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    <title>UTas ePrints - Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin</title>
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    <meta content="Yang, J." name="eprints.creators_name" />
<meta content="Large, R.R." name="eprints.creators_name" />
<meta content="Bull, S.W." name="eprints.creators_name" />
<meta content="Scott, D.L." name="eprints.creators_name" />
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<meta content="S.Bull@utas.edu.au" name="eprints.creators_id" />
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<meta content="2007-07-26" name="eprints.datestamp" />
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<meta content="Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin" name="eprints.title" />
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<meta content="260100" name="eprints.subjects" />
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<meta content="SEDEX, Zinc, massive sulfide, ore genesis, sedimentary basin, basinal brines, fluid flow modelling, faults, aquifers, convection." name="eprints.keywords" />
<meta content="Numerical fluid-flow and heat-transport modeling was undertaken on a well-constrained geologic section
through the northern Mount Isa basin in order to test the possibility of forming stratiform Zn-Pb-Ag deposits
by buoyancy-driven free convection of marine fluids. The major two-dimensional geologic section used for the
modeling was based on recent geologic mapping and sequence stratigraphic interpretation, combined with
geophysical interpretation from regional seismic, aeromagnetic, and gravity data sets. The basin fill, termed the Leichhardt, Calvert, and Isa superbasins, forms a south-dipping wedge of sedimentary and minor volcanic
rocks up to 25 km thick. A number of major subvertical synsedimentary normal faults cut through this fill and
are rooted in the basement. Two potential aquifer sequences have been identified: sandstones and volcanic
rocks of the Big supersequence at the base of the Calvert superbasin, and sandstones and conglomerates comprising
the Mount Guide Quartzite at the base of the older Leichhardt superbasin. There are three stratiform
Zn-Pb-Ag deposits in the younger Isa superbasin, close to the section-line selected for modeling. Century is a
world-class and high-grade stratiform zinc deposit which contains over 14 Mt of Zn metal hosted by 1595 Ma
black shales and siltstones. Pb-Pb isotope studies suggest the deposit formed about 1575 Ma. Walford Creek
and Blue Bush are large but low-grade, pyrite-rich, and zinc-poor stratiform deposits hosted in 1640 Ma carbonaceous
shales and siltstones.
Numerical modeling of fluid flow at about 1575 Ma shows that buoyancy-driven convection is controlled by
the relationship between the faults and aquifers. The synsedimentary faults, given high permeabilities in the
model because they were active during the mineralizing event, act as either recharge or discharge zones for
fluid flow. Marine fluids commonly recharge the basin via the minor faults and flow through the sandstone and
volcaniclastic aquifer sequences at depths of 5 to 10 km. These fluids have the potential to leach zinc and lead
from the clastic material comprising aquifer and adjacent volcanic rock layers. The heated metalliferous fluids
discharge to the surface where the aquifers intersect the major faults. Hydrothermal discharge temperatures
from the Termite Range fault were computed to be in the range 100 degrees to 180 degrees, with fluid velocities of 1 to 8
m per year. These conditions are suitable for the formation of a Century-sized Zn deposit at the discharge point
adjacent to the Termite Range fault over a period of 0.65 m.y., provided a suitable chemical trap environment
is present. Several numerical simulations were run with different aquifer and fault properties designed to understand the hydrological constraints for the formation of major Zn deposits. Aquifer permeability, fault permeability, and fault penetration depth were shown to be the major factors controlling the fluid-flow and temperature
regime. Significantly higher discharge fluid temperatures and velocities were obtained when the depth of penetration of the Termite Range fault was increased from 15 to 30 km.
The results of the numerical modeling are significant in understanding geologic and hydrological controls on
the formation and location of major stratiform Zn deposits. The permeability and thickness of potential
aquifers, their depth in the basin, the presence of stacked aquifer sequences, and the relationship between
aquifers and synsedimentary faults all have important exploration implications. In particular, the Termite
Range, Fish River, and Elizabeth Creek faults are interpreted to be major deep faults that have controlled
basin-wide convective fluid flow, and therefore the location of major base metal deposits." name="eprints.abstract" />
<meta content="2006-09" name="eprints.date" />
<meta content="published" name="eprints.date_type" />
<meta content="Economic Geology" name="eprints.publication" />
<meta content="101" name="eprints.volume" />
<meta content="6" name="eprints.number" />
<meta content="1275-1292" name="eprints.pagerange" />
<meta content="10.2113/gsecongeo.101.6.1275" name="eprints.id_number" />
<meta content="UNSPECIFIED" name="eprints.thesis_type" />
<meta content="TRUE" name="eprints.refereed" />
<meta content="0361-0128" name="eprints.issn" />
<meta content="http://dx.doi.org/10.2113/gsecongeo.101.6.1275" name="eprints.official_url" />
<meta content="Andrews, S.J., 1998, Stratigraphy and depositional setting of the upper Mc-Namara Group, Lawn Hill region: ECONOMIC GEOLOGY, v. 93, p. 1132-1152.
Barrie, C.T., Cathles, L.M., and Erendi A., 1999, Finite element heat and fluid-flow computer simulations of a deep ultramafic sill model for the Kidd Creek volcanic associated massive sulfide deposit, Abititi subprovince:
ECONOMIC GEOLOGY MONOGRAPH 10, p. 529-540.
Betts, P.G., Giles, D., and Lister, G.S., 2003, Tectonic environment of shalehosted massive sulfide Pb-Zn-Ag deposits of Proterozoic northeastern Australia:
ECONOMIC GEOLOGY, v. 98, p. 557-576.
Bradshaw, B.E., Lindsay, J.F., Krassay, A.A., and Wells, A.T., 2000, Attenuated basin-margin sequence stratigraphy of the Paleoproterozoic Calvert and Isa superbasins: The Fickling Group, southern Murphy inlier, Queensland:
Australian Journal of Earth Sciences, v. 47, p. 599-623.
Broadbent, G.C., Myers, R.E., and Wright, J.V., 1998, Geology and origin of shale-hosted Zn-Pb-Ag mineralization at the Century deposit, northwest Queensland, Australia: ECONOMIC GEOLOGY, v. 93, p. 1264-1294.
Broadbent, G.C., Andrews, S.J., and Kelso, I.J., 2002, A decade of new ideas: Geology and exploration history of the Century Zn-Pb-Ag deposit, Northwestern Queensland, Australia: Society of Economic Geologists Special
Publication Number 9, p. 119-140.
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Bull, S.W., and Rawlings, D.J., 1998, A tectono-stratigraphic review of the northern Australian Proterozoic zinc belt, in Holm, O., Pongratz, J., and
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Cooke, D.R., and Large, R.R., 1998, Practical uses of chemical modeling- defining new exploration targets in sedimentary basins: AGSO Journal of Australian Geology and Geophysics, v. 17, no. 4, p. 259-276.
Cooke, D.R., Bull, S.W., Large, R.R., and McGoldrick, P.J., 2000, The importance of oxidized brines for the formation of Australian Proterozoic stratiform sediment-hosted Pb-Zn (Sedex) deposits: ECONOMIC GEOLOGY,v. 95, p. 1-18.
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Glikson, M., Mastalerz, M., Golding, S.D., and McConachie, B.A., 2000, Metallogenesis and hydrocarbon generation in northern Mount Isa basin, Australia, in Glikson, M., and Mastalerz, M., eds., Organic Matter and Mineralization:
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Part 2: HYC deposit, McArthur River, Northern Territory: Journal of Geochemical Exploration, v. 68, p. 105-126.
Large, R.R., Bull, S.W., and Winefield, P.R., 2001, Carbon and oxygen isotope halo in carbonates related to the McArthur River (HYC) Zn-Pb-Ag deposit; implications for sedimentation, ore genesis and mineral exploration:
ECONOMIC GEOLOGY, v. 96, p. 1567-1593.
Large, R.R., Bull, S., Selley, D., Yang, J., Cooke, D., Garven, G., and McGoldrick, P. 2002, Controls on formation of giant stratiform sedimenthosted Zn-Pb-Ag deposits, with particular reference to the North Australian Proterozoic: Hobart, University of Tasmania, Centre for Ore Deposit Research Special Publication, no. 4, p. 107-149.
Large, R.R., Bull, S.W., McGoldrick, P.J., Walters, S., Derrick, G.M., and Carr, G.R., 2005, Stratiform and strata-bound Zn-Pb-Ag deposits in Proterozoic sedimentary basins, northern Australia: ECONOMIC GEOLOGY 100TH ANNIVERSARY VOLUME, p. 931-963.
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v. 33, p. 237-257.
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ECONOMIC GEOLOGY, v. 101, p. 1293-1312." name="eprints.referencetext" />
<meta content="Yang, J. and Large, R.R. and Bull, S.W. and Scott, D.L. (2006) Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin. Economic Geology, 101 (6). pp. 1275-1292. ISSN 0361-0128" name="eprints.citation" />
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<meta content="Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin" name="DC.title" />
<meta content="Yang, J." name="DC.creator" />
<meta content="Large, R.R." name="DC.creator" />
<meta content="Bull, S.W." name="DC.creator" />
<meta content="Scott, D.L." name="DC.creator" />
<meta content="260100 Geology" name="DC.subject" />
<meta content="Numerical fluid-flow and heat-transport modeling was undertaken on a well-constrained geologic section
through the northern Mount Isa basin in order to test the possibility of forming stratiform Zn-Pb-Ag deposits
by buoyancy-driven free convection of marine fluids. The major two-dimensional geologic section used for the
modeling was based on recent geologic mapping and sequence stratigraphic interpretation, combined with
geophysical interpretation from regional seismic, aeromagnetic, and gravity data sets. The basin fill, termed the Leichhardt, Calvert, and Isa superbasins, forms a south-dipping wedge of sedimentary and minor volcanic
rocks up to 25 km thick. A number of major subvertical synsedimentary normal faults cut through this fill and
are rooted in the basement. Two potential aquifer sequences have been identified: sandstones and volcanic
rocks of the Big supersequence at the base of the Calvert superbasin, and sandstones and conglomerates comprising
the Mount Guide Quartzite at the base of the older Leichhardt superbasin. There are three stratiform
Zn-Pb-Ag deposits in the younger Isa superbasin, close to the section-line selected for modeling. Century is a
world-class and high-grade stratiform zinc deposit which contains over 14 Mt of Zn metal hosted by 1595 Ma
black shales and siltstones. Pb-Pb isotope studies suggest the deposit formed about 1575 Ma. Walford Creek
and Blue Bush are large but low-grade, pyrite-rich, and zinc-poor stratiform deposits hosted in 1640 Ma carbonaceous
shales and siltstones.
Numerical modeling of fluid flow at about 1575 Ma shows that buoyancy-driven convection is controlled by
the relationship between the faults and aquifers. The synsedimentary faults, given high permeabilities in the
model because they were active during the mineralizing event, act as either recharge or discharge zones for
fluid flow. Marine fluids commonly recharge the basin via the minor faults and flow through the sandstone and
volcaniclastic aquifer sequences at depths of 5 to 10 km. These fluids have the potential to leach zinc and lead
from the clastic material comprising aquifer and adjacent volcanic rock layers. The heated metalliferous fluids
discharge to the surface where the aquifers intersect the major faults. Hydrothermal discharge temperatures
from the Termite Range fault were computed to be in the range 100 degrees to 180 degrees, with fluid velocities of 1 to 8
m per year. These conditions are suitable for the formation of a Century-sized Zn deposit at the discharge point
adjacent to the Termite Range fault over a period of 0.65 m.y., provided a suitable chemical trap environment
is present. Several numerical simulations were run with different aquifer and fault properties designed to understand the hydrological constraints for the formation of major Zn deposits. Aquifer permeability, fault permeability, and fault penetration depth were shown to be the major factors controlling the fluid-flow and temperature
regime. Significantly higher discharge fluid temperatures and velocities were obtained when the depth of penetration of the Termite Range fault was increased from 15 to 30 km.
The results of the numerical modeling are significant in understanding geologic and hydrological controls on
the formation and location of major stratiform Zn deposits. The permeability and thickness of potential
aquifers, their depth in the basin, the presence of stacked aquifer sequences, and the relationship between
aquifers and synsedimentary faults all have important exploration implications. In particular, the Termite
Range, Fish River, and Elizabeth Creek faults are interpreted to be major deep faults that have controlled
basin-wide convective fluid flow, and therefore the location of major base metal deposits." name="DC.description" />
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    <h1 class="ep_tm_pagetitle">Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin</h1>
    <p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Yang, J.</span> and <span class="person_name">Large, R.R.</span> and <span class="person_name">Bull, S.W.</span> and <span class="person_name">Scott, D.L.</span> (2006) <xhtml:em>Basin-Scale Numerical Modeling to Test the Role of Buoyancy-Driven Fluid Flow and Heat Transfer in the Formation of Stratiform Zn-Pb-Ag Deposits in the Northern Mount Isa Basin.</xhtml:em> Economic Geology, 101 (6). pp. 1275-1292. ISSN 0361-0128</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/1463/1/yang%2C_large_et_al_2006.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" class="ep_doc_icon" border="0" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/1463/1/yang%2C_large_et_al_2006.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />1282Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input accept-charset="utf-8" value="1869" name="docid" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.2113/gsecongeo.101.6.1275">http://dx.doi.org/10.2113/gsecongeo.101.6.1275</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">Numerical fluid-flow and heat-transport modeling was undertaken on a well-constrained geologic section&#13;
through the northern Mount Isa basin in order to test the possibility of forming stratiform Zn-Pb-Ag deposits&#13;
by buoyancy-driven free convection of marine fluids. The major two-dimensional geologic section used for the&#13;
modeling was based on recent geologic mapping and sequence stratigraphic interpretation, combined with&#13;
geophysical interpretation from regional seismic, aeromagnetic, and gravity data sets. The basin fill, termed the Leichhardt, Calvert, and Isa superbasins, forms a south-dipping wedge of sedimentary and minor volcanic&#13;
rocks up to 25 km thick. A number of major subvertical synsedimentary normal faults cut through this fill and&#13;
are rooted in the basement. Two potential aquifer sequences have been identified: sandstones and volcanic&#13;
rocks of the Big supersequence at the base of the Calvert superbasin, and sandstones and conglomerates comprising&#13;
the Mount Guide Quartzite at the base of the older Leichhardt superbasin. There are three stratiform&#13;
Zn-Pb-Ag deposits in the younger Isa superbasin, close to the section-line selected for modeling. Century is a&#13;
world-class and high-grade stratiform zinc deposit which contains over 14 Mt of Zn metal hosted by 1595 Ma&#13;
black shales and siltstones. Pb-Pb isotope studies suggest the deposit formed about 1575 Ma. Walford Creek&#13;
and Blue Bush are large but low-grade, pyrite-rich, and zinc-poor stratiform deposits hosted in 1640 Ma carbonaceous&#13;
shales and siltstones.&#13;
Numerical modeling of fluid flow at about 1575 Ma shows that buoyancy-driven convection is controlled by&#13;
the relationship between the faults and aquifers. The synsedimentary faults, given high permeabilities in the&#13;
model because they were active during the mineralizing event, act as either recharge or discharge zones for&#13;
fluid flow. Marine fluids commonly recharge the basin via the minor faults and flow through the sandstone and&#13;
volcaniclastic aquifer sequences at depths of 5 to 10 km. These fluids have the potential to leach zinc and lead&#13;
from the clastic material comprising aquifer and adjacent volcanic rock layers. The heated metalliferous fluids&#13;
discharge to the surface where the aquifers intersect the major faults. Hydrothermal discharge temperatures&#13;
from the Termite Range fault were computed to be in the range 100 degrees to 180 degrees, with fluid velocities of 1 to 8&#13;
m per year. These conditions are suitable for the formation of a Century-sized Zn deposit at the discharge point&#13;
adjacent to the Termite Range fault over a period of 0.65 m.y., provided a suitable chemical trap environment&#13;
is present. Several numerical simulations were run with different aquifer and fault properties designed to understand the hydrological constraints for the formation of major Zn deposits. Aquifer permeability, fault permeability, and fault penetration depth were shown to be the major factors controlling the fluid-flow and temperature&#13;
regime. Significantly higher discharge fluid temperatures and velocities were obtained when the depth of penetration of the Termite Range fault was increased from 15 to 30 km.&#13;
The results of the numerical modeling are significant in understanding geologic and hydrological controls on&#13;
the formation and location of major stratiform Zn deposits. The permeability and thickness of potential&#13;
aquifers, their depth in the basin, the presence of stacked aquifer sequences, and the relationship between&#13;
aquifers and synsedimentary faults all have important exploration implications. In particular, the Termite&#13;
Range, Fish River, and Elizabeth Creek faults are interpreted to be major deep faults that have controlled&#13;
basin-wide convective fluid flow, and therefore the location of major base metal deposits.</p></div><table style="margin-bottom: 1em" cellpadding="3" class="not_ep_block" border="0"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">SEDEX, Zinc, massive sulfide, ore genesis, sedimentary basin, basinal brines, fluid flow modelling, faults, aquifers, convection.</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/260100.html">260000 Earth Sciences &gt; 260100 Geology</a></td></tr><tr><th valign="top" class="ep_row">Collections:</th><td valign="top" class="ep_row">UNSPECIFIED</td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">1463</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Mrs Katrina Keep</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">26 Jul 2007</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">29 Jan 2008 19:59</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=1463;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&amp;eprintid=1463">item control page</a></p>
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