Fe-Zn-S system and the sphalerite geobarometer
Fe-Zn-S system and the sphalerite geobarometer
Fe-Zn-S system and the sphalerite geobarometer
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How do we get <strong>the</strong>m out?<br />
� Carbonates: phosphoric acid -> CO 2<br />
� Silicates: reaction w/ BrF 5, F 2, ClF 3 -> O<br />
� O + hot graphite -> CO 2<br />
� Sulfides: heat w/ oxidant e.g. CuO<br />
� S + O -> SO 2<br />
� Or S + F source -> SF 6<br />
� OH or H 2O: reaction w/ hot U or <strong>Zn</strong> -> H 2<br />
� Now: Direct laser fluorination<br />
Ratios: Del/Delta Terminology<br />
� δO 18 , δD, δC 13 , δS 34<br />
� δ = (R sample/R std -1) * 1000<br />
� where<br />
� R sample = (O 18 sample /O16 sample )<br />
� Ex: a δ of +10 => sample 1% heavier than<br />
<strong>the</strong> st<strong>and</strong>ard<br />
St<strong>and</strong>ards<br />
� Very difficult to measure absolute<br />
amounts so always use st<strong>and</strong>ards<br />
allowing ratio measurements<br />
� O & H: referred to SMOW<br />
� Soft rockers may refer O to PDB<br />
� C: belemnite from <strong>the</strong> Pee Dee Fm: PDB<br />
� S: Canyon Diablo meteorite troilite: CDT<br />
Fractionation Factors<br />
� See reading for relationship of <strong>the</strong> delta<br />
notation to more rigorous derivation of <strong>the</strong><br />
fractionation factor between 2 minerals or<br />
phases yielding diagrams with axis of:<br />
� 10 3 lnα A-B<br />
� 10 3 lnα A-B ~ δ A - δ B = Δ AB<br />
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