Geochemistry Part 2 Flashcards
Usually measured in percentage, and are commonly above 1% of the chemical composition of the material
Major Element
- by changing the major element, you are essentially changing the materila itself.
Elements that occur in such small comcentrations that they do not chnage the essence of what a material is. Usually below 0.1%
Trace elements
- it tells you what happens in the process and history of the rock.
In between of major and trcae elements, mostly accessory minerals. Ithas concentration between 1% and 0.1 percent
Minor elements
Oins that do not fit into the structure of the rock-forming minerals or minerals precipitating in the magma at the time when ions are present and therefore accumulate in the residual magma. Mostly concentrated in the melt
Incompatible elements
Iosn easily accomodate in the minerla structure, mostly concentrated in the solid.
Compatible elements
2 sub groups of incompatible elements
High Field Strength elements (HFS)
Large Ion lithophile elements (LIL)
17 chemical elements inperiodic table, specifically the 15 lanthanide plus scandium and ytrium.
Rare Earth Elements (REE)
-they are in fact not that rare and are relatively abundant in the earth’s crust, what is unsual is to find them in quantities significant enough to support economic mineral development.
Magma derived from the mantle with forsterite no. 88 to 92, magnesium no. Of 65 and above and low Cr number
Primitive magma
The first magma derived from primitive magma. Can be classified as parental magma
Primary magma
Not necessarily primitive nor primary but where other magmas derived
Parental magma
Petrogenetic indicators: highly compatible elemets, its high concentratins indicate a mantle source, limited fraction, or crystal accumulation
(Ni, Co, Cr)
Ni and Co - concentrated inolivine
Cr - spinel and cpx
Petrogenetic indicators: very incompatible elements that do not substitute into major silicate phases, high concentration imply an enriched source or extrusive liquid evolution
Zr and Hf
Petrogenetic indicators: HFS elements that partition into Ti-rich phases. Typically low concentrations in subduction-related melts
Nb and Ta
Petrogenetic indicators:Seredophiles mostly used to study melting and crystallization in maric-ultramafic systems.
Seredophiles: Ru, Rh, Pd, Re, Os, Ir
Petrogenetic indicators: concentrates in pyroxenes and may be used as an indicatr of pyroxene fractionation
Sc
Petrogenetic indicators: substitute for Ca in plagioclase and to a lesser extent, K for K-felds.
Sr
Petrogenetic indicators: myriad uses in modelling source characteristics and liquid evelution.
REE
Petrogenetic indicators:commonly incompatible. Strongly partitioned into garnet and amphibole.
Y
Non destructive analytical technique used to determine the elemental composition of materials.
XRF - X-ray flouresence
Uses of XRF
Petrology Soil survey Mining Cement Metallurgy Envi Studies Petroleum
Primary, non destructive tool for identifying and quantifying the mineralogy of crystalline compounds in rocks, soils, abd particulates.
XRD (X-ray Diffraction)
Spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the stable state.
Atomic Absorption Spectroscopy (AAS)
- it can determine over 70 elements in solition or solid sample
An analytical technique accompanied by counting the number of ions at a certain mass of the element. It only analyzes liquid samples.
Inductvely Coupled Plasma Mass Soectrometry (ICP-MS)
The time taken for the radioactivity of a specified isotope to fall to half its original value
Half life
