Combined ICP-OES and XPS analysis to evaluate the [AlO] concentration in quartz: limiting the formation temperature of quartz.

A proposed quartz thermometer is based on the concentration of [AlO] tetrahedra determined by combining inductively coupled plasma optical emission spectrometry (ICP-OES) with X-ray photoelectron spectroscopy (XPS) data. The concentration of [AlO] tetrahedra in the quartz lattice (/ppm) and the formation temperatures of quartz (/°C) from agate, gold deposits, and granodiorite are calculated by = (ppm) × and (°C) = 3.6 × (ppm) × + 33.0, respectively. Where is the total Al concentration of quartz measured by ICP-OES and is the relative percentage of [AlO] tetrahedra in the quartz lattice and can be obtained by fitting the Al(2p) XPS spectrum. The obtained formation temperatures of quartz () agree well with the equilibrium formation temperature () calculated by oxygen isotope data. By comparing the relative positions of the two temperature curves of quartz ( and ), the composition of the mineral-forming fluid can be inferred. The proposed quartz thermometer can be applied to quartz formed under equilibrium conditions and in Al-saturated environments over a wide temperature range (152-566 °C). The use of the quartz thermometer effectively eliminates interference from different fluid compositions and satisfies the requirements of convenience and economy.