2015-2016 Science Planning Summaries
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2015-2016 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:
Sune Tamm / Meghan Walker


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/ External Web Site


Location

Supporting Stations: McMurdo Station
Research Locations: Lakes Vanda and Joyce / Nussbaum Riegal / Hidden Lake in the Dry Valleys


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

This project will conduct detailed geologic mapping and collect lamprophyre and associated rock samples from the southern Dry Valleys. Four small tent campsites will be required: Lake Vanda, Nussbaum Riegal, Lake Joyce, and Hidden Lake. Four team members will be transported to the Dry Valleys by helicopter and will collect samples within walking distance of each camp. Helicopter close support to visit outcrops beyond walking distance will be used throughout the field season.


Deploying Team Members

  • Nicholas Browne
  • John Cottle (PI)
  • Robert Holder
  • Demian Nelson