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| Intrusive (plutonic) igneous rock |
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Definition
| magma that has solidified underground |
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| The texture of intrusive (plutonic) igneous rock that has cooled slowly forming large crystals to form. (gabbro, granite, peridotite) |
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| magma that has solidified above ground, above the surface of the earth forming igneous rock. |
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| the texture of extrusive (volcanic) igneous rock that has cooled above ground much faster causing smaller crystals to form. (basalt, obsidian, pumice) |
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| Fractional Crystallizaiton |
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Definition
| The crystallization of silicates in magma at different rates in a definite sequence due to their different melting points. |
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| Minerals with higher melting temperatures crystallize first, while those with lower melting temperatures crystallize last. |
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| Minerals with lower melting temperatures will melt first, while those with higher melting temperatures melt last. |
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| Low SiO2 content, low viscosity, highest tendancy to form lavas, lowest tendancy to form pyroclastic flows. Less likely to violently erupt due to lower viscosity, meaning the pressure would release before it could build up to a high enough point to violently erupt. |
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| Higher SiO2 content, high viscosity(thick), lowest tendancy to form lavas, highest tendancy to form pyroclastic flows. More likely to violently erupt due to thick viscosity trapping the pressure for longer and having more energy to release when it breaks. |
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| Form most of the surface of the earth. Created by sediments combining through diagenesis to form one cohesive rock structure. |
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| Can be mechanical or chemical. The breakdown/fragmentation of rock bidies into smaller particles, but does not modify the molecular structure or nature of the mineral |
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| Infiltration of water in cracks and pores of rocks in periglacial regions. There is a 9% volume expanison of water on freezing. Wedging splits the rock into smaller pieces. |
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| Important diurnal changes in temperatures in deserts. Contraction and expansion of the rock due to (daytime) heating and (night time) cooling cause the rock to split. |
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| Exposure of large masses of igneous rock after removal of overlaying material by erosion: pressure release-->expansion, breaks are parallel to the surface breaking in concentric slabs (like onion layers)separation of successive thin shells, or spalls, from massive rock such as granite or basalt; it is common in regions that have moderate rainfall. The thickness of individual sheet or plate may be from a few millimetres to a few metres. |
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| Physical Disintigration due to Roots |
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Definition
| Plant roots grow into cracks of rocks and split the rock with its growth and expansion. |
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| Physical Disintegration due to Salt Crystals |
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Definition
| Crystallization of salts as saline water evaporates leaving the crystals in small cracks and pores of the rock. As the crystals grow they force the rock to fracture and split. |
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| chemical process that breaks down the internal structure of the original material and new minerals can be formed. Can cause decomposition of the rock. |
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| Chemical reaction in which a solid material is dispersed as ions in a liqued (ie NaCl in water). Fluid travels through the rock depositing and picking up minerals. Creates stalactites and stalagmites in caves. |
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| Takes place when oxygen combines with other elements in rocks to form new types of rock. These new substances are usually much softer and break more easily. |
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| occurs when water combines with the substances in rocks to form new types of substances which are softer than the parent rock. This allows mechanical weathering to break the rock apart more easily. |
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| the solid particles and/or ions in solution are transported by trantport agents ie water, glaciers, wind, and gravity. |
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| All material must settle in a sedimentary basin, ultimately in the ocean basin. Sediments settle in successive layers. |
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| All of the process progressively changing a sediment into a rock. This includes all of the process occuring to a sediment immediately after its deposition. |
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| caused by weight exerted from the overlying sediments (overburden). It results in the tighter packing of the grains and thus a reduction of the pore space. In the case of sediments deposited in water, it also drives out the interstitial water. |
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| Precipitation of minerals in the pore space as water mores through the sediments, binding the loose sediments together. Also reduces the amount of pore space. |
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| Pre-compaction (cementation) |
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Definition
| sediment grains binding larger sediments and minerals together to form one cohesive rock. |
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| Cementation through Compaciton |
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| Pressure forces the rock particles to bind and fuse to one another and cement into one rock. |
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| Sedimentary rock classification |
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| Based on the nature, source, or origin of the sediments. |
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| come from the accumulation of grains that are fragments of pre-existing rocks and transported from the continent. |
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| come from the accumulation of grains produced by organisms ie exoskeletons, shells, other hard parts of organisms. can accumulate as a sediment into limestone, or be precipitated as a solid rock like coral reefs. |
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| CCD (Carbonate Compensation Depth) |
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Definition
| Where the dissolution of CaCO3 occurs and no calcite is preserved. |
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| A biochemical rock build on the sea floor and that does not transport. Consists of many corals built on top of each other. Coral has a calcite skeleton that anchors onto rock or other calcite corals. |
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| Are at some distance from land, a shallow basin between the reef and the land, the reef creates a barrier that the ocean waves break over and allow the basin to remain calm and neutral thus allowing a specific set of fauna to thrive. |
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| Directly adjacent to land. Corals begin to anchor on land for stability and grow outward around the land. |
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| Ring shaped reefs as a result from hotspot magmatism. Have land in the middle but it is hidden. |
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STAGE 1: starts as a volcanic island over a magmatic hot spot, the island shifts off of the hot spot to due lithospheric movement and a fringing reef grows on the land around the volcano. The weight causes the island to begin to subsidate. Coral and algae have a symbiotic relationship so the coral will continue to grow upwards towards the sunlight for the benefit of the algae and to keep up with the subsidation.
STAGE 2: The reef now forms a barrier reef with a lagoon in the middle. If it keeps subsiding then the volcano in completely underwater and the reef continues to grow towards the sunlight.
STAGE 3: the volcanic island has completely ssubsided and what remains is the coral ring atoll. |
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Definition
| solid-state recrystallizatoin of a rock subjected to physio-chemical conditions markedly different from those in which it originally formed. |
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| (parent-rock) Rock from which a metamorphic rock formed. |
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| Occurs immediately around an igneous rock intrusion (batholith, dyke, sill). Heat transfer and cooking of rocks surrounding the igneous body. Tied mainly to an increase in temperature. |
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| Zone of metamorphized rocks surrounding an igneous intrusiton: its thickness can vary from a few centimetres to several kilometres. The intensity of metamorphism decreases further away from the intrusion. |
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| Dynamothermal Metamorphism |
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Definition
| occurs at convergent plate boundaried where plates collide. Most intense metamorphic activity is at the roots of mountains associated with intense rock deformation. Tied to an important increase in both pressure and temperature. |
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| Preferential allignment of planar elements resulting fron a differential pressure during dynamothermal metamorphism. Alignment is perpendicular to the direction of maximum pressure. Foliation if achieved by crystallization of new minerals, rotation of existing particles, flattening of existing particles, and recrystallization of pre-existing minerals. |
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| alignment of microscopic minerals; tends to break into flat sheets along parallel planes like slates |
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| alignment of microscopic to very fine minerals along slightly undulated planed; recrystallized sheet silicates give the rocks their shiny lustre. |
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| parallel to sub-parallel alignment of macroscopic minerals along undulated planes; macroscopic sheet silicates give the rock a brilliant lustre. |
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| compositional layering, alternating light and dark coloured bands corresponding to layers of different compositions, macroscopic minerals (coarse). |
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| Causes: melting, dense minerals usually formed in the earth's mantle (diamond), deep fractures, release of natural gasses, and deformation features such as shock lamaellae and shatter cones. |
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