Validation of LA-ICP-MS fluid inclusion analysis with synthetic fluid inclusions

Abstract

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has become recognized as a sensitive, effi cient, and cost-effective approach to measuring the major-, minor-, and trace-solute compositions of individual fl uid inclusions in minerals. As a prerequisite for the routine analysis of natural inclusions in our laboratory, the precision and accuracy of the technique was assessed using sets of multi-element synthetic fl uid inclusions. Five multi-element standard solutions were prepared, and incorporated as fl uid inclusions in quartz crystals at 750 °C and 7 kbar. Fluid inclusions were ablated with a 193 nm ArF excimer laser and analyzed with a quadrupole ICP-MS, equipped with an octopole reaction cell for the removal of Ar-based interferences. The internal standard used in all cases was Na. Analytical precision for K, Rb, and Cs is typically better than 15% RSD, whereas Li, Mg, Ca, Sr, Ba, Mn, Fe, Cu, Zn, and Cl analyses are typically reproducible within 30% RSD. Measured concentrations approximate a Gaussian distribution, suggesting that analytical errors are random. Analyses for most elements are accurate within 15%. Limits of detection vary widely according to inclusion volume, but are 1 to 100 µg/g for most elements. These fi gures of merit are in excellent agreement with previous studies. We also demonstrate that, over the range investigated, precision and accuracy are insensitive to inclusion size and depth. Finally, the combination of our LA-ICP-MS analyses with microthermometric data shows that charge-balancing to NaCl-H 2 O equivalent chloride molality is the most valid approach to LA-ICP-MS data reduction, where chloride-dominated fl uid inclusions are concerned.

Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula, NW Turkey

“…based on [34]. The homogenization temperatures from the different locations (Figure 7) all have a large, and similar, range for either the P or PS inclusions that cannot be accounted for by normal uncertainties during measurement.…”

“…with galena from -9.0 to -9.8 (Table 4), and are more negative than the δ 34 S values of sulphides from the majority of the magmatic hydrothermal deposits (-3 to +1 ; [37]). They are also lower than those of mantle (0±3 ), igneous rocks (+1 to +3 ) sulphur [38], crustal sulphur (mean +7 ; [39]) and sulphur derived from seawater (+20 ; [40]).…”

“…They are also lower than those of mantle (0±3 ), igneous rocks (+1 to +3 ) sulphur [38], crustal sulphur (mean +7 ; [39]) and sulphur derived from seawater (+20 ; [40]). Negative δ 34 S sulphide values for low-sulphidation epithermal veins may have been be a consequence of interacting with an external, isotopically light S-source, such as biogenic sulphide minerals, however, no sedimentary sulphides were observed in any exposed sedimentary rocks in the area.…”

“…The δ 34 S values of chalcopyrite in the Tesbihdere deposit range from -5.4 to -2.4 , in the Azitepe deposit from -5.6 to -6.9…”

“…Integration of the standard and sample signals was achieved with the SILLS software package [33]. Full details of the analytical protocols and calibration of the instrument are presented in [34]. …”