Harvey-Cardiff domain and its relationship to the Composite Arc Belt, Grenville Province: insights from U–Pb geochronology and geochemistryThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

2011 ◽  
Vol 48 (2) ◽  
pp. 347-370 ◽  
Author(s):  
R. M. Easton ◽  
S. L. Kamo
Keyword(s):  
Deformation Zone ◽  
Thermal Ionization Mass Spectrometry ◽  
Potassium Feldspar ◽  
Ionization Mass ◽  
Intrusive Complex ◽  
Pegmatite Vein ◽  
Grenville Province ◽  
Metamorphic History ◽  
Geochemical Studies ◽  
Granite Suite

Combined mapping, U–Pb isotope dilution – thermal ionization mass spectrometry (ID–TIMS) geochronology and geochemical studies in Harvey-Cardiff domain in the western Composite Arc Belt reveal the presence of a long-lived magmatic–metamorphic history between 1290 and 1030 Ma. Following intrusion of gneissic tonalite of the Anstruther and Burleigh gneiss complexes at ca. 1290 Ma, diorite of the Salmon Burn intrusive complex was emplaced at 1242.1 ± 1.1 Ma. A potassium-feldspar megacrystic monzogranite in the Salerno Creek deformation zone that forms the boundary between Harvey-Cardiff domain and Bancroft terrane was emplaced at 1211.3 ± 1.5 Ma, similar to the 1220 ± 1.6 Ma old Junction pluton and a previously reported age of ca. 1229 Ma from another Methuen suite granite in the domain. All three ages are 20 to 30 million years younger than Methuen suite ages elsewhere in the Composite Arc Belt (1250–1240 Ma). Deformation along the Salerno Creek deformation zone is constrained between 1211 Ma, the age of the megacrystic monzogranite, and 1050 Ma, the age of titanite grains from the Salmon Burn intrusive complex and a late alkalic dike. A monzogranite of the newly recognized Catchacoma granite suite yielded an age of 1067 ± 3.7 Ma, similar to the 1059.2 ± 1.6 Ma age obtained from the Cavendish pegmatite vein. These ages suggest a temporal link between late granite and pegmatite emplacement in Harvey-Cardiff domain. Metamorphic zircon, monazite, and titanite ages fall into three clusters (1082–1070, 1063–1045, and 1037–1030 Ma) and may represent a protracted metamorphic event or reflect distinct pulses during the Ottawan orogeny.

Genesis of the Olden wollastonite skarn, Sharbot Lake domain, Central Metasedimentary Belt, Grenville Province, southeastern Ontario, Canada

2005 ◽  
Vol 42 (8) ◽  
pp. 1401-1417 ◽  
Author(s):  
T A Grammatikopoulos ◽  
A H Clark ◽  
T H Pearce ◽  
D A Archibald
Keyword(s):  
Thermal Ionization Mass Spectrometry ◽  
Alkali Feldspar ◽  
Hydrothermal Activity ◽  
Ionization Mass ◽  
Mississippi Valley ◽  
Grenville Province ◽  
Intrusive Rocks ◽  
Wide Compositional Range ◽  
Considerable Depth ◽  
Base Metal Mineralization

With a resource of ∼2.8 Mt at 30%–35% wollastonite occurring at a depth of about 75 m, the Olden (formerly Hawley) prospect is the largest of a swarm of skarns hosted by amphibolite facies, dominantly calcitic marble that occurs adjacent to and as inliers within the Mountain Grove pluton. The post-kinematic intrusion comprises units with a wide compositional range from anorthositic gabbro to alkali-feldspar granite and syenite and widely exhibits megascopic fabrics recording magma comingling and mixing. Isotope dilution – thermal ionization mass spectrometry (ID–TIMS) dating of zircon separates from a hornblende diorite unit yields a 207Pb–206Pb age of 1153 ± 2 Ma, significantly older than the contiguous 1070 ± 3 Ma McLean granite. Al-in-hornblende geobarometry on several Mountain Grove units indicates that the intrusion crystallized at pressures of 250–470 MPa, equivalent to mesozonal depths of 10–15 km. The main exoskarn body, ∼200 m long and up to 50 m wide, is dominated by wollastonite, clinopyroxene (Di73–94Hd2–19), and calcic garnet (Gr52–83And12–37) and ranges from massive to podiform. The eastern termination exhibits rhythmically alternating wollastonite- and calcite-rich layers, 10 cm wide and locally with chevron-shaped crenulations. These layers bear no relationship to bedding or metamorphic foliation and are interpreted as “wrigglitic,” i.e., they are a record of a metasomatic front that migrated. Veins of garnet–pyroxene–vesuvianite cut the main exoskarn. Retrograde phlogopite-rich skarns, with erratic serpentine and brucite, contain variable sphalerite and pyrite. Restricted pyroxene–garnet (–wollastonite–scapolite) endoskarn is developed in intrusive rocks contiguous with the exoskarn. Skarn development is ascribed to H2O-rich (XCO2 < 0.3) magmatogene brines and high temperatures (T = 500–650 °C), which caused intense Si, Al, and Fe metasomatism of the marbles, hydrothermal activity taking place at considerable depth. The occurrence of wollastonite around the periphery of the small Long Lake sphalerite deposit, restricted to a marble roof pendant in the Mountain Grove pluton 2.1 km east-northeast of the Olden prospect, indicates that this base-metal mineralization may be an exoskarn, rather than metamorphosed Mississippi Valley type. Incremental-heating 40Ar–39Ar dating of hornblende and biotite from the Mountain Grove diorite yields plateau ages of 1058 ± 14 and 1047 ± 4 Ma, respectively, and an exoskarn phlogopite age of 1074 ± 5 Ma. A genetic relationship between hydrothermal activity and the McLean pluton cannot be ruled out, but a parental role for the older Mountain Grove pluton is favoured on the basis of the close areal relationships of skarn bodies and that intrusion.

Age of the Cabonga nepheline syenite, Grenville Province, western Quebec

2006 ◽  
Vol 43 (9) ◽  
pp. 1237-1249 ◽  
Author(s):  
Pierre Hudon ◽  
Richard M Friedman ◽  
Gilles Gauthier ◽  
Jacques Martignole
Keyword(s):  
Nepheline Syenite ◽  
Thermal Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Grenville Province ◽  
X Ray ◽  
Electronic Imaging ◽  
Isotopic Analyses ◽  
Thermal Ionization Mass ◽  
Granite Magmatism

This study presents isotope dilution – thermal ionization mass spectrometry (ID–TIMS) U–Pb data for megacrystic zircon from the Cabonga Nepheline Syenite Complex of the Réservoir Cabonga terrane (Grenville Province). This terrane is an allochthonous slab metamorphosed under granulite-grade conditions ~1.18–1.14 Ga and transported onto migmatites of the Grenvillian Parautochthon at about 1.02 Ga. The very low uranium and lead concentrations of zircon from the Cabonga nepheline syenite (CNS) did not permit determination of a statistically significant crystallization age using laser ablation microbeam techniques. Consequently, extensive microsampling (15 zircon chips), guided by X-ray and electronic imaging, followed by ID–TIMS analyses were carried out on a single megacrystic zircon. A regression of 13 out of 15 U–Pb isotopic analyses results in a crystallization age of 1171 ± 3 Ma for the CNS. Criteria based on zircon morphologies, zoning patterns, varying Th/U ratios (0.3–0.9), and a highly fractionated Zr/Hf ratio (68) suggest an igneous derivation for the CNS. The Cabonga alkaline rocks, intruded under high-grade metamorphic conditions, preceded the onset of the widespread and ubiquitous (1.15 ± 0.01 Ga) anorthosite–mangerite–charnockite–granite magmatism in the southern part of the Grenville Province.

U–Pb geochronology of Cretaceous magmatism on Svalbard and Franz Josef Land, Barents Sea Large Igneous Province

2013 ◽  
Vol 150 (6) ◽  
pp. 1127-1135 ◽  
Author(s):  
FERNANDO CORFU ◽  
STÉPHANE POLTEAU ◽  
SVERRE PLANKE ◽  
JAN INGE FALEIDE ◽  
HENRIK SVENSEN ◽  
...  
Keyword(s):  
Thermal Ionization Mass Spectrometry ◽  
Barents Sea ◽  
Large Igneous Province ◽  
The Arctic ◽  
Ionization Mass ◽  
Franz Josef Land ◽  
Igneous Province ◽  
Stratigraphic Record ◽  
Single Grain ◽  
Cretaceous Magmatism

AbstractThe opening of the Arctic oceanic basins in the Mesozoic and Cenozoic proceeded in steps, with episodes of magmatism and sedimentation marking specific stages in this development. In addition to the stratigraphic record provided by sediments and fossils, the intrusive and extrusive rocks yield important information on this evolution. This study has determined the ages of mafic sills and a felsic tuff in Svalbard and Franz Josef Land using the isotope dilution thermal ionization mass spectrometry (ID-TIMS) U–Pb method on zircon, baddeleyite, titanite and rutile. The results indicate crystallization of the Diabasodden sill at 124.5 ± 0.2 Ma and the Linnévatn sill at 124.7 ± 0.3 Ma, the latter also containing slightly younger secondary titanite with an age of 123.9 ± 0.3 Ma. A bentonite in the Helvetiafjellet Formation, also on Svalbard, has an age of 123.3 ± 0.2 Ma. Zircon in mafic sills intersected by drill cores in Franz Josef Land indicate an age of 122.7 Ma for a thick sill on Severnaya Island and a single grain age of ≥122.2 ± 1.1 Ma for a thinner sill on Nagurskaya Island. These data emphasize the importance and relatively short-lived nature of the Cretaceous magmatic event in the region.

scholarly journals Monazite U–Th–Pb geochronology of the Central Metasedimentary Belt Boundary Zone (CMBbz), Grenville Province, Ontario Canada

2018 ◽  
Vol 55 (9) ◽  
pp. 1063-1078 ◽  
Author(s):  
Michelle J. Markley ◽  
Steven R. Dunn ◽  
Michael J. Jercinovic ◽  
William H. Peck ◽  
Michael L. Williams
Keyword(s):  
Shear Zone ◽  
Crustal Thickening ◽  
Boundary Zone ◽  
Grenville Province ◽  
Metamorphic History ◽  
Crustal Thinning ◽  
Tectonic Significance ◽  
History Of ◽  
Central Gneiss Belt ◽  
Scale Shear

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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