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Crystal chemistry of titanite from the Roxby Downs Granite, South Australia: insights into petrogenesis, subsolidus evolution and hydrothermal alteration

Published on Jul 1, 2019in Contributions to Mineralogy and Petrology 3.23
· DOI :10.1007/s00410-019-1594-2
Alkiviadis Kontonikas-Charos1
Estimated H-index: 1
(University of Adelaide),
Kathy Ehrig13
Estimated H-index: 13
+ 1 AuthorsCristiana L. Ciobanu28
Estimated H-index: 28
(University of Adelaide)
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Abstract
Titanite textures and chemistry have been investigated from the Roxby Downs Granite, host to the Olympic Dam Cu–U–Au–Ag deposit, South Australia. Three textural subtypes of titanite are documented: primary magmatic (cores and rims); deuteric; and hydrothermal (low T recrystallisation). Magmatic cores are defined by enrichment in LREE (~ 3 wt%), Nb (up to 1 wt%) and Zr relative to rims, which typically contain < 1 wt% LREE and Nb, as well as greater concentrations of Al, Ca, Fe and F. Deuteric titanite occurs as overgrowths on pre-existing titanite and other magmatic accessory minerals (magnetite and ilmenite), and is depleted in HFSE compared to magmatic rims, showing geochemical trends consistent with substitution of Ca2+ + Ti4+ ↔ REE3+ + (Al, Fe)3+. Hydrothermal titanite forms as a low-temperature hydrothermal overprint on primary titanite as well as an alteration product of chloritised phlogopite. Applying Zr-in-titanite geothermometry, three temperature ranges are obtained for titanite crystallisation: magmatic cores ~ 765 to 780 °C; rims ~ 705 to 740 °C; and deuteric ~ 680 to 690 °C. Titanite breakdown is a ubiquitous feature of the Roxby Downs Granite, and occurs through interaction with CO2- and F-rich fluids, forming pseudomorphs characterised by the presence of REE-fluorocarbonates, which are subsequently overprinted by REE-phosphates with increased proximity to the Olympic Dam Breccia Complex. This change is related to interaction with fluids containing appreciable PO42− liberated from local dissolution of fluorapatite. Such observations are consistent with and linked to later/retrograde stages in the formation of the Olympic Dam deposit.
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Published on May 1, 2019in Chemical Geology 3.62
Liam Courtney-Davies3
Estimated H-index: 3
(University of Adelaide),
Simon Tapster6
Estimated H-index: 6
(BGS: British Geological Survey)
+ 7 AuthorsBenjamin P. Wade18
Estimated H-index: 18
(University of Adelaide)
Abstract Hematite (α-Fe 2 O 3 ) is a common iron-oxide mineral known to incorporate U into its crystal lattice at up to wt% concentrations and has been previously used to date ore formation within iron-oxide copper gold and banded iron formation deposits. However, there has been no detailed evaluation of the potential challenges this novel mineral geochronometer may present for accurate temporal interpretation. We report a multi-technique U Pb geochronological study comprising laser ablation-ind...
Published on Jan 1, 2019in Canadian Mineralogist 1.40
Danielle S. Schmandt1
Estimated H-index: 1
(University of Adelaide),
Nigel J. Cook32
Estimated H-index: 32
(University of Adelaide)
+ 4 AuthorsVadim S. Kamenetsky52
Estimated H-index: 52
(UTAS: University of Tasmania)
Florencite, [REEAl 3 (PO 4 ) 2 (OH) 6 ], is the most abundant REE-phosphate mineral in the giant Olympic Dam Cu-U-Au-Ag deposit, South Australia. Florencite typically occurs as fine-grained crystals and occasional aggregates in the matrix of the granite-dominant breccia that hosts the majority of the copper mineralization. Olympic Dam florencite, with the compositional range and extended formula (Ca 0.01–0.24 Sr 0.03–0.40 La 0.14–0.49 Ce 0.20–0.47 Pr 0.00–0.03 Nd 0.00–0.05 ) Σ0.43–0.96 Al 2.89–3...
Published on Jan 1, 2019in Chemical Geology 3.62
Hugo K.H. Olierook7
Estimated H-index: 7
(Curtin University),
Richard J. M. Taylor1
Estimated H-index: 1
(University of Cambridge)
+ 5 AuthorsMilo Barham5
Estimated H-index: 5
(Curtin University)
Abstract Unravelling the spatio-temporal evolution of orogenic terranes requires a comprehensive understanding of the duration and extent of metamorphic events and hydrothermal alteration. Commonly used minerals such as zircon and monazite may not fully record geological histories in complex tectonic settings because their elemental constituents do not react under many metamorphic and metasomatic conditions. Here, we complement the current geochronological record of the Capricorn Orogen, Western...
Published on Apr 1, 2018in Mineralogy and Petrology 1.57
Alkis Kontonikas-Charos6
Estimated H-index: 6
(University of Adelaide),
Cristiana L. Ciobanu28
Estimated H-index: 28
(University of Adelaide)
+ 3 AuthorsVadim S. Kamenetsky52
Estimated H-index: 52
(UTAS: University of Tasmania)
Rare earth element (REE) fractionation trends in feldspars are reported from Olympic Dam (including Wirrda Well and Phillip’s Ridge) and Cape Donington (Port Lincoln), for comparison with two other igneous-hydrothermal terranes within the eastern Gawler Craton: Moonta-Wallaroo and Hillside. The case studies were selected as they represent ~ 1590 Ma Hiltaba Suite and/or ~ 1845 − 1810 Ma Donington Suite granites, and, aside from Cape Donington, are associated with Mesoproterozoic iron-oxide copper...
Published on Dec 1, 2017in Mineralogical Magazine 2.21
Edeltraud Macmillan5
Estimated H-index: 5
,
Nigel J. Cook32
Estimated H-index: 32
+ 1 AuthorsAllan Pring29
Estimated H-index: 29
(Flinders University)
The Olympic Dam iron-oxide copper-gold-silver-uranium deposit, South Australia, contains three dominant U minerals: uraninite; coffinite; and brannerite. Microanalytical and petrographic observations provide evidence for an interpretation in which brannerite and coffinite essentially represent the products of U mineralizing events after initial deposit formation at 1.6 Ga. Marked compositional and textural differences between the various types of brannerite and coffinite highlight the role of mu...
Published on Nov 20, 2017in Minerals 2.25
Cristiana L. Ciobanu28
Estimated H-index: 28
,
Alkis Kontonikas-Charos6
Estimated H-index: 6
+ 3 AuthorsKathy Ehrig13
Estimated H-index: 13
Atomic-scale high angle annular dark field scanning transmission electron microscopy (HAADF STEM) imaging and electron diffractions are used to address the complexity of lattice-scale intergrowths of REE-fluorocarbonates from an occurrence adjacent to the Olympic Dam deposit, South Australia. The aims are to define the species present within the intergrowths and also assess the value of the HAADF STEM technique in resolving stacking sequences within mixed-layer compounds. Results provide insight...
Published on Oct 23, 2017in Minerals 2.25
Danielle S. Schmandt1
Estimated H-index: 1
,
Nigel J. Cook32
Estimated H-index: 32
+ 4 AuthorsVadim S. Kamenetsky52
Estimated H-index: 52
Olympic Dam is a world-class breccia-hosted iron-oxide copper-gold-uranium ore deposit located in the Gawler Craton, South Australia. It contains elevated concentrations of rare earth elements (REE) which occur as the REE minerals bastnasite, synchysite, florencite, monazite, and xenotime. This is the first study to focus on the mineralogy and composition of the most abundant REE mineral at Olympic Dam, bastnasite, and subordinate synchysite. The sample suite extends across the deposit and repre...
Published on Aug 2, 2017in Minerals 2.25
Sasha Krneta6
Estimated H-index: 6
,
Cristiana L. Ciobanu28
Estimated H-index: 28
+ 2 AuthorsAlkis Kontonikas-Charos6
Estimated H-index: 6
Apatite is a common magmatic accessory in the intrusive rocks hosting the giant ~1590 Ma Olympic Dam (OD) iron-oxide copper gold (IOCG) ore system, South Australia. Moreover, hydrothermal apatite is a locally abundant mineral throughout the altered and mineralized rocks within and enclosing the deposit. Based on compositional data for zoned apatite, we evaluate whether changes in the morphology and the rare earth element and Y (REY) chemistry of apatite can be used to constrain the fluid evoluti...
Published on Jun 1, 2017in Journal of Petrology 3.38
Joshua M. Garber6
Estimated H-index: 6
(UCSB: University of California, Santa Barbara),
B. R. Hacker4
Estimated H-index: 4
(UCSB: University of California, Santa Barbara)
+ 2 AuthorsGareth Seward16
Estimated H-index: 16
(UCSB: University of California, Santa Barbara)
Published on Mar 1, 2017in Ore Geology Reviews 3.39
Craig D. Storey26
Estimated H-index: 26
(University of Portsmouth),
Martin Smith20
Estimated H-index: 20
(University of Brighton)
Abstract Titanite occurs as a widespread accessory phase in mineralised zones and alteration associated with iron oxide-copper gold (IOCG) and iron oxide-apatite (IOA) deposits of Norrbotten County, Sweden, and is a major host of the REE in these deposits. In situ analyses of Sm Nd isotope ratios in titanites previously analysed for U Pb geochronology and trace element composition confirms previous interpretations of grain scale isotopic heterogeneity. Initial Nd-isotope ratios expressed relativ...
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