On the weekend of the 12th of September ~70 students travelled around Booti Booti National Park, Port Macquarie and Mt Seaview to look at a traverse across an ancient arc-forearc-subduction/accretion system.
Over the two days we looked at the rock types, geological history, arc migration, volcanism, extension and formation of the Tasman Sea and eruption of basaltic lavas. GEOS1050 involves studying the crustal evolution and processes involved in the growth of continental crust and continent-ocean plate margins by subduction/accretion or terrane accretion as well as the addition of new crust from the mantle in the form of magmas. The best example of a subduction/accretion system on the Australian continent exists at our very doorstep, to the north in the New England Ranges.
We looked at highly deformed ultramafic rocks that occur in mafic fault zones between large crustal blocks, seafloor and trench-fill sediments, arc and fore-arc systems volcanic rocks interlayered with shallow marine and terrestrial sediments, magmatic arcs represented by granitic plutons and lava flows and breccias that erupted during crustal extension associated with the formation of the Tasman Sea.
Our first stop at Booti Booti National Park (near Forster) involved a challenging walk and a small amount of rock climbing to look at the arc and fore-arc system. After spending the morning discussing the different sedimentary and volcanic features we returned to the parks camping site for a BBQ provided by AusIMM.
We later stopped at Port Macquarie to look at an example of a subduction/accretion complex and basaltic lava flows.
That night, we stayed at the secluded Mt Seaview resort, where we later started a bonfire by the creek and discussed geology amongst other things. This provided an opportunity for the first years to bond with each other and the lecturers and staff for the first time.
The next day we looked at magmatism and metamorphism on the New England Tablelands. We stopped at Apsley Falls to see examples of intense compression and enjoy the views of the gorge and waterfall.