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Volatile Element Systematics of Hawaiian Shield Volcanoes
Erik Hauri, Jared Marske, Michael Garcia, Aaron Pietruszka, Frank Trusdell
• Shield-stage magmas; correlated majors, traces, isotopes • These correlations indicate variations in mantle source • Determine if there are differences in source volatile content • Test ideas on depth of magma delivery to rift zones • Determine magma ascent rates at summit and rift zones
• Requirements for accurate determination of volatiles in source • Fast quench rates
• Submarine glasses • Glassy melt inclusions (tephra)
• Minimal degassing (CO2 - S - H2O) • Deeply erupted (submarine) or deeply sourced (melt inclusions)
• Range of major element - trace element - isotope data
Now, that a heavy liquid should be mobile need not cause surprise…this is to be found, I believe, in its high gas content. – Frank Perret (1913), Lava Fountains of Kilauea, Am. J. Sci.
• Ion Microprobe • 10µm spatial resolution • Reproducibility 2-3% (2σ) • Accuracy ~10% • Rapid data acquisition (10 min)
Re/Os -> 187Os/188Os
Re
Os isotope variations are strongly controlled by mixing ratio of eclogite/peridotite
Os
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri et al. (1996)
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri et al. (1996)
• Shield-stage magmas; correlated majors, traces, isotopes
Lassiter & Hauri (1998)
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri (1996)
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri (1996)
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri (1996)
• Shield-stage magmas; correlated majors, traces, isotopes
Hauri (1996)
• Major elements + volatiles
Stolper et al. (2004)
n=4192
• Major elements + volatiles + trace elements
Stolper et al. (2004)
n=852
• Major elements + volatiles + traces + isotopes • Shield-stage • Minimal degassing (S - H2O)
Stolper et al. (2004)
n=94
Hauri (2002)
• Major elements + volatiles + traces + isotopes • Shield-stage • Minimal degassing (S - H2O)
Stolper et al. (2004)
n=94
Degassing
10%
90%
Cartigny et al. 2008
.
10
100
1000
10000
0.1 1 10 100 Nb [ppm]
CO2 [
ppm
]
Iceland NVZ CO2/Nb=400
Siqueiros MI CO2/Nb =240
MORB
Depleted
Enriched ?
Kilauea (Gerlach et al., 2002)
• Combined major-trace-isotope-volatile data sets very limited • H2O/Ce variations limited by data, uncertainties in degassing • Submarine glasses pervasively contaminated with seawater Cl • Suggestions of Cl differences among Hawaiian volcanoes (MI) • Insufficient data on F contents to evaluate • High primary CO2 contents consistent with global variations
Mahalo