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Mount Mageik, Katmai National Park, Alaska
Generally, I am interested in silicic magmatic systems, including plutonic, volcanic, and what lies in between. This includes differentiation of magmas, the fluid mechanics of crystal mushes, signatures of magmatic processes recorded in accessory minerals, assembly of plutons and sub-volcanic plumbing systems. I use fieldwork, petrography, geochronology, geothermometry, geochemistry, and theoretical and physical modeling to address magmatic questions.
I also enjoy geoscience and environmental education, whether as a Teaching Assistant or working with youth or the general public. I never miss an opportunity to share my love and my knowledge of the natural world with others, with hopes of instilling in them a better understanding and appreciation of the environment in which they live and thereby, a better awareness of their connection to and dependence and impact on the world outside themselves.
Mount Saint Helens, Washington, erupting on May 18, 1980 (http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/MSH80/
framework.html#may_18_1980)
- The sub-volcanic history of Mount St. Helens
- Composition of igneous zircon
- Physical processes in crystal mushes
- Volcano-pluton connections
Excerpt from most recent grant proposal:
Zoned zircons record the time-temperature-composition history of the magma in which they grew. Recent development of trace element analysis techniques using SHRIMP-RG (Mazdab and Wooden, 2006), combined with in situ U-Pb and U-series geochronology and the new Ti-in-zircon thermometer (Watson et al., 2006), provides a powerful tool for extracting this information. We have used this approach to delineate the complex history of the Spirit Mountain batholith in southern Nevada, including repeated episodes of crystallization, melt evolution, differentiation, recharge, and transport of magma between storage zones in the shallow, Miocene intrusive system (Lowery Claiborne, et al., 2006; Walker et al., in press). Zircons from individual samples, and even single zircon grains, record temperature variations of up to 100°C and order-of-magnitude variations in trace element concentration. Unfortunately, the timescales of closely-spaced events recorded by zoning are beyond resolution of in situ (SHRIMP) U-Pb geochronology (>105 years for Miocene zircons). By applying these methods to zircons erupted from very young volcanic systems, including U-series geochronology with its much higher age resolution (~104 years), we anticipate better constraining the timescales of pre-eruptive magmatic processes such as rejuvenation and differentiation, and providing insight concerning the connections between volcanic and plutonic systems.
While the recent history of Mount St. Helens is one of the most thoroughly investigated volcanic systems in the world, its more distant past is just beginning to be unraveled. No studies have yet attempted to read the magmatic history of the system recorded in zircons from its erupted units. The relatively low diffusivity of Zr in melts limits zircon growth and dissolution rates. Thus, analyzable zircon zones are likely to reflect relatively long-term growth (order of 103 years), and zircon grains may survive periods of undersaturation (<10 to 105 years, depending on conditions), for example in response to reheating immediately prior to eruption. This record, therefore, may provide clues as to how the magmas that erupted from Mount St. Helens were stored, differentiated, and mechanically interacted prior to eruption, both in the recent active history of the system and in less well known, earlier stages.
The dacites from Mount St. Helens, by far the most voluminous product throughout its history, appear somewhat monotonous in bulk composition, but studies of 1980-1986 and 2004-2006 mineral assemblages and phenocryst and trace-element compositions hint at a more complex history that may also be reflected in zircons from units throughout its existence. We have collected a suite of samples that span the eruptive history of Mount St. Helens, from the Ape Canyon Stage, beginning ~300 ka, to the most recent eruption (December 2005), and have extracted zircons from five samples thus far. A single analyzed sample, an Ape Canyon Stage quartz-biotite dacite, yielded a complex 238U-230Th age spectrum indicating multiple ages of growth ranging from ~50 ka to 300 ka or more. Elemental as well as U-series analyses of our samples (scheduled for May '07) will provide further insight into the evolution of the magmatic plumbing system sustaining Mount St. Helens since its beginnings ~300 ka.
- The history of the Spirit Mountain batholith, southern Nevada
- formation of high silica magmas
- crystal fractionation and melt segregation
- composition of igneous zircon
- physical processes in crystal mushes
Excerpt from project proposal:
Many lines of evidence have recently been cited from both plutonic and volcanic rocks to suggest that felsic magma systems have protracted histories, on the order of several hundred thousand to several million years, and that these histories require frequent replenishment (e.g., Wiebe and Hawkins, 2004; Davies et al., 1994; Reid et al., 1997; Brown & Fletcher, 1999; Schmitt et al., 2003; Vazquez & Reid, 2002; Charlier et al., 2005; Miller and Wooden, 2004; Glazner et al., 2004; Coleman et al., 2004). Such histories imply the possibility that temperature and quantity and composition of melt fluctuate in time and space (e.g. Vazquez & Reid, 2002; Harper et al., 2004), but elucidating the time-composition path has proven difficult. In order to fully characterize these magmatic systems, it is essential to identify and qualitatively comprehend processes such as fractionation that produce highly evolved melts, including high-silica rhyolites, to determine the timescales on which these processes operate, and understand the behavior of the products.
It is generally accepted that high-silica rhyolite forms from fractional crystallization (segregation of melt from a crystal assemblage) (Bachmann and Bergantz, 2004; Miller and Mittlefehldt, 1984), but the mechanisms by which it forms remain controversial. Apparent paucity of preserved plutonic equivalents, on a similar scale, has hampered testing of hypotheses concerning the origins of these magmas. The very large (>55 km2) roof zone of the Spirit Mountain batholith in southern Nevada provides an unusual opportunity to investigate the plutonic equivalent of a high-silica rhyolite and a network of compositionally similar aplite dikes and sills, records of the generation and behavior of these magmas and their role in pluton assembly. A roughly time-equivalent volcanic sequence in the nearby Black Mountains of Arizona may be the extruded products of the Spirit Mountain batholith. This sequence includes high-silica rhyolite that may provide a better understanding of these fractionated magmas and the dynamics of magma chamber and volcanic systems.
We have recently used rocks from the Spirit Mountain batholith to identify and develop a new tool that uses the ratio of zirconium (Zr) to hafnium (Hf) in zoned zircons to identify and track fractionation (segregation of melt from crystals, considered the most likely mechanism for production of highly evolved magmas) within a magma chamber (Lowery et al., in review). By combining data from in situ SHRIMP U-Pb geochronology, Ti-in-zircon thermometry (Watson and Harrison, 2005), and trace element analysis including Hf, it is possible to identify specific fractionation and reheating events in the history of a zircon crystal and, thereby, the magma in which it grew. In modern and recent volcanic rocks, U-Series disequilibria (by in situ SHRIMP analysis) can provide a high age resolution, and when combined with Hf-fractionation and Ti-in-zircon thermometry, may provide a new, unparalleled method for determining pre-eruptive histories of volcanic systems.
Papers as first author:
Claiborne, L.L., C.F. Miller, B.A. Walker, J.L. Wooden, F.K. Mazdab and F. Bea (2006) Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada, Mineralogical Magazine, v. 70, no. 5, p. 517-543.
Claiborne, L.L., Miller, C.F., Wooden, J.L. and Mazdab, F.K. (in prep) Trace element composition of igneous zircons: Analysis of zircons from the Spirit Mountain batholith, southern Nevada using SHRIMP-RG.
Presenter:
*Claiborne, L.L., Clynne, Michael A., Pallister, John S., Miller, Calvin F., Wooden, Joseph L., Mazdab, Frank K., Lowenstern, Jacob B., Wooden, J.L. (in press) Investigating the evolution of the Mount St. Helens plumbing system using SHRIMP-RG U-Pb, U-series, and trace element analysis of zircon. International Union of Geodesy and Geophysics – 2007 meeting abstracts.
*Claiborne, L. L., Furbish, D.J., Miller, C.F. (2006) Determining mechanics of segregation of small crystals from melt using modeling and SHRIMP-RG trace element analysis of zircons: Application to the Spirit Mountain batholith, Nevada. American Geophysical Union – 2006 Fall Meeting Abstracts with Programs.
*Lowery, L.E., C.F. Miller, J.L Wooden, F.K. Mazdab and F. Bea (2006) Hf and Ti zoning in zircons: detailed records of magmatic processes, European Geosciences Union Abstracts with Programs.
*Miller, C.F., *Claiborne, L.L. (2006) T-time-composition histories of magma preserved in zircon zoning: Rationale and potential application at Mount St. Helens. Presentation at the USGS-CVO 2006 Mount St. Helens Petrology Workshop.
abstracts.
Miller, C.F., *L.E. Lowery and F. Bea (2005) Zircons and Zr/Hf: Assessing magmatic fractionation in the crust. Geochimica et Cosmochimica Acta, v.69, no.10, Suppl., pp.10.
Papers and Presentations as co-author:
*Miller, C.F., J.E. Faulds, J.S. Miller, J.L. Wooden, R.V. Metcalf, D.J. Furbish, L.L. Claiborne, B.A. Walker, D.S. Perrault, K.F. Hodge(in press)The Miocene volcano-plutonic suite of the northern Colorado River Corridor, Nevada-Arizona, USA. International Union of Geology and Geophysics – 2007 meeting abstracts.
Miller, C.F., *Furbish, D.J., Lowery Claiborne, L., Walker, B.A., Bleick, H.A., Steinwinder, T.R., Koteas, G.C. (2006) Hiding the Evidence: Growth of plutons by incremental emplacement of sheets in crystal mush. American Geophysical Union – 2006 Fall Meeting Abstracts with Programs.
*Wooden, J.L., Mazdab, F.K., Lowery Claiborne, L., Miller, C.F., Barth, A.P. (2006) Elemental Analysis of Zircon by High Mass Resolution USGS-Stanford SHRIMP-RG: Measuring and Evaluating Ti-in-zircon Temperatures and Compositional Characteristics. American Geophysical Union – 2006 Fall Meeting Abstracts with Programs.
Walker, B.A., C.F. Miller, L.L. Claiborne, J.S. Miller and J.L. Wooden (in press) Batholith construction: New insights concerning timescales and physical processes from the Spirit Mountain Batholith, southern Nevada, Journal of Volcanological and Geothermal Research.
*Wooden, J.L., F.K. Mazdab, A.P. Barth, C.F. Miller and L.E. Lowery (in press) Temperatures (Ti) and Compositional Characteristics of Zircon: Early Observations Using High Mass Resolution on the USGS-Stanford SHRIMP-RG, Goldschmidt Abstracts with Programs.
*Miller, C.F., Lowery Claiborne, L., Wooden, J.L., Mazdab, F.K., Walker, B.A. (2006) Record of T-time-composition histories of magmas preserved in zircon zoning. G.P.L. Walker Memorial Symposium,
*Miller, C.F., B.A. Walker, L.E. Lowery, J.S. Miller, H.A. Bleick, J.E. Faulds, D.J. Furbish, G.C. Koteas (2005) Construction of plutons by horizontal depositional intrusive sheets. Abstracts with Programs - Geological Society of America, v. 37, no. 7, p. 130.
*indicates speaker
**note name change in 2006 – Lily E. Lowery to Lily Lowery Claiborne
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