Assessing Inheritance of Zircon and Monazite in Granitic Rocks from the Monashee Complex, Canadian Cordillera

Crowley, James L.; Brown, Richard L.; Gervais, Félix; Gibson, H. Daniel

doi:10.1093/petrology/egn047

Cited by 46 publications

(17 citation statements)

References 32 publications

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“…Reverse zoning pattern where the bright core has a high Th content and the dark rim has relatively low Th content is also observed ( Figure 3(b)). Several grains have weak oscillatory zoning (Figure 3(c), which is typical for monazite grown from melt-related monazite [25], though their trace element composition is similar to other grains (Figures 3-5). Monazite Table 1 and Table 2).…”

Section: Petrography and Mineralogymentioning

confidence: 91%

Crystal Chemistry and Geochronology of Thorium-Rich Monazite from Kovela Granitic Complex, Southern Finland

Al-Ani¹,

Hölttä²,

Grönholm³

et al. 2019

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Abundant porphyritic granites, including Grt-bearing and Bt-bearing porphyritic granites, and porphyritic potash-feldspar granite (trondhjemite-granitic composition) are widely distributed within the Kovela granitic complex Southern Finland, which associated with monazite-bearing dikes (strong trondhjemite composition). The investigated monazite-bearing dikes are dominated by a quartz + K-feldspar + plagioclase + biotite + garnet + monazite assemblage. The monazite forms complexly zoned subhedral to euhedral crystals variable in size (100-1500 μm in diameter) characterized by high Th content. The chemical zoning characterised as: 1) concentric, 2) patchy, and 3) intergrowth-like. Textural evidence suggests that these accessory minerals crystallized at an early magmatic stage, as they are commonly associated with clusters of the observed variations in their chemical composition are largely explained by the huttonite exchange

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Section: Petrography and Mineralogymentioning

confidence: 91%

Crystal Chemistry and Geochronology of Thorium-Rich Monazite from Kovela Granitic Complex, Southern Finland

Al-Ani¹,

Hölttä²,

Grönholm³

et al. 2019

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“…This core may be the result of secondary alteration, but the oscillatory zoning that parallels its boundaries suggests it may be a primary feature. Oscillatory-zoned monazite is also reported primarily from igneous and/or fluid-rich systems (e.g., [12,13,[64][65][66]). In both cases, its composition reflects local feedback between the monazite's growth surface and the fluid supply of elements (e.g., [64]).…”

Section: Evidence For Hydrothermal Originmentioning

confidence: 99%

“…The Llallagua monazite is also known for oscillatory zoning in backscattered electrons (BSE) (Figure 2) [7,11]. This type of zoning is considered rare for the mineral, which is more commonly seen as sector zoned in BSE [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Catlos

Miller

2017

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Monazite [(Ce,Th)PO 4 ] from the Llallagua tin ore deposit in Bolivia is characterized by low radiogenic element contents. Previously reported field evidence and mineral associations suggest the mineral formed via direct precipitation from hydrothermal fluids. Monazite compositions thus may provide insight into characteristics of the fluids from which it formed. Chemical compositions of three Llallagua monazite grains were obtained using Electron Probe Microanalysis (EPMA, n = 64) and laser ablation mass spectrometry (LA-ICP-MS, n = 56). The mineral has higher amounts of U (123 ± 17 ppm) than Th (39 ± 20 ppm) (LA-ICP-MS, ±1σ). Grains have the highest amounts of fluorine ever reported for monazite (0.88 ± 0.10 wt %, EPMA, ±1σ), and F-rich fluids are effective mobilizers of rare earth elements (REEs), Y, and Th. The monazite has high Eu contents and positive Eu anomalies, consistent with formation in a highly-reducing back-arc environment. We speculate that F, Ca, Si and REE may have been supplied via dissolution of pre-existing fluorapatite. Llallagua monazite oscillatory zoning is controlled by an interplay of low (P + Ca + Si + Y) and high atomic number (REE) elements. We suggest monazite compositions provide insight into fluid geochemistry, mineral reactions, and tectonic settings of ore deposits that contain the mineral.

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“…The earliest deformation and metamorphism occurred in the Paleoproterozoic and has been recognized in some of the deepest basement rocks of the Frenchman Cap culmination (Armstrong et al, 1991;Crowley, 1999;Crowley et al, 2008). Later penetrative Cordilleran deformation and metamorphism affected rocks of the Monashee complex and the Selkirk domain.…”

Section: Geological Backgroundmentioning

confidence: 99%

Effects of Paleogene faults on the reconstruction of the metamorphic history of the northwestern Thor-Odin culmination of the Monashee complex, southeastern British Columbia

Kuiper¹,

Williams²,

Hamilton³

2015

Lithosphere

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Differences in U-Pb metamorphic monazite ages in the northwestern Thor-Odin culmination of the Monashee complex, southern Canadian Cordillera, are explained in the context of the NNW-trending subvertical transcurrent Paleogene Victor Creek fault. Similar faults are present throughout the Canadian Cordillera. We demonstrate their potential importance in the interpretation of the history of Cordilleran deformation and metamorphism. A pervasive transposition foliation (S T) is present throughout the Thor-Odin culmination as a result of Cordilleran and possibly earlier deformation. A pre-S T (or early S T) foliation is preserved as aligned inclusion trails in porphyroblasts such as garnet and kyanite. Monazite U-(Th-)Pb isotope dilution-thermal ionization and secondary ion microprobe mass spectrometry (ID-TIMS, SIMS) ages are used to relate monazite growth to pre-and syn-S T fabrics and associated metamorphism. The ages of both pre-and syn-S T fabrics, and the gap between pre-and syn-S T ages decrease toward the east, in an apparently continuous manner. While monazite west of the Victor Creek fault is latest Cretaceous to earliest Eocene in age, monazite east of the Victor Creek fault is exclusively Eocene. Correlation of rock types across the faults is difficult because the same rock units are repeated many times on either side. However, distinctly different retained ages of metamorphism, and previously recognized differences in structures and detrital zircon signatures across the fault indicate 5-60 km offset along the fault. Similar trends occur across other faults along the western Monashee complex, and faults here and elsewhere in the Canadian Cordillera may have similar geological significance.

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Assessing Inheritance of Zircon and Monazite in Granitic Rocks from the Monashee Complex, Canadian Cordillera

Cited by 46 publications

References 32 publications

Crystal Chemistry and Geochronology of Thorium-Rich Monazite from Kovela Granitic Complex, Southern Finland

Crystal Chemistry and Geochronology of Thorium-Rich Monazite from Kovela Granitic Complex, Southern Finland

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Effects of Paleogene faults on the reconstruction of the metamorphic history of the northwestern Thor-Odin culmination of the Monashee complex, southeastern British Columbia

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