Tuesday, July 28, 2015

Ramping up for bigger, badder SUGAR Part 2

We are in Georgia gearing up for the second phase of field work for the SUGAR project, which will involve collecting seismic refraction data along two profiles spanning eastern Georgia. In the coming weeks, we’ll deploy thousands of small seismometers along county and state roads across the region, which will record sound waves generated by a series of controlled blasts. We can use the sound waves to make pictures of geology beneath the surface. Geological structures beneath Georgia record the most profound events involved in the formation and evolution of the eastern North America continent. In particular, we want to image an ancient suture between Africa and North America that formed when these continents collided to create the supercontinent Pangea, frozen magma bodies from one of the biggest volcanic outpourings in Earth’s history, and continental stretching and thinning that lead to the breakup of Pangea and formation of the Atlantic Ocean.

Map of SUGAR lines, showing two possible locations of the ancient suture (red dotted lines)

We collected similar data in western Georgia last year during the first phase of the SUGAR experiment imaging these same features. During that field program, we deployed 1200 seismometers and set off 11 controlled blasts along a 250-mile-long line, which felt like a big project at the time. But this year, we will go even bigger! In eastern Georgia, we need to span an even larger area to encompass our geological targets. One of the reasons that we need to look at a bigger swath of the earth is that there is a debate about the location of the suture here – it could be as far north as Milledgeville, GA or as far south as Baxley, GA. (In case you are not up on your Georgia geography, those towns are ~100 miles apart). This means longer profiles, more instruments and more blasts! We will deploy a total of 2700 seismometers and detonate 26 blasts along two profiles. The longer profile spans 350 miles from Winder, GA to the Florida-Georgia state line near St Mary’s Georgia. Stay tuned!

Donna Shillington, LDEO