Geology test #3

• decrease temperature

• Increase temperature

• add violates

The change in temperature with depth(red/ green line in diagrams)

Conductive heat transvers

• temperature changes significantly with depth

Convection heat transvers

• Adiabatic Geotherm : pressure changes a lot, temperature changes very little

• A mantle curves that resides at T and P to the left of the curve with remin solide

• Where as to the right it will be at a high enough T and P to melt

• occurs within plates

• away from plate boundaries

• Thinning of the lithosphere

• which allows partial melting to occur where geotherm crosses the solidus

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• Extension at midocean ridges

• continental rifts

• divergent boundaries

• changes the melting curve/ solidus/ liquidus such that it cross the geotherm

• The blue lines is the wet solius

• Cause by convergent margins

Ocean-continetial and ocean-ocean convergent plate boudries

• The deceding slab contains wet sediment and hydrate minerals formed by alteration of the basalt on the seafloor

• As the plate subducts is driven off the slub and into the overlaying mantle wedge

• The hyrdate mantle melts at lower temp than dry mantle

• Plates seperate and mantle rises at mid-ocean ridges ( decompostion melting)

• Hot spot- localized plumes of melt

• Fluid fluxing

Outermost 200km of earth

the slope is a function of geotherm thickness

• lithopsheric geotherm increase as you move the curve up

• astherospheric remains constant

increase the geotherm by the addition of heat from the mantle

• allow melting to occur in the triangular region

• happens at hot spots in Hawaii

• The ring of fire

• cotnains 75% of planets voclanoes

Is is where multiple tectonic plates meet

It measure and classify eruptions. It starts at zero and is a log scale. Does not have a upperlimit

VEI 8 which ocured thosands of millions of years ago

The most explosive volcanoe recorded was in Indonesia in 1815 which was a VEI of 7

• volcanic ash provide nutriest to nearby soil making the land fertile

• when lava hardens into rock and creates new landforms

volume of lava gas and other emmsions from the volcanoe

height of the eruption cloud above the summit

the degree of fragmentation

1. melting viscosity (the main control)

   Composition and temperature: felsic vs mafic

2. Volcaltiles- context of gasses

3. Interaction with external water

The higher the silica content and the lower content of FE and MG, the more viscous the melt

• this mean that these compsotions tend to be more explosive

• more mafic/ bastlic melts

• higher temerature

• more fluid

• Oceanic divergent plate boudnries

• oceanic hot spots

• contiential divergent plate boundries

• contienal hot spots

• convergent plate boundries

• they drive the volcanic erruptions

• dissolved magmas under pressure

• come out of solution and expand as magma rise

• H20, C02, so2

Mount St. Helens

• magma rises in the chamber

• at lower pressures the gases began to exsolve and the chamber expands

• creates a bulge in the side of the mountain

If rising magma contacts water the water can vaporize

Intermingle with melt and cause an erruption

The volume of ejecta

Tambora 1815

No, depends on composition and volatiles which change through the life of a volcano

• basaltic ( low viscosity magmas)

• volatile bubble out quietly

• not very explosive

• bit more explosive

• erruption chacterized by short term out put of pasty lava

• results in scoria cones

• example

• MT etna Italy

• Particun mexico

• much stronger

• eruption columns reach 45 km into stratosphere

• Examples

  Naples, Italy

  Vesuvius ( one of the most dangerous volcanoes in the world)

• results from basaltic eruption interacting with groundwater or surface water

• wet equivalent of Strombolian eruption

• water cause to be more explosive

• more explosive that surtseyan

• discrete canon like explosions

• followed by sustained eruption

Mass of compressed ice on land that moves under its own wight

Alpine, conteinal ice sheets

Antarctica and Greenland

downhill

move outward from the center where mass of ice is the greatest

plastic flow

basalt sliding

accumulation> ablation

Glacier advances (grows)

accumulation> ablation

Glacier retreats shrinks

Abrasion and frost wedging

angular poorly sorted grains

isolated large-grain remnants of glacial deposits

piles of sediment dropped or spit out by glacier

outwash plain

bigger the cirque

10 and 30

fragment of pre-existing rack (sandstone)

precepted from solution Carbonate)

organisms play a role (shell material)

comprising large amounts of organic material

The decomposition and disintegration of rocks and minerals at the earth’s surface by machinal and chemical processes

• converts rock to gravel, sand, clay and soil

The removal of weathered rocks and minerals for the place they were found

• water

• wind

• glaciers

• gravidity

The physical disintegration rock into smaller pieces each retaining there original characteristics

decomposition of rock and minerals and as a result f chemical reactions (removal and/or addition of elements)

• frost wedging

• salt cracking

• abrasion

• biological activity

• thermal expansion and contracting

• pressure release fracturing

when water freezes it expands and water migrates into cracks in rocks. Ice crystals growth puts tremendous pressure on surrounding rocks

Most effective in mountain areas where daily freeze/ thaw. Dangers to hikers

salts crystallize in cracks puts pressure on surrounding rock

Important in

dry climate:

costal areas

breakdown of rock by fiction and impact

• gilders(effective)

• wind

• running water(effective)

• waves(effective)

• plants growing in cracks in rocks

• burrowing animals

• human blasting for roads, development exploration

• buried rocks are under confining pressure

• when exposed they expand due to releasing

• problem for miners

water

produces ions ( not minerals) and are reversable is the solvent is removed

Ex dissolving soluble materials in water, the salt is re-participated if the water evaporates

Salt deposits are creating with the drying of ancient seas

Natural rain water fall through the soil and reacts with C02 to form carbonic acid.

Carbonic acid reacts with calcite (Limestone) to produce it

where dissolution involves the release of ions from a mineral

• is a reaction with water to form a hydrated mineral

reaction with oxygen

ex iron bearing minerals oxdize to form rust

• climate

• Oxygen and C02 in the atmosphere and soil

• Minerology

• Surface area- how fragmented the rock is

Clast textures:

Size

Shape

Sorting

Agents of transportation:

• gravity

• wind

• water

• ice

Limestone

• formed from shell fragments and test (shells of microfossils)