Journal articles: 'Carbonatites - Ontario'

1

Moecher, David P., Eric D. Anderson, Claudia A. Cook, and Klaus Mezger. "The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario." Canadian Journal of Earth Sciences 34, no. 9 (September 1, 1997): 1185–201. http://dx.doi.org/10.1139/e17-095.

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Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble mélange. Values of δ18OSMOW (9.9–13.3‰) and δ13CPDB (−4.8 to −1.9‰) for calcite are also distinct from those for marble and most marble mélange. Titanites extracted from clinopyroxene–calcite–scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U–Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U–Pb age of 1089 ± 5 Ma; zircon ages from two other bodies are 1170 ± 3 and 1143 ± 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of εNd(T) are 1.7–3.2 for carbonatites, −1.5–1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6–1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundances, REE contents, and O and Nd isotope compositions of the carbonatites.

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Jones, James M. C., Elizabeth A. Webb, Michael D. J. Lynch, Trevor C. Charles, Pedro M. Antunes, and Frédérique C. Guinel. "Does a carbonatite deposit influence its surrounding ecosystem?" FACETS 4, no. 1 (June 1, 2019): 389–406. http://dx.doi.org/10.1139/facets-2018-0029.

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Carbonatites are unusual alkaline rocks with diverse compositions. Although previous work has characterized the effects these rocks have on soils and plants, little is known about their impacts on local ecosystems. Using a deposit within the Great Lakes–St. Lawrence forest in northern Ontario, Canada, we investigated the effect of a carbonatite on soil chemistry and on the structure of plant and soil microbial communities. This was done using a vegetation survey conducted above and around the deposit, with corresponding soil samples collected for determining soil nutrient composition and for assessing microbial community structure using 16S/ITS Illumina Mi-Seq sequencing. In some soils above the deposit a soil chemical signature of the carbonatite was found, with the most important effect being an increase in soil pH compared with the non-deposit soils. Both plants and microorganisms responded to the altered soil chemistry: the plant communities present in carbonatite-impacted soils were dominated by ruderal species, and although differences in microbial communities across the surveyed areas were not obvious, the abundances of specific bacteria and fungi were reduced in response to the carbonatite. Overall, the deposit seems to have created microenvironments of relatively basic soil in an otherwise acidic forest soil. This study demonstrates for the first time how carbonatites can alter ecosystems in situ.

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Bell, Keith, John Blenkinsop, S. T. Kwon, G. R. Tilton, and R. P. Sage. "Age and radiogenic isotopic systematics of the Borden carbonatite complex, Ontario, Canada." Canadian Journal of Earth Sciences 24, no. 1 (January 1, 1987): 24–30. http://dx.doi.org/10.1139/e87-003.

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Rb–Sr and U–Pb data from the Borden complex of northern Ontario, a carbonatite associated with the Kapuskasing Structural Zone, indicate a mid-Proterozoic age. A 207Pb/206Pb age of 1872 ± 13 Ma is interpreted as the emplacement age of this body, grouping it with other ca. 1900 Ma complexes that are the oldest known carbonatites associated with the Kapuskasing structure. A 206Pb–238U age of 1894 ± 29 Ma agrees with the Pb–Pb age but has a high mean square of weighted deviates (MSWD) of 42. A Rb–Sr apatite–carbonate–mica whole-rock isochron date of 1807 ± 13 Ma probably indicates later resetting of the Rb–Sr system.An εSr(T) value of −6.2 ± 0.5 (87Sr/86Sr = 0.70184 ± 0.00003) and an εNd(T) value of +2.8 ± 0.4 for Borden indicate derivation of the Sr and Nd from a source with a time-integrated depletion in the large-ion lithophile (LIL) elements. These closely resemble the ε values for Sr and Nd from the Cargill and Spanish River complexes, two other 1900 Ma plutons. The estimated initial 207Pb/204Pb and 206Pb/204Pb ratios from Borden calcites plot significantly below growth curves for average continental crust in isotope correlation diagrams, a pattern similar to those found in mid-ocean ridge basalts (MORB) and most ocean-island volcanic rocks, again suggesting a source depleted in LIL elements. The combined Nd and Sr, and probably Pb, data strongly favour a mantle origin for the Borden complex with little or no crustal contamination and support the model of Bell et al. that many carbonatites intruded into the Canadian Shield were derived from an ancient, LIL-depleted subcontinental upper mantle.

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Mitchell, Roger H., Rudy Wahl, and Anthony Cohen. "Mineralogy and genesis of pyrochlore apatitite from The Good Hope Carbonatite, Ontario: A potential niobium deposit." Mineralogical Magazine 84, no. 1 (October 4, 2019): 81–91. http://dx.doi.org/10.1180/mgm.2019.64.

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AbstractThe Good Hope carbonatite is located adjacent to the Prairie Lake alkaline rock and carbonatite complex in northwestern Ontario. The occurrence is a heterolithic breccia consisting of diverse calcite, dolomite and ferrodolomite carbonatites containing clasts of magnesio-arfvedsonite + potassium feldspar, phlogopite + potassium feldspar together with pyrochlore-bearing apatitite clasts. The apatitite occurs as angular, boudinaged and schlieren clasts up to 5 cm in maximum dimensions. In these pyrochlore occurs principally as euhedral single crystals (0.1–1.5 cm) and can comprise up to 25 vol.% of the clasts. Individual clasts contain compositionally- and texturally-distinct suites of pyrochlore. The pyrochlores are hosted by small prismatic crystals of apatite (~100–500 μm × 10–25 μm) that are commonly flow-aligned and in some instances occur as folds. Allotriogranular cumulate textures are not evident in the apatitites. The fluorapatite does not exhibit compositional zonation under back-scattered electron spectroscopy, although ultraviolet and cathodoluminescence imagery shows distinct cores with thin (<50 μm) overgrowths. Apatite lacks fluid or solid inclusions of other minerals. The apatite is rich in Sr (7030–13,000 ppm) and rare earth elements and exhibits depletions in La, Ce, Pr and Nd (La/NdCN ratios (0.73–1.14) relative to apatite in cumulate apatitites (La/NdCN > 1.5) in the adjacent Prairie Lake complex. The pyrochlore are primarily Na–Ca pyrochlore of relatively uniform composition and minor Sr contents (<2 wt.% SrO). Irregular resorbed cores of some pyrochlores are A-site deficient (>50%) and enriched in Sr (6–10 wt.% SrO), BaO (0.5–3.5 wt.%), Ta2O5 (1–2 wt.%) and UO2 (0.5–2 wt.%). Many of the pyrochlores exhibit oscillatory zoning. Experimental data on the phase relationships of haplocarbonatite melts predicts the formation of apatite and pyrochlore as the initial liquidus phases in such systems. However, the texture of the clasts indicates that pyrochlore and apatite did not crystallise together and it is concluded that pyrochlores formed in one magma have been mechanically mixed with a different apatite-rich magma. Segregation of the apatite–pyrochlore assemblage followed by lithification resulted in the apatitites, which were disrupted and fragmented by subsequent batches of diverse carbonatites. The genesis of the pyrochlore apatitites is considered to be a process of magma mixing and not simple in situ crystallisation.

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WU, FU-YUAN, ROGER H. MITCHELL, QIU-LI LI, CHANG ZHANG, and YUE-HENG YANG. "Emplacement age and isotopic composition of the Prairie Lake carbonatite complex, Northwestern Ontario, Canada." Geological Magazine 154, no. 2 (February 12, 2016): 217–36. http://dx.doi.org/10.1017/s0016756815001120.

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AbstractAlkaline rock and carbonatite complexes, including the Prairie Lake complex (NW Ontario), are widely distributed in the Canadian region of the Midcontinent Rift in North America. It has been suggested that these complexes were emplaced during the main stage of rifting magmatism and are related to a mantle plume. The Prairie Lake complex is composed of carbonatite, ijolite and potassic nepheline syenite. Two samples of baddeleyite from the carbonatite yield U–Pb ages of 1157.2±2.3 and 1158.2±3.8 Ma, identical to the age of 1163.6±3.6 Ma obtained for baddeleyite from the ijolite. Apatite from the carbonatite yields the same U–Pb age of ~1160 Ma using TIMS, SIMS and laser ablation techniques. These ages indicate that the various rocks within the complex were synchronously emplaced at about 1160 Ma. The carbonatite, ijolite and syenite have identical Sr, Nd and Hf isotopic compositions with a 87Sr/86Sr ratio of ~0.70254, and positive εNd(t)1160 and εHf(t)1160 values of ~+3.5 and ~+4.6, respectively, indicating that the silicate and carbonatitic rocks are co-genetic and related by simple fractional crystallization from a magma derived from a weakly depleted mantle. These age determinations extend the period of magmatism in the Midcontinent Rift in the Lake Superior area to 1160 Ma, but do not indicate whether the magmatism is associated with passive continental rifting or the initial stages of plume-induced rifting.

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Symons, D. T. A. "Age of the Firesand River carbonatite complex from paleomagnetism." Canadian Journal of Earth Sciences 26, no. 11 (November 1, 1989): 2401–5. http://dx.doi.org/10.1139/e89-205.

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The 2.3 km diameter Firesand River complex intrudes Archean volcanics and granites of the Wawa Subprovince in the Superior Province about 8 km east of Wawa, Ontario. It has given differing Middle Proterozoic K–Ar biotite ages of 1018 ± 50 and 1097 Ma. Alternating-field and thermal step demagnetization of specimens from three calcific carbonatite sites, five ferruginous dolomitic carbonatite sites, and one lamprophyre dike site isolated a stable mean direction of 290°, 33 °(α95 = 12°). Isothermal remanent magnetization tests indicate the remanence is held by single-to pseudosingle-domain magnetite and hematite in the carbonatite. The dike remanence is Keweenawan in age, thereby confirming its genetic relationship to the complex, and it gives a positive partial contact test with its host rock, indicating no postintrusive remagnetization. The blocking-temperature spectra indicate that postintrusive uplift has not exceeded about 4 km. The pole position for the complex is 183°E, 27°N (dp = 8°, dm = 13°). This pole lies directly on the well-dated Keweenawan apparent polar wander path, giving an age of 1090 ± 10 Ma, in agreement with the older K–Ar age. It also confirms geologic and aeromagnetic evidence that the complex has not been tectonically tilted since emplacement.

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7

PRESSACCO, R. "Geology of the Cargill Township Residual Carbonatite-associated Phosphate Deposit, Kapuskasing, Ontario." Exploration and Mining Geology 10, no. 1-2 (January 1, 2001): 77–84. http://dx.doi.org/10.2113/10.1-2.77.

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8

Symons, D. T. A. "Paleomagnetism of the Keweenawan Chipman Lake and Seabrook Lake carbonatite complexes, Ontario." Canadian Journal of Earth Sciences 29, no. 6 (June 1, 1992): 1215–23. http://dx.doi.org/10.1139/e92-097.

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The Chipman Lake complex crops out as a series of carbonatite and related alkalic mafic dikes in the Wabigoon Subprovince of the Superior Province, whereas the Seabrook Lake complex crops out as an alkalic syenite – carbonatite stock in the Abitibi Subprovince. Paleomagnetic analysis was done on specimens from 23 and 19 sites located in and around the Chipman Lake and Seabrook Lake complexes, respectively, using detailed alternating-field and thermal step demagnetization and isothermal remanent magnetization tests. Contact tests with adjacent Archean host rocks show that both complexes retain a primary characteristic remanence (ChRM). The Chipman Lake's ChRM is retained in 11 dikes with normal polarity and one dike with reversed polarity and at one site with normal polarity and one site with reversed polarity from the fenite alteration zone. Its ChRM gives a pole position at 186°E, 38°N (dp = 7°, dm = 11°), which corresponds to a Keweenawan age of 1098 ± 10 Ma, suggesting that younger K–Ar amphibole ages do not date emplacement. The ChRM of the host rock, the Chipman Lake diorite stock, gives a pole at 49°E, 51°N (dp = 8°, dm = 13°), showing that it is not part of the Keweenawan complex but may be a 2.45 Ga Matachewan intrusive. The Seabrook Lake complex's ChRM is found at six normal polarity sites from within the complex and at four normal and three reversed polarity sites from within the fenitized Archean granite and Matachewan diabase of the contact aureole. It gives a pole position at 180°E, 46°N (dp = 11°, dm = 17°), which corresponds to a Keweenawan age of 1103 ± 10 Ma, agreeing with K/Ar biotite ages. The paleomagnetic data indicate that no significant motion on the Kapuskasing Structural Zone occurred after emplacement of the complexes excluding minor vertical uplift of less than about 4 km, and that there were multiple polarity transitions of a symmetric Earth's magnetic field during Keweenawan time.

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9

Garth Platt, R. "Perovskite, loparite and Ba-Fe hollandite from the Schryburt Lake carbonatite complex, northwestern Ontario, Canada." Mineralogical Magazine 58, no. 390 (March 1994): 49–57. http://dx.doi.org/10.1180/minmag.1994.058.390.05.

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AbstractWithin a suite of felsic-free, mica-rich alkaline ultramafic rocks of the Schryburt Lake carbonatite complex of northwestern Ontario, loparite and Ba-Fe hollandite occur in intimate association with perovskite. The host rocks have variable modal proportions of Mg-olivine, phlogopite, magnetite, ilmenite, apatite and carbonate (generally calcite) with minor Mg-salite. Thus, they correspond to ultramafic lamprophyres (i.e. aillikites), in the sense of Rock (1990) or the lamprophyric facies of the melilitite clan, in the sense of Mitchell (1993).Perovskite is the principal titanate phase, forming both euhedral and anhedral grains, the latter showing evidence of marginal resorption. It exhibits complex zonal patterns due principally to variations in the light rare earth elements, Na and Nb. In the nomenclature suggested, they may be termed perovskite and cerian perovskite. Loparite forms as small euhedral overgrowths on corroded perovskite cores. Chemically they are essentially solid solutions of loparite, lueshite and perovskite. Consequently, they may be termed calcian-loparite, calcian niobian loparite, niobian calcian loparite, loparite and niobian loparite. Titanates of the hollandite group are rare accessory minerals whose composition closely approach that of the septatitanate BaFe2+Ti7O16.The complex zoning of the perovskite grains has been attributed to the periodic introduction of carbonatite-derived fluids enriched in REE, Na and Nb into the silicate system during perovskite crystallization. Subsequent reaction of the early perovskite with F-bearing fluids leads to a localized environment enriched in Ti, Na, Nb and REE derived from both the fluid phase and the unstable perovskite. Loparite subsequently crystallizes from these micro-chemical environments.

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10

Ford, K. L., R. N. W. Dilabio, and A. N. Rencz. "Geological, geophysical and geochemical studies around the Allan Lake carbonatite, Algonquin Park, Ontario." Journal of Geochemical Exploration 30, no. 1-3 (January 1988): 99–121. http://dx.doi.org/10.1016/0375-6742(88)90054-4.

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11

Ford, K. L., R. N. W. Dilabio, and A. N. Rencz. "Preliminary results of multidisciplinary studies around the recently discovered Allan Lake carbonatite, Algonquin Park, Ontario." Journal of Geochemical Exploration 29, no. 1-3 (January 1987): 401–2. http://dx.doi.org/10.1016/0375-6742(87)90103-8.

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12

Moritz, Robert P., and James H. Crocket. "Mechanics of formation of the gold-bearing quartz–fuchsite vein at the Dome mine, Timmins area, Ontario." Canadian Journal of Earth Sciences 27, no. 12 (December 1, 1990): 1609–20. http://dx.doi.org/10.1139/e90-171.

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The highest grade orebody in the Dome mine is a steeply dipping 500 m long, 550 m high, and 3.5 m wide banded quartz-fuchsite vein (QFV) accompanied by subsidiary veins in the adjacent wall rock. The QFV is located in a subvertical zone of carbonatized komatiite near a slate unit and is composed of relatively unstrained massive quartz and strained ribbon quartz. Fuchsite and chlorite are the main ribbon components. Native gold, galena and tellurides are typically associated with ribbon quartz, whereas massive quartz is usually low grade.The quartz–fuchsite vein system is coeval with the regional penetrative deformation. Reverse oblique-slip faulting together with an intricate interplay between intermittent variations of the deviatoric stress regime and strain refraction due to layer anisotropy explain the overall anatomy of the vein system. The regional compressive stress regime and the syntectonic wall-rock alteration created the favorable requirements for the combined shear and hydraulic fracturing that led to vein formation.Massive quartz was deposited during prolonged episodes of vein growth, whereas ribbon quartz was emplaced in the course of repetitive and brief periods of crack-seal vein growth. The systematic association of high-grade ore with ribbon quartz suggests a genetic link whereby gold deposition is attributed to small pressure drops accompaning the crack-seal mechanism of vein growth. Thus, gold was introduced along with the bulk of the quartz.

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13

Zurevinski, Shannon E., and Roger H. Mitchell. "Petrogenesis of orbicular ijolites from the Prairie Lake complex, Marathon, Ontario: Textural evidence from rare processes of carbonatitic magmatism." Lithos 239 (December 2015): 234–44. http://dx.doi.org/10.1016/j.lithos.2015.11.003.

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14

Schandl, E. S., M. P. Gorton, and D. W. Davis. "Albitization at 1700 ± 2 Ma in the Sudbury – Wanapitei Lake area, Ontario: implications for deep-seated alkalic magmatism in the Southern province." Canadian Journal of Earth Sciences 31, no. 3 (March 1, 1994): 597–607. http://dx.doi.org/10.1139/e94-052.

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U–Pb geochronology of hydrothermal monazite in albitized rocks from two gold deposits east of the Sudbury complex indicates that albitization in the Sudbury – Wanapitei Lake area occurred at 1700 ± 2 Ma and was coeval with a period of granitic plutonism in the Southern structural province between 1750 and 1700 Ma.A variety of rare earth element (REE) minerals, such as two generations of hydrothermal monazite, bastnäsite, synchysite, and gadolinite were identified in the albitized Huronian sediments in the Espanola – Sudbury – Wanapitei Lake areas. The presence of these REE minerals, the extraordinary light rare earth element enrichment in rocks from the Sheppard gold property east of the Sudbury igneous complex and the elevated REE concentrations in some albitized rocks suggests that sodium-rich fluids may have been generated by carbonatitic or alkalic intrusions at depth.Gold mineralization occurs in rocks that have been altered by at least two different types of fluids: (1) peralkaline; Na–REE bearing and (2) low pH, Co bearing. The high Co content of most mineralized samples and the relatively weak correlation between Au and Na2O suggests that gold was probably concentrated to economic grade by the low pH, Co-bearing fluids. The spatial association of albite and gold suggests that the albitized rocks may represent earlier fluid conduits that were subsequently refractured and invaded by the mineralizing solutions.

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15

Roy, Derick J. W., Jesse D. Merriman, Alan G. Whittington, and Anne M. Hofmeister. "Thermal properties of carbonatite and anorthosite from the Superior Province, Ontario, and implications for non-magmatic local thermal effects of these intrusions." International Journal of Earth Sciences, March 29, 2021. http://dx.doi.org/10.1007/s00531-021-02032-w.

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Journal articles on the topic 'Carbonatites - Ontario'

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