GEMOC's research programs
index
GEMOC's activities involve four major interlinked programs:
Research Teaching and Training Technology Development Industry Interaction, Technology Transfer and Commercialisation
These programs are of approximately equal importance and are interdependent.
For example, the technology development program is driven by research
and industry needs and is incorporated in the teaching program.
the research aims
scientific context
Thermal energy transmitted through the mantle provides the energy
to drive lithosphere processes. Mantle-derived fluids and the
tectonic environment control element transfer across the crust-mantle
boundary and control the commodity distribution in the accessible
crust. The nature of mantle heat transmission reveals information
on fundamental deep Earth processes from the core-mantle boundary
to the surface. The Earth's interior can be mapped using fragments
of deep materials such as mantle rocks and diamonds, and the composition
of mantle-derived magmas.
The focus of GEMOC's research programs is the driving role of
the mantle in Earth processes and its control of element and commodity
distribution in the accessible crust.
This bottom-up approach involves
research program
The research program comprises four strands:
Lithosphere Mapping
Geotectonics
Crustal Generation Processes
Metallogenic Provinces
summary of major strands
The Lithosphere Mapping strand provides the
fundamental data for defining mantle domains in terms of composition,
structure and thermal state; relating these domains to refined
models of tectonic evolution will help to define the large-scale
evolution of mantle processes through time, and their influence
on the development of crustal material and metallogenic provinces.
The nature of mantle fluids and the mantle residence and abundance
of siderophile, chalcophile and noble elements and sulphur, carbon,
oxygen and nitrogen are keys to transfer of mineralising elements
into the crust.
The Crustal Generation strand seeks
to understand: the large-scale processes that have created and
modified continental crust; how these processes may have changed
through time; and how crustal processes influence the concentration
and localisation of economically important elements. The role
of crust-mantle interaction in granite genesis, coupled crust-mantle
formation and its influence on tectonism, and transport of elements
across the crust-mantle boundary link to the Lithosphere Mapping
and Metallogenesis strands.
The Geotectonics strand uses stratigraphic,
tectonic, and geophysical data to interpret the history and causes
of continental assembly and disruption, with a special focus on
Australia, East Asia and major cratons (Siberia, Kaapvaal, Canada).
It provides the fundamental framework to link the research on
crustal and mantle processes with the localisation and development
of metallogenic provinces.
The Metallogenesis strand seeks to
define the mantle and crustal reservoirs of economically important
elements, the mechanisms by which elements can be extracted from
the mantle and transported into the crust, and the mechanisms
of fluid transfer in the crust and mantle. The emphasis is on
understanding processes of regional scale, and relating these
processes to the tectonic framework and the processes of mantle
and crustal generation.
activities 1997
This section gives a brief overview of the philosophy
and framework of GEMOC's Research Projects and the major new activities
in 1997. A few of the important research outcomes in 1997 are
highlighted and a list of current funded Research Projects is
given in Appendix 5.
GEMOC's research programs aim to be interdisciplinary
and draw on our mix of geochemical and geophysical expertise and
the technology base that allows, for example, application of micron-scale
analytical data to the interpretation of geophysical modelling
and to lithosphere-scale Chemical Tomography as described in the
Siberian Craton study below.
The two major umbrella research initiatives shaped
through workshops in GEMOC's first year, were refined and implemented
in the first stage during 1997. These will fulfil part of GEMOC's
research and training brief and involve collaboration between
the GEMOC nodes and new cooperative linkages with other researchers.
New postgraduate and Honours for programs 1997 were initiated
as subset strands.
umbrella project initiatives
1. Timing and distribution of lithosphere formation and modification
in the eastern Australian Tasmanide Belt
The Tasman Orogen is a natural laboratory for the study of Phanerozoic
crust-mantle interaction. The geological and geophysical coverage
is excellent. A very large database on the geochemistry and metallogeny
of the abundant granitic rocks gives a reflection of variations
in middle to lower crustal composition across the region. Abundant
mantle-derived xenoliths occur in widespread Mesozoic-Tertiary
basalts, making it possible to study regional variations in lithosphere
and asthenosphere composition and relate these to crustal domains
defined by structural relations, granitoid chemistry, and geophysics.
The Tasmanide project focuses and integrates GEMOC's expertise
in mantle studies (basalts and xenoliths) with its expertise in
granite genesis and metallogenesis. Xenoliths of lower crustal
origin occur in several localities scattered across the region;
a traverse from Mt. Gambier in the west to the Monaro Province
in the east provides mantle samples from several crustal domains
defined by geophysics, granite chemistry and structural/stratigraphic
data. The traverse also crosses the I-S granite line, which is
believed to represent a major discontinuity in the nature of the
lower to middle crust. Xenolith-bearing basalts were erupted through
Proterozoic basement in western Tasmania, and through the Paleozoic
fold belt in the eastern part of the island. Because of this variety
of materials and data, this region provides an excellent opportunity
to investigate crust-mantle relationships in a major Phanerozoic
orogen, and to relate these to tectonics, geophysics and metallogeny.
Liaison with the Seismic Tomography Consortium identified the
New England Region as a major target for 1997. (Macquarie University
is a partner in this Consortium, led by Prof. Stewart Greenhalgh
now at the University of Adelaide.) An explosion seismic traverse
across the New England region has been planned and will interface
with detailed mantle studies in that area by a new postgraduate
student. This work will provide resolution of the crust-mantle
boundary region to complement seismic tomography models that give
resolution of deeper levels. Granite and metallogenesis studies
are characterising crust-mantle interaction and fluid processes.
New international funded projects started in 1997 (eg Southeastern
China igneous rocks, mineral deposits and tectonic setting) provide
a direct analogue to help interpret tectonic and magmatic events
in the Tasmanide Belt.
2. Lithosphere Generation Project
This umbrella project started as the "Western Pacific Lithosphere
Project" but research developments have revealed there is
secular and apparently irreversible geochemical evolution of newly-formed
lithospheric mantle. This has led to the modification of this
project to include work relevant to defining the nature of lithosphere
formed by identifiable processes such as accretion/subcretion
of oceanic plateaux. We have thus broadened the scope to include
other regions that serve as ideal natural laboratories to study
the evolution of several types of lithospheric mantle, which may
be analogues to the mantle beneath accreted continental margins
such as eastern Australia and China.
Some of the world's youngest ophiolite sequences outcrop in the
Solomon Islands and different tectonic units represent samples
of mantle formed in different settings: beneath Cretaceous ocean
ridges, in a forearc setting, and during the plume-induced eruption
of the basalts of the Ontong-Java Plateau (OJP). Mantle xenoliths
from volcanic rocks on Malaita and near Lihir Island provide samples
of deep OJP mantle and of relatively shallow forearc mantle, respectively.
The Lihir samples have been affected by fluids that may be related
to gold deposits in the overlying crust. The Kerguelen Plateau
yields a unique suite of deep-seated xenoliths that reflect young
plume and oceanic mantle material, and oceanic plateau lower crust.
Regional gravity and seismic data are available for both areas.
Field, petrological, geochemical and petrophysical studies of
the different types of mantle will be integrated with work on
the overlying cumulate and volcanic rocks to understand the processes
that have produced the spectrum of compositions in each mantle
type. Comparisons with similar "ancient" environments
in eastern Australia (the Tasmanide Project) will enable us to
construct a broad picture of the processes involved in the creation
and modification of lithosphere at convergent margins and above
plumes, and to relate these to fluid transfer and ore-forming
processes.
action 1997
Workshops of research groups across nodes set up a strategic plan
to address these projects. As a result:
for the Tasmanide project
for the Lithosphere Generation Project
new research appointments
Dr Yvette Poudjom Djomani arrived in August 1997
as a GEMOC Postdoctoral Research Fellow in Geophysics at Macquarie.
Her expertise is potential field geophysics (gravity, thermal,
magnetic), with special expertise in regional elastic thickness
modelling. She is the geophysicist in an interdisciplinary collaborative
project on gravity modelling of part of the Siberian platform
supported by Western Mining Corporation and with cooperation of
VSEGEI (St Petersburg). She has also received internal Macquarie
University Research Grant funding to commence elastic thickness
modelling in regions of Australia and has been invited to do the
gravity interpretation of a geophysical transect across the Dabie
Shan area in China with Professor Yuan Xuecheng from the Chinese
Academy of Geophysical Exploration, funded as a National Priority
Project by the China NSF. She is also modelling density/ depth/
temperature relationships for different types of lithospheric
mantle.
Ms Esmé van Achterbergh commenced as an ARC Research
Associate at Macquarie in April 1997. She has focussed on metasomatic
fingerprints and trace element residence in the mantle beneath
the Kaapvaal and Canadian cratons as part of a project in the
Lithosphere Mapping Strand and has had a principal role in developing
the GLITTER software (see Technology Development).
Dr Lev Natapov, new Research Associate in 1997 is formerly
Chief Geologist of Aerogeologiya State Enterprise (Moscow), the
Russian agency for geological mapping. He has an extensive and
varied background spanning stratigraphy, tectonics and economic
geology, and is one of Russia's leading experts on plate tectonics,
as well as the compiler of major paleogeographical atlases and
treatises on the plate tectonics of the northern hemisphere. At
GEMOC he is applying his expertise to the tectonic analysis of
several areas where Lithosphere Mapping projects are progressing,
including Siberia, east Asia, northern Canada and Australia.
Dr Phil Blevin was recruited as a Research Fellow
(50%) at the ANU in the last half of 1997. His primary research
focuses on the characterisation of metallogenic provinces in eastern
Australia, with particular reference to granitoid-related systems.
He and Professor Bruce Chappell are now integrating these studies
into the Tasmanide project.
Research projects feeding major strands
Lithosphere Mapping
Crustal Evolution
Metallogenesis
Geotectonics