2016-2017 Science Planning Summaries
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2016-2017 USAP Field Season
Project Detail

Project Title

Petrologic constraints on subduction termination from lamprophyres, Ross Orogen, Antarctica


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Summary

Event Number:
G-076-M

Program Manager:
Dr. Thomas Wilch

ASC POC/Implementer:
Judy Shiple / Jennifer Blum / Leslie Blank


Principal Investigator

Dr. John Cottle
cottle@geol.ucsb.edu

University of California Santa Barbara
Department of Geological Sciences
Santa Barbara, California

Project Web Site:
http://www.antarctica360.net/


Location

Supporting Stations: McMurdo Station
Research Locations: Miller Range / Gabbro Hills


Description

Rocks highly enriched in potassium such as lamprophyres potentially provide direct insight into foundering and the processes that occur during, and immediately after, termination of subduction. These enigmatic rocks are important because they represent near-primary mantle-melt compositions and therefore their age, geochemistry, and petrologic evolution reveal key information on both the composition of the upper mantle and its thermal state. Of equal importance, they reveal how these key parameters vary through both space and time. This project will study a suite of lamprophyres spanning approximately 1,300 kilometers along-strike and emplaced during the latest stages of the Neoproterozoic-Ordovician Ross Orogeny. High-precision geochronology, coupled with whole rock and mineral-scale elemental, isotope geochemical, and petrologic analysis, will elucidate the mechanisms for, and the temporal and spatial scales over which, deep crustal foundering/delamination occurred and the processes responsible for the significant isotopic heterogeneities observed in these rocks.


Field Season Overview

Field team members will travel by Basler aircraft to the Transantarctic Mountains where they will establish a light weight field camp in the Miller Range. After three weeks, they will make a camp move by Twin Otter aircraft to the Gabbro Hills through Shackleton Camp, at which time an ASC Field Safety Coordinator will join the team and the PI will depart. At both locations they will travel by foot and by snowmobile to collect rock samples and conduct geologic mapping. They will return to McMurdo via the Shackleton Field Camp. Samples will be returned to the home institution for analyses.


Deploying Team Members

  • Nicholas Browne
  • John Cottle (PI)
  • Demian Nelson (Team Leader)