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geology (Fach) / geology (Lektion)

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• difference lithosphere and asthenosphere lithosphere is rigid and asthenosphere is like a viscous fluid
• avergae rates of plate movements 10s-100mm/year
• trench pull convergent boundary: force that pulls slab downward
• trench pull convergent boundary: force that pulls slab downward
• trench pull convergent boundary: force that pulls slab downward
• calculation age of the ocean crust Hdepth(km)= 2,5+0,35 X √age
• Cslculation spreding rates km divided by Ma results in mm/a thus example 1600km /40 Ma = 40mm/a
• what is the temperature of the isotherm around 1300°C
• why are arthquakes restricted to shallow depth at ocean ridges bc destructive seismic waves cannot travel through liquid material like the asthenosphere. The litosphere however is really thin under the MOR- thus earthquake in shallow depth
• rates of subduction define a trenchs width and depth. The faster the subduction the ......the width and the........the depth The faster the narrower the trench and the deeper
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• composition of the oceanic crust layers 1= sediments 2A+B= basaltic lava 2C = basaltic dykes 3= Gabbro 4= peridotite
• Birch law almost linear reaction between seismic wave velocity and rock density (the deeper, the faster)
• seismic cycle rocks move cmms/year either aseismic: smooth stable gliding , no earthquakes or stick and slip: after period of coupling, sudden energy release (short coupling ~100yrs = frequent but less strong ones; long coupling: rare but strong
• Gutenberg Richter Law # of erathquakes against magnitude shows linear relationship between log10 and magn. -1
• Baths law average of difference in magnitudes & largest aftershock is 1.2 (the larger the earthquake the larger the aftershock)
• omori law aftershock rate propotional to inverse time to mainshock
• types of magnitudes Local magnitude ML = Richter magnitude surface magnitude Ms body w. magnitude = Mb Momentum Magnitude Mw (seismic Moment)
• Ghyben-Herzberg theoretical: fresh water water table around 1m above sea level, then the salne-freshwater interface would stabilize at around 40m depth  (absence of todes)
• inundation a) b) intrusion underground a)sea level rise: flooding on the surface b) : salt water entering underground
• impacts of global warming on the water cycle 1)more evaporation 2)less surface water - need for more ground water (pressure on ground water) 3) droughts :  less soil moisture -> less crops growth 4) ice caps melting 5) more severe floods and droughts 6)sea level rise ->intrusion of salt water =increase in salinity in ground water...
• average of sea level rise 2mm/year over last centuary ~0.2m risen
• high pressure zones low pressure zones high pressure: air comes down (becomes warmer)>favours evaporation low pressure: air goes up and condensates =favors evaporation
• what is teleconnection eg NOA Teleconnection in atmospheric science refers to climate anomalies being related to each other at large distances High and low pressure regions oscilliate (geographically and intensity) eg NOA: The NAO(North Atlantic Oscillation) is a meridional dipole of the pressure field between Icelandand the Azores. In its positive phase (NAO+) high pressures dominate over the Azores and lowpressures over Iceland, promoting warmer and wetter winters across northern Europe, while drierconditions prevail southward. In the opposite phase (NAO− NAO−) westerly winds and storm tracks areshifted southward, enhancing precipitation over southern Europe
• faults a) normal b)Strike and slip c) thrust faults/inverse faulta a)break with inclination eg in diverging boundaries b) form agt transform boundaries (horizontal movement) c) Thrust faults/inverse faults: form during eg conversion: loong faults with low angle (highest froces)
• faults a) normal b)Strike and slip c) thrust faults/inverse faulta a)break with inclination eg in diverging boundaries b) form agt transform boundaries (horizontal movement) c) Thrust faults/inverse faults: form during eg conversion: loong faults with low angle (highest froces)
• spreading rates slow: 1-5cm/a intermediate: 5-10cm/a fast:10-20cm/a
• spreading rates slow: 1-5cm/a intermediate: 5-10cm/a fast:10-20cm/a
• Moho Boundary between crust and mantle  ocean at around 7km continent around 30km
• isostatic compensation crust and mantle weight ratio is in an equilibrium as mantle is continous (below oceanic and continental crust) it has the same density everywhere, hence the densitiy of the crusts vary.  The oceanic crust is a lot denser and heavier as its a lot thinner and needs to compensate this thinness with more weight. Thus the continental crust has a lower density and is lighter
• Active margin and types convergent plate boundary =narrow continental margin and low in sediment =tectonically active a) Andean type: subduction ocean under continental b) Island arcs: oceanic under oceanic (shallow sea)
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• thne wilson cycle it explains the lifecycle of an ocean basin 1. Continent breaks apart (crust lays over hotspot and asthenosphere rises - graben forms and eventually maga breaks through (volcanic action) - the graben sinks and oceanic basaltic curst is formed = formation of an ocean 2. divergence stops and convergence begins at margins: Ocean subducts under the continental crust and decreases again until it disappears 3. soweit bis continental crusts collides -mountains eg himalaya  4. Ruhephase
• altitudes of ocean and continent ocean ~3686m continent: ~797m
• seamount formation plate progression over   hotspot eg in mexico
• diapiric minibasin more mobile and ductile material intrudes into brittle rock
• passive margin never at a plate boundary on the coast: have a wide continental margin with high sediment accumulation - abyssal plain 100skm away from the continent, little tectonic activity eg. African coast (continental and oceanic crust) but one plate = passive margin
• passive margin types magma rich (volcanic) magma poor (non volcanic)
• passive margin types magma rich (volcanic) magma poor (non volcanic)
• Continental break up -pre rift -syn rift -unconformities -post rift =lithosphere extension and rise of the moho = unconformities  /little erosion in the sediments = Pre-rift  --->Unconnected fault system leads to isolated basin =different sediments deposit in the fault systems and extension zone so called Synrift  =unconformities through break up in deposited materials =after process post rift material lays on top and is more conform
• stages of rifting 1) Stretching in the proximal domain: minor extension forming half graben/graben structure with high angle normal faults leading to rough topography.  2)Thinning and coupling in the necking domain: wedge shaped crustal geometry with major border faults limiting distal domain here: large scale MOHO uplift results in major crust thinning and smooth topography. once it becomes majorly thinned it becomes birttle enough that the upper and lower crust deformation structures conjugate and couple = coupling point 3) Hyperextension/exhumination in the Distal domain: sag type basin (lower basin) over thinned crust or/and exhumed mantle  4)Outer domain: magmatic : pulse in magmatic activity that triggers final breack up 5)Oceanic domain: volcanic rich: thick oceanic crust formation; volcanic poor; thin gradual breakup of contintenal 
• draw the earth layer model crust/mantle (rigid, notes page 4
• isostatic compenation which depth compensation at around 50km
• oceanic crust materials layers 1, 2A,B,C; 3 1=sediments 2A = basaltic lavas 2B= Dikes 2C =Transition zone (extrusive to intrusive) 3= Gabbro then Moho and the perodite(mantle)
• Gabbro composition heterogeneous of plagioclase & pyroxene
• Types of Moho seismic: petrological: seismic moho: velocity transition from 7,5Km/s to 8,1km/s petrological moho: transition between sialic or mafic crust to ultramafic rock
• seismic velocity increases with depth and pressure
• serpentinization process in which ultramafic is hydrated and metamorphically (heat/pressure cause chemical or physical change) transformed   -->hydration and oxidation of material forms new material
• ophiolite: continental crust subducts under oceanic crust -> find altered oceanic crust on surface eg in zyprus
• normal faults types and model (extension, dip angle, displacement nore p.6) a)emerging normal faults - on the surface b) blind normal faults: interior - Fault forms a shoulder and a extended zone  1. planar non rotational faults 2)planar rotaional faullts (detachement from base)
• overthrusting thrust sheet travels long distance (becomes allocthonous and rests on autochthonous rock
• combination of normal faults and thrust folds have a normal fault and at local areas small thrust faults develop (small compression zones due to the local structure at that point)

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