocks; part of a highly eroded mountain systems
Shields
Flat area of a craton where highly deformed rocks are overlain by a thin veneer of sedimentary rocks.
Stable Platforms
A portion of a seafloor adjacent to major landmasses
Continental Margins
refers to a flat expanse on the ocean floor located at considerable depths, typically ranging from 3,000 to 6,000 meters. These plains are commonly situated between the base of a continental rise and a mid-ocean ridge, constituting over half of the Earth’s surface.
Abbysal Plains
a prolonged, slender, and sharply sloped depression on the ocean floor where the greatest oceanic depths are found, ranging from approximately 7,300 to over 11,000 meters. These trenches usually develop in regions where one tectonic plate undergoes subduction beneath another.
Deep Ocean Trenches
The Benioff Zone, also known as the seismic zone or seismic plane, is a tilted, planar cluster of earthquake hypocenters that reaches up to 700 km deep. In the context of plate tectonics, the Benioff Zone serves as the location where one tectonic plate is subducted beneath another and is commonly termed a subduction zone.
Benioff Zone
The East African Rift is associated with what type of plate boundary
Divergent boundary
The distribution of the youngest mountain are located principally in two zones
> Circum-Pacific Belt
An eastward trending mountain belt from the Alps, Iran, Himalayas and then extending to Indonesia
What would be examples of older mountain belts
> Appalaichians, US
Urals, Russia
Shields vs Stable Platforms
> Sheilds are mostly deformed igneous and metamorphic
The continental margin are made of up three zones
Continental Shelf, Continental Slope, and Continental Rise
Define the continental shelf
> Gently sloping platforn extending seaward from shore
A flooded extension of continents
Define the continental slope
> Boundary between continents and deep-ocean basisn
Steep dropoff extending from outer edge of the continental shield to the deep ocean floor
Define the continental rise
> Found in regions without trenches
a gradual incline with thick wedges of sediments
Define deep-ocean basins
> large depressions or low areas on the ocean floor that are characterized by considerable depths.
Define Volcanic Island Arcs
> volcanic island chains associated with subduction zones
formed from volcanic activity resulted from subduction related magma generation
Define Mid-ocean ridge
> underwater mountain range that stretches across the Earth’s ocean basins
formed from divergent tectonic plates where the resulting crustal thinning encouraes mantle material to rise
The two broad areas of Geology
Physical Geology and Historical Geology
Physical vs Historical Geology
> Physical geology tackles the processes and phenomenon that shapes the structure, composition and, features of the Earth
Historical geology focuses on the Earth’s past and biological evolution through the geological time
Catastrophism vs uniformitarianism
> Catastrophism proposes that the geological features seen today are a result of sudden and violent events or catastrophies
Uniformitarianism proposes that the geological features today are shaped by the same processes since its formation
Positive vs negative feedback mechanisms
> In a positive feedback mechanism, an initial change in a system triggers responses that further intensify or amplify that change
a negative feedback mechanism works to counteract or dampen the effects of an initial change, promoting stability within a system.
Define Mantle Plumes
> upwellings of hot, buoyant rock from the Earth’s mantle that reach the surface, creating volcanic features. These plumes are thought to originate near the core-mantle boundary and ascend through the Earth’s mantle
Enumerate the plagiocalse mineral series
Albite, Bywotonite, Labradorite, Andesine, Oligoclase, Anorthite
Illustrate and describe the rock cycle
> Magma cools and solidies, then crystalizes into igneous rocks
Rock exposed to the elements is subjected to weathering, small material produced (called sediments) are transported and deposited
Deposited sediments lithifies and undergoes diagenesis in order to become sedimentary rocks
Sedimentary and Igneous rocks under the right pressure-temperature conditions are altered into metamorphic rocks
All kinds of rock, when deep enough will be subjected to very high temperatues which causes melting into magma
How are volcanic island arc formed and give examples
> Oceanic Plate-Oceanic Plate convergence occurs
Older and denser plate subducts, forming a trench
Part of the subducting slab is sbjected to increasing PT consitions, which promotes partial melting of magma
Generated magma rises through the crust, which would eventually generate an arc of volcanic islands parallel to the generated trench
Examples : Philippine Is., Aleutian Is., Japan
What would happen if two continental crust collides with each other
> No subduction occurs due to lighter density
Crustal shortening and thickening process occurs which paves way to orogenesis
Example: Himalayas
How is it that noble gases are chemically inert
> Noble gases has a complete set of valence electrons, thus making them stable and unlikey to form bonds with other molecules under normal conditios
Explain Ionic bonding by illustrating the chemical reaction of Na and Cl to form Halite
> Sodium donates a valence electron to chlorine
Both elements now has a stable configuration, Na donates its single electron leavin behind a complete and stable electron shell, Cl receive the electron and completes its outer shell
Coal, graphite and diamond are made up of carbon atoms and yet why is it that coal is not considered as a mineral?
> Graphite and diamond are substances that are fomed by inorganic matter, whereas coal is.
What makes a mineral exhibit cleavage and illustrate an example
> Weaknesses in the crystal lattice causes a mineral to have cleavages
An example would be the weak bonding between sheets seen in phyllosilicates
Color is typically not a powerful tool in identifying minerals. Why is that?
> A single mineral can exhibit colors and multiple different minerals can have the same color due to impurities in the lattice. Such minerals are called Allorchromatic minerals
Quarts has many varieties based on its color. Green quartz is called adventurine, violed is amethyst, yellow is citrine, and etc.
Expound more on the factors that dictates the viscosity of magma
> Silica content plays a factor in magma viscosity, The more the silica content, the more it is viscous
The amount of volatiles affect magma mobility. More volatiles would cause more fluidity and less viscosity
Explain the triggering factors on hawaiian-type eruptions
> involved low viscosity basaltic magma
triggered by the arrival of new batch of melt into a magma reservior
magma accumulates pressue which fractures the overlying rock, magma can move upward through these fractures creating outpourings for weeks to years.
How would density play a role in plate tectonics
> The density difference between continental and oceanic crust would allow the subduction of the latter which in turn enables forces such as slab pull to provide movement to the plates
The density differences between lithosphere are asthenosphere allows the former to “float” over the latter and move
