Barry Cameron's Research
My main fields of research are igneous petrology, volcanology, and terroir. At the moment, I am focused on four main broad research projects: the origin of arc magmas, the explosive behavior of silicic lava domes, the formation of subglacial volcanoes, and the unique terroir of volcanic soils.
The Origin of Arc Magmas:
Subduction environments host the most explosive volcanoes on Earth. One of the most enticing places to study these explosive volcanoes is in Central America. I have concentrated on the country of Guatemala to study arc magmas for a number of reasons. It currently has three active volcanic centers: Pacaya, Fuego, and Santiaguito. Guatemala also has the most extensive behind-the-front volcanic activity in all of Central America. Young cinder cone fields occur behind-the-front in southeastern Guatemala, whereas majestic stratovolcanoes occupy the volcanic front. Our research indicates that flux melting predominates under the volcanic front and decompression melting plays an important role in generating magma at the cinder cones. We utilize the new FTIR to measure the water and carbon dioxide content of melt inclusions in olivine crystals separated from scoria deposits collected at cinder cones. In January 2009, we will travel to Nicaragua to continue our investigations into arc magmas that have been less contaminated by crustal rocks. Our Research Growth Initiative grant from UW-Milwaukee explores the explosive-effusive transition at cinder cones in Guatemala and Nicaragua. Tanya Gregg successfully finished her MS thesis on cinder cones in southeastern Guatemala. Kyle Noll continues his GIS study on the morphology of cinder cones in Guatemala and Arizona. And we welcome Teri Gerard to the volcano team in September 2008. She will study melt inclusions from Nicaraguan cones.
The Explosive Behavior of Lava Domes:
Lava domes can experience explosive decompression eruptions that form dangerous pyroclastic flows when their high-pressure flow interiors are exposed. For many years, volcanologists targeted zones of high water content on lava domes. While a post doc at Arizona State University with Jonathan Fink, we wondered whether these high water contents were truly magmatic in origin or whether they contained significant secondary water. Consequently, we utilized step-heating hydrogen isotope analyses to distinguish between meteoric and magmatic water contents in glassy lavas from the domes. The step-heating technique showed that the high water contents in the surficial vesicular unit were largely secondary in origin. This NSF-sponsored project extended explorations into the nature of water in silicic lavas.
The Formation of Subglacial Volcanoes:
Our research group has been intrigued by the tempestuous relationship between volcanoes and glaciers. Snejana Boscov finished her MS thesis on how subglacial volcanoes from northern British Columbia release their gas and how this degassing process controls eruptive style beneath glaciers. In the summer of 2002, we conducted field studies on classic flat-topped volcanoes called tuyas in northern British Columbia. The remote location of the subglacial volcanoes required that we be transported by a twin-otter bush plane. The beauty and tranquility of the field area was memorable. The climate and glacial community have become greatly interested in our ability to estimate ice thicknesses from the measured volatile content of subglacial glasses. We have received NSF money to estimate water and ice thicknesses in Antarctica as part the Antarctic Drilling (ANDRILL) project. More recently, I have been working on another NSF sponsored project on the Mt. Edziza volcanic complex in northern British Columbia with colleagues Ben Edwards and Ian Skilling. Graduate student Michael Wright has made careful measurements of the water content of pillow glasses from the Tennena Cone at Mt. Edziza. This work was presented at the spectacular IAVCEI meeting in Iceland in the summer of 2008. These new subglacial research projects have been improved by measuring volatile contents in glasses using synchrotron FTIR at the Synchrotron Radiation Center at the UW-Madison.
Terroir defies easy definition. A French word, terroir has been used for centuries to describe and explain wine variability from place to place. Another perhaps less satisfying definition is: I know it when I see it. Or better yet, for those with refined palates, I know it when I taste it. One simplified answer, but appealing to geologists, is that it’s all about the soils. But it is obviously more than that. Terroir must reflect the complex interplay of a plethora of variables: bedrock geology, soils, climate (temperature and precipitation), slope, orientation, and all the human factors related to viticultural practices. In all ways, terroir is an ideal topic for earth science to flex its muscles, and a perfect way to convey the importance of earth science to the general public (shall we say) thirsting for knowledge. In these modern, enlightened times, the secrets of terroir may be unlocked with carefully designed research projects that take full advantage of a host of scientific approaches (geochemistry, pedology, hydrology, mineralogy, geophysics, remote sensing, GIS, etc.). Perhaps the most convincing illustration of terroir is expressed in the common observation of vineyard variability. Individual vineyards are divided into blocks for a reason. My research focuses on many aspects of terroir, at all scales, but especially tries to decipher the key factors that determine variations in grape and wine quality. A particular interest for me is wine made from grapes grown in volcanic soils. In a perfect scientific world, where one vineyard serves as an isolated system, one would hope all of the considered variables were constant except one. Instead, one must respect the complexity and nuances of this alluring earth system and conduct truly multidisciplinary research. The terroir research group at UWM has undertaken preliminary studies in Wisconsin, Nova Scotia, as well as Sicily and the Marche region in Italy. Great wine has inspired humans for millennia, and now it motivates our exploration of this quintessential scientific puzzle.