Texture, Crystal Structure, and Composition of Fluorapatites From Iron Oxide-Apatite (Ioa) Deposits, Eastern Adirondack Mountains, New York

Lupulescu, Marian; Hughes, John M.; Chiarenzelli, Jeffrey R.; Bailey, David G.

doi:10.3749/canmin.1600057

Cited by 13 publications

(20 citation statements)

References 54 publications

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“…The morphology of this fluorapatite is consistent with the hydrothermally altered type 3 fluorapatite discussed by Chakhmouradian et al (2017). Our secondary fluorapatite is also texturally similar to altered fluorapatites from carbonatites (e.g., Narasayya & Sriramadas 1974, Nadeau et al 2015, Feng et al 2016, Prokopyev et al 2017) and elsewhere (Pan et al 1993, Li & Zhou 2015, Uher et al 2015, Jonsson et al 2016, Ondrejka et al 2016, Lupulescu et al 2017. The two most common fluorapatite alteration products are REE-carbonates and Ce-Th-silicates.…”

Section: Petrographysupporting

confidence: 80%

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

Anenburg

Burnham

Mavrogenes

2018

The Canadian Mineralogist

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The geochemical behavior and genesis of rare earth element (REE) ores remains poorly understood. In addition, the processes responsible for many features observed in REE ore deposits are not easily determined. Importantly, the distinction between igneous versus post-magmatic genesis, or the nature of the mineralizing and modifying fluids or melts, remains in dispute. Nolans Bore is a P-REE-Th deposit in the Northern Territory, Australia, hosting REE mineralization in fluorapatite and its alteration products. These mineralization textures are imaged in 3D by X-ray computed tomography and in 2D by electron microscopy, cathodoluminescence, and X-ray mapping. Primary igneous REE-rich fluorapatite was replaced in two stages. The first, at high temperature, was to endmember fluorapatite-britholite symplectite. The second, at lower temperatures, was to hydrothermal veins and patches comprised of REE-Th phosphate, silicate, and carbonate minerals. Quadrivalent Ce occurs together with Th, suggesting oxidized, low-temperature conditions. Strikingly similar textures are observed at Hoidas Lake, Saskatchewan, Canada, where igneous immiscibility or a pegmatitic boundary layer have been implicated in their formation. Our textural and chemical investigations establish that these symplectites and other similar textures are not primary igneous textures, but formed by subsequent cooling and alteration. Understanding the processes that formed these symplectic and vein textures is key to their theoretical and experimental modeling and should lead to a better understanding of ''hydrothermal'' REE deposits globally. The decoupling of Ce from the rest of the REE and the mineralogical preferences of the light REE versus the heavy REE should be considered when evaluating similar ore deposits for their economic value and mineral processing.

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Section: Petrographysupporting

confidence: 80%

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

Anenburg

Burnham

Mavrogenes

2018

The Canadian Mineralogist

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“…The monazite and other REE-bearing minerals occur in a variety of textural settings including symplectite intergrowths that preserve a textural a record of a protracted alteration history. Herein we describe and present detailed phase compositions from monazite and associated fluorapatite and allanite, as well as Th-U-total Pb monazite petrochronology, of samples from the Cheever IOA-deposit as a companion contribution to other recent publications on the topic [11,12]. The textures are interpreted to have formed as part of two multi-step reaction sequences that occurred nearly simultaneously as a result of evolving fluid conditions long after ore-formation [9,11].…”

Section: Introductionmentioning

confidence: 94%

“…Recent work on the textural evolution of fluorapatite, REE abundances, and zircon U-Pb systematics have been reported from the Cheever deposit [11,12]. Lupulescu et al [12] described and reported detailed phase compositions from multiple assemblages that formed as a result of fluid-mediated processes preserved in the Cheever IOA-type deposit. The main conclusion was that coarse REE-enriched fluorapatite crystals formed within a late-magmatic setting from an iron and phosphorous-rich melt that formed via liquid-immiscibility [23].…”

Section: Geologic Settingmentioning

confidence: 99%

“…Of particular importance to this study are monazite within IOA-deposits not associated with any recognized volcanic activity in the Adirondack Mountains of New York, USA. The deposits of the Adirondack Mountains have been analyzed via zircon U-Pb methods [9][10][11], major and accessory phase textural analysis [10], in-situ major and trace element analysis [12], and other local isotopic analyses [13]. Here we incorporate experimental work from IOA-systems with in-situ monazite Th-U-total Pb petrochronology to better characterize the processes and timing recorded by monazite in a deeper (higher Pressure) IOA-type system.…”

Section: Introductionmentioning

confidence: 99%

“…The Cheever deposit (Port Henry, NY; Figure 1) contains, at present, the highest recognized modal abundance of REE-bearing phases, and is of particular interest. The deposit consists of many different mineral types, all preserving a wide array of reaction textures [12]. Monazite is common in the Cheever deposit in association with allanite, fluorapatite, and quartz.…”

Section: Introductionmentioning

confidence: 99%

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Age and Origin of Monazite Symplectite in an Iron Oxide-Apatite Deposit in the Adirondack Mountains, New York, USA: Implications for Tracking Fluid Conditions

et al. 2019

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Monazite crystals, intergrown with allanite, fluorapatite, and quartz from the Cheever Mine iron oxide-apatite (IOA-type) deposit in Essex County, New York, USA, display rare symplectite textures. Electron probe wavelength-dispersive spectrometry (WDS) mapping and major and trace element characterization of these features reveal a natural experiment in fluid-mediated monazite recrystallization. Two types of monazite with symplectite intergrowths have been recognized (Type I and II). Both types of symplectite development are associated with a decrease in HREE, Si, Ca, Th, and Y, but an increase in both La and Ce in monazite. Electron microprobe Th-U-total Pb analysis of Type I monazite with suitable ThO2 concentrations yielded a weighted mean age of 980 ± 5.8 Ma (MSWD: 3.3), which is interpreted as the age of monazite formation and the onset of symplectite development. Both types of monazite formed during a series of reactions from fluorapatite, and possibly britholite, to produce the final assemblage of monazite, allanite, and fluorapatite. Monazite formation was likely a response to evolving fluid conditions, which favored monazite stability over fluorapatite at ca. 980 Ma, possibly a NaCl brine. A subsequent transition to a Ca-dominated fluid may have then promoted the consumption of monazite to produce another generation of allanite and fluorapatite. Our results indicate that recrystallized monazite formed during fluid-mediated processes that, over time, trended towards an increasingly pure end-member composition. Regionally, these data are consistent with a magmatic-origin followed by fluid-mediated remobilization of select phases at subsolidus conditions for the Adirondack IOA deposits.

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Formation of magnetite-(apatite) systems by crystallizing ultrabasic iron-rich melts and slag separation

Tornos,

Hanchar,

Steele-MacInnis

et al. 2023

Miner Deposita

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Magnetite-(apatite) ore deposits are interpreted as being formed by the crystallization of iron-rich ultrabasic melts, dominantly generated by the interaction of silicate melts with oxidized P-F-SO4-bearing sedimentary rocks. This hypothesis is supported by geologic evidence, experimental studies, numerical modeling, stable and radiogenic isotope geochemistry, mineralogy, and melt- and mineral-inclusion data. Assimilation of crustal rocks during ascent promotes separation from a silicate magma of Fe-rich, Si-Al-poor melts with low solidus temperatures and viscosities, allowing coalescence, migration, and emplacement at deep to subaerial crustal environments. When the iron-rich melt attains neutral buoyancy, fractional crystallization leads to melt immiscibility similar to that observed in industrial blast furnaces, which promotes separation of massive magnetite ore overlain by different types of “slag” containing actinolite or diopside ± phosphates ± magnetite ± feldspar ± anhydrite ± scapolite, commonly enriched in high field strength elements. The mineralogy and morphology of this iron-depleted cap strongly depend on the depth of emplacement and composition of the iron-rich magma. Most of these systems exhibit high oxygen fugacity, which inhibits the precipitation of significant sulfide mineralization. The initially high fO2 of these systems also promotes the formation of low-Ti (< 1 wt%) magnetite: Ti acts as an incompatible component and is enriched in the iron-poor caps and in the hydrothermal aureole. High fluid-phase pressures produced during massive crystallization of magnetite from the melt further facilitate the exsolution of magmatic-hydrothermal fluids responsible for the formation of aureoles of alkali-calcic-iron alteration with hydrothermal replacement-style iron mineralization. On the whole, these systems are dramatically different from the magmatic-hydrothermal systems related to intermediate to felsic igneous rocks; they are more akin to carbonatite and other ultramafic rocks.

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Texture, Crystal Structure, and Composition of Fluorapatites From Iron Oxide-Apatite (Ioa) Deposits, Eastern Adirondack Mountains, New York

Cited by 13 publications

References 54 publications

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

REE Redistribution Textures in Altered Fluorapatite: Symplectites, Veins, and Phosphate-Silicate-Carbonate Assemblages from the Nolans Bore P-REE-Th Deposit, Northern Territory, Australia

Age and Origin of Monazite Symplectite in an Iron Oxide-Apatite Deposit in the Adirondack Mountains, New York, USA: Implications for Tracking Fluid Conditions

Formation of magnetite-(apatite) systems by crystallizing ultrabasic iron-rich melts and slag separation

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