科研之友
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摘要
Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti-in-quartz (TitaniQ) geothermometer applicable to geological conditions up to similar to 20kbar. We present a new method for determining Ti-48 mass fractions in quartz by LA-ICP-MS at the 1gg(-1) level, relevant to quartz in HP-LT terranes. We suggest that natural quartz such as the low-CL rims of the Bishop Tuff quartz (determined by EPMA; 41 +/- 2gg(-1) Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are insignificant, thus allowing for the use of Ti-48 as a normalising mass. Average titanium mass fraction from thirty-three analyses of low temperature quartz from the Czech Erzgebirge is 0.9 +/- 0.2gg(-1) (2s) using Ti-48 as a normalising mass and Bishop Tuff quartz rims as a reference material. The 2s average analytical uncertainty for individual analyses of Ti-48 is 8% for 50m spots and 7% for 100m spots, which offers much greater accuracy than the 21-41% uncertainty (2s) incurred from using Ti-49 as an analyte.
- 出版日期2017-3
