Midterm - review and sedimentary structures/environments

Earth’s mechanical layers (name, depth)

Lithosphere (includes both crust and uppermost mantle, 100-150km),

Asthenosphere (down to 250km),

Mesosphere,

Outer Core,

Inner Core

Earth’s chemical layers (names, depth, elements)

Continental Crust (30-70km; Si, O, Na, K, Al, Ca)

Oceanic Crust (3-10km; Si, O, Fe, Al, Ca)

Mantle (2900km; Si, O, Fe, Mg)

Core (3400km; Fe, Ni)

ways to predict eruption

heat flow, gas emissions, earthquakes, shape of volcano

Why is the ocean so much deeper around the edges than it is at the mid-ocean ridges?

Isostasy – the crust is hot at the mid-ocean ridges and has no mantle lithosphere weighing it down, away from the ridges the crust cools and gets heavier(more dense), and more mantle freezes to the bottom of the lithosphere, pulling it down

Stratovolcano hazards

ash cloud, ash fall, explosive blast, lahars, pyroclastic flows, landslides 

Layers at an ocean-continent subduction zone:

continental crust (upper plate),

ocean crust (subducting plate),

mantle lithosphere (under the crust on both plates),

asthenosphere under the lithosphere.

The oceanic crust is quite thin,

the continental crust is thicker, and the mantle lithosphere is the thickest.

The crust on the upper plate gets thicker at the subduction zone

Layers at a mid-ocean ridge:

thin oceanic crust with thicker mantle lithosphere underneath, on both sides of the mid-ocean ridge.

The mantle lithosphere gets thinner

closer to the divergent boundary and pinches out right at the ridge. Asthenosphere under the lithosphere, welling up to the surface at the ridge.

describes large-scale sweeping beds that cut each other at angles

cross-bedding

form in water current running one direction

asymmetric ripples

form in wind-blown sand dunes

cross-bedding

form in a water current moving back and forth

symmetric ripples

form in coastal environments

symmetric ripples

form in river environments

asymmetric ripples

basin that is asymmetric

rift and foreland basins

associated with ocean-continent subduction zones

foreland basins

found on the edges of the continents

passive margin basin

very narrow basin

rift basin

the largest and deepest basin

passive margin basin

found at continental rifts

rift basin

bordered by tall mountains

rift and foreland basin

transgression

A relative rise in sea level which results in clast sizes getting smaller, lower energy

regression

a relative drop in sea level and results in clast sizes getting bigger, higher energy

factors that can affect relative sea level

rising and lowering of sea level,

uplift or subsidence of the land

sediment building out from the coast

features in a glacial environment

arge (boulder to gravel) clasts,

sand-sized clasts,

mud-sized clasts,

immature clast composition (arkosic/lithic),

angular clasts,

poor sorting of clasts,

no bedding

features that describe the sediment deposited in a mountain river environment.

large (boulder to gravel) clasts

immature clast composition (arkosic/lithic)

moderately rounded clasts

moderate sorting of clasts

the features that describe the sediment deposited in an alluvial fan.

large (boulder to gravel) clasts

sand-sized clasts

immature clast composition (arkosic/lithic)

moderately rounded clasts

moderate sorting of clasts

the features that describe the sediment deposited in sand dunes.

sand-sized clasts,

well rounded clasts

well sorted clasts

crossbedding

the features that describe the sediment deposited in fluvial systems (lowland river, fluvial=river)

sand-sized clasts

mud-sized clasts

mature clast composition (quartz/clay)

well rounded clasts

well sorted clasts 

asymmetric ripples

the features that describe the sediment deposited on beaches.

 

sand-sized clasts 

mature clast composition (quartz/clay) 

well rounded clasts 

well sorted clasts 

symmetric ripples

the features that describe the sediment deposited in tidal flats.

 

sand-sized clasts 

mud-sized clasts 

mature clast composition (quartz/clay) 

crystals composed of gypsum or halite 

well rounded clasts  

well sorted clasts 

symmetric ripples

the features that describe the sediment deposited in deep water clastic environments (such as lakes and oceans).

 

mud-sized clasts 

mature clast composition (quartz/clay) 

well rounded clasts 

well sorted clasts

the features that describe the sediment deposited in a warm, shallow oceans where life flourishes.

 

visible fossil fragments (fossiliferous),  

mud-sized calcite grains 

fragments composed of calcite

conditions for chemical sedimentary rocks to form

dry climate

stagnant mineral rich water

hot climate

supply of minerals

Continental Crust

(30-70km; Si, O, Na, K, Al, Ca)

Oceanic Crust

(3-10km; Si, O, Fe, Al, Ca)

Mantle

(2900km; Si, O, Fe, Mg)

Core

(3400km; Fe, Ni)