25-27 July 2023 | Fremantle, Perth, Western Australia

Conference field trips

Five diverse field trips are offered to you as part of this symposium.

Two pre-conference trips, that will respectively allow you to take a tour through the exquisitely exposed Pilbara Craton, exploring evolving Archean tectonic styles, or have a look at the newly defined boundary between the Youanmi Terrane and the SW Terrane.

Three different post-conference trips are organised, that will explore the unique Archean and Precambrian geology of Western Australia. Individual trips will focus on the tectono-magmatic and metamorphic evolution of the northern Yilgarn Craton, mineralization in the eastern Goldfields of the Yilgarn Craton, as well as the Archean–Proterozoic boundary preserved in the Mount Bruce Supergroup.

Pre-conference field trips

FT1 – Pilbara Craton: evolving Archean tectonic styles (July 17 – 23)

(Guides: Martin Van Kranendonk, Hugh Smithies) A week-long trip across the beautifully exposed Pilbara Craton, investigating two contrasting litho-stratigraphic terranes. This trip will commence with an exploration of the 3.5-3.2 Ga East Pilbara Terrane, with its classic granite dome-and-greenstone keel geometry indicative of “vertical tectonics”, and sites with traces of early life. It will then move to the western part of the craton, where we will investigate successions and structures that document a drastically different tectonic style, including an arc complex, and crustal-scale shear zones indicative of terrane accretion.

FT2 – Redefining Archean terrane boundaries: A radical update within the Yilgarn Craton (20-22 July)

(Guides: Raphael Quentin de Gromard, Tim Ivanic) The far west and southwest Yilgarn represents perhaps the most geodynamically complex portion of the Yilgarn Craton and has recently become one of Western Australia’s prime new exploration frontiers. Recent work by the Geological Survey of Western Australia has proposed that the boundary between the c. 3010–2635 Ma Youanmi Terrane and the c. 2705–2610 Ma South West Terrane of the Archean Yilgarn Craton be relocated approximately 200 km to the southwest along the southwestern deformation front of the newly defined c. 2665–2635 Ma Corrigin Tectonic Zone (CTZ). This three day excursion will visit key exposures of tectonized greenstones and high-grade gneisses in the well-exposed Toodyay-Northam area (about 100 km from Perth). The field sites will be an ideal platform from which to discuss the geological history of the southwest Yilgarn, the rationale for location of the terrane boundary and implications for Au–Cu, Ni–PGE, Ti–V, VMS, and Fe mineral systems.

Simplified interpreted bedrock geology (IBG) of the southwest Yilgarn produced during the 2020–2021 Accelerated Geoscience Program (AGP) of the Geological Survey of Western Australia (GSWA) showing the location of the old and updated terrane boundary between the South West Terrane and the Youanmi Terrane as well as the fieldtrip area.

Post-conference field trips

FT3 – Out with the old, in with the new — a traverse across the Archean-Proterozoic boundary in the Mount Bruce Supergroup (July 29-Aug 4)

(Guides: David Martin, Heather Howard) The Archean-Proterozoic boundary has always been regarded as reflecting a fundamental change in Earth surface processes and environments. However, the practicality of the currently accepted chronometric definition is increasingly being questioned. This trip will explore these processes and their products as documented in the exceptional Neoarchean to earliest Paleoproterozoic exposures of the Fortescue, Hamersley and Turee Creek Groups in Western Australia, and evaluate candidates for a chronostratigraphic GSSP related to the Great Oxidation Event.

FT4 – A traverse across the Yilgarn Craton in Western Australia – from the Jack Hills to the Youanmi Terrane (July 29-Aug 4)

(Guides: Tony Kemp, Ivan Zibra) The one-week excursion will feature an west to east traverse across the northern Yilgarn Craton, combining geophysical, structural, geochemical, geochronological and isotopic data to outline the tectono-magmatic and metamorphic evolution of this large remnant of Eo- to Neoarchean continental crust. The excursion will start in the western corner of the craton, in the Narryer Terrane. Rocks of the Mt Narryer and Jack Hills metasedimentary belts, which both contain Hadean (> 4000 Ma) detrital zircon crystals, will be examined, along with flanking ancient quartzofeldspathic gneisses that have protolith ages from 3730 Ma to 2750 Ma. Granitic outcrops associated with cratonisation from 2680-2620 Ma will also be visited. In the western part of the Youanmi Terrane, the excursion will mainly focus on the structures developed during the c. 2730–2660 Ma Yilgarn Orogeny, with the aim of discussing the relationship between shearing, magmatism and crustal evolution from the thin-section scale up to the crustal scale. Main highlights include the Moyagee Fault near Mount Magnet, which represents the oldest-known seismogenic fault on Earth. The final part of the excursion will offer an overview on the c. 2750 Ma Yalgoo Dome, offering a glimpse of the tectonic style that prevailed during preorogenic times, which was characterized by large-scale granitic diapirism.

FT5 – Mineral Deposits in the Yilgarn Craton (July 29th to August 4th or 5th)

(Guides: Steffen Hagemann, Nico Thébaud) The Yilgarn Craton has long been recognised as having world class Au endowment. Yet the endowment varies dramatically between terranes of the Yilgarn and between constituent geological domains, showing a tendency to cluster in districts or ‘camps’. The one week excursion will visit classic geological localities and gold deposits from the Yilgarn Craton showcasing the deposit style diversity and focusing on Au mineral system formation from regional down to deposit scale formation.