This was a big year for the Structure Tectonics Team. Jiadong Shi completed his Honours degree, writing a thesis on “The northern extant of the Australian plate”, and is now employed in the teaching profession. Tomas O’Kane completed his PhD “4D Tectonic Reconstruction” and is on track for the award of his degree in early 2016. PhB student Fangqin Chen completed her special unit on the seismotectonics of Tibet. PhD candidate Fang Fang completed her mid-term. Two brand new Master of Earth Sciences (Advanced) candidates joined the group, Lin Shi and Fan Yin, and they have now completed the first six months of what will be an 18-month effort. In particular we congratulate Musri Mawaleda who sat his defence at Institut Teknologi Bandung in December 2015, with his co-supervisor, Dr Marnie Forster, in attendance.
The Master of Earth Sciences (Advanced) at RSES is a program aimed at bringing students adventure and training at the forefront of the discipline. The students spent one month camped in the Australian desert, southwest of Mount Isa, as part of an Advanced Structural Mapping special topic, supported by the Queensland Geological Survey (Sarah Sargent and Paul Donchak) and Chinova Resources (Mark McGeough).
The year ended with two of our PhD candidates in the final months of their candidature, writing up. Sarah Rajabi and Oleg Koudashev are on track for completing their theses during 2016. Sanjay Govindan and Ewout Rohling joined the group as Research Assistants.
It was a busy year also in terms of scientific visits. Professor Talat Ahmad interrupted his busy schedule as Vice–Chancellor of Jamia Millia University (JMI), Delhi, India to further our research together as part of our Australia India Strategic Research Fund (AISRF) project on the timing of events in the Himalayan orogeny. A paper is now in preparation as a result. His visit also set the scene in terms of organising interactions with ANU on other fronts, noting that JIM is a major focus for Islamic studies. ANU’s Centre for Arab and Islamic Studies was also able to take advantage of his visit, and hosted a visit while he was with us. Other visitors included Dr Daniel Viete (Durham University) and Ms Adriana Rajkumar, a PhD candidate at The University of Sydney, both of whom have collaborative projects in the argon lab, and Prof. Wiki Royden from MIT.
During the year members of the group also visited collaborating groups: Dr Marnie Forster visited Dr Fred Jourdan, at her partner argon facility, at John de Laeter, Curtin University. She also visited collaborating scientists, Prof. Alan Collins, Prof. John Foden and PhD students including Ms Fun Meeuws who has worked at ANU in her lab. Dr Jonathan Pownall visited Prof. Robert Hall at the South East Asia Research Group (SEARG) at Royal Holloway University of London, and Prof. Nick Rawlinson, University of Aberdeen, in connection with a Linkage Project in which these groups are involved, working with the Structure-Tectonics-Team at ANU.
Research conducted by the Structure Tectonics Team in 2015 largely focussed on the link between tectonics and mineralisation. On the very large scale the group continued its efforts in respect to 4D Tectonic Reconstruction. On the ground, a considerable geochronology program has been underway, with SHRIMP U–Pb analyses conducted by Dr Richard Armstrong, and 40Ar/39Ar analyses conducted by Dr Marnie Forster, shown here with Mr Musri Mawaleda in the course of field work in Western Sulawesi. Our interactions with Institut Teknologi Bandung are of key importance to the group, and Musri has been a regular visitor to ANU.
A decade long effort on the part of Dr Marnie Forster came to fruition during 2015, with the formal opening of the new ANU argon facility, by Prof. Margaret Harding, Deputy Vice-Chancellor Research at ANU. The opening took place amid considerable pomp and ceremony, not the least of which was the first Poetry Competition ever held at RSES (won by Dr Antony Burnham).
The ANUX summer school took place in late 2015, with three students from India, in the context of our AISRF project, and Mr Conrad Alderton and Ms Wulandari Mandradewi from G-resources in Sumatra, in the context of joint research in conjunction with our Australian Research Council funded Linkage Project.
The ANUX The Summer School involved a massive effort by the group, with citations for their teaching efforts to Oleg Koudashev, Sareh Rajabi and Dr Marnie Forster for training in respect argon geochronology, mineral separation and microstructural analysis, Dr Richard Armstrong for training in the use of SHRIMP for U–Pb geochronology, Shane Paxton for his course of Lapidary and Mineral Separation, and Dr Frank Brink, Operations Manager for the Centre for Advanced Microscopy at ANU, for his intensive six week course on analytical and observational methods using the Hitachi Scanning Electron Microscope. The Indian students involved in the Summer School were visited by the First Consul from the Indian Embassy, The Honourable Mukesh Kumar, who inspected the students while they were busy with the Scanning Electron Microscope.
In other notable achievements for 2015, Jonathan Pownall won a Discovery Early Career Research Award to further investigate the tectonic drivers of extreme metamorphism in Eastern Indonesia. This will build on research carried out in 2015 into the study of ultra-high-temperature (UHT) metamorphism and mantle exhumation linked to slab rollback of the Banda Arc, in Indonesia. This work incorporated fieldwork, seismotectonic analysis, 40Ar/39Ar and U–Pb geochronology.
Retentive core domains in K-feldspar
Dr Marnie Forster and Dr Richard Armstrong demonstrated that SHRIMP U–Pb and 40Ar/39Ar ages coincide because K-feldspar in granite may contain retentive core domains that survive temperatures near to or above the granite solidus.
K-feldspar from the Miocene Capoas Granite on Palawan in The Philippines may contain core domains that closed to argon diffusion at temperatures near the solidus during cooling of this ~7km diameter pluton. This research involved collaboration with Dr Barry Kohn at The University of Melbourne, who provided the (U–Th)/He ages. This work was published in AJES, during 2015.
This is an important result, for K-feldspar is supposedly not retentive in terms of its ability to retain argon. Closure temperatures for argon diffusion in K-feldspar are routinely claimed to be in the range ~150-400°C. Yet the release of 39Ar from irradiated K-feldspar during furnace step-heating experiments in vacuo yield Arrhenius data that imply highly retentive core domains, with inferred closure temperatures that exceed ~500-700°C.
Controlling Lineaments for the 2011 Tohoku-Oki Great Earthquake
Earthquakes involve mechanical failure of large structures. Just as engineers do after a building or a dam collapses, forensic examination of the evidence identified critical elements that focussed the onset of failure, and which could therefore be monitored more closely in the interests of forecasting future events. The analysis showed that significant lineaments localized the onset of failure for events >Mw=7, both prior and subsequent to the 2011 Tohoku-Oki Great Earthquake.
The data were analysed in the context of the “Satellites, Seismometers and Mass Spectrometers” initiative at RSES, involving cooperation and collaboration between three groups: the Geodesy and Seismology groups in the Geophysics cluster, and the Structure Tectonics Team, in Petrology, Geochemistry and Tectonics.