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GSA 2010 Session: T103 Accessory minerals as monitors of magmatic processes: New ideas, applications, and pitfalls
From: "Calvin Miller " <calvin.miller@xxxxxxxxxxxxxx>
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To the volcano/magmatic processes community--
We would like to bring to your attention a session at the national GSA meeting this October titled, "Accessory minerals as monitors of magmatic processes: New ideas, applications, and pitfalls." The session description and full rationale is below. We are hoping to highlight young scientists and fresh perspectives, and in that spirit, our invited speakers for the session are Amy Hofmann (Cal Tech), Dustin Trail (RPI), and Jorge Vazquez (USGS). If you or your students or colleagues are interested, we strongly encourage you to submit an abstract.
Abstracts are due August 10 and can be submitted at
http://www.geosociety.org/meetings/2010/techprog.htm (session number T103). We are very excited about this session, and hope that you can present or attend!
Sincerely,
Lily Claiborne, Calvin Miller, & Jonathan Miller
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Rationale for Topical Session:
Accessory Minerals as Monitors of Magmatic Processes: New Ideas, Applications, and Pitfalls
Sponsored by Mineralogical Society of America and the newly formed GSA Mineralogy, Geochemistry, Petrology, and Volcanology Division
The last five years have seen explosive growth in application of accessory mineral analysis to interpretation of magmatic processes and crustal evolution. This has been facilitated by new experimental studies and development and refinement of analytical techniques and driven by an array of challenging questions that can now be addressed.
As quickly as promising new methodologies are developed, they are both applied and questioned. In this session, we hope to summarize and highlight this new work, what it has accomplished, where it may lead, and why some of the results and potential applications must be regarded with caution.
An array of minerals, including zircon, sphene (titanite), monazite, allanite, chevkinite, apatite, and rutile, have the potential to provide information on melt chemistry, temperature, volatiles, and (possibly) pressure, as well as time of growth. Sulfides, sulfates, and oxides also contribute to the characterization of magmatic environments. Most of these minerals retain chemical zoning so that individual grains provide a record of evolving conditions, and these records can be compared to constrain the physical and chemical processes that produce magmas. Furthermore, isotopic studies are effective at identifying the sequence of materials that contributed to the magmas from which individual crystals grew. Finally, textural analysis (grain size and shape and inclusion relations) provide further information about magma history.
Reliability of new methods and of interpretations based on them are being stridently debated - e.g., is the Ti-in-zircon thermometer reliable, and if not, is it because of uncertainty in a(TiO2), disequilibrium, improper calibration…? Are the magmas that have erupted to form some giant-scale ignimbrites formed by wholesale melting of the upper crust, as inferred from some zircon studies?
Calibration of new accessory mineral-based thermometers and refinements in analytical techniques that emphasize either increasingly high spatial resolution or precision (e.g. nanosims) promise new breakthroughs in the near future.
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