Sulfur isotopic characteristics of volcanic products from the September 2014 Mount Ontake eruption, Japan

Earth, Planets and Space

Table 1 Sulfur isotopic values and concentrations of sulfur species of the pyroclastic materials of the 2014 Mt. Ontake eruption

Sample	Sulfur species	S (wt%)	δ³⁴S (‰)	±1σ (‰)
OT-1	Water-leached sulfate (H₂O-S)	0.50	+15.53	0.10
OT-1	Hydrochloric acid-leached sulfate (HCl-S)	0.62	+15.92	0.08
OT-1	Acetone-leached native sulfur (Native-S)	0.22	−3.86	0.07
OT-1	Pyrite (Pyrite-S)	1.79^a	−5.24	0.24^b
OT-3	Water-leached sulfate (H₂O-S)	0.54	+15.22	0.09
OT-3	Hydrochloric acid-leached sulfate (HCl-S)	0.58	+16.04	0.07
OT-3	Acetone-leached native sulfur (Native-S)	0.22	−3.77	0.08
OT-3	Pyrite (Pyrite-S)	1.12^a	−5.17	0.37^b

^aSome pyrite grains attached to lighter minerals (e.g., silicate minerals) might not have precipitated during density separation; therefore, the values should be considered as minimum sulfur concentrations
^bThe errors for pyritic sulfur in this study were larger than the precision determined for other samples; however, such larger errors likely originated from isotopic heterogeneity