Alkaline sulphate fluids produced in a magmatic hydrothermal system

More documents

Recommendations

Info

hot springs at Savo, alkaline and acidic, which can be defined on the basis of chemistry, stable isotope ratios and physical nature of the spring. 4.1 Alkaline Sulphate Hot Springs Hot springs defined as alkaline sulphate type are pH C 7–8 and have a restricted δ 34 S SO4 of 5.4 ± 1.5‰ (Table 1; Table 2; Fig. 3) and δ 18 O H2O values only slightly greater than local nonthermal groundwater. Sulphate δ 18 O values for alkaline hot springs vary between 4.0 and 7.9‰. Crater Wall springs (Table 1) are sulphate-rich (600–680 mg/l), with very low chloride (~5 mg/l) and moderate DIC (~90 mg/l HCO − 3 equivalent) and SiO 2 (~250 mg/l). Calcium is as high as ~250 mg/l, Na ~90 mg/l, K ~17 mg/l, and Mg ~12 mg/l. Only trace iron and aluminium are present (
enrichment of both 18 O and D, and also has the lowest δ 34 S SO4 value (+3.8‰) of the alkaline sulphate springs. 4.2 Acid Sulphate Hot Springs Springs classified as acid sulphate type have a distinct δ 34 S SO4 of −0.6 ± 2.5‰ (Fig. 3), contrasting markedly with alkaline sulphate springs. They also display high δ 18 O H2O and δD H2O relative to non-thermal groundwater, and pH C
Page 1 and 2: Alkaline sulphate fluids produced i
Page 3 and 4: low-chloride fluids which precipita
Page 5 and 6: timescales of a few minutes, and in
Page 7 and 8: 3 Sampling and Analytical Methods 3
Page 9 and 10: Comparison of SO 2− 4 as determin
Page 11: isotopes were measured relative to
Page 15 and 16: average meteoric water composition
Page 17 and 18: The thermometer discrepancies indic
Page 19 and 20: same process. Evidence of mixing in
Page 21 and 22: the addition of magmatic volatiles
Page 23 and 24: The Black Pool in the crater of El
Page 25 and 26: Dilution is the key process whereby
Page 27 and 28: Coleman, M.L. and Moore, M.P., 1978
Page 29 and 30: Petterson, M.G., Cronin, S.J., Tayl
Page 31 and 32: 9 Tables Table 1: Data for Crater W
Page 33 and 34: temperature >30°C) are shaded; the
Page 35 and 36: Fig. 5: 87 Sr/ 86 Sr versus δ 34 S
Page 37 and 38: Fig. 8: Plots showing effects of mi

Alkaline sulphate fluids produced in a magmatic hydrothermal system

Create successful ePaper yourself

Delete template?

Save as template?