AusLAMP marine: Extending the national MT array to the continental margins
A modern scientific voyage with a diverse team and NCRIS-enabled magnetotelluric (MT) earth imaging kit on board the vessel Salt River. Image: Robert Lang Photography
In November, an international team of scientists, led by AuScope’s Earth Imaging group at the University of Adelaide, set out to obtain new AusLAMP MT sites on the seafloor of the Spencer Gulf in South Australia — an area that represents a missing piece of the larger Gawler Craton puzzle. The team share details of this NCRIS-enabled journey and explain why these measurements will allow us to better image the whole of the Australian continent.
In true collaborative stye, the team of scientists from the University of Adelaide, the Geological Survey of South Australia, Geoscience Australia and the Scripps Institute of Oceanography at the University of California adopted an ‘all hands on deck’ attitude, successfully deploying and retrieving 12 marine MT instruments in the southern Spencer Gulf over a period of eight days.
From left to right: Jake Perez (SIO), Goran Boren (UA), Ben Kay (UA), Stephan Thiel (GSSA), Kate Robertson (GSSA) and Darren Kyi (GA). Image: Robert Lang Photography
Graham Heinson from The University of Adelaide explains:
“This project is the first phase of a marine MT program to extend the AusLAMP array to the continental shelf. The initial program is just a pilot of 12 sites to see how well the marine instruments work in less than 50 m depth of water, and we selected a short time window in early November when the tidal ranges in the Spencer Gulf are smallest.”
Bathymetric maps showing marine MT imaging sites (black triangles) in the Spencer Gulf. Images: Kate Robertson
The team say that this pilot project fills a significant gap in MT data coverage across the important eastern margin of the prospective Gawler Craton and will lead on to further deployments in the Spencer Gulf and across the southern continental margin over the next year.
Left, Jake Perez and Goran Boren start the data loggers, and right, Kate Robertson makes final adjustments to the marine MT instruments onboard the Vessel Salt Water. Images: Robert Lang Photography
If the results from the Spencer Gulf are successful, the next phase is to extend AusLAMP to key marine areas such as the Gulf Of Carpentaria, North West Shelf, Bass Strait and the Lord Howe Rise. Graham Heinson from The University of Adelaide explains the importance of this program of work:
“Marine MT deployments provide an exciting opportunity to image the electrical properties to the true edge of the Australian continent margin. New marine measurements will provide greater insight as how the continent evolved through time, and will also allow us to model our AusLAMP land sites with more confidence.”
Background
The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative, national survey that acquires long-period magnetotelluric (MT) data. It is being conducted over multiple years, at approximately 3000 sites, to create the first national MT dataset in the world. This dataset will be an essential input to Geoscience Australia’s Exploring for the Future programme as well as a valuable Earth imaging resource for researchers to reconstruct the tectonic evolution of the Australian continent.
AUTHORS
By Stephan Thiel (GSSA), Jo Condon (AuScope), Graham Heinson (University of Adelaide) and Kate Robertson (GSSA)
LEARN MORE
For information about this story, please contact Prof Graham Heinson from The University of Adelaide.