Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

Details Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

Dec 1989

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1989e%26psl..96..199b&link_type=abstract

Earth and Planetary Science Letters, Volume 96, Issue 1-2, p. 199-208.

Other

22

Scientific paper

Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower δ18O values (-3.4 to +4.9‰) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0‰). Oxygen isotope fractionation between phases in granitoids is consistent with equilibrium at T >= 900°C following subsolidus exchange with hydrothermal fluids of meteoric origin. Assimilation of ~ 10-20% of material similar to these granitoids can account for the O and Sr isotopic compositions of lavas and juvenile pyroclasts derived from the climactic magma chamber, many of which have δ18O values ~ 0.5‰ or more lower than comparable lavas of Mount Mazama. The O isotope data provide the only clear evidence for such assimilation because the mineralogy and chemical and radiogenic isotopic compositions of the granitoids (dominantly granodiorite) are similar to those of erupted juvenile magmas. The granitoid blocks from Crater Lake serve as direct evidence for the origin of 18O depletion in large, shallow silicic magma bodies.

Affiliated with

Also associated with

No associations

Rating

Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1569526