EES test
Igneous rocks
An igneous rock such as basalt might break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent.
Driving forces of the rock cycle such as plate tectonics and the water cycle cause rocks not to remaining equilibrium and force them to change as they encounter new environments.
Diagram in word book
Initially the cycle starts when liquid rock called magma solidifies either to or below the surface of the earth to form igneous rocks. Tectonic movements then cause uplift of the igneous rocks to form mountain chines such as the Andes and Himalayas that we see today.
The exposure of the igneous rocks to weathering and erosion at the earths surface breaks them down into smaller grains and soil is formed. The soil grains are then transported by wind water and gravity and eventually deposited as sediment sin rivers, lakes and streams.
The sediments are then deposited in layers and become buried, compacted and cements to for sedimentary rocks.
Igneous rocks
95% of the earths crust is made up of igneous rocks or metamorphic rocks formed from igneous rocks
Aphantic texture= fine grained crystals-rapid. Cooling magma formed at or close to the surface, described as light intermediate or dark in colour
Phaneritic texture= coarse grained crystals-slow cooling maga formed deep within the earths crust
The Essay on The Rock Cycle Rocks Igneous Sedimentary
... them down into smaller grains ... below the surface of the earth to form igneous rocks. Uplifting occurs forming mountains made of rock. The exposure of weathering and erosion at the earth's surface breaks ...
Porphyritic texture= large crystals in smaller crystals-in magma at depth, different minerals crystallize at different temperature
Glassy texture=none- molten rock hits the atmosphere too rapidly for crystals to form. Very rapid cooling
Pyro clastic texture= not crystals but individual rock fragments-rock fragments from violent volcanic eruptions combine to form an igneous rock
Pegmatite texture= very coarse grained crystals-formed in fluid rich, late magma crystallization
Rocks with a composition between granitic and basaltic are said to have an intermediate or andesitic composition named after their common volcanic rock:andesite
Rocks with almost entirely ferromagnesian minerals with no feldspar or quartz have an ultramafic composition. Peridotite is an igneous rock made up of the ferromagnesian minerals olivine and pyroxene and is thought to be the main components of the earth’s upper mantle
Common felsic igneous rocks
granite: is a major component of the earths continental crust, it is coarsed grained rock
Made up of around 25% quartz and 65% sodium and potassium rich feldspars.
Granit: is an intrusive igneous rock forms from the partial melting of the earths continental crust which is very rich in silica and therefore can easily form silica rich felsic magma
Rhyolite: is an extrusive equivalent of granite and has a similar mineral composition. fine grained and often contains glass fragments and voids which which tells us that it cooled rapidly at the surface of the earth.
Obsidian: is dark colored, glassy rock formed when silica rich (felsic) magma is quickly quenched. Obsidian is not composed of minerals like other igneous rocks
Pumice: also he a glassy texture and is often found with obsidian. It forms when a lot of gas escapes with a volcanic lava eruption and contains a lot of holes or voids giving it a vesicular texture, often floats in water if it contains enough holes
Common intermediate rocks
A desires and diorites are the most common intermediate igneous rocks. Andesite is a medium grained extrusive volcanic igneous rock while diorite is coarser grained intrusive equivalent.
Common magic igneous rocks
Basalt is Very dark green to black in colour fine grained rock and is most common extrusive igneous rock, made up of mainly pyroxene and calcium rich plagioclase feldspar crystals with possibly some olivine and Amphibole crystals.
The Term Paper on Igneous Rock
... sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or ... in a stable association with quartz. Igneous rocks which have crystals large enough to be seen by ... rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. [edit]Classification Igneous rocks ...
Gabbros is an intrusive equivalent of basalt and is also common in the earths oceanic crusts.
Dole rite is the medium grained equivilant of gabbro and is often found as a dyke or sill type intrusion.
Common pyro clastic igneous rocks are made up of fragments ejected during a volcanic eruption. A tuff is one of the most common and is small ash particles cemented together.
The viscosity of the magma is important in the type of pluton that is formed. If the viscosity is low the magma is more likely to intrude along narrow fractures or fissures.
How ever a viscous lava will move very slowly upwards pushing the country rock aside and forming large irregular shaped intrusions. This means that fled magmas like basalt tend to intrude narrow opening where as granitic magmas form massive features.
Dykes
Tabular intrusions that cut across the bedding or strata. Dyke swarms: when magma is injected into many fissures close together.
Sills
Tabular concordat plutonium intruded along the bedding surfaces of sedimentary rocks sills generally form at shallow depths where the pressure of overlying rock is less.
Laccoliths
Are similar to sills but formed from magmas with higher viscosity. As a result the magma forms thicker intrusion that can push overlying sedimentary strata up producing a dome like feature.
Batholiths
Very large igneous intrusions are called batholiths. Many hundreds of km wide. Batholiths are very thick and in many cases the actual depths difficult to determine.
Plate tectonics
The jigsaw fit
Pieces of the continent could join on the sure lines.
Previous glacial ions
When glaciers move they carry sediment of boulders, pebbles, sand and finer particles. These frozen into the base of the glacier. The glacier become large sanding machine.
As the glacier melts it deposits these sediments or other minerals frozen and this is the glacial theory. Two same types of sediments are found in two different continents from the same glacier.
Rock types that match
Rocks of similar age, type and formations can be found in west Africa NE Brazil, in the Appalachian mountains of eastern US and in the mountains of NW Europe.
The Term Paper on Sedimentary Rock 2
Sedimentary rock formation begins with igneous, metamorphic, or other sedimentary rocks. When these rocks are exposed at the earth’s surface they begin the long slow but relentless process of becoming sedimentary rock. Weathering All rocks are subject to weathering. Weathering is anything that breaks the rocks into smaller pieces or sediments. This can happen by the forces of like wind, rain, and ...
Fossils that match can be found in different continents
Plate boundary A- divergent. Movement-two plates move apart, new oceanic crust appears
Volcanic/earthquake-quite volcanic and earthquake activity rock types formed-basalt lava plains low viscosity
B-convergent movement-ocean crust moves towards and sinks below continental crust in subduction one. Volcanic/earthquake- violent and explosive volcanic activity, strong earthquakes varying in depth. rock type formed- andesite and pyro clastic high viscosity produces classic cone shaped volcanoes
C-convergent collision-two continental move towards each other collision forces crust up. Volcanic/earthquake- some earthquakes activity no volcanic activity. Rock types formed-granites, rhyolites, ,metamorphic schists and gneiss
D-convergent. Older more dense oceanic crust moves towards and sinks below younger less dense oceanic crust in subduction zone. Volcanic/earthquake- violent and explosive volcanic activity strong earthquakes varying in depth rock types formed- andesite sand pyro classics, high viscosity produces cone shaped composite volcanoes.
E- transform two plates move past each other, material is not created or destroyed. Volcanic/earthquake- strong earthquake activity at intervals, no volcanic activity. Rock types formed- some small metamorphic zones and granite intrusions.
A fault is a brake in the rocks that make up the earths crust along which rocks on either side have moved past each other. SLIP is relative movement of geological features present on either side of a fault plane
Faults
Normal= hanging wall down, foot wall up
Reverse fault= hanging wall up, foot wall down
Sinistral= top goes left bottom goes right
Dextran= top goes right bottom goes left