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 1998 these were advanced by the following:
 

• The amalgamation of Geology and Geophysics at Macquarie into a single administrative unit from February, 1998 facilitated closer linkages and interfacing in teaching, research and industry interaction.  From January, 1999, we are the Department of Earth and Planetary Sciences incorporating Geology and Geophysics.
• The arrival of Professor Paul Morgan to the Chair of Geology at Macquarie.  He has a double degree in Geology and Physics. He is GEMOC's Program Leader for Geophysics and plans to integrate research and teaching across the Geology and Geophysics interface.
• Equipment upgrades funded by Macquarie University have resulted in an excellent array of new instrumentation for teaching and research including:
•  a 48 channel seismic recorder
•  seismic reflection cable and geophone set with roll-along capability
•  a gravity meter
•  electrical resistivity/IP equipment funded for 1999
•  magnetic susceptibility/temperature apparatus funded for 1999
•  interactive seismic 2D/3D processing software funded for 1999
• We had continuing access to 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 the University of Sydney continues in teaching and research.
• Dr Mark Lackie and Dr Phil Schmidt set up a major new rock magnetism joint facility with ARC RIEFP funding (involving CSIRO, and SUCOGG Universities, with Macquarie as the lead institution) for rock magnetism research.
• A preliminary seismic study of Moho depth and deep crustal structure in the Sydney region was carried out with a Macquarie seeding grant.  This provided the basis for an Honours project in 1998 (Michael Burke).
• Dr Yvette Poudjom Djomani, GEMOC Postdoctoral Fellow, has applied her expertise in potential field geophysics (including gravity, magnetic and thermal modelling) in collaborative projects including an investigation of the Siberian Platform with Western Mining and VSEGEI (see Research Highlights).
• Ongoing collaborative agreements with Chinese colleagues gave us access to extensive geophysical datasets for China and a new agreement was made for a collaborative project with the Institute for Gravity, Xi'an.
• Agreements were reached with VSEGEI (St Petersburg) to extend collaboration with access to extensive geophysical datasets. This is a collaborative project with Western Mining and continued with gravity interpretation across part of the Siberian Platform (see front cover and Research Highlights).
• 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 by Karsten Gohl 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) provided data for an Honours project in 1998 (Michael Seargent).
• Paul Morgan was one of nine scientific investigators for the New Millenium Program Deep Space 2 Microprobe Project Science Team chosen by NASA to guide the science on this mission.  Two microprobes in this project were launched from the Kennedy Space Centre on January 3, 1999 aboard a Delta III launch vehicle with the Mars Polar Explorer spacecraft.  The microprobes will arrive at Mars on December 3, 1999.
• Major advances were made in understanding the interpretation of geophysical signatures of some types of large-scale lithosphere domains (eg Publications, 113, 121,132, 137, 139, 144, 154, Appendix 2).

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 research programs and projects have been formulated or implemented in 1998 1.  Deep crust and upper mantle structure and depth of Moho beneath the Sydney Basin

2.  Nature and location of the Moho in two traverses across New England, NSW, and the eastern Lachlan Fold Belt (Snowy Mountains, NSW). This has been set up (by Karsten Gohl) as an integrative project involving a range of GEMOC geophysicists and petrologists and Professor Randy Keller from the University of Texas at El Paso.  This ties in with the Tasmanide project and related postgraduate and honours projects on the nature of the lithosphere in this region.

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 commenced 1998, Mark Pirlo)

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 the origin and composition of oceanic Agulhas Plateau, SW Indian Ocean. This includes further testing hypotheses of continental fragments, an anomalous upper mantle density and its origin, and a revised plate-tectonic reconstruction of the region. (In collaboration with the Antarctic Survey vessel cruise.)

8.  Investigation of the palaeomagnetism and rock magnetism of Ordovician eastern Australia alteration systems.

9.  Two new petrophysics projects were funded by ARC and MURG.  The first is to collect xenoliths from the Potrillo Volcanic Field, New Mexico, USA, to develop a lithosphere stratigraphy for this location and compare laboratory studies with field physical properties.  The second is to collect core samples from a series of drillholes in Cyprus from the Troodos ophiolite suite in order to characterise the thermal properties of oceanic crust.

new teaching activities

at Macquarie

• A new named degree, Bachelor of Geophysics, was introduced for 1998 to increase the visibility of Geophysics
• The Bachelor of Technology in Exploration Geoscience introduced in 1998 has a Geophysics strand streamed from the second year level (see flow sheet on Appendix 6)
• Use of an extensive pool of GPS units for undergraduate (and postgraduate) fieldwork continued.  Subscription to time signal allows real time differential applications with mapping resolution of 10-15 metres.
• Upgrade of differential GPS units to allow cm resolution required for detached gravity surveys.
• Extended implementation of new seismic, gravity and resistivity for student field projects in exploration, groundwater, environmental and engineering geophysics
• A SUCOGG Honours course addressing seismic and radar data-processing was offered in cooperation with the University of Sydney in 1998.
• Honours research programs integrating Geology and Geophysics components were completed in 1998 (Michael Seargent and Michael Burke)
• A postgraduate research program integrating Geology and Geophysics components commenced 1998.
• Involvement of excellent senior students in teaching activities such as seismic fieldwork

• The third year geophysics course GEOL3005 was extensively revised this year. Increased emphasis has been placed on exploration geophysics with modules added on airborne geophysics, geophysical well logging and seismic methods. A greater emphasis was placed on practical skills with assistance from AGSO staff and facilities.