Week 2 D1 Flashcards
The ocean occupies an approximate of what percent of the earth’s surface.
71%
The average depth of the ocean is about _____ meters
3800 m
Freshwater consitutes _____ of the hydrosphere
2.56%
These features hold the most percetage of the Earth’s freshwater suppy
Glaciers
A thin veneer of material found on the surface. Supports pland growth and is considered to be a part of all of Eath’s physical spheres.
Soil
A group of interacting or interdependent pieces that comprises a complex whole.
System
The process where igneous, metamorphic, and sedimentary rock alters from one type to another
Rock cycle
Circulation of water above and below the earth’s surface
Hydrologic cycle
The main driver that powers external processes.
Solar Energy
A secondary source of energy that produces volcanoes, earthquakes and mountains.
Internal heat from Radioactive Decay
______ billion years ago the Big Bang happened
13.7
This theory proposes that all of the bodies in our current solar system originated from a enormous rotating cloud termed the solar nebula
Nebular Theory
The process found in stars that converts hydrogen and helium into more heavier elements
Nuclear Fusion
The average thickness of oceanic crust is ____ while the continental crust is ______
7 km ; 35 km
A granitic rock called ________ is the average composition of the upper crust
Granodiorite
The two energy sources that powers much of earth’s processes
Radiation from the Sun and internal heat from radioactive decay
Define mineraloid
A naturally occuring solid substance that lack the properties that defines a mineral
What is a rock
An aggregate of minerals and/or mineraloids
What is a monominerallic rock and give an example
A monominerallic rock is an aggregate of crystals of a singe minerals. An exampe would be dunite where it can consists only of olivine crystals
Enumerate the mineral assemblage of granite
Qtz, K-Fels, Plag, Hb, and Bt
Difference between Oceanic and Continental Crust
Oceanic Crust: Dense, thin, mafic
Continental Crust: Buoyant, thick, felsic
What are Ophiolites
Sliver of oceanic crust that are emplaced above the continental crust due to thrusting
Difference of upper continental crust and lower continental crust in terms of rock composition.
The upper continental crust consists of igneous and metamorphic rocks of granitic composition while the lower continental crust has dioritic and gabbronoic compositions.
What does the term ultrabasic composition mean?
A composition containing 30-40% magnesium oxides and minor amounts of iron oxides
Enumerate the minerals dominant in the upper portions of the mantle
Olivine, Pyroxene, Spinel, Plagioclase, and Garnet
What are the likely minerals present in intermediate rocks
Plagioclase, Hornblende, Pyroxenes, Biotite
Define the LVZ
The LVZ, otherwise known as the lowe velovity zone, is an area within depths of 100-250 km where the P-wave velocity decreases. The top of the zone marks the contact of the lithosphere and asthenosphere.
Inferred to be responsible for the changes in seismic wave velocity at depths of 410 to 660 km.
Mineral phase changes involving olivine to wadleysite and rinwoodite to perovskite
What are the major minerals that make up the mesophere
Perovskite, periclase, magnesiowustite, stishovite, ilmenite and ferrite
Define the D’’ layer
An area 130-340 km aboce the core-mantle boundary where anomalous seismic signals are found.
Enumerate the composition of the core along with its percentages
Iron (85%), Nickel (5%), and lighter elements (8-10%)
Define hotspot
A plume of mantle material that rises far from plate boundaries.
Extrusive vs Intrusive igneous rocks
Extrusive: Formed from rapid cooling; found at surface
Intrusive: Formed from slow cooling; formed under subsurface conditions
Evidences supporting continental Drift
> shape of the continents roughly fits like a jigsaw puzzle
matching fossils with faraway places
rock types and geological features match regarless of distance
fossils indicating paleoclimates different from the current one
Whole mantle model vs layer cake model
Whole mantle: sinking cold oceanic crust makes its way to the core-mantle boundary where it is heated and rises towards the surface
Layer cake: two disconnected layers; upper layer is dynamic and moves around lithospheric material and the sluggish lower layer which only serves to provide heat to the upper layer
Give the definition of a system and list examples.
Interdepended or interrelated object that comprises a single whole. An example would be the Geosphere.
Explain the formation of the solar system based on the Nebular theory
> Nebular cloud starts to gravitationally collapse due to external forces such as shockwaves from a supernova
Nebula contracted into a disc, gravitational ebergy is converted to thermal energy
the Nebular disc cools which causes heaver materials to condense
Repeated collisions causes accretion of materials which would eventually progress to larger heavenly bodies such as planets
The chemical formula of Olivine is (Mg,Fe)2SiO4. This means that magnesium and iron can substitute freely for one another in olivine. Why is this possible?
Magnesium and Iron have similar atomic radii which makes ionic susbtitution possible
Describe the compositional layer of the earth
The earth can be composinonally categorized as crust, mantle, and core.
The crust can be catergoried into a basaltic oceanic crust and a granitic continental crust
Mantle compositions are primarily magensium and iron rich materials such as peridoties
Crust is mainly composed of an Iron-Nickel alloy with minor amounts of elements that readily form compounds with iron
Describe the mehcanical layer of the earth
The earth can be mecanically categorized as lithosphere, asthenosphere, mesosphere, inner core, and outer core. The lithosphere is describes as a strong and rigid layer comprising the crust and upper part of the mantle. Asthenosphere is the weaker and plastic layer underneath. Mesosphere or the lower mantle with found at depths of 660-2900 km. The core is divided into the outer liquid core and the solid inner core.
Briefly discuss the layers of the Oceanic crust
Layer 1 is the outmermost zone comprised of a sedimentary carapace
Layer 2a are pillow and sheet lava flows
Layer 2b are Dikes
Layer 3 are Gabbros
Layer 4 is comprised of mantle peridotites
Describe the lithology and mineralogy of oceanic crust
Oceanic crust is mainly comprised of basalt and gabbros that are made up of mineals pyroxene and calcic plagiocalse
Describe the lithology and mineralogy of continental crust
Rocks in the continental crust is genrally described as granitic in composition enriched with Potassium, Sodium and Silicon Oxides.
Why is it that the surfaces of continenral crust tends to be above sea level.
Continenral crust are thicker and more buoyant than oceanic crust. One reason of such difference in densities is that continetal crust is comprised of lighter sodium and potassium oxides and silicates. Oceanic crust on the other hand is mainly comrpised of the heavier magnesium and iron oxides.
Why is it that most continental crust is older than oceanic crust
Oceanic crust tends to subduct beneath continental crust and would eventually be destroyed deep in the mantle. Continental crust, due to is buoyancy, would not experience such process and stays in the crust.
Give an explanation as to why most earthquakes happen in the lithosphere.
Due to the rigid nature of the lithosphere, it responds to stress in brittle manner which results to earthquakes.
What causes the plasticity of the asthenosphere
The pressure and temperature conditions are high enough to encourage the partial melting of mantle material (such as peridotite) to the point where it becomes pliable or plastic
What made geologists conclude that the outer core is liquid.
Due to the property of S-waves being unable to propagate in liquids, the fomation of S-wave shadow zones (areas where such waves are not detected) in the outer core led to the conclusion that the layer is liquid.
What is seismic anisotropy and what causes such configuration in the earth’s core
Seismic anisotropy means that the seismic velocity is faster in one direction than the other. Such configuration in the crust is inferred due to the parallel arrangement of the iron-rich crystals
How does continental rift systems form and give examples of such.
Continental rift systems are manifestations of divergent plate boundaries. In such tectonic setting horizontal extention mainly dominates the continental lithosphere where crustal thinning and rising of asthenosphering material occures.
