GEMOC ARC National Key Centre

Strengthening Geophysics and crossing the
geology/geophysics interface

activities 1997

Strengthening of Geophysics and integration across the boundaries of Geology and Geophysics are major aims of GEMOC. In 1997 these were advanced by:

• the amalgamation of Geology and Geophysics at Macquarie into a single administrative unit from 1998 will facilitate closer linkages and interfacing in teaching, research and industry interaction
• first use for a Macquarie-funded project of the pool of seismic detectors which form part of the ARC Seismic Consortium (headed by the University of Adelaide/Flinders University with Macquarie, Monash, Sydney, Queensland and ANU as partners and with strong support from AGSO and the Australian Geodynamics CRC)
• collaboration between GEMOC and Geophysics at Sydney University has been strengthened with development of a major collaborative project and application for 1999 funding
• the new 48 channel seismic recorder (purchased in 1997 with part GEMOC funding) was used for both research and teaching in geophysics
• a new gravimeter and additional seismic equipment (geophones and cables) for both teaching and research were funded for 1998 through the Macquarie University Capital Equipment scheme
• Dr Mark Lackie and Dr Phil Schmidt were successful in obtaining ARC RIEFP funding for a major new rock magnetism joint facility (involving CSIRO, and SUCOGG Universities, with Macquarie as the lead institution) for rock magnetism research
• a seismic study of MOHO depth and deep crustal structure in the Sydney region was commenced with a Macquarie seeding grant
• appointment of Professor Paul Morgan to Chair of Geology at Macquarie. He has a double degree in Geology and Geophysics and plans to integrate research and teaching across the Geology and Geophysics interface.
• Dr Yvette Poudjom Djomani, a GEMOC Postdoctoral Fellow, arrived in August 1997: she has expertise in potential field geophysics including gravity, magnetic and thermal modelling
• two of China's leading geophysicists (Professor Yuan Xuecheng, compiler of the "Geophysical Atlas of China" and Deputy Director of the China Academy of Exploration; Professor Wang Ji-Yang, Academician and author of "Geothermics of China") gave lectures and presented geophysical data not previously available, at the Workshop on Tectonic Evolution of East and Southeast Asia.
• ongoing collaborative agreements with Chinese colleagues gave us access to extensive geophysical datasets for China
• agreements were reached with VSEGEI (St Petersburg) for collaborative access to extensive geophysical datasets and a collaborative project with Western Mining commenced on gravity interpretation across part of the Siberian Platform
• GEMOC is participating in the Geophysical Transect across the northern boundary of the Yangtse Craton, funded by the China NSF and organised by the Chinese Academy of Exploration. GEMOC's role is to interpret the gravity data on a collaborative basis and to integrate petrological and geochemical data with all the available geophysics on the Transect.
• Macquarie-funded participation in a deep crustal marine seismic survey program across the Agulhas Plateau, SW Indian Ocean, in cooperation with the Alfred Wegener Institute (Germany) and the University of Cape Town (South Africa)
• major advances in understanding the interpretation of geophysical signatures of some types of lithosphere domains (eg Publications, 64, 66, 74, 90 109).

new research projects

As a result of workshops, joint discussions, industry advice, seismic consortium meetings and feedback from GEMOC attendance at national and international meetings, the following medium term research projects have been formulated or implemented in 1997

1. Deep crust and upper mantle structure and depth of Moho beneath the Sydney Basin
2. Nature and location of Moho in two traverses: Snowy Mountains and New England. The latter ties in with one of the first targets identified for the deployment of the seismic tomography array for the Seismic Tomography Consortium and links into the Tasmanide project and related postgraduate and honours projects
3. Modelling of the effective elastic thickness of selected regions in Siberia, Australia, China and specific other regions globally (relevant to exploration targeting) and integration with thermal and magnetic signatures and datasets.
4. Thermal studies of the Australian lithosphere including: silica heat flow studies, modelling heat flow and paleo-heat flow with experimentally determined parameters for thermal conductivity (at different T and P) and heat production of realistic geological lithospheric sections. (A relevant PhD project commences 1998)
5. Focus of mantle petrological studies in the New England Region NSW, the southern Lachlan Orogen and across the Tasman Line in Tasmania to interface with the seismic, gravity, thermal and magnetic geophysical datasets
6. Modelling of density of different types and compositions of lithospheric mantle to assess mechanisms of mantle overturn and thinning in regions of different age, thermal structure and tectonic environment
7. Identifying and modelling of continental fragments of the oceanic Agulhas Plateau, SW Indian Ocean. This includes testing hypotheses of an anomalous upper mantle density and its origin.

new teaching activities at Macquarie

• A new named degree, Bachelor of Geophysics, was introduced for 1998 to increase the visibility of Geophysics
• The new (1998) Bachelor of Technology in Exploration Geoscience has a Geophysics strand streamed from the second year level (see flow sheet on Appendix 6)
• Use of 18 GPS (1 da Silva, 9 Garmin/45 and 8 Magellan) units for fieldwork use and implementation of GPS use in all undergraduate (and postgraduate) fieldwork. Subscription to time signal allows real time differential applications with mapping resolution of 10-15 metres.
• Extended implementation of new seismic equipment and gravimeter for student field projects in exploration, groundwater and engineering geophysics
• Discussions with the Universities of Sydney and NSW about shared teaching of seismic and radar data-processing and integration of Geology and Geophysics in some courses. A shared SUCOGG Honours course is offered in 1998.

Honours research programs integrating Geology/Geophysics components (see description of Honours programs below) A postgraduate research program integrating Geology/Geophysics components commences 1998 Integration of excellent senior students in research activities such as seismic fieldwork at ANU Revision of the 3rd year Geophysics course (GEOL3005) by RSES staff (Jean Braun and Gianna Bassi) has taken place over the past 2 years, with emphasis on solutions of geophysical problems including computer simulations and analytical approaches relevant to tectonic problems such as mountain building/destruction and basin formation.

Students using geophysical equipment to survey the location of buried material in the fill beneath a community park