Journal articles: 'U-Pb monazite geochronology'

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Tang, Xu, Qiu-Li Li, Bin Zhang, Peng Wang, Li-Xin Gu, Xiao-Xiao Ling, Chen-Hui Fei, and Jin-Hua Li. "The Chemical State and Occupancy of Radiogenic Pb, and Crystallinity of RW-1 Monazite Revealed by XPS and TEM." Minerals 10, no. 6 (May 31, 2020): 504. http://dx.doi.org/10.3390/min10060504.

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Monazite ((Ce, La, Nd, Th)PO4) is one of the widely used minerals for U–Th–Pb dating in geochronology. To better understand the possible effects of radiogenic Pb on the in situ dating method, a natural monazite U–Th–Pb standard sample (RW-1) was chemically and structurally characterized down to atomic scales by using the combination of Raman spectrum (RM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The experimental results revealed that radiogenic Pb exists as Pb2+ and substitutes for the Ce site in the monazite crystal lattice. Moreover, TEM imaging demonstrated that monazite is well crystalline revealed by an atomic structure in most areas except for a few tiny defects, which are likely attributed to alpha self-healing from an electronic energy loss of α particles. The characterization of the chemical state and occupancy of radiogenic Pb, and the distribution of Pb and Th in monazite at the nanoscale and atomic scale could provide insight for us to understand the mechanisms of the nanogeochronology.

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Li, Li, Hai-Li Li, Guo-Guang Wang, and Jian-Dong Sun. "Geochronology of the Baishi W-Cu Deposit in Jiangxi Province and Its Geological Significance." Minerals 12, no. 11 (October 30, 2022): 1387. http://dx.doi.org/10.3390/min12111387.

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The Baishi W-Cu deposit is located in the Nanling metallogenic belt, which is famous for its numerous W deposits and reserves. The formation age of this deposit remains unclear. In order to further infer the formation age of the deposit, this study conducted detailed LA-ICP-MS U-Pb isotopic analyses of zircon and monazite selected from ore-related Baishi granite. The LA-ICP-MS zircon U-Pb weighted average ages of Baishi granite were determined to be 223 ± 2 Ma and 226 ± 1 Ma, and the LA-ICP-MS U-Pb weighted average ages of monazite were determined to be 224 ± 2 Ma and 223 ± 1 Ma. The BSE image of monazite was homogeneous, and the pattern of rare earth elements had an obvious negative Eu anomaly, indicating that monazite was of magmatic origin. Combining the ages of zircon and monazite, this study inferred that Baishi granite and the Baishi W-Cu deposit formed in the Triassic. The determination of the ore-forming event of the Baishi W-Cu deposit provides new data regarding the important Indosinian (Triassic) mineralization events in the Nanling metallogenic belt and suggests that geologists should strengthen the prospecting work of Indosinian tungsten deposits in the Nanling area. In terms of tectonic setting, it was inferred that the Triassic Baishi W-Cu deposit was formed in the extensional environment after intracontinental orogeny.

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Mohammadi, Nadia, Christopher R. M. McFarlane, David R. Lentz, and Kathleen G. Thorne. "Timing of magmatic crystallization and Sn–W–Mo greisen vein formation within the Mount Douglas Granite, New Brunswick, Canada." Canadian Journal of Earth Sciences 57, no. 7 (July 2020): 814–39. http://dx.doi.org/10.1139/cjes-2019-0043.

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U–Pb geochronology was applied to a combination of magmatic and hydrothermal minerals to help constrain the timing of emplacement of three units in the Mount Douglas Granite (MDG) and reveal their association with a complex mineralized hydrothermal system containing endogranitic Sn–W–Mo–Zn–Bi–U-bearing greisen/sheeted veins within the pluton. Magmatic monazite and zircon U–Pb ages obtained by LA–ICP–MS overlap at 368 Ma, recording a Late Devonian crystallization age for the MDG. Although discrimination, outside analytical error, of sequential pulses of magmatism is beyond the resolution of LA–ICP–MS U–Pb geochronology, geochemical variations of monazite accompanied by previous whole-rock geochemical analyses support a progressive fractional crystallization process starting from a parental magma (Dmd1), leading to the generation of Dmd2, and finally Dmd3 as the most fractionated unit. Hydrothermal uraninite, cassiterite, and monazite, collected from endogranitic greisen/sheeted veins, reveal evidence for syn-magmatic-related mineralization and a longer-lived post-magmatic hydrothermal system. The first stage is recorded by concordant uraninite dates at 367 ± 3 Ma and by an inverse isochron lower intercept of 362 ± 8 Ma for cassiterite. In contrast, hydrothermal monazite crystallized over a wider range of ages from 368 to 344 Ma, demonstrating post-magmatic hydrothermal activity within the MDG. These magmatic and hydrothermal ages combined with the geochemical signature of the MDG are similar to those documented for the nearby Mount Pleasant Sn–W–Mo–Bi–In granite-related deposit, which suggests that the two mineralizing systems occur at different levels of the same magmatic system.

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STEPANYUK, L. M., N. M. KONOVAL, T. I. DOVBUSH, O. V. KOVTUN, O. B. VYSOTSKY, and V. P. SNISAR. "Uranium-Lead Age of Granites of Kirovohrad Massif of the Inhul Megablock of the Ukrainian Shield." Mineralogical Journal 43, no. 4 (2021): 56–62. http://dx.doi.org/10.15407/mineraljournal.43.04.056.

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The porphyry-like biotite-garnet granites (sample KВ-5-1) of the Sokolivkа quarry were studied. The quarry is located in the Kirovohrad granite massif on the southwest of Kropyvnytsky city. The aim of our geochronology investigation is to determine the age of granites of the Kirovohrad massif by the U-Pb isotope method using monazite. The age of granites from Kirovohrad massif by the U-Pb method using monazite has not been determined yet. According to our data, the porphyry granites of the Kirovohrad massif (Sokolivkа quarry) were formed 2034 million years ago. This U-Pb data of the porphyry-like granites is significantly lower than the U-Pb age of the granites from other parts of this massif. This may be due to the multistage formation of the Kirovohrad massif, for example, the Novoukrainskiy and some granite massifs of the Zhytomyr complex from Volyn’ megablock.

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C.A. NETO, CARLA, CLAUDIO M. VALERIANO, CLAUDIA R. PASSARELLI, MONICA HEILBRON, and MARCELA LOBATO. "Monazite ID-TIMS U-Pb geochronology in the LAGIR laboratory, Rio de Janeiro State University: protocols and first applications to the assembly of Gondwana supercontinent in SE-Brazil." Anais da Academia Brasileira de Ciências 86, no. 1 (March 2014): 171–86. http://dx.doi.org/10.1590/0001-3765201420120005.

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The chemical and spectrometric procedures of the U-Pb geochronology method on monazites, recently installed in the LAGIR laboratory, are described in detail. In addition, preliminary results on monazite samples from the Brasília and Ribeira belts are reported and discussed in the context of the regional geology. Several experiments for calibration of ion exchange chromatographic columns with the AG-1x8 resin, were performed with HCl, using dissolved natural monazite samples. The Pb blanks of reagents are ∼0.5 pg/g in acids and ∼1 pg/g in H2O. The total Pb blanks in chemical procedures were below 22 pg. Preliminary results are presented from three case studies related to Brasiliano orogenic belts of SE-Brazil, which correlate very well with previous age determinations from literature: two sub-concordant grains from an Araxá Group quartzite (southern Brasília belt) define a concordia age of 602.6 ±1.4 Ma; a -0.8% discordant grain from a quartzite of the São Fidelis Group (Costeiro Domain, central Ribeira belt) yielded a concordia age of 535.3 ± 2.4 Ma; two 0.4 % and 1.3 % discordant monazite grains from the post-collisional Itaoca Granite (Costeiro Domain, central Ribeira belt) define a concordia age of 476.4 ± 1.8 Ma.

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Peterman, Emily M., James M. Mattinson, and Bradley R. Hacker. "Multi-step TIMS and CA-TIMS monazite U–Pb geochronology." Chemical Geology 312-313 (June 2012): 58–73. http://dx.doi.org/10.1016/j.chemgeo.2012.04.006.

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Yan, Taotao, Dongsheng Liu, Chen Si, and Yu Qiao. "Coupled U–Pb Geochronology of Monazite and Zircon for the Bozhushan Batholith, Southeast Yunnan Province, China: Implications for Regional Metallogeny." Minerals 10, no. 3 (March 6, 2020): 239. http://dx.doi.org/10.3390/min10030239.

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Constraining the duration of magmatism is of vital importance to the understanding of the magmatic-hydrothermal mineral system. The Bozhushan batholith, located in the middle section of the southeastern Yunnan ore district, mainly consists of biotite monzogranite and monzogranite. Many Sn–W–polymetallic deposits are developed around the Bozhushan batholith, but their temporal and genetic relationships remain controversial. LA-ICP-MS U–Pb zircon and monazite dating were respectively conducted on the same two samples, yielding weighted mean 206Pb/238U zircon ages of 85.1 ± 0.7 and 85.6 ± 0.9 Ma, and weighted mean 206Pb/238U monazite ages of 87.1 ± 0.9 and 88.1 ± 1.1 Ma. The crystallization ages of S-type granites obtained from the zircon U–Th–Pb system and monazite U–Th–Pb system are consistent within the analytical errors. After combining the new ages obtained in this study with recently published U–Pb zircon and cassiterite ages from the giant Baniuchang Ag–Sn–Pb–Zn deposit in the north, and U–Pb zircon and Re-Os molybdenite ages from the large Guanfang W deposit in the south, a temporal framework of magmatism-mineralization in the Bozhushan region has been established. The duration of magmatic activity at Bozhushan is about 7 Ma, with W mineralization occurring at ca. 92 Ma and Sn mineralization at 88–87 Ma.

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Torab, F. M., and B. Lehmann. "Magnetite-apatite deposits of the Bafq district, Central Iran: apatite geochemistry and monazite geochronology." Mineralogical Magazine 71, no. 3 (June 2007): 347–63. http://dx.doi.org/10.1180/minmag.2007.071.3.347.

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AbstractThe Bafq mining district is in the Early Cambrian Kashmar-Kerman volcano-plutonic arc in Central Iran and hosts important ‘Kiruna-type’ magnetite-apatite deposits. The hydrothermal magnetite-apatite mineralization occurs mostly as massive orebodies, metasomatic replacements, veins and stockworks. Apatite (low-Sr fluorapatite containing small amounts of hydroxyl) has undergone a partial hydrothermal overprint which involved leaching of Na, Cl and REE. The REE were remobilized into monazite (and minor allanite, parisite and xenotime) which nucleated as inclusions within apatite or as individual crystals. The monazites have very small ThO2 contents (usually <1 wt.%), but they occasionally show an inner core of high-Th monazite, with low-Th overgrowth rims. The chemical Th-U-total Pb dating of the high-Th monazites by electron microprobe analysis yields an isochron age of 515±21 Ma (initial PbO intercept = 68 ppm), or 529±21 Ma (forced initial PbO = 0), which is contemporaneous with the emplacement of the volcano-plutonic host rocks of the magnetite-apatite mineralization, as well as with widespread sedimentation of Late Proterozoic to Cambrian evaporitic rocks in Central Iran. The monazite age and the mineralogical and geochemical data suggest that the magnetite-apatite deposits are probably related to large-scale brine circulation induced by felsic magmatism during the Cambrian.

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Lucas, S. B., E. C. Syme, and K. E. Ashton. "Introduction to Special Issue 2 on the NATMAP Shield Margin Project: The Flin Flon Belt, Trans-Hudson Orogen, Manitoba and Saskatchewan." Canadian Journal of Earth Sciences 36, no. 11 (November 10, 1999): 1763–65. http://dx.doi.org/10.1139/e00-005.

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The Shield Margin Project of the National Geoscience Mapping Program (NATMAP) resulted in a new understanding of the Paleoproterozoic Flin Flon Belt (Manitoba and Saskatchewan) in four dimensions. A multidisciplinary approach was utilized in the NATMAP project, based on partnerships with government, university, and private sector geoscientists, and close cooperation with the Lithoprobe's Trans-Hudson Orogen Transect. Research areas spanned from bedrock and surficial geoscience, to crustal and mantle geophysics, to high precision U-Pb geochronology and tracer isotope studies. This Special Issue contains nine papers covering a wide variety of topics related to the NATMAP Shield Margin Project, including volcanic-hosted massive sulphide deposits in the Flin Flon and Snow Lake camps; structural geology of the Flin Flon townsite and southern flank of the Kisseynew Domain; geochronology and the U-Pb systematics of monazite in metasedimentary rocks; and the geoelectrical and crustal conductivity structure of the Flin Flon Belt.

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Passarelli, Cláudia R., Miguel A. S. Basei, Oswaldo Siga Jr., Kei Sato, Walter M. Sproesser, and Vasco A. P. Loios. "Dating minerals by ID-TIMS geochronology at times of in situ analysis: selected case studies from the CPGeo-IGc-USP laboratory." Anais da Academia Brasileira de Ciências 81, no. 1 (March 2009): 73–97. http://dx.doi.org/10.1590/s0001-37652009000100010.

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Since 1964, the Center for Geochronological Research - CPGeo, one of the interdepartmental centers of the Instituto de Geociências (IG) of São Paulo University, has developed studies related to several geological processes associated with different rock types. Thermal Ionization Mass Spectrometry Isotopic Dilution (ID-TIMS) has been the technique widely used in the CPGeo U-Pb Laboratory. It provides reliable and accurate results in age determination of superposed events. However, the open-system behavior such as Pb-loss, the inheritance problem and metamictization processes allow and impel us to a much richer understanding of the power and limitations of U-Pb geochronology and thermochronology. In this article, we present the current methodology used at the CPGeo-IGc-USP U-Pb laboratory, the improvements on ID-TIMS method, and report high-precision U-Pb data from zircon, monazite, epidote, titanite, baddeleyite and rutile from different rock types of several domains of the Brazilian south-southeast area, Argentina and Uruguay.

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Vozárová, Anna, Patrik Konečný, Marek Vďačný, Jozef Vozár, and Katarína Šarinová. "Provenance of Permian Malužiná Formation sandstones (Hronicum, Western Carpathians): evidence from monazite geochronology." Geologica Carpathica 65, no. 5 (October 1, 2014): 329–41. http://dx.doi.org/10.2478/geoca-2014-0023.

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Abstract The Permian Malužiná Formation and the Pennsylvanian Nižná Boca Formation are Upper Paleozoic volcano- sedimentary complexes in the Hronicum nappe system. Sandstones, shales and conglomerates are the dominant lithological members of the Malužiná Formation sequence. Detrital monazites were analysed by electron microprobe, to obtain Th-U-Pb ages of the source areas. The majority of detrital monazites showed Devonian-Mississippian ages, ranging from 330 to 380 Ma with a weighted average of 351 ± 3.3 (2σ), that correspond well with the main phase of arcrelated magmatic activity in the Western Carpathians. Only a small portion of detrital monazites displayed Permian ages in the range of 250-280 Ma, with a significant maximum around 255 Ma. The weighted average corresponds to 255 ± 6.2 Ma. These monazites may have been partially derived from the synsedimentary acid volcanism that was situated on the margins of the original depositional basin. However, some of the Triassic ages (230-240 Ma), reflect, most likely, the genetic relationship with the overheating connected with Permian and subsequent Triassic extensional regime. Detrital monazite ages document the Variscan age of the source area and also reflect a gradual development of the Hronicum terrestrial rift, accompanied by the heterogeneous cooling of the lithosphere.

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Markley, Michelle J., Steven R. Dunn, Michael J. Jercinovic, William H. Peck, and Michael L. Williams. "Monazite U–Th–Pb geochronology of the Central Metasedimentary Belt Boundary Zone (CMBbz), Grenville Province, Ontario Canada." Canadian Journal of Earth Sciences 55, no. 9 (September 2018): 1063–78. http://dx.doi.org/10.1139/cjes-2018-0039.

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The Central Metasedimentary Belt boundary zone (CMBbz) is a crustal-scale shear zone that juxtaposes the Central Gneiss Belt and the Central Metasedimentary Belt of the Grenville Province. Geochronological work on the timing of deformation and metamorphism in the CMBbz is ambiguous, and the questions that motivate our study are: how many episodes of shear zone activity did the CMBbz experience, and what is the tectonic significance of each episode? We present electron microprobe data from monazite (the U–Th–Pb chemical method) to directly date deformation and metamorphism recorded in five garnet–biotite gneiss samples collected from three localities of the CMBbz of Ontario (West Guilford, Fishtail Lake, and Killaloe). All three localities yield youngest monazite dates ca. 1045 Ma; most of the monazite domains that yield these dates are high-Y rims. In comparison with this common late Ottawan history, the earlier history of the three CMBbz localities is less clearly shared. The West Guilford samples have monazite grain cores that show older high-Y domains and younger low-Y domains; these cores yield a prograde early Ottawan (1100–1075 Ma) history. The Killaloe samples yield a well-defined prograde, pre- to early Shawinigan history (i.e., 1220–1160 Ma) in addition to some evidence for a second early Ottawan event. In other words, the answers to our research questions are: three events; a Shawinigan event possibly associated with crustal thickening, an Ottawan event possibly associated with another round of crustal thickening, and a late Ottawan event that resists simple interpretation in terms of metamorphic history but that coincides chronologically with crustal thinning at the base of an orogenic lid.

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Zotto, S. C., D. P. Moecher, N. A. Niemi, J. R. Thigpen, and S. D. Samson. "Persistence of Grenvillian dominance in Laurentian detrital zircon age systematics explained by sedimentary recycling: Evidence from detrital zircon double dating and detrital monazite textures and geochronology." Geology 48, no. 8 (May 18, 2020): 792–97. http://dx.doi.org/10.1130/g47530.1.

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Abstract Grenvillian ages dominate Neoproterozoic to Paleozoic detrital zircon (DZ) populations across eastern Laurentia and persist through the present. The persistence of this dominance is inferred to result from recycling of DZ grains ultimately sourced from exceptionally Zr-rich and zircon-fertile Grenvillian granitoids. Pennsylvanian arenites of the Appalachian Basin (eastern United States) exhibit DZ U-Pb age distributions that are nearly identical to those of Neoproterozoic to Cambrian strata, and contain detrital diagenetic monazite grains formed via metamorphism or diagenesis of sedimentary rocks in the source region. Detrital zircon (U-Th)/He ages are mostly 475–300 Ma, yielding lag times [Δt = U-Pb age − (U-Th)/He age] of 500–1000 m.y. and 1200–2400 m.y. for Grenvillian and Paleoproterozoic to Archean DZ grains, respectively. Detrital monazite Th-Pb ages are comparable to (U-Th)/He cooling ages, reflecting formation of monazite during Paleozoic regional metamorphism of Neoproterozoic to Cambrian strata that reset the (U-Th)/He systematics of Grenvillian DZ grains within those metasediments. These results are either consistent with or prove recycling. Incorporation of other geological constraints permits definition of at least three (and potentially five) recycling events and their timing following initial post-Grenvillian exhumation and erosion (the “great Grenvillian sedimentation episode”). Recycling events include dispersal of post-Grenvillian sediment during deposition of Neoproterozoic to Cambrian strata (formation of the “Great Unconformity”: cycle 1), subsequent erosion of metamorphosed Neoproterozoic to Cambrian strata generating detritus for the Pennsylvanian arenites sampled here (cycle 2), and modern erosion of those arenites (cycle 3). Pancontinental river systems facilitated dispersal of sediment of ultimate Grenvillian age during or after each cycle.

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Zi, Jian-Wei, Birger Rasmussen, Janet R. Muhling, and Ian R. Fletcher. "U-Pb geochronology of monazite in Precambrian tuffs reveals depositional and metamorphic histories." Precambrian Research 313 (August 2018): 109–18. http://dx.doi.org/10.1016/j.precamres.2018.05.015.

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Mohammadi, Nadia, Les Fyffe, Christopher R. M. McFarlane, Kay G. Thorne, David R. Lentz, Brittany Charnley, Laurin Branscombe, and Sheena Butler. "Geological relationships and laser ablation ICP-MS U-Pb geochronology of the Saint George Batholith, southwestern New Brunswick, Canada: implications for its tectonomagmatic evolution." Atlantic Geology 53 (May 6, 2017): 207–40. http://dx.doi.org/10.4138/atlgeol.2017.008.

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The Late Silurian to Late Devonian Saint George Batholith in southwestern New Brunswick is a large composite intrusion (2000 km2) emplaced into the continental margin of the peri-Gondwanan microcontinent of Ganderia. The batholith includes: (1) Bocabec Gabbro; (2) equigranular Utopia and Wellington Lake biotite granites; (3) Welsford, Jake Lee Mountain, and Parks Brook peralkaline granites; (4) two-mica John Lee Brook Granite; (6) Jimmy Hill and Magaguadavic megacrystic granites; and (6) rapakivi Mount Douglas Granite. New LA ICP-MS in situ analyses of six samples from the Saint George Batholith are as follows: (1) U-Pb monazite crystallization age of 425.5 ± 2.1 Ma for the Utopia Granite in the western part of the batholith (2) U-Pb zircon crystallization ages of 420.4 ± 2.4 Ma and 420.0 ± 3.5 Ma for two samples of the Utopia Granite from the central part of the batholith; (3) U-Pb zircon crystallization age of 418.0 ± 2.3 Ma for the Jake Lee Mountain Granite; (4) U-Pb zircon crystallization age of 415.5 ± 2.1 Ma for the Wellington Lake Granite; and (5) U-Pb monazite crystallization age of 413.3 ± 2.1 Ma for the John Lee Brook Granite. The new geochronological together with new and existing geochemical data suggest that the protracted magmatic evolution of the Late Silurian to Early Devonian plutonic rocks is related to the transition of the Silurian Kingston arc-Mascarene backarc system from an extensional to compressional tectonic environment during collision of the Avalonian microcontinent with Laurentia followed by slab break-off.

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Wasteneys, Hardolph A., Richard J. Wardle, and Thomas E. Krogh. "Extrapolation of tectonic boundaries across the Labrador shelf: U–Pb geochronology of well samples." Canadian Journal of Earth Sciences 33, no. 9 (September 1, 1996): 1308–24. http://dx.doi.org/10.1139/e96-099.

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Near Saglek Fiord, a northerly trending boundary between the early Archean Saglek block and the middle Archean Hopedale block extends between drill sites which, respectively, sampled Uivak amphibolite gneiss with U–Pb zircon intercept ages of 3742 ± 12 and 2752 ± 42 Ma, and migmatitic Lister gneiss with concordant ages of [Formula: see text] for restite and [Formula: see text], for leucosome. Titanite ages of ca. 2508 Ma are common to both rocks. A nearby metapsammitic gneiss has detrital zircon and monazite ages of 2681 ± 5, 2700 ± 4, ca. 2730, and 2750 ± 2 Ma representing high-grade metamorphism related to the Hopedale–Saglek collision and metamorphic monazite of ca. 2560 Ma age representing metamorphism of the sediment during reactivation of the Saglek–Hopedale suture. Two hundred kilometres southeast, a gneissic granite records a protolith age of 3170 Ma and Late Proterozoic Pb loss. Near the Nain–Makkovik boundary, 1269 ± 4 Ma zircons indicate a significant extension of the Nain Platonic Suite. South of the Makkovik boundary, a foliated granite yielded an upper intercept age defining intrusion at 1895 ± 8 Ma and concordant 1872 ± 5 Ma titanite ages that date subsequent metamorphism. Discordant U–Pb ages from an alkali-feldspar granite also constrain crystallization to ca. 1890 Ma and together with the gneiss represent the previously defined Iggiuk event in the Kaipokok domain. Wells near the southerly end of the transect record 1801 ± 5, 1813 ± 3, and 1806 ± 8 Ma ages, respectively, that are typical of the synorogenic granitoid suite representing the Cape Harrison domain of southern Makkovik Province.

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Machado, N., N. Goulet, and C. Gariépy. "U–Pb geochronology of reactivated Archean basement and of Hudsonian metamorphism in the northern Labrador Trough." Canadian Journal of Earth Sciences 26, no. 1 (January 1, 1989): 1–15. http://dx.doi.org/10.1139/e89-001.

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The Labrador Trough is a Proterozoic orogenic belt bordering the eastern margin of the Archean Superior Province. The volcano-sedimentary sequences of the trough were deformed and metamorphosed during the Hudsonian Orogeny (ca. 1800 Ma). The eastern basement, present as domal inliers, was remobilized during this orogeny, whereas the western basement remained unaffected.In this study we present U–Pb ages of the western and eastern basement of the Proterozoic Labrador Trough orogen between Leaf River and Koksoak River and of the northernmost extension of the DePas batholithic complex farther east. From the western basement, the Leaf Bay granodiorite has an age of 2721 ± 3 Ma (zircon). From the gneiss domes of the eastern basement the ages are as follows: Lac Moyer—2883 ± 6 Ma (zircon), 1793 ± 5 Ma (monazite), and 1746 Ma (minimum age, rutile); Lac Boulder—an upper-intercept age of 2868 ± 8 Ma and a lower-intercept age of 1783 ± 11 Ma (zircon–titanite regression) and an age of 1740 ± 5 Ma (rutile); Lac Olmstead Lake—2721 ± 4 Ma (zircon) and 1774 ± 5 Ma (titanite); Leaf Strait—2719 ± 7 Ma (zircon) and 1783 ± 2 Ma (monazite). The DePas Batholith contains four generations of zircon: the minimum ages of the three oldest are 2688, 2779, and 2922 Ma; we also obtained a monazite age of 1808 ± 2 Ma.These results lead us to the following conclusions: (i) The age of the Leaf Bay granodiorite, 2721 ± 3 Ma, is a minimum age of the gneisses of the Minto Subprovince, (ii) The westernmost gneiss domes of the eastern basement (Lac Moyer and Lac Boulder), bounded by two major faults, contain zircon formed during metamorphic events dated at 2868 ± 8 and 2883 ± 6 Ma and may be part of an allochthon. (iii) The Lac Olmstead and Leaf Strait domes contain metamorphic zircon dated at 2719–2721 Ma. (iv) The minimum age of migmatization of the DePas complex is 2688 Ma. (v) The monazite ages date the latest phase of metamorphism in the area, (vi) The titanite ages probably represent post-deformational cooling, whereas the rutile ages could represent late-metamorphic hydrothermal activity, (vi) The available data suggest the presence of continuous Archean basement—remobilized during the Hudsonian Orogeny—between the Labrador Trough and the DePas Batholith, which could represent a collision zone. The final stages of this collision could be slightly older (1808 Ma) than the equivalent activity in the Labrador Trough. These speculations raise the possibility that the evolution of the Labrador Trough is closely related in time and space to events occurring in its "hinterland".

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Ziemniak, Grzegorz, Karolina Kośmińska, Igor Petrík, Marian Janák, Katarzyna Walczak, Maciej Manecki, and Jarosław Majka. "Th–U–total Pb monazite geochronology records Ordovician (444 Ma) metamorphism/partial melting and Silurian (419 Ma) thrusting in the Kåfjord Nappe, Norwegian Arctic Caledonides." Geologica Carpathica 70, no. 6 (December 1, 2019): 494–511. http://dx.doi.org/10.2478/geoca-2019-0029.

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Abstract The northern extent of the Scandinavian Caledonides includes the Skibotn Nappe Complex of still debated structural position. This paper is focused on part of this complex and presents new U–Th–total Pb monazite dating results for the migmatitic gneiss of the Kåfjord Nappe. The rocks show mineral assemblage of garnet + plagioclase + biotite + white mica + kyanite + rutile ± K-feldspar ± sillimanite. Thermodynamic modelling suggests that garnet was stable at P–T conditions of ca. 680–720 °C and 8–10 kbars in the stability field of kyanite and the rocks underwent partial melting during exhumation following a clockwise P–T path. This episode is dated to 444 ± 12 Ma using chemical Th–U–total Pb dating of the Y-depleted monazite core. Second episode highlighted by growth of secondary white mica resulted from subsequent overprint in amphibolite and greenschist facies. Fluid assisted growth of the Y-enriched monazite rim at 419 ± 8 Ma marks the timing of the nappe emplacement. Age of migmatization and thrusting in the Kåfjord Nappe is similar to the Kalak Nappe Complex, and other units of the Middle Allochthon to the south. Nevertheless, the obtained results do not allow for unambiguous definition of the tectonostratigraphic position of the Skibotn Nappe Complex.

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Barnes, C. J., J. Majka, P. Jeanneret, G. Ziemniak, E. Kooijman, K. Kośmińska, M. Kielman-Schmitt, and D. A. Schneider. "Using Th-U-Pb geochronology to extract crystallization ages of Paleozoic metamorphic monazite contaminated by initial Pb." Chemical Geology 582 (November 2021): 120450. http://dx.doi.org/10.1016/j.chemgeo.2021.120450.

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20

Griffin, Brendan J., Duncan Forbes, and Neal J. McNaughton. "An Evaluation of Dating of Diagenetic Xenotime by Electron Microprobe." Microscopy and Microanalysis 6, S2 (August 2000): 408–9. http://dx.doi.org/10.1017/s143192760003453x.

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Xenotime is an igneous mineral commonly present in pegmatite and fractionated granite. Recent studies reveal that it also forms as a diagenetic mineral. Minute (0.1-5 μm) xenotime overgrowths typically crystallise on the surfaces of detrital zircon shortly after sedimentation, in a wide range of siliciclastic sedimentary units. For example, in backscattered electron (BSE) imaging using a scanning electron microscope (SEM), two minute, euhedral, pyramidal, xenotime overgrowths on an oscillatory-zoned detrital Ambergate zircon are evident (figure 1).Electron microprobe analysis (EMPA) geochronology is a chemical dating method that uses precisely measured concentrations of U, Th, and Pb, and the decay rates of U238, U235, and Th232, to calculate an age for a mineral. The EMPA dating method used in this study to date igneous xenotime and igneous-metamorphic monazite is the chemical isochron method (CHIME). EMPA geochronology is not a widely used technique because of the higher precision of isotopic geochronology.

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21

Carson, Chris J., Robert G. Berman, Richard A. Stern, Mary Sanborn-Barrie, Tom Skulski, and Hamish AI Sandeman. "Age constraints on the Paleoproterozoic tectonometamorphic history of the Committee Bay region, western Churchill Province, Canada: evidence from zircon and in situ monazite SHRIMP geochronology." Canadian Journal of Earth Sciences 41, no. 9 (August 18, 2004): 1049–76. http://dx.doi.org/10.1139/e04-054.

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In situ UPb sensitive high-resolution ion microprobe (SHRIMP) analyses of monazite from upper amphibolite-facies paragneiss of the Committee Bay supracrustal belt, central Rae domain, Canada, reveal three age populations: ca. 2350, 1850, and 1780 Ma. The ca. 1850 Ma age also corresponds to growth of low Th/U zircon as indicated by UPb SHRIMP analyses of zircon separates from melanosome and leucosome. The contextual advantage of the in situ monazite analysis allows evaluation of the geochronological data in terms of the regional structural and metamorphic evolution. The region is dominated by a northeast-striking S2 (±S1) fabric, axial planar to tight, northwest-vergent F2 folds. Early garnet is enveloped by this biotitesillimanite ± cordierite S2 fabric. GarnetI hosts ca. 1850 Ma monazite inclusions (with ca. 2350 Ma cores), placing a maximum age on garnetI growth and S2 development. D2 metamorphic conditions progressed through ~3.5 kbar (1 kbar = 100 MPa) and 600 °C to near-peak conditions of ~5 kbar and 675 °C. A minimum age for S2 is provided by unstrained ca. 1820 Ma monzogranite that locally, and regionally, truncates S2. Dominantly ca. 1780 Ma matrix monazite is interpreted to date post-S2 garnetII and cordierite, which record ~5 kbar and 675 °C. These data indicate that the Committee Bay region experienced penetrative D2 tectonometamorphism at ca. 18501820 Ma, with a subsequent static overprint. The absence of a ca. 1.85 Ga plutonic suite in the region suggests that low-pressure metamorphism was a response to thick-skinned crustal thickening initiated at ca. 1870 Ma. The new data highlight the importance of Paleoproterozoic reworking of the central Rae domain in the hinterland of the Trans-Hudson orogen.

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Skrzypek, Etienne, Shuhei Sakata, and Dominik Sorger. "Alteration of magmatic monazite in granitoids from the Ryoke belt (SW Japan): Processes and consequences." American Mineralogist 105, no. 4 (April 1, 2020): 538–54. http://dx.doi.org/10.2138/am-2020-7025.

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Abstract The alteration of magmatic monazite and its consequences for monazite geochronology are explored in granitoids from the western part of the Ryoke belt (Iwakuni-Yanai area, SW Japan). Biotite-granite samples were collected in two plutons emplaced slightly before the main tectono-metamorphic event: the first one, a massive granite (Shimokuhara) adjoins schistose rocks affected by greenschist facies metamorphism; and the second, a gneissose granite (Namera) adjoins migmatitic gneiss that experienced upper-amphibolite facies conditions. Despite contrasting textures, the granite samples have similar mineral modes and compositions. Monazite in the massive granite is dominated by primary domains with limited secondary recrystallization along cracks and veinlets. It is variably replaced by allanite+apatite±xenotime±Th-U-rich phases. The outermost rims of primary domains yield a weighted average 206Pb/238U date of 102 ± 2 Ma while the Th-U phases show Th-U-Pb dates of 58 ± 5 and 15 to 14 ± 2–3 Ma. Monazite in the gneissose granite preserves sector- or oscillatory-zoned primary domains cross-cut by secondary domains enriched in Ca, Y, U, P, and containing numerous inclusions. The secondary domains preserve concordant 206Pb/238U dates spreading from 102 ± 3 to 91 ± 2 Ma while primary domain analyses are commonly discordant and range from 116 to 101 Ma. Monazite alteration textures in the two granites chiefly reflect differences in their post-magmatic histories. In the massive granite, monazite replacement occurred via a nearly stoichiometrically balanced reaction reflecting interaction with an aqueous fluid enriched in Ca+Al+Si±F during hydrothermal alteration of the granitic assemblage, likely below 500 °C. In the gneissose granite, a small amount of anatectic melt, probably derived from the neighboring metasedimentary rocks, was responsible for pseudomorphic recrystallization of monazite by dissolution-reprecipitation above 600 °C. Regardless of whether monazite underwent replacement or recrystallization, primary monazite domains preserve the age of magmatic crystallization for both plutons (102 ± 2 and 106 ± 5 Ma). Conversely, the age of monazite alteration is not easily resolved. Monazite replacement in the massive granite might be constrained using the Th-U-rich alteration products; with due caution and despite probable radiogenic Pb loss, the oldest date of 58 ± 5 Ma could be ascribed to chloritization during final exhumation of the granite. The spread in apparently concordant 206Pb/238U dates for secondary domains in the gneissose granite is attributed to incomplete isotopic resetting during dissolution-reprecipitation, and the youngest date of 91 ± 2 Ma is considered as the age of monazite recrystallization during a suprasolidus metamorphic event. These results reveal a diachronous, ca. 10 Ma-long high-temperature (HT) history and an overall duration of about 15 Ma for the metamorphic evolution of the western part of the Ryoke belt.

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23

Denholm, J. L., A. S. Stepanov, S. Meffre, R. S. Bottrill, and J. M. Thompson. "The Geochronology of Tasmanian Tin Deposits Using LA-ICP-MS U-Pb Cassiterite Dating." Economic Geology 116, no. 6 (September 1, 2021): 1387–407. http://dx.doi.org/10.5382/econgeo.4837.

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Abstract The island state of Tasmania is the most important tin producer in Australia. The spatial and genetic relationship between Tasmanian tin deposits and Devonian-Carboniferous granites, which intruded throughout the Tabberabberan orogeny, has long been understood. However, little geochronological data is available to link mineralization to nearby intrusions. In this study, we investigate the connection between 19 Tasmanian tin deposits and their potential source granites, using U-Pb cassiterite dating by laser ablation-inductively coupled plasma-mass spectrometry. Archean pegmatitic cassiterite was also characterized and used for the calibration of U-Pb ratios. Tin mineralization in Tasmania occurred between 391 ± 6.3 and 359 ± 7.8 Ma, which is coincident with most postorogenic granites of the Tabberabberan orogeny. In conjunction with the granite ages, cassiterite ages become younger from the east of the state to the west, and tin mineralization occurred over a protracted period spanning 32 m.y. Dating of several placer cassiterite samples produced unexpected results, such as the occurrence of 374 ± 4.7 Ma cassiterite on eastern King Island, an area known only to contain the 350 Ma Grassy granite, suggesting a distant provenance. Tasmanian cassiterite rarely shows evidence of Pb loss; however, some analyses are characterized by elevated Th and U, likely caused by microinclusions such as monazite, which may have a detrimental effect on cassiterite U-Pb dating. This study demonstrates the utility of cassiterite dating for understanding the origin of tin deposits in complex terrains with protracted periods of tin mineralization.

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24

Scott, David J. "Geology, U – Pb, and Pb – Pb geochronology of the Lake Harbour area, southern Baffin Island: implications for the Paleoproterozoic tectonic evolution of northeastern Laurentia." Canadian Journal of Earth Sciences 34, no. 2 (February 1, 1997): 140–55. http://dx.doi.org/10.1139/e17-012.

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Geological and geochronological results of an investigation of the Paleoproterozoic siliciclastic and carbonate supracrustal rocks of the Lake Harbour Group (LHG) and surrounding tonalitic gneisses on southern Baffin Island are presented. Conventional U – Pb geochronology of monazite from rocks of the LHG suggest that penetrative deformation of these rocks occurred prior to, or during, peak metamorphic conditions at ca. 1845 –1840 Ma. Conventional U – Pb zircon results indicate that much of the tonalitic gneiss ranges in age from [Formula: see text] to 1827[Formula: see text]. The tonalitic gneisses and Lake Harbour Group units were tectonically imbricated by ca. 1805 Ma, and are part of a southwest-verging thrust belt interpreted from regional considerations to represent the northern continuation of the Ungava Orogen. The present results indicate that current tectonic models for the evolution of northeastern Laurentia that involve a dominantly Archean southeastern Rae province require revision. It is proposed that much of the metaigneous material that lies between the Archean Superior and Nain cratons represents a composite subduction-related domain.

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25

Scott, D. J., N. Machado, S. Hanmer, and C. Gariépy. "Dating ductile deformation using U–Pb geochronology: examples from the Gilbert River Belt, Grenville Province, Labrador, Canada." Canadian Journal of Earth Sciences 30, no. 7 (July 1, 1993): 1458–69. http://dx.doi.org/10.1139/e93-126.

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The Gilbert River Belt, in the Grenville Province in southeastern Labrador, is a distinctive, west–northwest-trending zone of locally intense deformation and voluminous granitoid plutonism, up to 30 km in width. In an attempt to directly quantify the timing of deformation in ductile shear zones within the belt, rocks interpreted as having been intruded synchronously with ongoing deformation were sampled for U–Pb isotopic analysis. Three of these samples are <2 m wide granitic veins that have sharp intrusive contacts that truncate ductile deformation fabrics, but are themselves deformed at metamorphic conditions similar to their host rocks and are therefore interpreted as having intruded after the initiation of deformation and fabric development, but prior to cessation of this deformation. The first vein is syntectonic with respect to amphibolite-facies deformation and yielded a zircon age of [Formula: see text]. The second vein intruded synchronously with the development of a zone of amphibolite-facies straight gneisses, which defines the southern limit of the Gilbert River belt at [Formula: see text]. The third vein is syntectonic with respect to greenschist-facies deformation and yielded a zircon age of [Formula: see text] and a monazite age of 1078 ± 2 Ma. A sample of the K-feldspar megacrystic granite that underlies much of the belt and is interpreted as having intruded during ongoing amphibolite-facies deformation yielded a zircon age of [Formula: see text]; a mildly deformed granitic vein that crosscuts the megacrystic granite at the same location contained zircon that indicate a [Formula: see text] crystallization age. Monazite from a granodioritic gneiss yielded a concordant age of 1077 ± 3 Ma, interpreted as the time of final cooling during gneiss formation. These results indicate that much of the amphibolite-facies deformation (1664 – 1644 Ma) in the Gilbert River Belt is correlative with the regionally extensive Labradorian orogenic event, whereas greenschist-facies deformation (1113 – 1062 Ma) and monazite growth (1078 Ma) are the result of renewed tectonomagmatic activity during Grenvillian orogenesis.

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26

Bersch, Michael G. "Electron Microprobe Dating of Uraninite from the Mcallister Pegmatite, Alabama." Microscopy and Microanalysis 5, S2 (August 1999): 538–39. http://dx.doi.org/10.1017/s1431927600016019.

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In the early days of geochronology, attempts were made to date U-Th bearing rocks and minerals using the Pb-U-Th chemical method, but fundamental assumptions that all the lead was of radiogenic origin, and the system was closed, often were invalid. With the advent of the U-Th-Pb isotopic and common-lead methods of dating rocks and minerals, the chemical method was deemed clinically dead. However, several workers, for example, Montel et al., Suzuki and Adachi, have recently demonstrated new life for the chemical method. Using, the same theoretical basis as the chemical method, geologically reasonable dates often can be obtained by electron microprobe analysis of U-Th rich monazite (Ca-REE-U-Th phosphate). Other U- or Thrich minerals sometimes can be used to obtain microprobe U-Th-Pb dates, e.g., zircon, xenotime, uraninite.Microprobe U-Th-Pb dates of uraninites from the McAllister Ta-Sn pegmatite, Coosa County, Alabama, are reported here. The McAllister pegmatite is a NW-SE dike-like body in the western part of the Rockford granite pluton. Polished grain mounts were made from screened table runs of heavy mineral separates. Wodginite (Mn, Sn, Nb, Ta-oxide), tantalite-columbite, zircon, cassiterite comprise most of the grains in the samples. Uraninite occurs as inclusions, generally <0.01 mm, in these grains (Figure 1).U, Th, Pb concentrations were measured using a JEOL 8600 Superprobe. Operating conditions were 100 nA, 20 kV, and count times up to 200 seconds for peak plus background. The U Mβ, Th Mα, and Pb Mα peaks were measured. Standards were UO2, ThO2, and PbS.

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27

Digel, Scott G., Edward D. Ghent, Sharon D. Carr, and Philip S. Simony. "Early Cretaceous kyanite-sillimanite metamorphism and Paleocene sillimanite overprint near Mount Cheadle, southeastern British Columbia: geometry, geochronology, and metamorphic implications." Canadian Journal of Earth Sciences 35, no. 9 (September 1, 1998): 1070–87. http://dx.doi.org/10.1139/e98-052.

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Mapping of isograds related to regional amphibolite-facies metamorphism constrains a three-dimensional model of isogradic surfaces near Mount Cheadle in the northern Shuswap metamorphic complex (lat. 52°20'N, long. 119°05'W). Kyanite and sillimanite coexist in a lens-shaped zone, bounded by the kyanite-out and sillimanite-in isogradic surfaces, that is 50 km long, up to 10 km thick, and up to 20 km wide. Textural equilibrium, simple regular geometry of isogradic surfaces, and simple mineral assemblages suggest that metamorphism occurred at P-T conditions near those of the kyanite-sillimanite equilibrium curve. Reconstruction of isotherms in the kyanite + sillimanite zone suggests that the metamorphic field gradient was about 14°C·km-1. A 5 km thick, staurolite-free kyanite zone adjacent to the sillimanite-in isograd suggests a pressure range of about 1.5 kbar (1 kbar = 100 MPa) for Bathozone 5 of D.M. Carmichael. Regional metamorphism was Early Cretaceous (monazite U-Pb geochronology) with quenching in the Late Cretaceous, possibly caused by motion on the basal thrust beneath the Malton complex. A younger generation of sillimanite grew in discrete outcrop-scale ductile shear zones, veins, and pods in a north-south-oriented belt (50 km by 20 km). U-Pb dates on zircon, monazite, and titanite indicate an age of the sillimanite overprint of 65-59 Ma. It may have resulted from the influx of hot fluids associated with widespread Late Cretaceous and Paleocene leucogranite emplacement concomitant with extensional faulting.

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Payne, J. L., B. P. Wade, M. Hand, K. Barovich, and C. Clark. "Optimising the spatial resolution, fractionation and temporal precision of monazite U–Pb LA-ICP-MS geochronology." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A476. http://dx.doi.org/10.1016/j.gca.2006.06.1414.

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29

Sepahi, Ali A., Hamed Vahidpour, David R. Lentz, Chris RM McFarlane, Mohammad Maanijou, Sedigheh Salami, Mirmohammad Miri, Mehrak Mansouri, and Razieh Mohammadi. "Rare sapphire-bearing syenitoid pegmatites and associated granitoids of the Hamedan region, Sanandaj–Sirjan zone, Iran: analysis of petrology, lithogeochemistry and zircon geochronology / trace element geochemistry." Geological Magazine 157, no. 9 (February 24, 2020): 1499–525. http://dx.doi.org/10.1017/s0016756820000023.

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AbstractPegmatites and associated granitoids are integral parts of the Alvand plutonic complex in the Sanandaj–Sirjan zone, Iran. Whole rock major- and trace-element lithogeochemistry together with zircon U–Pb geochronology and zircon geochemistry are examined to evaluate the petrogenesis of sapphire-bearing pegmatites and other peraluminous pegmatites in the region. Pegmatites vary in their chemical compositions from mostly peraluminous, high-K calc-alkaline to shoshonitic signatures. A rare variety of extremely peraluminous sapphire-bearing syenitoid pegmatite (Al2O3 > 30 wt %; A/CNK > 2) exists. This silica-undersaturated pegmatite and its sapphire crystals have a primary igneous origin. U–Pb zircon geochronology of three separate samples from this pegmatite indicates the following ages: 168 ± 1 Ma, 166 ± 1 Ma and 164 ± 1 Ma. The zircon grains have notable amounts of Hf (up to 17 200 ppm), U (up to 13 580 ppm), Th (up to 5148 ppm), Y (up to 4764 ppm) and ∑REE (up to 2534 ppm). There is a positive correlation between Hf and Th, Nb and Ta, U and Th, and Y and HREE and a negative correlation between Hf and Y values in the zircons. These zircons exhibit pronounced positive Ce anomalies (Ce/Ce* = 1.15–68.06) and negative Eu anomalies (Eu/Eu* = 0.001–0.56), indicative of the relatively oxidized conditions of the parent magma. Ti-in-zircon thermometry reveals temperatures from as low as ~683 °C up to ~828 °C (average = 755° ± 73 °C). Zircon and monazite saturation equilibria are also consistent with these temperatures. Zircon grains are magmatic (average La < 1.5, (Sm/La)N > 100 and Th/U > 0.7), with chemical characteristics similar to zircons from continental crust.

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30

BINGEN, BERNARD, FERNANDO CORFU, HOLLY J. STEIN, and MARTIN J. WHITEHOUSE. "U–Pb geochronology of the syn-orogenic Knaben molybdenum deposits, Sveconorwegian Orogen, Norway." Geological Magazine 152, no. 3 (November 11, 2014): 537–56. http://dx.doi.org/10.1017/s001675681400048x.

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AbstractPaired isotope dilution – thermal ionization mass spectrometry (ID-TIMS) and secondary ion mass spectrometry (SIMS) zircon U–Pb data elucidate geochronological relations in the historically important Knaben molybdenum mining district, Sveconorwegian Orogen, south Norway. This polyphase district providedc. 8.5 Mt of ore with a grade of 0.2%. It consists of mineralized quartz veins, silica-rich gneiss, pegmatites and aplites associated with a heterogeneous, locally sulphide-bearing, amphibolites facies gneiss called Knaben Gneiss, and hosted in a regional-scale monotonous, commonly weakly foliated, granitic gneiss. An augen gneiss at the Knaben I deposit yields a 1257±6 Ma magmatic zircon age, dating the pre-Sveconorwegian protolith of the Knaben Gneiss. Mineralized and non-mineralized granitic gneiss samples at the Knaben II and Kvina deposits contain some 1488–1164 Ma inherited zircon and yield consistent intrusion ages of 1032±4, 1034±6 and 1036±6 Ma. This age links magmatism in the district to the regional 1050–1020 Ma Sirdal I-type granite suite, corresponding to voluminous crustal melting during the Sveconorwegian orogeny. A high-U, low-Th/U zircon rim is present in all samples. It defines several age clusters between 1039±6 and 1009±7 Ma, peaking atc. 1016 Ma and overlapping with a monazite age of 1013±5 Ma. The rim records protracted hydrothermal activity, which started during the main magmatic event and outlasted it. This process was coeval with regional high-grade Sveconorwegian metamorphism. Molybdenum deposition probably started during this event when silica-rich mineralizing fluids or hydrous magmas were released from granite magma batches. An analogy between the Knaben district and shallow, short-lived porphyry Mo deposits is inappropriate.

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31

Hartmann, Léo A., João O. S. Santos, Jayme A. D. Leite, Carla C. Porcher, and Neal J. Mcnaughton. "Metamorphic evolution and U-Pb zircon SHRIMP geochronology of the Belizário ultramafic amphibolite, Encantadas Complex, southernmost Brazil." Anais da Academia Brasileira de Ciências 75, no. 3 (September 2003): 393–403. http://dx.doi.org/10.1590/s0001-37652003000300010.

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The integrated investigation of metamorphism and zircon U-Pb SHRIMP geochronology of the Belizário ultramafic amphibolite from southernmost Brazil leads to a better understanding of the processes involved in the generation of the Encantadas Complex. Magmatic evidence of the magnesian basalt or pyroxenite protolith is only preserved in cores of zircon crystals, which are dated at 2257 ± 12 Ma. Amphibolite facies metamorphism M1 formed voluminous hornblende in the investigated rock possibly at 1989 ± 21 Ma. This ultramafic rock was re-metamorphosed at 702±21 Ma during a greenschist facies eventM2; the assemblage actinolite + oligoclase + microcline + epidote + titanite + monazite formed by alteration of hornblende. The metamorphic events are probably related to the Encantadas Orogeny (2257±12 Ma) and Camboriú Orogeny (~ 1989 Ma) of the Trans-Amazonian Cycle, followed by an orogenic event (702±21 Ma) of the Brasiliano Cycle. The intervening cratonic period (2000-700 Ma) corresponds to the existence of the Supercontinent Atlantica, known regionally as the Rio de la Plata Craton.

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32

Mohammadi, Nadia, Christopher R. M. McFarlane, and David R. Lentz. "U–Pb Geochronology of Hydrothermal Monazite from Uraniferous Greisen Veins Associated with the High Heat Production Mount Douglas Granite, New Brunswick, Canada." Geosciences 9, no. 5 (May 15, 2019): 224. http://dx.doi.org/10.3390/geosciences9050224.

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A combination of in situ laser ablation inductively coupled plasma–mass spectrometry (LA ICP–MS) analyses guided by Scanning Electron Microscope–Back-Scattered Electron imaging (SEM–BSE) was applied to hydrothermal monazite from greisen veins of the Late Devonian, highly evolved, uraniferous Mount Douglas Granite, New Brunswick, Canada. Understanding the uraniferous nature of the suite and characterizing the hydrothermal system that produced the associated mineralized greisen veins were the main goals of this study. The uraniferous nature of the Mount Douglas Granite is evident from previous airborne radiometric surveys, whole-rock geochemical data indicating high U and Th (2–22 ppm U; 19–71 ppm Th), the presence of monazite, zircon, xenotime, thorite, bastnaesite, and uraninite within the pluton and the associated hydrothermal greisen veins, as well as anomalous levels of U and Th in wolframite, hematite, and martite within greisen veins. New U–Pb geochronology of hydrothermal monazite coexisting with sulfide and oxide minerals yielded mineralization ages ranging from 344 to 368 Ma, with most of them (90%) younger than the crystallization age of the pluton (368 ± 3 Ma). The younger mineralization age indicates post-magmatic hydrothermal activities within the Mount Douglas system that was responsible for the mineralization. The production of uraniferous greisen veins by this process is probably associated with the High Heat Production (HHP) nature of this pluton, resulting from the radioactive decay of U, Th, and K. This heat prolongs post-crystallization hydrothermal fluid circulation and promotes the generation of hydrothermal ore deposits that are younger than the pluton. Assuming a density of 2.61 g/cm3, the average weighted mean radiogenic heat production of the Mount Douglas granites is 5.9 µW/m3 (14.1 HGU; Heat Generation Unit), in which it ranges from 2.2 µW/m3 in the least evolved unit, Dmd1, up to 10.1 µW/m3 in the most fractionated unit, Dmd3. They are all significantly higher than the average upper continental crust (1.65 µW/m3). The high radiogenic heat production of the Mount Douglas Granite, accompanied by a high estimated heat flow of 70 mW/m2, supports the assignment of the granite to a ‘hot crust’ (>7 HGU) HHP granite and highlights its potential for geothermal energy exploration.

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Simonetti, Antonio, and Ronald Doig. "U–Pb and Rb–Sr geochronology of Acadian plutonism in the Dunnage zone of the southeastern Quebec Appalachians." Canadian Journal of Earth Sciences 27, no. 7 (July 1, 1990): 881–92. http://dx.doi.org/10.1139/e90-091.

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U–Pb zircon and (or) titanite or monazite ages have been obtained for five major, undeformed, calc-alkaline plutons of the Appalachians of southeastern Quebec. These are interpreted as ages of crystallization for the Scotstown (384 ± 2 Ma), Lac aux Araignées (383 ± 3 Ma), Winslow (377 ± 7 Ma), Aylmer (375 ± 3 Ma), and Ste-Cécile (374 ± 2 Ma) plutons. Many other titanite samples gave 206Pb/238U dates that are 2–16 Ma younger than the concordant zircon dates from the same samples, and this is probably the result of Pb loss. Variation in 207Pb/206Pb ages of titanite from some samples is attributed to incorrect common Pb correction.Rb–Sr data for the same plutons show considerable isotopic heterogeneity and correspondingly high errors in ages. The isotopic heterogeneity is likely caused by postsolidification metasomatic alteration by host rock fluids. Where the scatter is least (Ste-Cécile), the Rb–Sr age (364 ± 14 Ma) is similar to the U–Pb mineral age (374 ± 2 Ma). The 87Sr/86Sr initial ratios range from 0.7065 to 0.710 and are probably related to the source of the magmas. The relatively high initial ratios and the peraluminous nature of the plutons preclude a significant mantle contribution to the magmas. These undeformed plutons are probably the result of melting of the lower continental crust near the end of crustal thickening caused by compression during the Acadian Orogeny.

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Guimarães, Frederico Sousa, Rongqing Zhang, Bernd Lehmann, Alexandre Raphael Cabral, and Francisco Javier Rios. "CASSITERITE U-Pb GEOCHRONOLOGY OF THE SANTA BÁRBARA TIN DISTRICT, RONDÔNIA TIN PROVINCE, BRAZIL." Economic Geology 117, no. 3 (May 1, 2022): 719–29. http://dx.doi.org/10.5382/econgeo.4876.

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Abstract The Mesoproterozoic Rondônia Tin Province of the Amazonian craton records a protracted history of about 600 m.y. of successive rare-metal granite intrusions and hosts the youngest known event of tin-granite emplacement of the craton—a rare-metal granite suite known as the Younger Granites of Rondônia intrusive suite. The ~1 Ga suite is currently interpreted as intracratonic magmatism resulting from a Grenvillian-age orogeny during the assembly of Rodinia. The Santa Bárbara massif is a tin-granite system of the Younger Granites of Rondônia intrusive suite that hosts Sn-Nb-Ta-W–bearing endogreisen and stockwork, as well as important placer deposits. The Santa Bárbara mine produces about 800 to 1,000 t Sn/year from placers and weathered greisen and represents about 20% of the tin mine output of the Rondônia Tin Province. Here, we report laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) cassiterite U-Pb ages of 989 ± 3 and 987 ± 6 Ma for the Santa Bárbara greisen and the cassiterite-quartz vein system, respectively. Alluvial cassiterite from placer mining has a U-Pb age of 995 ± 4 Ma, which is, within uncertainty, indistinguishable from those of primary cassiterite. These ages agree well with the previously published zircon and monazite U-Pb ages for the Santa Bárbara granite (978 ± 13 and 989 ± 13 Ma), which indicate a coeval relationship between hydrothermal tin mineralization and granite magmatism. The previously suggested 20- to 30-m.y. time span between granite magmatism and hydrothermal tin mineralization, which was based on mica K-Ar and Ar-Ar age data, is likely due to younger thermal disturbance of the isotopic systems.

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Bertrand, Jean-Michel, J. Christopher Roddick, Martin J. van Kranendonk, and Ingo Ermanovics. "U–Pb geochronology of deformation and metamorphism across a central transect of the Early Proterozoic Torngat Orogen, North River map area, Labrador." Canadian Journal of Earth Sciences 30, no. 7 (July 1, 1993): 1470–89. http://dx.doi.org/10.1139/e93-127.

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The Early Proterozoic Torngat Orogen resulted from the oblique collision of the Archean Nain and southeastern Rae provinces and evolved in four stages: (0) deposition of platformal supracrustal assemblages followed by subduction-related arc magmatism in the margin of the Rae Province; (I) crustal thickening and nappe tectonics; (II) sinistral transpression and formation of the Abloviak shear zone; (III) uplift on steeply dipping, east-verging mylonites along the eastern orogenic front.U–Pb geochronology on zircon and monazite from major rock units and syntectonic intrusions indicates that arc magmatism at ca. 1880 Ma was followed by 40 Ma. of deformation and high-grade metamorphism from ca. 1860 to 1820. Subsequent uplift and final cooling occurred ca. 1795 – 1770 Ma. Several ages of mineral growth that correspond to distinct structural and metamorphic events have been recognized: (1) 1858 – 1853 Ma zircon and monazite dates are interpreted as the minimum age of stage I and peak metamorphic conditions; (2) 1844 Ma zircons from anatectic granitoids in the Tasiuyak gneiss complex (TGC), syntectonic with stage II deformation, are interpreted to date the formation of the Abloviak shear zone; (3) 1837 Ma magmatic zircons from an intrusive granite vein deformed along the western contact of the TGC represent a discrete intrusive event; (4) 1825 – 1822 Ma metamorphic overgrowths and newly grown zircons in granitic veins from the western portion of the orogen (Lac Lomier complex) represent a period of renewed transpressional deformation; (5) 1806 Ma magmatic zircons from a post-stage II granite emplaced along the eastern edge of the Abloviak shear zone defines the transition between stage II and stage III events; (6) 1794 – 1773 Ma zircons from leucogranites and pegmatites that are associated with uplift of the orogen (stage III). 1780 – 1740 Ma dates for monazite and a 40Ar/39Ar hornblende age correspond to the latest stages of uplift and cooling of the orogen.

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Parent, Martin, Nuno Machado, and Herman Zwanzig. "Comportement du système U-Pb dans la monazite et chronologie de la déformation et du métamorphisme des metasédiments du domaine de Kisseynew, orogène trans-hudsonien (Manitoba, Canada)." Canadian Journal of Earth Sciences 36, no. 11 (November 10, 1999): 1843–57. http://dx.doi.org/10.1139/e99-051.

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The Kisseynew domain is the central unit of the Reindeer Zone of the Paleoproterozoic Trans-Hudson Orogen, in Manitoba and Saskatchewan. The southern flank of the domain is a transition zone between the greenschist facies of the volcano-plutonic assemblage of the Flin Flon - Snow Lake belt and the upper amphibolite facies of Kisseynew paragneisses. The Jungle Lake area, in the southern flank of the Kisseynew Domain, comprises mainly quartzofeldspathic gneisses representing continental clastic units of the Missi suite and migmatitic metagraywackes of the Burntwood suite. The area was affected by several phases of deformation, metamorphism, and migmatisation. Detailed mapping and U-Pb geochronology were carried out in order to establish the timing of the deformational and metamorphic phases. The oldest leucosome contains sillimanite formed during peak metamorphism and is associated with F2 folding and S2 fabric. Five single monazites from this leucosome yield ages between 1809 and 1803 Ma taken as the best estimate for the duration of peak metamorphism. Biotite schlieren in diatexites in the Burntwood suite show a S2 fabric folded by F3. Zircon from one of these diatexites yield a crystallization age of 1798+3-2 Ma, considered as the lower limit for the F2 event. Single monazites from the same rock yield ages between 1812 and 1789 Ma, the oldest of which are considered to be inherited. The youngest mobilisate is a pegmatite crosscutting F2 and F3 fabrics and yielded single monazite ages between 1875 and 1788 Ma. The youngest age is taken as the age of the pegmatite and is a minimum age for F3 fabrics. These results, together with those from other areas of the southern Kisseynew Domain, indicate a ca. 30 million year period (1818 and 1785 Ma) of continuous deformation and metamorphism. The data also show the presence of monazite crystals of different ages in the same rock illustrating the need to analyse single grains to obtain geologically meaningful ages.

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Hiess, J., T. Ireland, and M. Rattenbury. "U-Th-Pb zircon and monazite geochronology of Western Province gneissic rocks, central-south Westland, New Zealand." New Zealand Journal of Geology and Geophysics 53, no. 4 (December 2010): 241–69. http://dx.doi.org/10.1080/00288306.2010.495450.

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Savko, K. A., A. B. Kotov, E. B. Sal’nikova, E. Kh Korish, S. M. Pilyugin, G. V. Artemenko, and S. P. Korikovskii. "The age of metamorphism of granulite complexes of the Voronezh crystalline massif: The monazite U-Pb geochronology." Doklady Earth Sciences 435, no. 2 (December 2010): 1575–80. http://dx.doi.org/10.1134/s1028334x10120056.

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39

Corfu, Fernando, and R. Michael Easton. "Sharbot Lake terrane and its relationships to Frontenac terrane, Central Metasedimentary Belt, Grenville Province: new insights from U–Pb geochronology." Canadian Journal of Earth Sciences 34, no. 9 (September 1, 1997): 1239–57. http://dx.doi.org/10.1139/e17-099.

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The Sharbot Lake terrane of the Central Metasedimentary Belt in Ontario comprises marbles, minor tholeiitic basalts and siliciclastic rocks, metamorphosed at low to moderate degrees, and is intruded by several suites of mafic to felsic plutons. Gabbroic and associated monzogranitic phases of the Lavant complex in northwestern parts of the terrane yield ages of 1224 ± 2 Ma for zircon and monazite, and 1221–1211 Ma for titanite. The Wolf Grove structure, a gneissic domain in the northeastern part of the area, was migmatized and intruded by granites at 1168 Ma prior to its tectonic juxtaposition on amphibolites and marbles of the Sharbot Lake terrane. Correlative events recorded by gneiss, quartzite, and marble from Carleton Place farther east stress the strong affinity of the Wolf Grove structure with rocks of the Frontenac terrane. The 1156 ± 2 Ma posttectonic Maberly stock intrudes rocks near the boundary zone between the Frontenac and Sharbot Lake terranes, suggesting that the two terranes were linked by 1156 Ma. The distribution of U–Pb ages for titanite, monazite, and rutile throughout the area emphasizes the distinctive metamorphic evolution characterizing different domains of the region, documents the lack of 1168 Ma metamorphic overprint in western domains, records the main 1168 Ma high-grade event and slightly younger subsidiary events in eastern domains, and indicates local resetting events. The combined data underline the geological complexity of the eastern Central Metasedimentary Belt, confirming the existence of significant compressional and metamorphic events in the period 1170–1160 Ma.

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Milenkov, Georgi, Rossitsa Vassileva, Sylvina Georgieva, Valentin Grozdev, and Irena Peytcheva. "Trace-element signatures and U-Pb geochronology of magmatic and hydrothermal titanites from the Petrovitsa Pb-Zn deposit, Madan region, Central Rhodopes (Bulgaria)." Geologica Balcanica 51, no. 2 (August 30, 2022): 79–91. http://dx.doi.org/10.52321/geolbalc.51.2.79.

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The current study presents new geochronological and geochemical data for the Petrovitsa Pb-Zn deposit, Central Rhodopes, South Bulgaria. Based on in-situ U-Pb dating of titanites from pegmatites and skarnified mineralized marbles, it aims to provide new insights into the pegmatite formation and their relation to the hydrothermal system in the region. Titanite is an abundant accessory mineral in pegmatites and skarns within the Madan ore district. Commonly, it associates with feldspars, epidote, clinopyroxene, chlorite, hematite, zircon, apatite, allanite and monazite in both lithologies. Crystal size varies from 5 μm to 600 μm. The combined analytical approach revealed compositional and age variations of the studied titanites divided into: (i) early formed magmatic; and (ii) later hydrothermal. The magmatic crystals are characterized by mean Th/U of 1.91, Lu/Hf averaging at 0.59, and Dy/Yb of 2.03. The chondrite-normalized REE patterns show LREE dominance over HREE. The average ƩREE is 6548 ppm. The hydrothermal titanites have a mean Th/U of 0.22, Lu/Hf of 1.20, and average Dy/Yb of 1.50. HREE content slightly prevails over LREE. ƩREE is two times lower compared to magmatic titanites – 3388 ppm. Negative Eu-anomaly is common for both types. The LA-ICP-MS U-Pb geochronology shows a well-defined age distinction of magmatic and hydrothermal titanites. The calculated U-Pb weighted average age for the magmatic titanites is 48.9±2.3 Ма, while the pegmatite-hosted hydrothermal titanites are dated at 39.2±1.5 Ma. The hydrothermal titanites from skarns yield a weighted average age of 37.7±1.3 Ma. Data suggest pegmatite emplacement in the Rhodope metamorphic complex during the late Ypresian. Later hydrothermal fluids precipitated younger titanites with different signature.

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Isachsen, C. E., and S. A. Bowring. "The Bell Lake group and Anton Complex: a basement – cover sequence beneath the Archean Yellowknife greenstone belt revealed and implicated in greenstone belt formation." Canadian Journal of Earth Sciences 34, no. 2 (February 1, 1997): 169–89. http://dx.doi.org/10.1139/e17-014.

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U–Pb zircon and monazite geochronology indicates the presence of a >2.93 Ga basement (Anton Complex) and >2.8 Ga cover sequence (Bell Lake group) beneath the 2.70 to >2.72 Ga Kam Group of the Yellowknife greenstone belt in the southern Slave Province. The Bell Lake group comprises remnants of a quartzite – rhyolite – banded iron formation succession. The ages of detrital zircons from the quartzite unit constrain its deposition to be younger than 2.92 and range up to 3.7 Ga. U–Pb ages for gneisses beneath the Bell Lake group are in excess of 2.93 Ga and they are locally overlain by the quartzite. The contact between the tholeiitic to calc-alkaline Kam Group and the Bell Lake group is poorly exposed and equivocal. Approximately 6 km higher in the section, the Ranney chert, a felsic volcaniclastic layer, separates 2.70 – 2.72 Ga tholeiitic to calc-alkaline upper Kam Group rocks from a lower tholeiitic section containing sheeted-dike complexes. Zircons from the Ranney chert yield Pb –Pb ages ranging from 2.72 to >2.8 Ga. The older ages suggest proximity of older basement during deposition of mostly tholeiitic lower Kam Group volcanic rocks in an extensional setting, followed by deposition of the upper Kam Group, which is more arc-like in character, on this earlier-formed tholeiitic crust beginning at 2.72 Ga.

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Mortensen, J. K. "Geology and U–Pb geochronology of the Klondike District, west-central Yukon Territory." Canadian Journal of Earth Sciences 27, no. 7 (July 1, 1990): 903–14. http://dx.doi.org/10.1139/e90-093.

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Geological mapping and U–Pb geochronology of the Klondike District provide new information on the nature and evolution of the Yukon–Tanana terrane (YTT) in western Yukon. The area is underlain by a sequence of thrust panels of regional extent. A continuously mappable sequence of interlayered metasedimentary and metavolcanic rocks is intruded by a variety of deformed metaplutonic rocks within two of these thrust sheets. Layering in the metasediments and metavolcanics is considered to be at least in part transposed stratigraphy. Small bodies of greenstone and altered ultramafic rocks thought to be part of the Slide Mountain terrane occur discontinuously along the thrust faults.U–Pb age determinations indicate that the uppermost thrust panel (assemblage I), which underlies much of the Klondike District, consists largely of metamorphosed, mid-Permian felsic plutonic, subvolcanic, and tuffaceous rocks. Beneath assemblage I is a second thrust panel (assemblage II), also of large areal extent, of mid-Paleozoic or older metasedimentary and mafic and felsic metavolcanic rocks, intruded by a large body of latest Devonian – Early Mississippian granitic augen orthogneiss. U–Pb analyses of zircon from the orthogneiss reflect both lead loss and a significant inherited zircon component. A third structural unit (assemblage III), which consists mainly of carbonaceous schist and phyllite, crops out in the northern part and along the southwestern edge of the study area, where it underlies both assemblages I and II.The earliest stage of deformation and metamorphism that affected the area (F1) produced the pervasive recrystallization fabric characteristic of all of the metamorphic rocks in assemblages I, II, and III, and occurred between mid-Permian and Late Triassic time. Thrust faulting, presumed to be northerly or northeasterly directed, postdates Late Triassic but predates mid-Cretaceous. The second phase of deformation (F2) was either synchronous with or later than thrust faulting. Monazite ages for the augen orthogneiss indicate that at least local metamorphism and (or) deformation lasted until Early Cretaceous time.Close similarities between composition, U–Pb ages, as well as timing and style of deformation, documented in the Klondike District and observed elsewhere in the YTT in southeastern Yukon and east-central Alaska suggest that much of the YTT either evolved as a single entity or else shared a very similar history.

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Melleton, Jérémie, Michel Faure, and Alain Cocherie. "Monazite U-Th/Pb chemical dating of the Early Carboniferous syn-kinematic MP/MT metamorphism in the Variscan French Massif Central." Bulletin de la Société Géologique de France 180, no. 3 (May 1, 2009): 283–92. http://dx.doi.org/10.2113/gssgfbull.180.3.283.

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AbstractIn situ U-Th-Pb geochronology on monazite using Electron Probe Micro Analyser, constrained by structural and textural observations, has been performed on four samples from the Limousin area (northwest part of the French Massif Central) in order to date the syn-kinematic MP/MT metamorphism related to the top-to-the-NW shearing that deformed the stack of nappes in this zone of the Variscan belt. All the analyzed samples lead to a mean age at 360 ± 4 Ma. The close range of ages obtained during this study (360 Ma) and with the previous 40Ar-39Ar ones (360–350 Ma) suggests fast processes of cooling and exhumation during the Early Carboniferous in internal zones of the Variscan belt. The geodynamic significance of this Early Carboniferous event is discussed at the scale of the Ibero-Armorican orocline.

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Scott, David J. "U–Pb geochronology of the Nain craton on the eastern margin of the Torngat Orogen, Labrador." Canadian Journal of Earth Sciences 32, no. 11 (November 1, 1995): 1859–69. http://dx.doi.org/10.1139/e95-143.

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New U–Pb geochronological results provide insight into the geological evolution of the northernmost Nain craton. A tonalitic orthogneiss, retrogressed from granulite to amphibolite facies, is interpreted to have crystallized at 2832 ± 3 Ma; zircon overgrowths, dated at 2769 ± 5 Ma, are interpreted as metamorphic in origin, whereas metamorphic monazite crystallized at 2692 ± 2 Ma. The crystallization age of this sample suggests it may be correlative with similar rocks of the Kanairiktok Plutonic Suite of the Hopedale block, whereas the age of the zircon overgrowths is synchronous with metamorphism in the Saglek block and may indicate a link at this time. A foliated tonalité crystallized at 2802 ± 2 Ma; titanite in this sample records deformation at 1745 ± 4 Ma; the emplacement age suggests a link with Hopedale block, whereas the titanite growth is clearly related to Torngat orogeny. Two foliated granites crystallized at 2587 ± 3 and 2564 ± 2 Ma, respectively, synchronous with late magmatic events recognized in the southern Nain craton. An Avayalik mafic dyke was emplaced at [Formula: see text] Ma, and subsequently metamorphosed at [Formula: see text] Ma. An intraboudin granitic pegmatite crystallized at 1780 ± 2 Ma, and titanite in a diorite formed at 1735 ± 3 Ma, recording the effects of deformation in the Komaktorvik shear zone during Torngat orogeny.

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Zhou, X., G. Zhao, C. Wei, Y. Geng, and M. Sun. "EPMA U-Th-Pb monazite and SHRIMP U-Pb zircon geochronology of high-pressure pelitic granulites in the Jiaobei massif of the North China Craton." American Journal of Science 308, no. 3 (March 1, 2008): 328–50. http://dx.doi.org/10.2475/03.2008.06.

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Ducharme, Yan, Ross K. Stevenson, and Nuno Machado. "Sm–Nd geochemistry and U–Pb geochronology of the Preissac and Lamotte leucogranites, Abitibi Subprovince." Canadian Journal of Earth Sciences 34, no. 8 (August 1, 1997): 1059–71. http://dx.doi.org/10.1139/e17-086.

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The Lacorne Block in the Southern Volcanic Zone of the Abitibi Subprovince is composed of interleaved metavolcanic and metasedimentary rocks that are intruded by syn- to posttectonic diorites, granodiorites, and granites. These rocks form the Lacorne, Lamotte, and Preissac plutons, which can be divided into an early suite of dioritic–granodioritic rocks and a later suite of S-type, leucocratic granites with an estimated age of 2640 Ma. This study presents Sm–Nd data and U–Pb monazite and titanite ages for the late leucocratic granites of the Preissac and Lamotte plutons. A biotite–muscovite monzogranitic phase of the Lamotte pluton is dated at 2647 ± 2 Ma, but similar phases of the Preissac pluton are dated at 2681–2660 Ma. These ages extend the period of leucogranitic plutonism for this area to 40 Ma and suggest that the age of collision of the Abitibi and the Pontiac subprovinces occurred before 2685 Ma. The εNd values for the leucogranites range from −1 to +3 and suggest an origin largely through melting of sediments having a juvenile isotopic signature (i.e., a short crustal residence time). Possible sources of the leucogranites include metasedimentary rocks of the Pontiac Subprovince, the Lacorne Block, and the Southern Abitibi Volcanic Zone, but the εNd values of the granites are most consistent with melting of metasediments of the Southern Volcanic Zone. We suggest that sediments of the Southern Volcanic Zone formed an accretionary prism along the southern continental margin of the Abitibi before collision with the Pontiac Subprovince. This prism was subsequently trapped between the two colliding margins, subducted, and partially melted to produce the Lamotte, Preissac, and Lacorne leucogranites.

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Tomascak, Paul B., Eirik J. Krogstad, and Richard J. Walker. "U-Pb Monazite Geochronology of Granitic Rocks from Maine: Implications for Late Paleozoic Tectonics in the Northern Appalachians." Journal of Geology 104, no. 2 (March 1996): 185–95. http://dx.doi.org/10.1086/629813.

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Valle Aguado, B., M. R. Azevedo, U. Schaltegger, J. R. Martínez Catalán, and J. Nolan. "U–Pb zircon and monazite geochronology of Variscan magmatism related to syn-convergence extension in Central Northern Portugal." Lithos 82, no. 1-2 (May 2005): 169–84. http://dx.doi.org/10.1016/j.lithos.2004.12.012.

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Dias, G., J. Leterrier, A. Mendes, P. P. Simões, and J. M. Bertrand. "U–Pb zircon and monazite geochronology of post-collisional Hercynian granitoids from the Central Iberian Zone (Northern Portugal)." Lithos 45, no. 1-4 (December 1998): 349–69. http://dx.doi.org/10.1016/s0024-4937(98)00039-5.

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Ayers, John C., Calvin Miller, Betsy Gorisch, and John Milleman. "Textural development of monazite during high-grade metamorphism; hydrothermal growth kinetics, with implications for U, Th-Pb geochronology." American Mineralogist 84, no. 11-12 (December 1, 1999): 1766–80. http://dx.doi.org/10.2138/am-1999-11-1206.

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Journal articles on the topic 'U-Pb monazite geochronology'

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