Tectonic Suture Zones
Background
The Earth's geography is in a perpetual state of change. Erosional processes tirelessly chip away at mountains, allowing rivers to sculpt valleys and contributing to the formation of the soils that blanket the land. Tectonic processes, although unfolding on grander time scales, wield a significant impact. Mountains rise at convergent plate margins, a result of continents colliding or volcanic ranges emerging from the melt of a subducting plate. Seaways ebb and flow, altering oceanic currents and impeding the migration of organisms by both land and sea.
In areas of convergence, especially between two continents, a region known as a suture zone emerges, where colossal forces literally stitch together the colliding behemoths. These zones can be expansive, featuring rocks undergoing blueschist-grade metamorphism. More ancient suture zones, like those found in the Appalachian Mountains, boast complex histories that vary depending on location.
The objective of my research is to delve into a recognized suture zone in central Piedmont, Virginia, unraveling the intricate history it has undergone. Many of these older suture zones likely bore witness to multiple tectonic events. The questions guiding my investigation include: Which events left their mark on this area? When did these tectonic events transpire? How does this impact the local and regional geologic history? And, what were the temperature and pressure conditions these rocks endured?
Why does it matter?
Being able to accurately reconstruct the paleogeography of the Earth’s surface is crucial in understanding the past. Tectonic processes play a huge role in a wide range of processes. When seaways open and close, the Earth’s climate can drastically change from icehouse conditions to modern conditions. If continents collide, the biosphere interacts with each other, potentially shifting how organisms evolve. To be able to accurately map suture zones and determine the timing of the collisions, we can then understand other events as well. How did this collision impact global or regional climate? Did is cause evolutionary changes?
Methods
Field-mapping using both traditional mapping techniques and digital mapping using geologic field mapping software.
Sample collection for petrographic, geochronological, and structural analysis.
Thin-sections for composition and microstructures.
Geochronology and thermochronology using multiple systems: U-Pb zircon, U-Pb apatite, and Ar-Ar muscovite.
Compiling structural data to create stereograms.
Map building using a combination of Adobe Illustrator and ArcGIS Pro.