ARC Centre of Excellence for Core to Crust Fluid SystemsAppendix 2: CCFS workplan 2017
1. DEEP-EARTH FLUIDS IN COLLISION ZONES AND CRATONIC ROOTS (TARDIS II)
Continued research in Tibet will focus on the complete mapping the Kangjinla chromitite bodies and mapping of lherzolite/ harzburgite boundaries in other massifs. In addition, mineral separation and analysis of SiC isotopes and inclusions as well as other SuR-UHP phases will be carried out.
Work in Israel will be summarised in papers on the SiC isotopes, alloy phases and zircons. Mineral separations and analysis will be undertaken on samples from selected vents. Upstream tracking of specific phases will also be used to identify primary sources for alluvials.
Pyroxenite studies will include the publication of EBSD and petrological work on Cabo Ortegal Complex in northern Spain. A field trip is planned to sample the Trinity Ophiolite in California.
Analysis of these samples will be compared with results from the Cabo Ortegal. Studies of Victorian pyroxenites will also be completed and published.
Activities planned for samples from Iran include:
1) Completing the Hf isotope analysis on detrital zircons from the Neoproterozoic sediments and publication of results, 2) Completing zircon U-Pb ages and publication of data on the Cenozoic ‘flare-up’, 3) Completing and publishing EBSD and petrological work on mantle peridotites, 4) Completing and publishing data on Neoproterozoic delaminated gabbros and pyroxenites from the deep crust.
Kimberlite work will focus on completing and publishing isotopic/petrographic studies of primary carbonates.
2. GENESIS, TRANSFER AND FOCUS OF FLUIDS AND METALS
The integrated plan of action for 2017-2018 aims to take all currently ongoing studies to a successful completion. The focus on porphyry studies will continue into next year, consolidating datasets from Tibet. Bob Loucks will continue his effort to unravel the relationship between volatile endowment (and speciation) and emplacement dynamics of mineralising felsic magmas in arcs. The PhD thesis of Katarina Bjorkman will be submitted in early 2017, whereas the other studies in the Ivrea Zone and in South America will continue into 2018. Work on alkaline magmatism in the Yilgarn Craton will be accelerated in 2017, with a large campaign of isotopic and trace element data acquisition that began in late 2016. This work will strengthen collaboration among different CCFS nodes as different expertise is available at multiple institutions. In terms of modelling, we will investigate the fate of carbonated sediments during subduction and slab break-off. Three implications arise from this work: 1) these models confirm that carbon is filtered out at upper mantle conditions, suggesting a carbon increase in the upper mantle over time; 2) carbonate melting in the mantle transition zone may be an important source component for organic carbon signatures of eclogitic diamonds; and 3) the base of the subcontinental lithospheric mantle may be enriched by percolation of carbonatitic melts acting as a nucleation point for continental breakup.
3. MODELLING FLUID AND MELT FLOW IN MANTLE AND CRUST
In 2017, the matured modelling techniques will be applied to a variety of geodynamic problems in the mantle and crust. This will involve a suite of simulations exploring the dynamics of subduction over Earth’s history, and its effect on fluid systems. We will also further integrate the newly developed advanced methods for multiphase/component flow with large-scale geodynamic flow models to explore the effects of realistic fluid release and migration on geodynamic model predictions. These will then be integrated with seismology constraints.
Seismology components of this project will focus on imaging the lithosphere-asthenosphere system in NE China, where the oceanic subduction in the east has profound impacts on geological features such as the destruction of NE China Craton keels, extensive intraplate volcanism and a systematic variation of topography from west to east.
Activities in the experimental laboratory will be transferred to the piston-cylinder laboratory, which will remain open whilst the multi-anvil laboratory is being renovated. Projects will include formation of early continental crust, melting of volatile-rich mantle rocks, partitioning of nitrogen between minerals and melts, and interactions between carbonate and mantle rocks. Construction of the laser-heated diamond-anvil cells will be finalised during 2016.
4. ATMOSPHERIC, ENVIRONMENTAL AND BIOLOGICAL EVOLUTION
Research will continue on established CCFS FP4 projects, including:
(1) the early life setting and composition at North Pole - Van Kranendonk (CI), Djokic (PhD), Steller (PhD), Tadbiri (MPhil), Fiorentini (CI), Baumgartner (Post-doc), Johnson (UWisc), Satkowski (UWisc), Nakamura (Okayama U);
(2) the composition of Archean seawater and organics - Reitner and Duda (Gottingen);
(3) the adaptation of life across GOE - Erica Barlow (UNSW), Soares (PhD), Nomchong (PhD), Bannister (MPhil), Blake (MPhil, with Simon George);
(4) the planetary driver of atmospheric, environmental and biological change through the Precambrian (Van Kranendonk, Kirkland); and
(5) the characterisation of sulfur in the history of Mars (Fiorentini, Baumgartner).
5. AUSTRALIA’S PROTEROZOIC RECORD IN A GLOBAL CONTEXT
All the new findings from southwest Yilgarn and the Gawler craton, including the newly dated mafic dyke suites/swarms and their paleomagnetic implications in terms of supercontinent cycles, will be written up for publication as a series of high- impact papers. Final results from the detailed geochemical analyses and isotope studies of the Bunger Hills (Antarctica) dyke samples will be published. Paleomagnetic samples from the Kimberley will be analysed, and additional sampling may be carried out on a ca. 1.85 Ga ring complex and the ca. 1.8 Ga Davenport Province of the Northern Territory.
The study on the Ediacaran-Silurian of the western Yangtze will be finished in 2017, and summarised in a tectonostratigraphic history of the targeted strata, including how the detritus may have been shed from the Gondwana source regions to the Yangtze Block. The South China record will be compared with the new results from Western Australia, and we will synthesise their possible past connections at the dynamic northern margin of Gondwana.
One of the major showcases of our work will be the CCFS co-sponsored IGCP 648 event, the Rodinia 2017 conference to be held in Townsville in June 2017 (for information see http://geodynamics.curtin.edu.au/rodinia-2017/)
6. FLUID REGIMES AND THE COMPOSITION OF EARLY EARTH
Work in Australia will focus on Jack Hills. The oldest zircons from the original W74 sample will be identified and characterised for all isotopic systems in order to place the most stringent constraints yet on the nature of Earth’s oldest crust. In addition, the extent of the younger events in the Jack Hills belt will be re-investigated to resolve the depositional age and any affects related to metamorphism. The Pb nanospheres in ancient zircons from the Napier Complex, Antarctica, will be investigated using the atom probe to precisely determine their distribution and isotopic composition. Work on the Kemp Land samples will be completed. Another fieldtrip to Labrador will be undertaken in mid-2017 to more closely define the distribution of the most ancient gneissic components. A fieldtrip is planned to the Kongling area in South China to sample the most ancient rocks in the South China block in order to investigate their similarity or otherwise to the ancient gneisses in the North China Craton. Work will continue on both Lunar rocks and Martian meteorite samples with the aim of constraining the precise timing of events in the early solar system.
7. PRECAMBRIAN ARCHITECTURE AND CRUSTAL EVOLUTION IN WA
The structural imaging of the seismic data will be the first main task for 2017. With now over two thirds of the study area covered, Capricorn orogen-wide images of the crustal velocity and the spatial variation of crustal discontinuities (for example the Moho) will be produced, and the results will be passed to other research groups within the SIEF Capricorn project for mineral potential analyses. Secondly, seismic velocities of the entire lithosphere of the orogen will be developed using body wave tomographic techniques. The model will provide direct input to correlate mineralised crustal provinces and lithospheric structural anomalies. Thirdly, the crust and lithosphere imaging tools developed and tested in the Capricorn region can now be used in other regions in Western Australia. High-resolution crustal velocity images will be produced following the previous and planned deployments in the western-central region and the southwestern margin of the Yilgarn Craton.
A major focus will be the development of more field projects through various collaborating efforts in Western Australia. An initial agreement between Macquarie University, GSWA and the Institute of Geology and Geophysics, Chinese Academy of Sciences states that in the middle of 2017 a major 60 broadband seismic deployment will commence which targets the Canning Basin and the margins of the neighbouring Pilbara and Kimberley cratons. A 30-site ocean bottom seismic deployment is planned to follow later in the year, which will provide spatial coverage to offshore areas of the Canning basin. Early in 2017 collaboration between CET-UWA and GSWA has resulted in a 25-station deployment in the Perth region to target the young Perth Basin and the southwest Yilgarn craton margin.