Forel. Flashcards
(42 cards)
What is nucleosynthesis?
The process that forms new atomic nuclei from pre-existing nucleons (fusion), primarily protons and neutrons.
How far can fusion of nuclides go?
All the way to 56Ni
How are heavier elements made (heavier than Ni)?
Neutron capture:
- S-process, slow
- R-process, fast
What are the three main types of meteorites?
Stony, iron, stony-iron
What are the common rocks of the continental crust and islandic arc with main minerals and chemical composition?
Granite/rhyolite - feldspar, quartz - much SiO2, less FeO and CaO, very little MgO
Diorite/andesite - feldspar, quartz, pyroxene - less SiO2, more Al2O3 and others
What are the common rocks of the oceanic crust?
Gabbro/basalts - feldspar, pyroxene, olivine - less SiO2, more CaO
What are the common rocks of the mantle?
Peridotite - olivine, pyroxene - less SiO2 than the others, much MgO.
What does refractory mean?
Any material that has a relatively high equilibrium condensation temperature is called refractory.
Super: Re, Os, W, Zr
Refractory: Al, Ca, Ti, REE
What are siderophile elements?
Iron-loving, e.g., gold, palladium, chromium etc.
Transitional metals
What are lithophile elements?
Elements that remains close to the surface because they combine readily with oxygen.
E.g., Al, Ca, Cl, Rb etc.
What are chalcophile elements?
Remain close to the surface because they combine with sulfur
Ag, As, Bi, Ga, Ge.
What are atmophile elements?
Remain on or above the surface (volatile)
E.g., H, C, N, and noble gases
What permits partial melting?
When mixtures of molecules that form solutions in the solid state, melt over a range of temperatures - not ONE temperature.
Which minerals will yield a melt that differ in composition from that of the mineral that is melting?
Minerals with solid solution, unless mineral is completely melted -> then same composition in melt as mineral.
What is the upper crust composition?
Granodioritic
What are the composition of the middle and lower crust?
Middle: andesitic
Lower: basaltic
How is the layering of the oceanic crust?
- Sediment
- Basaltic pillows
- Sheeted dikes (ganger)
- Isotropic gabbro /layered under
What can systematic variations of the MORB composition be explained by?
- Fractional crystallization
- Ridge-hotspot interactions
- Degree and depth of melting
What is the distribution coefficient?
When a mineral is in chemical equilibrium with a liquid, elements are partitioned between the phases according to their chemical activity in each.
Conc. in mineral/conc. in liquid =D
Define batch melting
Simplest model for partial melting of a complex mineral assemblage.
Liquid remains at the site of melting and is in chemical equilibrium with the solid until mech. conditions allow it to escape as a batch.
Describe the batch melting equation
Cl/Ci = 1/ (D(1-F)+F
The smaller the degree of partial melting, the higher the concentration of an inkel.
The lower the D, the higher conc. of element.
What ar the two main subduction types?
Chilean: young lithosphere, shallow dip of W-B, back-arc compression, crustal melts.
Mariana: old lithosphere, steep dip of W-B, back-arc extension, mantle partial melts.
What happens when adding volatiles to mantle?
The temperatures of solidus are strongly depressed.
Name 3 dehydration reactions
Amphibole -> CPX
Albite + Epidote -> Plagioclase
Serpentine -> Olivine
