Magma residence time

A similar model is proposed for the Piton de la Fournaise, where there are significant differences between the constant ( Ra/ °Th) ratios of the lavas inside the Enclos caldera and the higher ratios of the lavas erupted outside this caldera, which are assumed to have bypassed the shallow magma chamber. Sigmarsson et al. (in preparation) explain these data by the existence of a steady state shallow reservoir and calculate a magma residence time of about 400 years. 

Ra- Th disequilibria have also been measured in several prehistoric and historic lava flows from Hawaiian volcanoes (e.g., Cohen and O Nions 1993 Hemond et al. 1994 Sims et al. 1999 Pietruszka et al. 2001). All these authors assume that the ( Ra/ Th) ratios have not been affected by radioactive decay in the shallow open-system reservoirs of tholeiitic volcanoes like Kilauea, and this is supported by independent evidence for short magma residence times (e.g., < 200 years Pietruszka and Garcia 1999). 

Figure 19. ( °Po/ °Pb)G and ( °Bi/ °Pb)o activity ratios in the gas phase as a function of the magma residence time t in the degassing reservoir. Curves are drawn from the equations ...

Black S, Macdonald R, De Vivo B, Kilbum CRJ, Rolandi G (1998) U-series diseqnilibria in yonng (A.D. 1944) Vesnvins rocks Preliminary implications for magma residence times and volatile addition. J Volcanol Geotherm Res 82 97-111... 

Heath E, Turner SP, Macdonald R, Hawkesworth CJ, van Calsteren P (1998) Long magma residence times at an island arc volcano (Sonfriere, St. Vincent) in the Lesser Antilles Evidence from isochron dating. Earth Planet Sci Lett 160 49-63... 

The magma residence time can be estimated by recasting equation (7.2.23) as... 

In particularly favorable cases, inferences about magma residence times can be derived from other isotopic systematics, most notably Rb- Sr (Davies et al., 1994 Halliday et al., 1989). Extremely evolved magmas can have sufficiently high Rb/Sr for Sr isotope signatures to evolve detectably on timescales commensurate with magmatic processes, enabhng the time since differentiation to high Rb/Sr to be delimited. Correlations between diverse Rb/Sr and Sr/ Sr in some suites of silicic lavas may be dominantly those of in situ decay rather than open-system processes, in which case they delimit the differentiation events... 

Black S., Macdonald R., DeVivo B., Kilburn C. R. J., and Rolandi G. (1998b) U-series disequilibria in young (AD 1944) Vesuvius rocks preliminary implications for magma residence times and volatile addition. J. Volcanol. Geotherm. Res. 82, 97-111. 

Brown S. J. A. and Fletcher I. R. (1999) SHRIMP U-Pb dating of the preemption growth history of zircons from the 340 ka Whakamaru Ignimbrite, New Zealand evidence for >250 ky magma residence times. Geology 27, 1035-1038. 

Francalanci L., Tommasini S., Conticelli S., and Davies G. R. (1999) Sr isotope evidence for short magma residence time for the 20th century activity at Stromboli volcano, Italy. Earth Planet Sci. Lett. 167, 61-69. 

Bourdon B., Woerner G., and Zindler A. (2000) U-series evidence for crustal involvement and magma residence times in the petrogenesis of Parinacota Volcano, Chile. Contrib. Mineral. Petrol. 139, 458-469. 

Cocherie,A.,Fanning, CM., Jezequel, R, Robert, M. (2009) LA-MC-ICPMS and multi-ion counting system, and SHRIMP U-Pb dating of complex zircons from quaternary tephras from the French Massif Central magma residence time and geochemical implications. Geochimica et Cosmochimica Acta, 73,1095-1108. 

The CSD of the product from a continuous crystallizer is determined by a direct relationship between nucleation and crystal growth rates and magma residence time distributions. Since a priori prediction of crystallization kinetics is not yet possible, however, experimentally determined and statistically correlated nucleation and growth rates are needed for the design and analysis of industrial crystallizers. Analysis of the CSD from continuous MSMPR (mixed-suspension, mixed-product-removal) crystallizers has proved to be a popular way of inferring such crystallization kinetics. This approach has been widely... 

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