− | Ti-in-Zircon geothermometry is considered to be a relatively reliable and accurate method of determining crystallization temperatures of zircons, with a error of only 10-16 degrees Celsius. However, the major constraint of this process is that it is only usable in systems that contain titanium, or the mineral [[rutile]] (TiO<sub>2</sub>). In systems that have no or very little titanium, this method is pointless, as zircons will not incorporate titanium if it is not present in the magmatic melt.<ref name="Watson and Harrison 2005" /> However, recent models have taken into account zircon's ability to replace either silicon or zirconium in the crystal with titanium by using independent activities of Si and Zr.<ref name="Ferry and Watson 2007 New Thermo models and revised calibrations">{{cite journal|last1=Ferry|first1=J.M.|last2=Watson|first2=E.B.|title=New thermodynamic models and revised calibrations for the Ti-in-zircon and Zr-in-rutile thermometers|journal=Contributions to Mineralogy and Petrology|date=Oct 2007|volume=154|issue=4|page=429-437|doi=10.1007/s00410-007-0201-0|url=http://link.springer.com/article/10.1007%2Fs00410-007-0201-0|accessdate=29 November 2014}}</ref> This has expanded the potential uses for zircons with unknown origins, due to the abundance of silicon in Earth's crust. In some zircon crystals, inclusions of the mineral [[quarts]] (SiO<sub>2</sub>) can be used as proof that silicon was present during crystallization, thus validating the use of this geothermometer. | + | Ti-in-Zircon geothermometry is considered to be a relatively reliable and accurate method of determining crystallization temperatures of zircons, with a error of only 10-16 degrees Celsius. However, the major constraint of this process is that it is only usable in systems that contain titanium, or the mineral [[rutile]] (TiO<sub>2</sub>). In systems that have no or very little titanium, this method is pointless, as zircons will not incorporate titanium if it is not present in the magmatic melt.<ref name="Watson and Harrison 2005" /> However, recent models have taken into account zircon's ability to replace either silicon or zirconium in the crystal with titanium by using independent activities of Si and Zr.<ref name="Ferry and Watson 2007 New Thermo models and revised calibrations">{{cite journal|last1=Ferry|first1=J.M.|last2=Watson|first2=E.B.|title=New thermodynamic models and revised calibrations for the Ti-in-zircon and Zr-in-rutile thermometers|journal=Contributions to Mineralogy and Petrology|date=Oct 2007|volume=154|issue=4|page=429-437|doi=10.1007/s00410-007-0201-0|url=http://link.springer.com/article/10.1007%2Fs00410-007-0201-0|accessdate=29 November 2014}}</ref> This has expanded the potential uses for zircons with unknown origins, due to the abundance of silicon in Earth's crust. In some zircon crystals, inclusions of the mineral [[quartz]] (SiO<sub>2</sub>) can be used as proof that silicon was present during crystallization, thus validating the use of this geothermometer. |
| Another difficulty with this microanalysis is the contamination of Ti on external surfaces. Recent studies have expressed concern over the [[gold]] coating on the surface of the ion microprobe mounts, which contains small amounts of Ti (~1 ppm) that could provide an error during measurement. In [[detrital]] zircons found in sedimentary sources, a Ti-bearing oxide coating on the surface and in fractures of zircons can also contaminate the crystal with excess titanium.<ref name="Watson Wark Thomas 2006" /> | | Another difficulty with this microanalysis is the contamination of Ti on external surfaces. Recent studies have expressed concern over the [[gold]] coating on the surface of the ion microprobe mounts, which contains small amounts of Ti (~1 ppm) that could provide an error during measurement. In [[detrital]] zircons found in sedimentary sources, a Ti-bearing oxide coating on the surface and in fractures of zircons can also contaminate the crystal with excess titanium.<ref name="Watson Wark Thomas 2006" /> |