Rare Earth Element Phosphate Minerals from the Olympic Dam Cu-U-Au-Ag Deposit, South Australia: Recognizing Temporal-Spatial Controls On Ree Mineralogy in an Evolved IOCG System

Research Article| January 01, 2019 Rare Earth Element Phosphate Minerals from the Olympic Dam Cu-U-Au-Ag Deposit, South Australia: Recognizing Temporal-Spatial Controls On Ree Mineralogy in an Evolved IOCG System Danielle S. Schmandt; Danielle S. Schmandt § School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia § Corresponding author e-mail address: danielle.schmandt@adelaide.edu.au Search for other works by this author on: GSW Google Scholar Nigel J. Cook; Nigel J. Cook School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar Cristiana L. Ciobanu; Cristiana L. Ciobanu School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar Kathy Ehrig; Kathy Ehrig BHP Olympic Dam, Adelaide, South Australia 5000, Australia Search for other works by this author on: GSW Google Scholar Benjamin P. Wade; Benjamin P. Wade Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar Sarah Gilbert; Sarah Gilbert Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar Vadim S. Kamenetsky Vadim S. Kamenetsky School of Physical Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Danielle S. Schmandt § School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia Nigel J. Cook School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia Cristiana L. Ciobanu School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia Kathy Ehrig BHP Olympic Dam, Adelaide, South Australia 5000, Australia Benjamin P. Wade Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5005, Australia Sarah Gilbert Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5005, Australia Vadim S. Kamenetsky School of Physical Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia § Corresponding author e-mail address: danielle.schmandt@adelaide.edu.au Publisher: Mineralogical Association of Canada First Online: 17 Jan 2019 Online Issn: 1499-1276 Print Issn: 0008-4476 © 2019 Mineralogical Association of Canada The Canadian Mineralogist (2019) 57 (1): 3–24. https://doi.org/10.3749/canmin.1800043 Article history First Online: 17 Jan 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Danielle S. Schmandt, Nigel J. Cook, Cristiana L. Ciobanu, Kathy Ehrig, Benjamin P. Wade, Sarah Gilbert, Vadim S. Kamenetsky; Rare Earth Element Phosphate Minerals from the Olympic Dam Cu-U-Au-Ag Deposit, South Australia: Recognizing Temporal-Spatial Controls On Ree Mineralogy in an Evolved IOCG System. The Canadian Mineralogist 2019;; 57 (1): 3–24. doi: https://doi.org/10.3749/canmin.1800043 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyThe Canadian Mineralogist Search Advanced Search Abstract Florencite, [REEAl3(PO4)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 (Ca0.01–0.24Sr0.03–0.40La0.14–0.49Ce0.20–0.47Pr0.00–0.03Nd0.00–0.05)Σ0.43–0.96Al2.89–3.33(P1.42–1.96S0.05–0.34As0.0–0.20)Σ1.77–2.21O4(OH)6], is LREE-enriched, typically La-dominant, while HREEs are minor. There is also compositional variability with respect to Sr, Ca, SO4, and AsO4 components. Chondrite-normalized fractionation trends are steeply downwards-sloping with a relatively low and flat HREE segment. Such a fractionation trend is markedly different from that seen for REE-fluorocarbonates, the dominant REE host at Olympic Dam, which contain relatively higher MREE and HREE components. Xenotime is relatively rare at Olympic Dam and is most commonly seen as overgrowths on zircon. Compositional data for xenotime show HREE concentrations in which Y > Yb > Er > Dy > Ho. Thorium, U, and Pb are minor components in both xenotime and florencite. Monazite is a minor phase and co-existing monazite and florencite are never observed. Texturally, florencite appears to belong to a later stage of LREE mineralization at Olympic Dam, following and less prominent than the main REE-fluorocarbonate stage. Olympic Dam florencite is more La-rich and Ca-poor than it is in most of the localities worldwide for which compositional data have been published. The REE mineralization trends of florencite are compared with published REE trends for other mineral groups from Olympic Dam. Uraninite, brannerite, coffinite, and apatite show patterns of progressive LREE depletion from generation to generation, suggesting enhanced solubility of LREE over geological time. All LREE minerals (fluorocarbonates and phosphates), on the other hand, display progressive LREE enrichment correlating with a paragenetic sequence from REE-fluorocarbonates with essential Ca, through bastnäsite, to florencite. The late-stage florencite reported here is the most La-rich of all REE-bearing phases and is interpreted to record either the end of a continuous fluid evolution, or a later separate event at changed physicochemical conditions under which REE-aluminum phosphate minerals are stable. 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