GEO 381R Field Excursion to Western Australia

The 2003 offering of GEO 381R was taught by Rich Kyle and Sharon Mosher and focused on the Geologic Evolution and Mineral Resource Development of Western Australia.  The course culminated in a three-week trip to Western Australia in May 2003 that provided an exceptional educational opportunity for 12 UT graduate students with diverse interests to study many classic geologic sites.   Western Australia offers an excellent 381R destination, as it has varied geologic environments and is one of the worlds major mineral producers.  The Geology Foundation provided scholarships to help cover the international airfare for the students.  Other costs were kept low by camping for most of the trip.   

This trip represented a return visit for a trip that Sharon organized for a group of University of Western Australia graduate students and faculty three years ago.  Annette George, Senior Lecturer in Sedimentology & Basin Analysis at UWA, organized and led most of the trip, along with other UWA colleagues and local authorities.  The trip began and ended in Perth and consisted of a 6,800-km clockwise traverse through a large part of Western Australia.

Following a day for travel recovery and trip organization, the caravan headed north along the Western Australia coast to Kalbarri with the first stop to look at the Ordovician Tumblagooda sandstone and its trace fossils at Red Bluff.  The next day started with similar exposures along the Z-bend of the Murchison River in Kalbarri National Park, followed by a long drive to arrive near dusk at low tide at the world famous modern stromatolites at Hamelin Pool at Shark Bay.  The next morning provided an even more intimate experience with stromatolites and related sediments at the Carbla Point.

After night in Carnavon and a dust storm along the coast, the group turned toward the interior to begin a several day tour of the Hamersley Basin, known for its extensive banded iron formations that supply much of the worlds iron for the steel industry.  The origin of these unusual sedimentary rocks remains controversial, but commonly is tied to the evolution of the early Earth atmosphere, hydrosphere, and biosphere.  Extensive exposures of the Hamersley Group were provided by traverses near Woongarra Pool, the gorges in Karinjini National Park, and on Mt. Nameless (Jarndunmunha).  The group later toured the commercial iron concentrations developed from the BIFs at BHPs Mt. Whaleback mine near Newman that produces about 80 million tonnes of iron ore per year.

The next major site was the Marble Bar and North Pole regions of the Archean Pilbara Craton.  The region represents one of the worlds oldest greenstone-granite terranes with classic structural styles, but of particular current interest are the silica- and barite-rich chemical sediments on which much research continues in the search for early life on Earth.  These include the controversial stromatolites in dolostones at the North Pole dome that are arguably the Earths oldest biogenic structures.  Martin Van Kranendonk of the Geological Survey of Western Australia and Malcolm Walter, Director of the Australian Centre for Astrobiology, and graduate students from Macquarie University shared their extensive knowledge of the geology of the region and on the early life issues.  Travels through the outback on the primitive tracks to view these features provided considerable challenges for the rental minivan and the skills of the driver!

The group headed south to Newman, where Rich departed for the Geological Association of Canada meeting in Vancouver and Annette returned to Perth for teaching obligations. Warrick Crowe of the University of Western Australia guided the group for the remainder of the tour.  The caravan continued with a long drive south to Kalgoorlie, one of the worlds most famous gold mining regions within the Archean Yilgarn Craton, for a several day visit. Kevin Cassidy of Geoscience Australia gave us an excellent overview of the Yilgarn Craton and took us on a field excursion to see the Mt. Hunt komatiite-felsic volcanic sequence; we were fortunate to have several other geologists join us including Bruce Groenewald from the Western Australia Survey and Chris Swager from a local mining company.   In contrast to the well-exposed Pilbara Craton, the Yilgarn is best exposed in the mines or drill core.  We visited the gold mine superpit in Kalgoorlie and had a fascinating underground mine tour of a komatiite-hosted nickel-sulfide deposit in Kambalda, plus viewed core at the mine and at the Geological Survey of Western Australia core library.  A visit to the Mining Hall of Fame was gave us a good historical perspective on mining in Western Australia.

The group next drove to the southern coast to see some superb exposures of the Grenville-age Albany-Fraser belt.  Warwick Crowe led us along white sand beaches and rocky coves to spectacular structures in multiply folded pelites at Hopetown and high-grade gneisses at Bremer Bay.  As we headed towards Perth along the southern coast, we visited the Greenbushes pegmatite mine, a major tantalum producer and high-grade lithium resource. On our last day we drove to Perth with a brief tourist stop at Margaret River.

The trip to Western Australia was a great geoadventure and learning experience, and we are grateful for the support of the School of Earth & Geographical Sciences at the University of Western Australia, particularly Annette George who converted our diverse interests into a working travel plan.  Discussions are already underway about destinations for the next international field excursion. 

                        Modified from story by Rich Kyle and Sharon Mosher in the 2003 DGS Newsletter

Photo 1.  Domal stromatolites in the Shark Bay intertidal zone at Carbla Point, Western Australia. 

Photo 2.  Dawn at the GEO 381R campsite at Woongarra Pool in the Hamersley Basin.  Steeply dipping banded iron formations in the background.

Photo 3.  Mt. Whaleback open pit iron mine at Newman, Western Australia. 

Photo 4.  GEO 381R field trip group prepared to go on the underground tour at the komatiite-hosted nickel mine at Kambalda, Western Australia.

Photo 5.  Large scale boudins in high grade gneisses of the Grenville-age Albany-Fraser belt at Bremer Bay, Western Australia.

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