Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

Mao, Mao; Rukhlov, Alexei S.; Rowins, Stephen M.; Spence, Jody; Coogan, L. A.

doi:10.2113/econgeo.111.5.1187

Cited by 315 publications

(184 citation statements)

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“…REY-signatures measured in magmatic apatite of the RDG, HRQM and DD closely resemble those for apatite from analogous intrusive elsewhere [8,9,46]. Similarly, the LREE-enriched signatures characteristic for DM and DS apatite (REY-, S-and Cl-rich cores and REY-, S-rich cores, respectively) are almost identical to apatite REY-signatures measured in apatite from similar magnetite-apatite ± pyrite assemblages elsewhere within the Olympic Cu-Au Province [1,10,47], as well as globally [11,14].…”

Section: Rey-signatures In Apatite and The Transition From Magmatic Tmentioning

confidence: 53%

“…Crystal structures of apatite group minerals are described by Hughes and Rakovan [39]. In detail, the atomic arrangement is made up of 3 cation polyhedra: a tetrahedron, XO 4 , and two calcium positions; a tri-capped trigonal prism, A1O 9 , and an irregular polyhedron, A2O 6 Z, where Z is one of the anions F, Cl, OH.…”

Section: Apatite Mineral Chemistrymentioning

confidence: 99%

“…Of particular relevance to apatite is how, under different conditions, LREE may be partitioned relative to HREE due to the increased stability and solubility as LREE-Cl complexes, thus explaining the LREE-enriched nature of many hydrothermal deposits, including IOCG systems [6]. Mao et al (2016) [9] recognized that hydrothermal, and particularly ore-related, apatite may contain concentrations of trace elements, which are significantly lower than those of magmatic origin. This may relate to the co-crystallization, in ores, of apatite with other minerals that can incorporate certain trace elements more effectively than apatite but which seldom occur as magmatic accessories.…”

Section: Apatite Mineral Chemistrymentioning

confidence: 99%

“…In contrast, the characteristics that define the signatures of later generations of apatite associated with hematite-sericite alteration and high-grade ore (MREE-enrichment, positive Eu-and negative Y-anomalies) are less commonly reported. MREE-enriched REY-signatures with weak positive Eu anomalies are particularly scarce in the literature and their description has thus far been limited to orogenic-Au deposits [9,48] and IOCG mineralization within the Olympic Cu-Au belt [10]. Table 1) displaying core-to-rim-and fracture-related zoning consisting of cores rich in REY and REY-depleted rims and fractures.…”

Section: Rey-signatures In Apatite and The Transition From Magmatic Tmentioning

confidence: 99%

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Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

et al. 2017

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Abstract: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 evolution from early to late hydrothermal stages at OD. The~1.6 Ga Roxby Downs granite (RDG), host to the OD deposit, contains apatite as a magmatic accessory, locally in the high concentrations associated with mafic enclaves. Magmatic apatite commonly contains REY-poor cores and REY-enriched margins. The cores display a light rare earth element (LREE)-enriched chondrite-normalized fractionation pattern with a strong negative Eu anomaly. In contrast, later hydrothermal apatite, confined to samples where magmatic apatite has been obliterated due to advanced hematite-sericite alteration, displays a conspicuous, convex, middle rare earth element (MREE)-enriched pattern with a weak negative Eu anomaly. Such grains contain abundant inclusions of florencite and sericite. Within high-grade bornite ores from the deposit, apatite displays an extremely highly MREE-enriched chondrite-normalized fractionation trend with a positive Eu anomaly. Concentrations of U and Th in apatite mimic the behaviour of ∑REY and are richest in magmatic apatite hosted by RDG and the hydrothermal rims surrounding them. The shift from characteristic LREE-enriched magmatic and early hydrothermal apatite to later hydrothermal apatite displaying marked MREE-enriched trends (with lower U, Th, Pb and ∑REY concentrations) reflects the magmatic to hydrothermal transition. Additionally, the strong positive Eu anomaly in the MREE-enriched trends of apatite in high-grade bornite ores are attributable to alkaline fluid conditions.

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Section: Rey-signatures In Apatite and The Transition From Magmatic Tmentioning

confidence: 53%

Section: Apatite Mineral Chemistrymentioning

confidence: 99%

Section: Apatite Mineral Chemistrymentioning

confidence: 99%

Section: Rey-signatures In Apatite and The Transition From Magmatic Tmentioning

confidence: 99%

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Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

et al. 2017

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“…Nonetheless, apatite is still a very useful U-Pb chronometer as its typical closure temperature of around 375-600°C (Cochrane et al, 2014;Schoene and Bowring, 2007) potentially can provide additional time-temperature constraints on retrograde or lowtemperature prograde processes. Apatite can accommodate high concentrations of REE (Henrichs et al, 2018), Sr,Mn, Na, U, and Th, and other trace elements, making it potentially powerful in charting the trace element chemistry of the rock system (Fleet and Pan, 1997;Gawęda et al, 2014;Mao et al, 2016;Piccoli and Candela, 2002). So, as apatite is highly susceptible to a range of fluid-induced (metasomatic) changes that occur at variable pressures and temperatures (Harlov, 2015;Krenn and Finger, 2004;Nutman, 2007;Spear and Pyle, 2002), its chemistry linked to age may be powerful intracking fluidrock interaction from the deep crust to near surface (Glorie et al, 2017;Henrichs et al, 2018;Kirkland et al, 2017;Schoene and Bowring, 2007).…”

Section: Introductionmentioning

confidence: 99%

Apatite: a U-Pb thermochronometer or geochronometer?

Kirkland

Yakymchuk

Szilas

et al. 2018

Lithos

122

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Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600°C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a b600°C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic population during new rim growth. The younger, c. 1800 Ma U-Pb age is interpreted to date new apatite growth from a compositionally distinct reservoir driven by tectonothermal and fluid activity, consistent with regional mica Ar-Ar ages. Results from these two samples show that recrystallization, dissolution and regrowth processes likely formed the younger rim overgrowths, and at temperatures below those often considered to be closure temperatures for Pb diffusion in apatite. The results from these samples imply many apatite grains may not record simple thermally activated Pb diffusion profiles and cautions against inversion of apatite U-Pb data to thermal histories without detailed knowledge of the grain growth/alteration processes.

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Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

et al. 2018

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The Amba Dongar carbonatite‐alkaline complex is regarded as a late phase intrusion (ca. 65 Ma) associated with Deccan volcanism. Existing age constraints on the Amba Dongar carbonatite are based on phlogopite 40Ar–39Ar plateau ages derived from carbonatite and associated alkaline rocks within the complex. We explore the utility of apatite, a common accessory mineral in Amba Dongar carbonatites, as a petrogenetic and geochronological tool to constrain further the evolution of the carbonatites. Apatite exhibits different crystal forms—from hexagonal stubby prisms to ovoid and elongate grains. Apatite occurs as cumulate and disseminated grains that are either primary, fractured, or recrystallized. SrO content is high in primary apatite (3.17 wt%) but less in recrystallized (1.90 wt%) and disseminated grains (0.47 wt%). MnO and Cl are negligible while FeO is typically low in all samples. SiO2 content is low except for a few primary grains which measure up to 1.35 wt%, correlating with high REE content. LREEs dominate the total REE budget of Amba Dongar apatite, with HREEs below EPMA detection limit in most samples. Total REE content is generally low, though some primary apatite contains up to 3.19 wt% REEs. We also report UPb apatite ages from the carbonatites analysed in situ by LA‐ICP‐MS. The data from all samples combined on a UPb Tera–Wasserburg concordia yield a lower intercept age of 65.4 ± 2.5 Ma (MSWD = 2.8, 207Pb/206Pbi = 0.8272 ± 0.0028), and the Amba Dongar carbonatites are thus interpreted to represent a phase of coeval magmatic activity with Deccan volcanism.

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Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

Cited by 315 publications

References 133 publications

Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

Apatite: a U-Pb thermochronometer or geochronometer?

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

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