Ring of fire extrusive igneous rocks and plate

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Ring of Fire extrusive igneous rocks and plate tectonics located on plate boundaries in Pacific Ocean and Mediterranean Sea Mid- oceanic crust divergent boundary forming new oceanic crust More Population, more fatalities
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Causes of fatalities in order (worst first) pyroclastic flow, indirect (famine), tsunami… lava is the lowest Chapter 7: Metamorphism, Metamorphic Rock, and Hydrothermal Rocks (higher temperature and pressure) Metamorphism solid-state changes to rocks in the earth’s interior, produced by increased in agents of metamorphism : - Heat - Pressure - Reactive fluids Prolith + agents of metamorphism = metamorphic rock = increasing the heat to the point where you are changing the rock, not melting it Texture and Mineral content of Metamorphic rocks depend on 6 things: Most important 1) the composition of the parent rock before metamorphism, 2) temperature and pressure during metamorphism, 3) the effect of tectonic forces, 4) the effects of fluids, such as water 1. Composition of parent rock (original rock): a) Usually no new material is added b) Metamorphic rock similar composition to parent rock b.i. Exception – hydrothermal bring in new ions b.ii. Sandstone quartz 2. Temperature : a) Stability over a finite temperature range b) Remember, equilibrium c) The upper limit on temperature in metamorphism overlaps the temperature of partial melting of rock 3. Pressure : a) Confining pressure pressure applied equally in all directions a.i. Ex: lithostatic pressure a.ii. Proportional to depth within the Earth (~1 / 3.3 km) 4. Tectonic Forces : cause differential stress (if the forces on a body are stronger or weaker in different directions) a) Compressive stress “squeezing” along one direction Ex: dough ball b) Shearing sliding relative to one another along the plane c) Note * Stress deforms the shape of object, not just the volume d) * Creates foliation planer or tabular texture in metamorphic rocks caused by differential stress … compressive perpendicular & shearing parallel pg 174
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d.i. Slaty cleavage if a rock splits easily along flat planes … indicates that preexisting, microscopic, platy minerals were realigned during metamorphism d.ii. Schistose = platy (needle-shaped) minerals have grown in parallel planes d.iii. Gneissic = bonding of light and dark layers 5. Fluids : a) Hot water (as vapor) released from unstable minerals(result of temperature rising) or sedimentary rocks b) Acts as rapid transport agent from mobile ions 6. Time : a) Millions of years b) Longer times allow nearly stable minerals to grow larger and increase foliation 2 types of change in proliths: - Textural - Mineralogical - Metamorphic rocks are classified based on texture and composition Classification (textural terms) Non-foliated = no preferential alignment - Marble parent rock is dolomite marble … highly susceptible to chemical weathering - Quartize being hard as a single quartz crystal, it is difficult to crush or break and it’s the most durable of common rocks used for construction - Hornfels
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  • Fall '07
  • Manger
  • Geology, rocks

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