GEMOC ARC National Key Centre
GEMOC Research Projects listed by
strands and years
Research Projects initiated
1997
Lithosphere Mapping
L97-1. 4-D Lithosphere Mapping III: fingerprinting
the nature and mechanisms of secular evolution of the Earths'
lithosphere. (O'Reilly) Methodologies developed and refined
in previous work will be used to produce 4-D pictures (with time)
of the thermal and compositional structure of the upper mantle,
including a traverse through China, Mongolia and Siberia along
about one-third of the Earth's circumference. Mantle samples from
regions of contrasting age (ancient to modern) and tectonic environment
will be used to define the nature of irreversible changes with
time in the composition of the upper mantle and the mechanisms
that cause formation of new, and destruction of old, continental
mantle. The results will provide new information about the large-scale
controls on tectonics and magmatism in space and time within Australia
and Asia and can be applied to the selection of areas prospective
for diamonds and other magma-related economic deposits (eg nickel,
base metals, platinum group and rare-earth elements, copper and
gold). Funded by ARC large grant from 1998 and previously by
ARC, Industry, Macquarie University. (SEE Case Histories)
L97-2. Lithosphere Structure Beneath Siberia:
an integrated Geophysical, Petrological and Tectonic Analysis
(Griffin, Poudjom Djomani, Natapov, O'Reilly) Kimberlite fields
in the eastern Siberian Platform provide mantle samples along
a 1000-km traverse across several major terrane boundaries. This
project investigates methodologies for mapping large lithospheric
blocks by a combination of petrological, geophysical and tectonic
analysis of this region. Gravity and magnetic data, provided
through a collaboration with VSEGEI (St. Petersburg), are being
used to map the regional extent of lithospheric mantle of different
types beneath the Siberian Platform and to relate the distribution
of lithospheric blocks in this region to the distribution of different
types of mineralisation. Funded by ARC and MU collaborative grant
with Western Mining Corporation. (SEE Case Histories)
L97-3. Lithosphere structure and origin
of diamonds, Slave Craton, Canada (Griffin, O'Reilly, Davies,
Pearson). This project is part of a larger program that uses
xenoliths, heavy mineral concentrates and diamonds from newly
discovered kimberlites in the Slave Craton, to map the structure,
composition and thermal state of the lithospheric mantle. In
this module, we are studying the nitrogen contents and aggregation
state, carbon isotopic composition and mineral inclusions to place
the diamonds in their lithospheric context. This is leading to
new models for the formation of the cratonic mantle beneath this
little-known craton, with implications for the formation of continental
roots in general. Funded by MU collaborative grant with Kennecott
Canada Inc. (SEE Case Histories)
L97-4. Igneous rocks, mineral deposits
and tectonic setting: Southeastern China and eastern Australia
(O'Reilly, Griffin, Zhang). This project is providing enhanced
collaboration between the National Key Centre for Geochemical
Evolution and Metallogeny of Continents (GEMOC) at Macquarie University
in Australia and Nanjing University in China. It is a focussed
study of the relationships between igneous rocks, metallogeny
and geological architecture of southeastern China, capitalising
on the Nanjing participants' expertise of the in the field of
igneous rocks and associated mineralisation. Southeastern China
and Australia have geological similarities and contrasts. Southeastern
China, with its more complex geological structure and areas of
recent tectonic activity, provides analogues to interpret the
geological structure and metallogenic framework of the Australian
continent. The "4D lithosphere mapping" project now
being carried out at GEMOC has already identified major changes
in mantle structure beneath eastern China since Mesozoic time,
and this project is specifically designed to study the effects
that these changes have had on crustal generation and metallogeny.
This project will have practical outcomes in assisting area selection
and evaluation for mineral exploration. Funded by AusAID ACILP
and reciprocal funding from Chinese sources including China NSF
and China Ministry of Education.
L97-5. Basalts as probes to unravel the
evolution of the subcontinental lithosphere in East Australia
and East China (O'Reilly and Zhang) The chemical compositions
of basaltic magmas that erupted through different tectonic regions
in eastern Australia and eastern China are being used as probes
to understand the composition of the Earth's mantle down to depths
of ~100 km. This will help trace the evolution of the mantle beneath
the supercontinent of Gondwanaland since it split into small pieces.
The project will provide new insights into the genesis of the
basalts, the evolution of the mantle and continental crust, the
nature of mantle convection at a global scale, and a framework
for targeting resources related to volcanic processes. Funded
by small ARC
L97-6. Lithospheric architecture of an
oceanic plateau with continental affinity: seismic investigation
of the Agulhas Plateau, SW Indian Ocean (Gohl). Dredged basalt
samples of the southern plateau indicate a Proterozoic age of
continental fragments adjacent to overthickened oceanic crust.
A deep crustal seismic reflection and wide-angle/refraction transect
across the southern plateau was recently acquired to determine
its crustal thickness and composition, and to test an hypothesis
of an apparent anomalously low density upper mantle. Funded by
Macquarie University
L97-7
Nature and evolution of the oceanic
upper mantle at a convergent plate boundary: trace elements study
of the mantle xenoliths from the Tubaf Volcano (south of Lihir
Island, New Ireland, Papua New Guinea)
(Grégoire, McInnes (CSIRO) and O'Reilly). Trace element
signatures of bulk rocks and minerals in mantle xenoliths from
the Tubaf volcano provide a better understanding of the role of
fluids derived from a subducted slab in the modification of an
oceanic upper mantle showing evidences of early partial melting
processes. It gives new insights on the nature and evolution of
the deep lithosphere beneath a young gold deposit in the geodynamic
setting of an oceanic plateau in a collisional zone. Funded by
a GEMOC seeding grant and CSIRO.
L97-8. The nature of the upper mantle
beneath the southwestern margin of the Siberian platform (Ionov,
Griffin, O'Reilly, Malkovets). Mantle-derived xenoliths from the
Minusa region, southern Siberia are used to characterise the nature
of the upper mantle beneath a Paleozoic terrain at the southwestern
margin of the ancient East Siberian platform. This study will
provide analogue data to interpret similar tectonic regions globally,
including eastern Australia Funded by MURG and a GEMOC seeding
grant.
L97-9. Diamonds and their inclusions, Zarnitsa
and Dalnaya pipes, Siberia (Griffin, Davies, Bulanova). Most
data on diamonds and their inclusions from the Siberian Platform
have come from two major mines (Mir and Udachnaya). This project
examines material, made available through a collaboration with
TsNIGRI (Moscow), from two small uneconomic kimberlites in the
Daldyn field, for comparison with the diamonds from the nearby
Udachnaya pipe. An integrated study, it involves analysis of
nitrogen content and aggregation state, carbon isotopes, and the
composition of mineral inclusions, as well as examination of the
internal structure of the diamonds, in an effort to characterise
the nucleation and growth environment of the diamonds. Funded
by GEMOC seeding and TsNIGRI.
Crustal Generation
C97-1. Sulfide partitioning between felsic
melts and residues during ultrametamorphism of the deep crust
(Ellis, Sheraton, Mavrogenes). A suite of partially melted
(migmatitic) deep crustal hornblende granulites is being studied.
These rocks were saturated with sulfides during partial melting
and thus provide remarkable information for the partitioning of
sulfur and chalcophile elements between felsic melts and residues
in the deep crust. Whole rock geochemical, mineralogical and trace
element data (using the ANU laser ablation equipment for oxides,
sulfides and silicates) are being gathered. This will provide
valuable information on the role of partial melting and melt extraction
in infracrustal differentiation of sulfides. Funded by ARC.
C97-2. Crustal evolution in a Mesozoic Circum-Pacific
magmatic arc - the Peninsular Ranges batholith of Baja California,
Mexico (Johnson, Vernon, Tate). The project investigates
the ways in which large bodies of magmatic rocks (plutons) are
emplaced, the timing of their intrusion relative to regional deformation
and heating of the crust, the extent to which the plutons are
responsible for this deformation and heating, and the relative
roles of source and diversification processes in granitoid chemistry.
Funded by ARC and Mexican CONACyT.
C97-3. Accessory mineral solubility and
experimentally-determined constraints on trace element behaviour
in proposed mantle metasomatic melts (Green, Adam). The trace
element characteristics of metasomatic melts may be determined
by the accessory minerals that they are saturated in at high pressure.
Early experiments show that apatite and a Ti-rich phase in high-silica
and alkali melts have contrasting solubility behaviour with both
increasing pressure and K content. Funded by ARC Small Grant.
C97-4. The ages of mafic underplating in
central coastal Queensland. (C.M. Allen with I.S. Williams
(RSES)). Mafic crustal xenoliths from Cretaceous and younger
basalt flows are being dated by SHRIMP analysis of zircon in an
effort to tie the ages of mafic underplating to granite production.
Initial results suggest that these granulites are good recorders
of the major heating events that produced granites. Pilot project
funded by ANU; external funding being sought.
C97-5.A major review of the trace-element
geochemistry of granitic rocks and implications for petrogenesis
(John Sheraton, Lesley Wyborn and John Tarney, University
of Leicester). Funded by AGSO.
C97-6. An old method for studying element
mobility revised (John Sheraton and Wendelin Himmelheber,
University of Gottingen). This research deals with the use of
statistical methods for comparing chemical analyses of high-grade
gneisses with their retrogressed equivalents, with a view to identifying
any geologically significant changes in composition. Funded by
ANU.
C97-7.A regional geochemical study of the
island-arc and other volcanic rocks of the Papua New Guinea area
(John Sheraton and R. W. Johnson). Analyses of about 1600
whole-rock samples have been processed and plotted, and preparation
of a summary paper has begun. Funded by AGSO
Metallogenesis
M97-1. Tracing sulfur, chalcophile and
precious metals behaviour during differentiation and vapour evolution
from subduction zone magmas (Eggins). Metals in magma derived
ores, specifically porphyry Cu-Mo and epithermal Au deposits .
This research also has implications for understanding the sulfur
dioxide yields and atmospheric loading from past and future volcanic
eruptions. Funded by ARC, ANU.
M97-2. Metals behaviour in ultramafic-mafic
intrusions in southernmost NZ (Arculus, Eggins). This project
examines specifically the origin of primary platinoid mineralisation
in chromite lenses and their behaviour during magmatic differentiation.
Funded by ARC.
Geotectonics
GT97-1. Hot Rock Geothermal Energy: a
major new Australian energy source
(Chopra, Wyborn). Research has established that Australia has
enormous reserves of Hot Rock Energy. The successful utilisation
of this environmentally benign energy source could go a long way
to solving Australia's current greenhouse gas problems. Current
work involves refinement of hot rock resource models and detailed
planning for a field trial in the Hunter Valley, NSW. Funded in
part by ERDC.
Technology Development
TD97-1. Laser ablation ICP-MS developments
at ANU (Eggins). Laser ablation ICP-MS ablation environment
and applications development (inductively coupled plasma mass
spectrometry): specifically (1) design and testing of a high efficiency
ablation cell and transport system, (2) in situ analysis of precious
metals (PGE and Au) at ultra trace levels, (3) analysis of trace
elements in Li borate fusions prepared for XRF analysis, (4) metals
analysis in tiny (<100µm) melt inclusions trapped in phenocrysts.
Funded by ARC, ANU.
Research Projects initiated
1996
Lithosphere Mapping
L96-1. The nature of the upper mantle and
lower crust in eastern Mongolia and the Siberian Pacific margin
(Ionov, O'Reilly). Part of an integrated program to reveal the
nature of the upper mantle beneath lithospheric blocks of different
age, geological history and tectonic environment in a xenolith-based
traverse across the northern Asian continent. It focuses on two
localities (Dariganga in eastern Mongolia, and NW Sikhote-Alin
near the Pacific margin of Siberia) in the central-SE segment
of the transect. This study also characterises mantle heterogeneity
on a m-km scale and provides a better insight into mantle processes.
Funded by ARC small grant.
L96-2. Geochemical structure of lithospheric
mantle: key to interpretation of regional geophysics (Griffin).
Uses detailed studies of mineral chemistry in mantle xenoliths
to interpret data from mineral concentrates, so these can be used
for detailed mapping of mantle composition and structure. Focuses
on application of these geochemical/geological data to the interpretation
of regional geophysical surveys, for mapping large-scale variations
in the nature of the upper mantle. Funded by ARC.
L96-3. Deep structure of the Canadian Shield (Griffin, Pearson, O'Reilly). Mantle xenoliths, xenocrysts and diamonds from kimberlites are being used to map the lithospheric mantle beneath the Slave Province of the Canadian Shield. Funded by Macquarie University Collaborative Grant with Kennecott Canada Inc.
L96-4. Eastern Australian and Indochinese
diamonds (Davies, Griffin, O'Reilly, Win, Metcalfe, Wathanakul
(Kasetsart Univ)). Morphological and geochemical studies of alluvial
diamonds and their inclusions, to determine the nature of the
mantle source(s) and to develop new models for exploration in
regions without known kimberlite/lamproite source rocks. Funded
by CRA Exploration and GEMOC, and in cooperation with the Myanmar
Ministry of Mines and Kasetsart University, Bangkok.
L96-5. Seismic imaging of the MOHO and
deep crust and upper mantle in SE Australia (Gohl). The depth
of the eastern Australian crust as well as the nature of the crust-mantle
boundary are not yet well defined. With the new pool of seismic
recorders available through the Joint-University Seismic Facility,
new data will be recorded using quarry blasts as the seismic source.
Seismic models will integrate results from petrology of xenoliths.
Funded by MURG and MU Seeding Grant for ARC.
L96-6. Evolution of oceanic lithosphere
and crustal growth in the Kerguelen archipelago (Grégoire,
O'Reilly). Combined petrological, geochemical and petrophysical
analysis of upper mantle and lower crustal xenoliths of the Kerguelen
islands provides detailed stratigraphy of rock types in this lithosphere
section. This new dataset and its interpretation will have global
significance for the understanding of the formation of oceanic
plateaus and their possible contribution to the lithosphere beneath
continents. Funded by IRF.
L96-7. Abundance, residence and significance
of heat-producing and other trace elements in mantle peridotites
(O'Reilly, Griffin, Ionov, Norman, Pearson). Laser microprobe
ICPMS analyses in situ of rare earth elements and other
key trace elements such as U, Th, Rb, Sr will provide baseline
data on trace element contents to ppm levels of the main minerals
present in the Earth's mantle and for some accessory minerals.
These new data will provide heat production values which will
have important implications for thermal models of the Earth's
lithosphere. Funded by MURG.
Crustal Genesis
C96-1. Evolution of a hotspot volcano:
geochemistry of glasses from Mauna Loa (Norman, Garcia (Univ.
Hawaii)). Traces the magmatic evolution of Mauna Loa volcano,
using laser microprobe trace element analysis of quenched melt
inclusions in olivine crystals. Funded by MURG.
C96-2. Composition of the oceanic mantle
beneath Hawaii (Norman; M. Garcia (Univ. Hawaii)). Explores
the composition and thermal structure of the oceanic crust and
mantle beneath the Hawaiian hotspot, the classic example of a
mantle plume, through study of xenoliths from a previously inaccessible
locality on Kauai. Funded by MURG.
C96-3. Silurian and Early Devonian tectonic
development of the Tumut-Gundagai region, southeastern NSW
(Dadd). The complex history of extensional and compressional
events in the region is being analysed by studies of back-arc
lavas intercalated with felsic volcanic rocks and extensive units
of serpentinised ultramafic rocks, intruded by Silurian(?) granodiorite.
C96-4. Age, tectonic affinity and economic
potential of volcanic rocks in the Louth area, western NSW (Dadd).
Volcanic rocks intersected in drill holes in the Louth area of
western NSW form the northernmost occurrence of such rocks in
the Lachlan Fold Belt. The Louth rocks may correlate with Ordovician
volcanic arc rocks in the Mt. Dijou area to the east, or with
younger Devonian continental rift sequences to the south near
Mt Hope. Both sequences contain significant but distinct mineralisation.
Determination of the age and magmatic affinity of the Louth rocks,
will give a better understanding of the large-scale tectonic evolution
of the region and be better able to establish target areas for
mineralisation. Funded by MURG.
C96-5. Depositional style of subaqueous
volcanogenic debris deposits, regional facies analysis, metallogenesis
and tectonic setting of the Mount Hope group, central western
NSW. (Dadd) Very few convincing examples of subaqueously deposited
and welded pyroclastic flows exist in the world although references
abound in the literature. The Mount Hope Group provides numerous
examples of welded and non-welded pyroclastic debris deposits
intercalated within a subaqueous sedimentary package. Documentation
of these deposits will either prove that flows can maintain their
integrity and weld in the subaqueous environment or lead to the
development of models for flow transformation from pyroclastic
to debris flow. The location of the source areas for these flows
will aid in mineral exploration within the area and within similar
volcanic terrains. Funded by Macquarie University ARC Large Grants
Scheme Seeding Fund.
C96-6. A metamorphic transect through the
Himalayan Main Central Thrust (MCT) (Nichols, Pearson, Johnson).
The MCT is a significant Himalayan structure, which experienced
south-directed movement during the Tertiary. This project aims
to understand the kinematics of the MCT by quantifying the associated
change in P-T across the thrust zone. Funded by MURG.
C96-7. Proterozoic uplift in East Antarctica
(Nichols; F. Fahey (NIST, Washington)). Three generations of
mylonites cut ca. 1000 Ma granulite facies rocks in East Antarctica,
and are distinguished on the basis of orientation, texture, and
associated mineral assemblages. Second generation mylonites are
ubiquitous in the northern Prince Charles Mountains, and are granulite-grade
ultramylonites associated with a total uplift of ca. 6 km across
the region. The ion microprobe is used to date the timing of mylonitic
deformation, and thereby place better constraints on the formation
and exhumation of this lower crustal segment.
C96-8. The stability of zirconolite in
the crust and mantle (Ellis, Allen). Various zirconium-
and titanium- rich phases occur in kimberlites, calcareous skarns
and form the mineral basis for the synthetic nuclear waste disposal
material invented at ANU - Synroc. The project is reviewing the
occurrence of zirconolite and carrying out experiments on its
stability. These phase relations will lead to a better understanding
of Zr-Ti accessory mineral stability fields as an aid to diamond
exploration. Funded by ANSTO and ARC.
C96-9. Magmatic roots of an island arc
system - Green Hills - Pahia Point, South Island of New Zealand.
(Eggins, Arculus, Price (LaTrobe)). The magmatic evolution of
island arc systems is fundamental to the growth of continental
crust, and global geochemical recycling. Fortuitously excellent
exposure of the magmatic roots of a ~250 million year old arc
system in New Zealand provides the kind of access which we need
to understand the processes of magmatic fractionation, recharge,
eruption tapping, and interaction with preexisting crust. A comprehensive
analytical effort is planned with colleagues from other Australian
and NZ universities. Funded by ARC Small Grant.
C96-10. In search of olivine-saturated
arc high-alumina basalt (Draper). Experimental studies testing
alternative models for the origins of mafic arc high-alumina basalt
: either a derivative magma from a parental high-magnesia basalt,
or a direct melt of the subducted lithospheric slab. The two
hypotheses have fundamentally different ramifications for the
thermal and physical structure the mantle in subduction zones.
Funded by Small ARC.
C96-11. Trace element studies of mineral
growth and metamorphic reactions (Pearson, Nichols). Development
of trace element zonation patterns to interpret growth mechanisms
and P-T history of minerals in metamorphic rocks and applications
for models for element redistribution in high-grade metamorphism.
Funded by MURG.
Metallogenesis
M96-1. Origin of mineralisation in the Browns
Creek Gold Mine, NSW (Blevin, Wilkins (Uni of Sydney)). Recent
discovery of monzonitic intrusives intimately associated with
gold mineralisation at Browns Creek indicates the presence of
a previously undescribed igneous suite of economic significance
in the eastern Lachlan Fold Belt. The top of this intrusive is
aplitic to pegmatitic and shows good textural evidence of the
evolution of a volatile phase. Funded by AMIRA.
Geotectonics
GT96-1. Neoproterozoic earth history of
Australia: Tectonics, Isotope-, volcanic- and bio-stratigraphy.
(Veevers, Walter). Isotopic chemostratigraphy and acritarch
biostratigraphy will elucidate the history of the Neoproterozoic
in Australia and enable convincing correlation to other regions.
This work will provide an effective basis for petroleum exploration
of the Neoproterozoic succession of Australia. Funded by ARC.
Research Projects initiated
1995
Lithosphere Mapping
L95-1. Lithosphere evolution in eastern
China (O'Reilly, Griffin, Zhang, Guo). Integrates petrological
data on basalts, xenoliths and xenocrysts from kimberlites and
basalts, and a range of regional geophysical data, to examine
the evolution of the continental lithospheric mantle from Archean
to present. A large-scale collaborative project involving personnel
from several Chinese institutions. Funded by ARC, DEET Targeted
Institutional Links, Academia Sinica, China NSF, China Ministry
of Geology, China Education Ministry, Macquarie University.
L95-2. Lithosphere mapping in Australia
(O'Reilly, Griffin, Zhang, Norman, Gaul, McCarron). Links studies
of mantle petrology (using xenoliths and xenocrysts in volcanic
rocks) with regional geophysical data, in collaboration with Prof.
B. Kennett's tomography group at ANU-RSES. Funded by ARC, Stockdale
Prospecting Ltd. (APA-I).
L95-3. Siberia-Mongolia lithosphere traverse
(Griffin, O'Reilly, Ionov). Mantle xenoliths and xenocrysts from
kimberlites and basalts are being used to map the mantle along
a traverse extending from the Arctic sea, south across Siberia
into the Baikal Rift and further into Mongolia and the Russian
Far East. Funded by ARC, Macquarie University and Almazy Rossii-Sakha
(Russian diamond exploration and mining conglomerate).
L95-4. Alkali and heat-producing elements
in the lithosphere of eastern Australia (Norman). The distribution
of K, Rb, Cs, Th and U in the continental crust and lithospheric
mantle of eastern Australia is being studied to determine the
composition of the continental crust and the primitive mantle
of the Earth, constrain the origin of the Earth and Moon, and
measure the contribution of mantle sources to lithospheric heat
production. Funded by ARC.
L95-6. Experimentally determined Zr and
Hf partition relationships at high pressure (Green, Fujinawa
(Ibaraki University)). Partitioning relationships of Zr
and Hf between amphibole, clinopyroxene, garnet and basanitic
and andesitic melts are being determined at high pressure and
temperature. Results show a consistent decrease in partition
coefficients (D) with increasing pressure for amphibole, clinopyroxene/
melt pairs, and Hf D values are always greater than Zr values.
In contrast, for garnet D (Zr) is greater than D (Hf). Funded
by MURG.
L95-7. Garnet-clinopyroxene 2-mineral partition
coefficients at high pressure (Green, Blundy (Bristol Univ.),
Yaxley (RSES), Adam) . Large (>30um) crystals of coexisting
gnt and cpx crystallised from tholeiitic and basanitic compositions
at 2, 3 and 4 GPa. At 6 GPa gnt was confined to the tholeiite
only. Analyses on initial runs were by ion microprobe at Edinburgh
University, but two later runs at 2 and 4 GPa will be analysed
by LAM ICPMS at MU. Funded by MURG.
L95-8. Phase relations of extreme-composition
xenolith glasses (Draper, Green). Anhydrous and fluid-saturated
liquidus phase relations, of melts rich in SiO2, Al2O3, Na2O and
K2O and poor in MgO, FeO, and CaO, typical of the extreme range
of compositions of glasses found in many mantle xenoliths worldwide,
show that such liquids are in equilibrium with a harzburgitic
to lherzolitic residue. Such liquids can act as agents of cryptic
mantle metasomatism, but will not result in wholesale reaction
with mantle minerals. The experiments document the surprisingly
large extent of dissolution of major-element components into supercritical
hydrous fluids at mantle conditions. Funded by MURG.
Crustal Genesis
C95-1. Evolution of magmas in the Peninsular
Ranges Batholith, Baja California (Vernon, Johnson, Tate).
80-140 million years ago, subduction of Pacific Ocean crust
beneath the North American plate caused melting of the lower continental
crust, forming the Peninsular Ranges batholith. This study of
the evolution of these granitic melts provides insights into the
chemical evolution of magmatic arcs. Funded by MURG, ARC and AINSE.
C95-2. Microstructural processes in metamorphic
rocks (Vernon). This project investigates the microstructures
(shapes and arrangements of crystals) of metamorphic rocks in
selected parts of Earth's deeper crust, now exposed at the surface,
to determine the heating and deformation histories at the time
of their formation. Funded by MURG and ARC.
C95-3. Crustal evolution in a Mesozoic
Circum-Pacific magmatic arc (Johnson, Vernon). The project
investigates the ways in which large bodies of magmatic rocks
(plutons) are emplaced, the timing of their intrusion relative
to regional deformation and heating of the crust, and the extent
to which the plutons are responsible for this deformation and
heating. Funded by ARC.
C95-4. High pressure vapour-melt partitioning
experiments (Nichols, Green). Models for the genesis of subduction-zone
magmas usually require a hydrous fluid component. This experimental
project seeks to quantify the trace element attributes of hydrous
fluids equilibrated with basanitic melts, using the laser-ablation-microprobe-ICPMS
technique. Funded by ARC.
C95-5. P-T studies across the central Nagssugtoqidian
Orogen, west Greenland (Nichols, Kriegsman (UNSW). The Nagssugtoqidian
is thought to represent a Palaeoproterozoic continental collision
zone. This project is aimed at defining P-T-t changes and melting
processes across the region in order to elucidate the tectonic
processes active during collision. Funded by Danish Lithosphere
Centre.
C95-6. Granite emplacement: New England
Batholith (Shaw, Flood). Investigation of the emplacement
mechanisms of two granite bodies in a well documented batholith.
A cross-disciplinary project with structural mapping, geochemistry,
geochronology, rock magnetism and geophysical modelling. Funded
by MURG.
C95-7. Magma genesis and tectonics in western
Pacific island arcs (Arculus). Investigation of the impacts
of lithospheric filtering on arc magmatism in the northeast Japan
arc, the origin and tectonics of the Ontong Java Plume portion
obducted onto Santa Isabel in the Solomon Islands (SI), and the
petrogenesis of (multiply sourced) peridotites on Choiseul, Santa
Isabel and San Jorge (SI). Funded by ARC.
C95-8. Evolution of continental crust:
examples from the San Francisco Volcanic Field, AZ (Arculus).
Investigating the evolution of the Proterozoic - Phanerozoic
lower crust of the Colorado Plateau through integrated geochemical
and petrological studies of volcanic rocks and crustal xenoliths.
Funded by ARC.
C95-9. Origin of granites and their role
in the production and development of new crust at continental
margins (Chappell). Geochemical studies of granites, mainly
in eastern Australia, and their importance in crust formation
processes. Funded by ARC to end 1995.
C95-10. Geochemistry of granites formed
at accreted continental margins (Chappell). This project
aims to relate the composition of granitic rocks to the processes
occurring at collisional margins. Funded by ARC.
C95-11. The stability of titanite in the
crust (Ellis, Troitzsch). The aim of this project is twofold
- to calibrate the Al content of titanite as a geobarometer, and
to determine the PH2O, fO2 conditions under which titanite is
a magmatic phase in I-type, hornblende bearing granites. Funded
by ARC.
C95-12. An experimental examination of
eclogite partial melting: Liquids, residues and trace element
partitioning (Ellis, Gust (Univ. Qld)). Experimental determination
of the composition (major and trace element) of the magmas formed
by partially melting natural basaltic compositions during subduction.
Funded by ARC.
C95-13. An experimental study of the diffusion
of lead in zircon (Ellis, Lee (RSES)). Determination of the
behaviour of lead during heating and cooling events, to improve
the interpretation of U-Pb geochronology data. Funded by ARC.
Metallogenesis
M95-1. Geochemistry of mantle sulfides:
probing the Earth's core-mantle-crust system (Guo, Griffin,
O'Reilly). Geochemical and petrological studies of sulfides in
mantle-derived xenoliths and ophiolites, and included in diamonds,
to define the size and nature of the sulfide reservoir for chalcophile
elements, and to enhance our understanding of the genesis of base-metal
sulfides and platinum-group elements mineralisation in the crust.
Funded by ARC and Macquarie University.
M95-2. Volatile, chalcophile, and noble
siderophile elements in subduction zone magmas (Arculus, Eggins).
Tracking the origin and distribution of the chalcophile and
noble siderophile elements in subduction zone systems, with particular
reference to volatile associations and episodes of volatile phase
loss. Funded by ARC.
M95-3. Magmatic and hydrothermal evolution
of intrusiverelated gold deposits (Chappell, Blevin).
metallogeny of gold deposits in eastern Australia, with particular
emphasis on the internal magmatic and hydrothermal evolution of
Ordovician copper-gold systems in New South Wales. Funded by AMIRA
and ARC.
Geotectonics
GT95-1. Palaeomagnetic studies of the northern
New England Orogen Queensland (Lackie) Palaeomagnetic analysis
is being used to interpret the tectonic and thermal history of
the region, with emphasis on the effects of magnetic overprinting
and events leading to the opening of the Tasman Sea. Funded by
ARC.