Guilherme Gualda

Education – Interests – Research – Publications – Software

Assistant Professor
g.gualda@vanderbilt.edu
Personal Page
Office: 5717 Science & Engineering Bldg
Phone: (615) 322-3840

Education

Ph.D. University of Chicago, 2007 
M.S. Universidade de São Paulo, 2001
B.S. Universidade de São Paulo, 1999

Specializations

• Igneous Petrology
• Volcanology
• Mineralogy
• Geochemistry

 

Education                                   Top - Education – Interests – Research – Publications – Software

Ph.D., Geophysical Sciences, The University of Chicago, 2007
Dissertation: Crystal and bubble populations in the Bishop pre-eruptive magma: Microscopy, x-ray tomography and microanalysis of pumice clasts Download (15 Mb)

M.Sc., Mineralogy and Petrology, Universidade de São Paulo, 2001
Thesis: Petrographic and mineralogical evolution of the alkaline and aluminous associations of the Graciosa A-type Granites, PR Download (12 Mb)

B.Sc., Geology, Universidade de São Paulo, 1999
Senior Thesis: Chemical variations in mafic minerals and the evolution of agpaitic magmas from the Anel Norte Lujavritic-Khibinitic Body - Poços de Caldas Alkaline Massif (MG-SP) Download (7 Mb)

 B.Sc. Secondary Education, Geology, Universidade de São Paulo, 1999

 

Interests                                     Top - Education – Interests – Research – Publications – Software

General: Igneous petrology, volcanology, mineralogy, geochemistry

 Specific: Supereruptions and the magma bodies from which they form, crystals and bubbles in magmas, silicic magmatism, quantitative petrography, mineral zoning

 Approaches: X-ray tomography, microscopy and microanalysis

 

Research                                     Top - Education – Interests – Research – Publications – Software

Motivation

The existence of molten rock within the Earth is an idea that has fascinated scientists for millennia, and understanding the origins and the evolution of magmas is a subject at the core of the geological sciences.

The fundamental goal of my research is to better understand the evolution of magma bodies, in particular silica-rich magma bodies. I aim to unravel the processes that shape the evolution of these magma bodies, and to constrain their physical state at various stages of their evolution. I pay particular attention to the stages leading to eruption, and in the conditions that make eruptions possible, likely, or inevitable. I am especially interested in combining the volcanic and plutonic records in this effort.

I pursue these problems by exploring the detailed record of magmatic processes preserved in minerals and vesicles (i.e. bubble casts), such that my research lies at the interface between petrology, mineralogy, and geochemistry. I study two facets of the rock record. On one hand, I use the physical distribution of crystals and vesicles, their sizes and contact relations – what we call textures. On the other hand, I use mineral compositions and compositional variations (zoning) not only to yield information on the internal histories of crystals, but also to correlate the textural evolution with the more studied chemical evolution.

What we seek is a clearer picture of the spatio-temporal evolution of magma bodies, the processes that shape their evolution, and the conditions that lead to or prevent eruptions from happening.

The nature of my work calls for detailed documentation of rock textures, and one of the main challenges lies in developing methods that allow better observation, quantification, and interpretation of the relevant parameters. Of particular interest is the development of techniques that allow three-dimensional imaging, and we have focused on the use of x-ray tomography, which can provide a more complete view of rocks, to be added to the suite of observations in two dimensions possible with optical and electron microscopy.

Ongoing Research

I currently divide my research efforts into five interdependent projects, variable in nature but all dealing with the evolution of silica-rich magmatic systems along the lines discussed above. All of these efforts benefit from the participation of students, from undergraduates to Ph.D. students.

(1) Conditions and timescales of crystallization of the Bishop Tuff giant magma body and its supereruption  (with Alfred Anderson, Steve Sutton, Mark Rivers – Chicago)

In this project, we are using a combination of crystal size distributions, trace-element zoning of quartz and sanidine crystals, and textures of melt inclusions in quartz to assess the conditions and the timescales of crystallization of the Bishop magma, which culminated with a supereruption that deposited > 600 km3 of rock at the surface and formed the Long Valley Caldera (California).

Three lines of evidence indicate that crystallization was much faster than originally thought, on the order of thousands of years, rather than hundreds of thousands of years (see image, click to enlarge). An important event took place close to eruption time and led to significant crystallization in disequilibrium conditions. Results have important implications to the evolution of silicic systems and to the assessment and mitigation of hazard related to supereruptions.

Graduate student Ayla Pamukçu documented the textures of late-erupted pumice using x-ray tomography for her senior thesis in Chicago. Undergraduate Mitchell Williams and I started working towards developing a method for fast evaluation of crystal and bubble size distributions in pumice, which may allow us to study a much larger number of samples than currently possible.

(2) Accessory mineralogy and evolution of the Peach Spring Tuff magma
(with Calvin Miller, John Ayers - VU, Charles Ferguson - Arizona State Survey, Jonathan Miller - San Jose State)

The Peach Spring Tuff is a very large rhyolitic deposit exposed in Nevada, Arizona, and California formed during a supereruption ca. 18.75 Ma. It is remarkable by its rich accessory mineralogy, which provides a unique opportunity to understand the evolution of silicic magmas that feed supereruptions.

We are using a combination of mineral and glass chemistry, detailed textural analysis using x-ray tomography, whole-rock geochemistry, and age-dating to explore the evolution of this magma body; results thus far reveal intriguing textural relationships between the various accessory phases (see image), which we are currently documenting in more detail.

Ph.D. student Ayla Pamukçu just finished a M.Sc. thesis in which she combined textural documentation using x-ray tomography, zircon and titanite (sphene) chemical compositions and zoning, and glass compositions to understand the magmatic evolution of the Peach Spring Tuff. Ph.D. student Tamara Carley also studied the Peach Spring Tuff as part of her M.Sc. research, in which she studied whole-rock and glass major element geochemistry, in combination with the thermodynamic modeling software MELTS to unravel potential evolutionary paths for magma that formed the Peach Spring Tuff.

(3) Volcano-pluton connections in silicic magmatic systems of the Colorado River Extensional Corridor (with Calvin Miller - VU, Alfred Anderson - Chicago)

We are studying rocks from the Highland Range volcanic sequence and the potentially correlative Searchlight Pluton in southern Nevada, in an attempt to better understand the connections between volcanic and plutonic (deep-seated) systems exquisitely exposed in the area.

Lindy Colombini completed her M.Sc. thesis in 2009, in which she used field, petrographic, and age-dating (U-Pb SHRIMP on zircon, Ar-Ar on sanidine) data to show that the Highland Range sequence grades from dacitic and predominantly effusive at the bottom to rhyolitic and predominantly explosive at the top, suggesting a shift in eruptive style with differentiation. The data on sphene and zircon suggest the two minerals record different stages of the crystallization interval (see plot), while glass compositions reflect significant sphene fractionation.

Undergraduate Evan Kelly and masters student Abe Padilla are currently combining field, petrographic, and whole-rock data to investigate the origin of lava units that provide compelling evidence for the coexistence of various magma types at the same time in the magmatic system at depth.

(4) Eruptive potential of silicic magmas: Thermodynamic and fluid dynamics modeling
(with Mark Ghiorso - OFM Research, Josef Dufek - Georgia Tech)

In this recently funded project, we want to better understand why some silicic magmas erupt while others stall in the subsurface, and, in particular, why do some magmas erupt effusively while others erupt explosively. As part of this project, we are (a) developing thermodynamic models that can more accurately reproduce phase equilibria in silicic magmas; (b) coupling these models with fluid dynamics models of the time-dependent evolution of silicic magma bodies and surrounding country rocks (see diagram); and (c) comparing critical modeling results to natural occurrences of systems that have erupted, with the aim of illuminating differences in eruptive style and mechanisms that trigger explosive activity.

Undergraduate Robin Vaum used a modified version of MELTS to simulate the evolution of a variety of silicic magmas representative of the Highland Range, with the goal of better constraining crystallization conditions, in particular water contents. In her M.Sc. thesis, Ph.D. student Tamara Carley used this modified version of MELTS to constrain the effect of initial fluid concentration on the eruptibility of high-silica rhyolites, using the Peach Spring Tuff as an example.

(5) Age and evolution of the Graciosa A-type Province, southern Brazil
(with Brendan Bream - VU, Renato Almeida - São Paulo)

The focus of this study is the use of zircon geochronology and geochemistry by means of Laser Ablation ICP Mass Spectrometry to assess the age and the magmatic evolution of a series of A-type rocks in southern Brazil.

We are studying zircons from granitic, volcanic and sedimentary rocks in order to better understand the chronology of the magmatic evolution, and how it relates to the sedimentary and tectonic evolution of basins in southern Brazil.

Undergraduate student Steven Braun just finished a senior thesis focused on this project. As part of his work, we (a) established a protocol for routine analysis of zircon; (b) characterized zircon from Zirconia (NC) and evaluated its potential as an analytical standard (see plot); and (c) studied the geochronology of a set of granites and syenites in the Graciosa Province, for which we were able to distinguish between magmatism, alteration and inheritance.

Opportunities for Students

Opportunities for students are immediately available under the projects above, and I am open to discussing projects outside of these with prospective students.

 

Publications (*denotes Students)                                           Top - Education – Interests – Research – Publications – Software

Articles

Ghiorso MS & Gualda GAR (in review) A method for estimating the activity of titania in magmatic liquids from the compositions of coexisting rhombohedral and cubic iron-titanium oxides. Contributions to Mineralogy and Petrology

Baker DR, Mancini L, Polacci M, Higgins M, Gualda GAR, Hill R, Rivers ML (in review) An introduction to the application of X-ray microtomography to the three-dimensional study of igneous rocks. Lithos

*Pamukcu AS, *Carley TL, Gualda GAR, Miller CF, Ferguson CA (in revision) The evolution of the Peach Spring Tuff magmatic system as revealed by accessory mineral textures and compositions. Journal of Petrology

Gualda GAR, *Pamukcu AS, Anderson AT Jr., Ghiorso MS, Sutton SR, Rivers ML (revised) Timescales of quartz crystallization and the longevity of the Bishop giant magma body. PLoS One

Gualda GAR, Ghiorso MS, *Lemons RV, *Carley TL (2012) Rhyolite-MELTS: A modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Journal of Petrology, in press [ DOI:10.1093/petrology/egr080 ]

*Pamukcu AS, Gualda GAR, Anderson AT Jr. (2012) Crystallization stages of the Bishop Tuff magma body recorded in crystal textures. Journal of Petrology, in press [ DOI:10.1093/petrology/egr072 ]

*Colombini LL, Miller CF, Gualda GAR, Wooden JL, Miller JS (2011) Sphene and zircon in the Highland Range volcanic sequence (Miocene, southern Nevada, USA): Elemental partitioning, phase relations, and influence on evolution of silicic magma. Mineralogy & Petrology, 102: 29-50 [ DOI:10.1007/s00710-011-0177-3 ]

Vlach SRF, Siga Jr O, Harara OM, Gualda GAR, Basei MAS, Vilalva FCJ (2011) Crystallization ages of the A-type magmatism of the Graciosa Province (Southern Brazil): Constraints from zircon U-Pb (ID-TIMS) dating of coeval K-rich gabbro-dioritic rocks. Journal of South American Earth Sciences, 32: 407-415 [ DOI:10.1016/j.jsames.2011.03.017 ]

Gualda GAR & Ghiorso MS (2011) Comment on ‘A metamodel for crustal magmatism: Phase equilibria of giant ignimbrites’ by S. J. Fowler and F. J. Spera. Journal of Petrology, 52: 431-434 [ DOI:10.1093/petrology/egq097 ]

Gualda GAR, *Pamukcu AS, *Claiborne LL, Rivers ML (2010) Quantitative 3D petrography using x-ray tomography. 3: Documenting accessory phases with differential absorption tomography. Geosphere, 6: 782-792 [ DOI:10.1130/GES00568.1 ]

*Pamukcu AS & Gualda GAR (2010) Quantitative 3D petrography using x-ray tomography. 2: Combining information from various resolutions. Geosphere, 6: 775-781 [ DOI:10.1130/GES00565.1 ] 

Gualda GAR, Baker DR, Polacci M (2010) Introduction: Advances in 3D imaging and analysis of geomaterials. Geosphere, 6: 468-469 [ DOI:10.1130/GES00639.1 ]

Gualda GAR & Ghiorso MS (2007) Magnetite scavenging and the buoyancy of bubbles in magmas. Part 2: Energetics of crystal-bubble attachment in magmas. Contributions to Mineralogy and Petrology, 154: 479-490 [ DOI:10.1007/s00410-007-0206-8 ]

Gualda GAR & Anderson AT Jr. (2007) Magnetite scavenging and the buoyancy of bubbles in magmas. Part 1: Discovery of a pre-eruptive bubble in early-erupted Bishop rhyolite using x-ray tomography. Contributions to Mineralogy and Petrology, 153: 733-742 [ DOI:10.1007/s00410-006-0173-5 ]

Vlach SRF & Gualda GAR (2007) Allanite and chevkinite in A-type granites and syenites of the Graciosa Province, southern Brazil. Lithos, 97: 98-121 [ DOI:10.1016/j.lithos.2006.12.003 ]

Gualda GAR & Vlach SRF (2007) The Serra da Graciosa A-type Granites & Syenites, southern Brazil. Part 3: Magmatic evolution and post-magmatic breakdown of amphiboles of the alkaline association. Lithos, 93: 328-339 [ DOI:10.1016/j.lithos.2006.03.070 ]

Gualda GAR & Vlach SRF (2007) The Serra da Graciosa A-type Granites & Syenites, southern Brazil. Part 2: Petrographic and mineralogical evolution of the alkaline and aluminous associations. Lithos, 93: 310-327 [ DOI:10.1016/j.lithos.2006.06.002 ]

Gualda GAR & Vlach SRF (2007) The Serra da Graciosa A-type Granites & Syenites, southern Brazil. Part 1: Regional setting and geological characterization.Anais da Academia Brasileira de Ciências, 79: 405-430 [ DOI:10.1590/S0001-37652007000300006 ]

Gualda GAR (2006) Crystal size distributions derived from 3D datasets: Sample size versus uncertainties. Journal of Petrology, 47: 1245-1254 [ DOI:10.1093/petrology/egl010 ]

Gualda GAR & Rivers M (2006) Quantitative 3D petrography using x-ray tomography: Application to Bishop Tuff pumice clasts. Journal of Volcanology and Geothermal Research, 154: 48–62 [ DOI:10.1016/j.jvolgeores.2005.09.019 ]

Gualda GAR & Vlach SRF (2005) Stoichiometry-based estimates of ferric iron in calcic, sodic-calcic and sodic amphiboles: A comparison of various methods.Anais da Academia Brasileira de Ciências, 77: 521-534 [ DOI:10.1590/S0001-37652005000300012 ]

Gualda GAR, Cook DL, Chopra R, Qin L, Anderson AT Jr., Rivers M (2004) Fragmentation, Nucleation and Migration of Crystals and Bubbles in the Bishop Tuff Rhyolitic Magma. Transactions of the Royal Society of Edinburgh: Earth Sciences, 95: 375-390 [ DOI:10.1017/S0263593300001139 ]

Vlach SRF & Gualda GAR (2000) Microprobe monazite dating and the ages of some granitic and metamorphic rocks from Southeastern Brazil. Revista Brasileira de Geociências, 30: 214-218 [ http://www.sbgeo.org.br/rgb/vol30_down/3001/3001214.pdf ]  

Abstracts

Gualda GAR & Ghiorso MS (2011) Low pressure origin of high-silica rhyolites. Eos Transactions AGU, Fall Meeting Supplement, V11A-2499 Link

Ghiorso MS & Gualda GAR (2011) A method for estimating the activity of titania in magmatic liquids from the compositions of coexisting rhombohedral and cubic iron-titanium oxides. Eos Transactions AGU, Fall Meeting Supplement, V11A-2486 Link

*Pamukcu AS, Gualda GAR, Rivers ML, Anderson AT (2011) 3D imaging of glass inclusions in quartz using propagation phase-contrast x-ray tomography: Application to the Bishop Tuff (California, USA). Eos Transactions AGU, Fall Meeting Supplement, V11A-2490 Link

*Brooks CE, Ghiorso MS, Gualda GAR (2011) A new internally consistent thermodynamic model for calculating hornblende-bearing phase equilibria with rhyolite-MELTS. Eos Transactions AGU, Fall Meeting Supplement, V11A-2484 Link

*McCracken RG, Miller CF, Dufek J, Gualda GAR, Buesch D, *Brooks CE (2011) Understanding the Peach Spring Tuff supereruption through its basal layer deposits (Southwestern USA). Eos Transactions AGU, Fall Meeting Supplement, V51F-2572 Link

Miller CF, Gualda GAR, *Padilla AJ, *Pamukcu AS, *Claiborne LL, *Carley TL, *Flanagan DM (2011) Reviving moribund intrusive complexes: Mafic thermal input, the accessory mineral record, and the pluton-volcano connection. Eos Transactions AGU, Fall Meeting Supplement, V11G-05  Link

Gualda GAR, Ghiorso MS, *Lemons RV, *Carley TL (2010) Rhyolite-MELTS: A modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Eos Transactions AGU, 91, Fall Meeting Supplement, Abstract V43A-2352 Link

*Pamukcu AS, Gualda GAR, Miller CF, Wooden JL (2010) The evolution of the Peach Spring Tuff magmatic system as revealed by accessory mineral textures and compositions. Eos Transactions AGU, 91, Fall Meeting Supplement, Abstract V43A-2350 Link

*Carley TL, Gualda GAR, Ghiorso MS, Miller CF (2010) Modeling the destabilization of large-volume silicic magmatic systems using rhyolite-MELTS and the Peach Spring Tuff. Eos Transactions AGU, 91, Fall Meeting Supplement, Abstract V43A-2351 Link

*Braun SA, Gualda GAR, Bream BR, Vlach SRF (2010) Importance of LA-ICP-MS zircon geochronology and geochemistry in determining the history of magmatic systems: Insights from the Graciosa A-type Province, Southern Brazil. Eos Transactions AGU, 91, Fall Meeting Supplement, Abstract V41B-2287 Link

*Claiborne LL, Wooden JL, Miller CF, Gualda GAR, Clynne MA, Flanagan DM (2010) Putting zircon surface geochronology and geochemistry in textural context using 3D x-ray tomography: Probing the magmatic history of Mount St. Helens. Eos Transactions AGU, 91, Fall Meeting Supplement, Abstract V51E-03 Link

Gualda GAR, *Pamukcu AS, *Claiborne LL, Rivers ML (2010) Quantitative 3D petrography using x-ray tomography: Documenting accessory phases with differential absorption tomography. GSA Abstracts with Programs, 42(5): Abstract 181136  Link

Miller CF, *Pamukcu AS, Gualda GAR, Colombini LL, *Flanagan DM, Ayers JC (2010) Sphene (titanite) as tracer of processes in felsic magmas: Examples from Miocene rocks of the Colorado River Extensional Corridor (CREC), NV-AZ-CA. GSA Abstracts with Programs, 42(5): Abstract 181059  Link

*Padilla AJ, Miller CF, Gualda GAR, Colombini LL, *Kelly EA, Cribb JW (2010) Death throes of a silicic system: Final re-activation of granitic crystal mush and transition to andesitic volcanism, Highland Range, southern Nevada. GSA Abstracts with Programs, 42(5): Abstract 181196  Link

*Kelly EA, Miller CF, Gualda GAR, Colombini LL, *Padilla AJ, Cribb JW (2010) Multi-component magma mingling revealed in a rhyolite-dacite-andesite coulee, southern Highland Range (southern Nevada). GSA Abstracts with Programs, 42(5): Abstract 181476  Link

Gualda GAR & Ghiorso MS (2009) Crystallization of the Bishop magma body (or magma bodies?): Lessons from thermodynamics. Eos Transactions AGU, 90(52), Fall Meeting Supplement, Abstract V23C-2096  Link

*Vaum RC, Gualda GAR, Ghiorso MS, Miller CF, *Colombini LL (2009) Using MELTS to understand the evolution of silicic magmas: Challenges and successes in modeling the Highland Range Volcanic Sequence (NV). Eos Transactions AGU, 90(52), Fall Meeting Supplement, Abstract V13D-2058  Link

*Pamukcu AS, Gualda GAR, Miller CF, Wooden JL, Ferguson CA (2009) Evolution of the Peach Spring Tuff (Southwest USA) magma body revealed by textures and compositions of accessory minerals. Eos Transactions AGU, 90(52), Fall Meeting Supplement, Abstract V23C-2087  Link

*Hall MR, *Pamukcu AS, Gualda GAR, Miller CF (2009) Using differential absorption radiography and acid dissolution to determine crystal size distributions of zircons: Methods and application to volcano-pluton connections in the Searchlight Magmatic System (Nevada). Eos Transactions AGU, 90(52), Fall Meeting Supplement, Abstract V51A-1639  Link

*Colombini LL, Miller CF, Gualda GAR, Wooden JL, Miller JS (2009) Geochemistry and petrogenetic significance of sphene: Evidence from the Miocene Highland Range volcanic sequence, southern Nevada. Eos Transactions AGU, 90(52), Fall Meeting Supplement, Abstract V51A-1637  Link

*Braun SA, Bream BR, Gualda GAR (2009) Age and chemistry of megacrystic zircons from Zirconia, North Carolina. GSA Abstracts with Programs, 41(7): 671  Link

*Carley TL, Miller CF, Ferguson CA, Gualda GAR, *Pamukcu AS, Wooden JL, Miller J, Gaudio SJ, Varga RJ (2009) supereruption of Peach Spring Tuff: New insights from caldera-fill and outflow pumice and accessory minerals. GSA Abstracts with Programs, 41(7): 141  Link

Miller CF, Wooden JL, Claiborne LL, *Colombini LL, *Carley TL, Miller JS, Gualda GAR, *Pamukcu AS (2009) Accessory minerals in volcanic sequences: Elucidating magma chamber processes and the linkage between plutons and volcanism. GSA Abstracts with Programs, 41(7): 707  Link

Gualda GAR, *Pamukçu AS, Rivers ML (2009) X-ray tomography: The ultimate petrographic tool for studying pumice. Eos Transactions AGU, 90(22), Joint Assembly Supplement, Abstract V74A-05  Link

*Pamukcu AS & Gualda GAR (2009) Determining crystal size distributions over a wide range of crystal sizes from multiple tomographic runs. Eos Transactions AGU, 90(22), Joint Assembly Supplement, Abstract V13A-05  Link

Rivers ML & Gualda GAR (2009) 'tomo_display' and 'vol_tools': IDL VM packages for tomography data reconstruction, processing, and visualization. Eos Transactions AGU, 90(22), Joint Assembly Supplement, Abstract V13A-06  Link

Miller CF, *Colombini LL, Wooden JL, Mazdab FK, Gualda GAR, Claiborne LL, Ayers JC (2009) Sphene (titanite) as both monitor and driver of evolution of felsic magma: Miocene volcanic and plutonic rocks of the Colorado River Region, NV-AZ, USA. Eos Transactions AGU, 90(22), Joint Assembly Supplement, Abstract V73B-01  Link

Gualda GAR, *Pamukçu A, Anderson AT Jr., Sutton SR (2008) Magma heterogeneity and the transition towards the Bishop supereruption recorded in crystals of the Bishop Tuff. Eos Transactions AGU, 89(53), Fall Meeting Supplement, Abstract V23E-2172  Link

*Colombini LL, Gualda GAR, Miller CF, Faulds J, Miller J, Wooden J, Mazdab F (2008) Mid-Miocene rhyolite sequence, Highland Range, NV: Record of magma evolution and eruption from the Searchlight Pluton magma chamber. Eos Transactions AGU, 89(53), Fall Meeting Supplement, Abstract V21C-2125  Link

*Pamukçu A, Anderson AT Jr., Gualda GAR, Miller CF, (2008) Assessing Volcano-pluton connections in the Searchlight Magmatic System (Nevada) using zircon size distributions. Eos Transactions AGU, 89(53), Fall Meeting Supplement, Abstract V21C-2116  Link

Miller CF, Miller JS, Claiborne LL, Gualda GAR, Peters TJ (2008) Highly-evolved silicic magmas: Volcanic vs. plutonic conundrums. Geochimica et Cosmochimica Acta, 72(12, Supplement 1): A629  Link

Gualda GAR, Anderson AT Jr., Sutton SR (2007) Rapid crystallization of the Bishop magma. Eos Transactions AGU, 87(52), Fall Meeting Supplement, Abstract V24C-04  Link

Gualda GAR, *Pamukçu A, Anderson AT Jr., Sutton SR (2007) The onset of decompression recorded in phenocrysts of the Bishop Tuff. 24^th IUGG General Assembly, Perugia, 2007  Link

Gualda GAR & Anderson AT Jr. (2006) The pre-eruptive texture of the Bishop magma. Eos Transactions AGU, 87(52), Fall Meeting Supplement, Abstract V24C-04  Link

*Pamukçu A, Anderson AT Jr., Gualda GAR (2006) Crystal sinking and bubble rising in late-erupted Bishop Tuff: A study of pumice clasts by x-ray tomography and physical separation. Eos Transactions AGU, 87(52), Fall Meeting Supplement, Abstract V33C-0684  Link

*Pamukçu A, Gualda GAR, Anderson AT Jr. (2006) Phenocryst size distributions of late-erupted Bishop Tuff. GSA Abstracts with Programs, 38(7): 446  Link

Vlach SRF & Gualda GAR (2006) Allanite and chevkinite in A-type granites and syenites of the Graciosa Province, Southern Brazil. GSA Abstracts with Programs, 38(7): 558  Link

Gualda GAR & Anderson AT Jr. (2006) Zoning in sanidine and quartz from the Bishop Tuff: Insights into the evolution of the magma body. Eos Transactions AGU, 87(36), Joint Assembly Supplement, Abstract V53A-06  Link

Vlach SRF, Siga O Jr, Gualda GAR, Basei MAS, Hyppolito T, Vilalva FCJ (2006) Precise zircon U-Pb (TIMS) dating of dioritic rocks and implications for the age of the Graciosa Province of A-type granites and syenites, southern Brazil. Workshop on A-type Granites and Related Rocks Through Time (IGPC 510): 77

Gualda GAR & Ghiorso MS (2005) Magnetite scavenging and the buoyancy of bubbles in magmas. Eos Transactions AGU, 86(52), Fall Meeting Supplement, Abstract V53A-1531  Link

Gualda GAR, Miller CF, Anderson AT Jr., Rivers M (2005) Bubble accumulation and the origin of a vesicular microgranite. GSA Abstracts with Programs, 37(7): 309  Link

Gualda GAR & Anderson AT Jr. (2005) Magnetite clusters on vesicle walls: Evidence for pre-eruptive bubbles in the early-erupted Bishop Tuff, CA. Geochimica et Cosmochimica Acta, 69(10, Supplement 1): A235  Link

Bleick HA, Miller CF, Furbish DJ, Koteas C, Ericksen SM, Miller JS, Gualda GAR, Walker BA (2005) Production and distribution of hybridized magma in a replenished, open-system magma chamber; Aztec Wash Pluton, Eldorado Mountains, Nevada. GSA Abstracts with Programs, 37(4): 66  Link

Gualda GAR & Anderson AT Jr. (2004) Pre-eruptive bubbles in the Bishop magma? An x-ray tomography study of vesicle size distributions. Eos Transactions AGU, 85(47), Fall Meeting Supplement, Abstract V43D-1448  Link

Gualda GAR & Rivers M (2004) Quantitative 3D petrography using x-ray tomography: application to Bishop Tuff pumice clasts. GSA Abstracts with Programs, 36(5): 245  Link

Miller CF, Miller JS, Furbish DJ, Bleick HA, Walker BA, Koteas GC, Gualda GAR, Faulds JE, Wiebe RA, Metcalf RD, Steinwinder TR, Ericksen SM (2004) Miocene intrusions, Colorado River Rift, Nevada-Arizona: Crystal- to crustal-scale dynamics in an open magmatic system. In: 32^nd International Geological Congress, Florence, 2004. Abstracts Volume, A194-10  Link

Gualda GAR & Vlach SRF (2004) Petrographic and mineralogical evolution of the alkaline and aluminous associations of the Graciosa A-type granites, Brazil.Geochimica et Cosmochimica Acta, 68(11, Supplement 1): A675  Link

Gualda GAR, Cook DL, Chopra R, Qin L, Anderson AT Jr., Rivers M (2003) Crystal Sinking and Bubble Rising in the Bishop Tuff Rhyolitic Magma. Eos Transactions AGU, 84(46), Fall Meeting Supplement, Abstract V12A-0557  Link

Gualda GAR, Cook DL, Chopra R, Qin L, Anderson AT Jr., Rivers M (2003) Fragmentation, Nucleation and Migration of Crystals and Bubbles in the Bishop Tuff Magma: Evidence from Crystal Size Distributions. 5^th Hutton Symposium on the Origin of Granites and Related Rocks. Abstracts with Program. Geological Survey of Japan, Interim-Report 29, pp. 37

Gualda GAR & Vlach SRF (2002) Stoichiometry-based estimates of ferric iron in calcic, sodic-calcic and sodic amphiboles: A comparison of various methods. In: IMA 2002, 18^th General Meeting of the International Mineralogical Association, Edinburgh, 2002

Gualda GAR, Ferreira FJF, Portela CV Filho, Vlach SRF (2001) Integration of geological and airborne gamma-ray spectrometric data for the individualization of granitic massifs in the Serra da Graciosa Area (PR). In: 7^th International Congress of the Brazilian Geophysical Society, Salvador, 2001 [in Portuguese]  Link

Gualda GAR & Vlach SRF (2001) Geology and petrography of the Graciosa Granites (southern Brazil). Anais da Academia Brasileira de Ciências, 73: 467  Link

Gualda GAR & Vlach SRF (2000) Chemical and textural evolution of mafic minerals from agpaitic nepheline syenites from the Poços de Caldas Alkaline Massif - Southeastern Brazil. 31^st International Geological Congress, Rio de Janeiro, 2000  Link

Gualda GAR & Vlach SRF (1999) Compositional variations and crystallization history of some pyroxenes from the Poços de Caldas Alkaline Massif (MG-SP).Acta Microscopica 8: 143-144  Link

Vlach SRF, Gualda GAR, Chiessi CM (1999) Electron microprobe Th-Pb and U-Pb monazite dating. Acta Microscopica 8: 141-142

Vlach SRF, Gualda GAR, Chiessi CM (1999) Electron microprobe monazite dating: First results for two granites from Southeastern Brazil. 2^nd South American Symposium on Isotope Geology, Córdoba, 1999. Actas…, 518-521

Gualda GAR & Vlach SRF (1998) Controls on the accessory mineralogy of intermediate to agpaitic rocks from Taquari – Poços de Caldas Alkaline Massif (MG-SP). In: 40^th Congresso Brasileiro de Geologia, Belo Horizonte, 1998. Anais…, p. 460 [in Portuguese]  Link

Gualda GAR & Vlach SRF (1998) Lamprophyllite and normandite (titaniferous låvenite) in agpaitic nepheline syenites from the Poços de Caldas Alkaline Massif (MG-SP): mineralogical and petrological characterization. In: 40^th Congresso Brasileiro de Geologia, Belo Horizonte, 1998. Anais…, p. 284 [in Portuguese]  Link

Vlach SRF & Gualda GAR (1998) Chemistry of mafic minerals from the Graciosa Granitic Massif, PR: preliminary results and petrogenetic inferences. In: 40^th Congresso Brasileiro de Geologia, Belo Horizonte, 1998. Anais…, p. 518 [in Portuguese]  Link

Gualda GAR & Vlach SRF (1996) Eudialyte-eucolite from the Poços de Caldas Alkaline Massif, MG-SP: chemistry and correlation with optic behavior. In: 39^th Congresso Brasileiro de Geologia, Salvador, 1996. Anais…, 3: 34-36 [in Portuguese]  Link

Vlach SRF, Ulbrich MNC, Ulbrich HHGJ, Gualda GAR (1996) Rocks of alnoitic and silico-carbonatitic affinity peripheral to the Poços de Caldas Alkaline Massif (MG-SP). In: 39^th Congresso Brasileiro de Geologia, Salvador, 1996. Anais…, 2: 128-130 [in Portuguese]

 

Software                                     Top - Education – Interests – Research – Publications – Software

vol_tools:
A set of IDL tools for processing and visualization of 3D tomographic datasets
http://people.vanderbilt.edu/~g.gualda/vol_tools.htm

Mincal:
Microsoft EXCEL© workbooks to calculate mineral formulae
http://people.vanderbilt.ed/~g.gualda/mincal.htm