Changes

==Errors and Limitations==

==Errors and Limitations==

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]] (TiO₂). 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]] (SiO₂) 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]] (TiO₂). 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]] (SiO₂) 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" />