Genetic significance of fluid inclusions in the CSA Cu-Pb-Zn deposit Cobar Australia

Giles, A; Marshall, B

Genetic significance of fluid inclusions in the CSA Cu-Pb-Zn deposit Cobar Australia

Giles, A Marshall, B

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Publisher:: Elsevier Science Bv
Publication Type:: Journal Article
Citation:: Ore Geology Reviews, 2004, 24 (3-4), pp. 241 - 266
Issue Date:: 2004-01

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Field	Value	Language
dc.contributor.author	Giles, A	en_US
dc.contributor.author	Marshall, B	en_US
dc.date.issued	2004-01	en_US
dc.identifier.citation	Ore Geology Reviews, 2004, 24 (3-4), pp. 241 - 266	en_US
dc.identifier.issn	0169-1368	en_US
dc.identifier.uri	http://hdl.handle.net/10453/688
dc.description.abstract	CSA mine exploits a `Cobar-type CuPbZn±Au±Ag deposit within a cleaved and metamorphosed portion of the Cobar Supergroup, central New South Wales. The deposit comprises systems of `lenses that encompass veins, disseminations and semi-massive to massive CuPbZn ores. The systems and contained lenses truncate bedding, are approximately coplanar with regional cleavage and similarly oriented shear zones and plunge parallel to the elongation lineation. Systems have extreme vertical continuity (>1000 m), short strike length (not, vert, similar400 m) and narrow width (not, vert, similar100 m), exhibit vertical and lateral ore-type variation and have alteration haloes. Models of ore formation include classical hydrothermalism, structurally controlled remobilisation and polymodal concepts; syntectonic emplacement now holds sway. Fluid inclusions were examined from quartz±sulphide veins adjacent to now-extracted ore, from coexisting quartzsulphide within ore, and from vughs in barren quartz veins. Lack of early primary inclusions precluded direct determination of fluids associated with D2D3 ore and vein emplacement. Similarly, decrepitation (by near-isobaric heating) of the two oldest secondary populations precluded direct determination of fluid phases immediately following D2D3 ore and vein emplacement. Post-decrepitation outflow (late D3 to early post-D3) is recorded by monophase CH4 inclusions. Entrained outflow of deeply circulated meteoric fluid modified the CH4 system; modification is recorded by H2O+CH4 and H2O+(trace CH4) secondary populations and by an H2O+(trace CH4) primary population. The contractional tectonics (D2D3) of ore emplacement was superseded by relaxational tectonics (D4P) that facilitated meteoric water penetration and return flow.	en_US
dc.publisher	Elsevier Science Bv	en_US
dc.relation.ispartof	Ore Geology Reviews	en_US
dc.relation.isbasedon	10.1016/j.oregeorev.2003.05.003	en_US
dc.subject.classification	Geology	en_US
dc.title	Genetic significance of fluid inclusions in the CSA Cu-Pb-Zn deposit Cobar Australia	en_US
dc.type	Journal Article
utslib.citation.volume	3-4	en_US
utslib.citation.volume	24	en_US
utslib.for	0402 Geochemistry	en_US
utslib.for	0403 Geology	en_US
utslib.for	0499 Other Earth Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	closed_access
pubs.consider-herdc	true	en_US
pubs.issue	3-4	en_US
pubs.volume	24	en_US

Abstract:

CSA mine exploits a `Cobar-type CuPbZn±Au±Ag deposit within a cleaved and metamorphosed portion of the Cobar Supergroup, central New South Wales. The deposit comprises systems of `lenses that encompass veins, disseminations and semi-massive to massive CuPbZn ores. The systems and contained lenses truncate bedding, are approximately coplanar with regional cleavage and similarly oriented shear zones and plunge parallel to the elongation lineation. Systems have extreme vertical continuity (>1000 m), short strike length (not, vert, similar400 m) and narrow width (not, vert, similar100 m), exhibit vertical and lateral ore-type variation and have alteration haloes. Models of ore formation include classical hydrothermalism, structurally controlled remobilisation and polymodal concepts; syntectonic emplacement now holds sway. Fluid inclusions were examined from quartz±sulphide veins adjacent to now-extracted ore, from coexisting quartzsulphide within ore, and from vughs in barren quartz veins. Lack of early primary inclusions precluded direct determination of fluids associated with D2D3 ore and vein emplacement. Similarly, decrepitation (by near-isobaric heating) of the two oldest secondary populations precluded direct determination of fluid phases immediately following D2D3 ore and vein emplacement. Post-decrepitation outflow (late D3 to early post-D3) is recorded by monophase CH4 inclusions. Entrained outflow of deeply circulated meteoric fluid modified the CH4 system; modification is recorded by H2O+CH4 and H2O+(trace CH4) secondary populations and by an H2O+(trace CH4) primary population. The contractional tectonics (D2D3) of ore emplacement was superseded by relaxational tectonics (D4P) that facilitated meteoric water penetration and return flow.

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