Examples of Current Research

The best geological research problems are rooted in fieldwork. We select research targets by focusing on areas around the globe that provide world-class examples of important phenomena, such as the Sierra Nevada (granitic batholith generation), the Scottish Highlands and New England (Barrovian metamorphism), and Greece and New Zealand (subduction zone processes). Importantly, recent advances in digital mapping have led to greatly increased mapping efficiency and accuracy. Laboratory work involving the chemical and isotopic analysis of rocks and minerals is essential for providing the basic data necessary to test field-generated hypotheses. Fieldwork and lab work in concert produce invaluable constraints on geologic, geochemical, and geophysical initial and boundary conditions needed for modeling. Model results, in turn, provide a better understanding of process and, perhaps even more importantly, new hypotheses that can be tested by solid, field-based research. Scientific programs in our group are designed so that students have great flexibility in developing their research interests. Examples of some current projects are provided below.

Scotland
We are sampling and mapping in the Scottish Highlands in the classic Barrovian zones to better understand how the heat and crustal fluids of metamorphism were distributed across the mountain belt. One key aspect of the Barrovian is that magmatism and metamorphism appear closely linked such that magmas and associated fluids provided much of the heat. Consequently, the field area offers the opportunity to study both magmatic and metamorphic problems. The area was once a large subduction zone and we are focused on the metamorphism of sediments in the overlying accretionary prism. We are interested in the chemical changes caused by fluid flow, the interactions between deformation and metamorphism, and how heat input by magmas and metamorphic fluids impacts pressure-temperature-time paths. The chemical transport by fluids has many important implications for seismicity, ore deposition and the global cyling of elements and even greenhouse gases.



Greece
We are studing paleo fluid flow in the subduction complex exposed on several of the Cycladic islands (Greece). This work focuses on gaining a better understanding of the fluxes and pathways of fluid flow in subducted crust and examining the implications for mantle metasomatism and arc magmatism. Major goals include determination of processes of volatile generation and pathways of volatile escape from downgoing slabs, as well as the relationships between metamorphic fluids and the genesis of arc magmas. Selected results include documentation of: (1) regional conduits for exhumation-related flow using digital field mapping and numerical modeling (Breeding et al., 2003) and (2) prograde, fluid-driven chemical alteration in subducted mélange and implications for arc magma chemistry (Breeding et al., 2004). Ongoing projects are targeting: channelized fluid flow in subducted metasediments; numerical modeling of flow in mélange zones; chemical alteration of mafic crust in mélange; and the kinetics of the blueschist-eclogite facies transition.


New England
We are beginning a project that will examine metamorphism and devolatilization of the massive marble sequences of western Connecticut. Most studies of metacarbonate rocks in New England have focused on intercalated metacarbonates and metapelites, but not on the great metamorphosed carbonate platforms. A major goal is to determine the processes and rates of devolatilization on continental margins caught up in continental collisions. Ultimately, the release and large-scale migration of metamorphic fluids is of interest because the flux of CO₂ out of the deep roots of mountain belts remains the most poorly-constrained of all the fluxes in the global carbon cycle. The results have many implications, including the long-term evolution of greenhouse gases/climate, and geologic carbon sequestration for present-day waste CO₂.