Tectonic implications of new SHRIMP and TIMS U–Pb geochronology of rocks from the Sask Craton, Peter Lake Domain, and Hearne margin, Trans-Hudson Orogen, Saskatchewan

2005 ◽  
Vol 42 (4) ◽  
pp. 635-657 ◽  
Author(s):  
N M Rayner ◽  
R A Stern ◽  
M E Bickford
Keyword(s):  
Thermal Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Ion Microprobe ◽  
Geochronological Data ◽  
Zircon Growth ◽  
Precursor Material ◽  
Three Samples ◽  
Limited Support ◽  
Age Range ◽  
Superior Craton

This study reports new sensitive high-resolution ion microprobe (SHRIMP) and thermal ionization mass spectrometry (TIMS) U–Pb geochronological data for thirteen rocks from the Archean to Paleoproterozic Sask Craton, the Peter Lake Domain and Hearne margin, Saskatchewan. Seven samples from the exposed Sask Craton in both the Glennie Domain and Pelican Window record zircon growth between 2425 and 2525 Ma and at ~1800 Ma. Older precursor material has been identified, most notably a refined crystallization age of 3117 Ma for a sample of quartzofeldspatic gneiss ("Q-gneiss") in the Pelican Window, which also experienced ca. 2450 Ma zircon growth. Three samples from the Peter Lake Domain and a sample from the Linn Island inlier of the Wollaston Domain yield ages of ~2575 Ma. One sample from the Peter Lake Domain is distinctly older, yielding an age of 2640 Ma, but also displays zircon growth at 2575 Ma. The simplest interpretation of these data is that the Peter Lake Domain is likely a part of the Hearne margin, although the significance and distribution of 2575 Ma ages within the larger Hearne craton is unclear. Conversely, the age range of most samples from the Sask Craton is distinctly younger than those of the Peter Lake and Hearne margin rocks. We suggest that 2.45 Ga was a major episode of magmatic reworking of older material within the Sask Craton, which includes, but is not restricted to, 3.1 Ga precursors. These ages do not coincide with typical ages reported from the Superior craton and thus the data, although limited, support an exotic origin for the Sask Craton.

scholarly journals Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Geology ◽  
2021 ◽  
Author(s):  
Cedric Djeutchou ◽  
Michiel O. de Kock ◽  
Hervé Wabo ◽  
Camilo E. Gaitán ◽  
Ulf Söderlund ◽  
...  
Keyword(s):  
Thermal Ionization Mass Spectrometry ◽  
Black Hills ◽  
Large Igneous Province ◽  
Ionization Mass ◽  
Data Sets ◽  
Geochronological Data ◽  
Pb Isotope ◽  
Kalahari Craton ◽  
Igneous Province ◽  
Superior Craton

The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton’s position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.

U–Pb ages constraining structural development of an Archean terrane boundary in the Lake of the Woods area, western Superior Province, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 967-993 ◽  
Author(s):  
M Melnyk ◽  
D W Davis ◽  
A R Cruden ◽  
R A Stern
Keyword(s):  
Greenstone Belt ◽  
Thermal Ionization Mass Spectrometry ◽  
Magmatic Zircon ◽  
Ionization Mass ◽  
Structural Development ◽  
Ion Microprobe ◽  
Widespread Occurrence ◽  
Lake Of The Woods ◽  
Second Stage ◽  
Winnipeg River

Layered gneisses in the Winnipeg River subprovince contain magmatic zircon with U–Pb ages of 3317 ± 9 and 3055 ± 4 Ma at Tannis Lake, and ~3170 and 3255 ± 5 Ma at Cedar Lake, indicating widespread occurrence of Mesoarchean crust. This is in contrast to the well-documented Neoarchean age of the western Wabigoon subprovince. Further geochronology using both SHRIMP (sensitive high resolution ion microprobe) and ID-TIMS (isotope dilution thermal ionization mass spectrometry), combined with structural observations, in the Kenora area and Lake of the Woods greenstone belt show the effects of juxtaposition of these two terranes. Isoclinally folded gneiss north of the subprovince boundary zone near Kenora gives a magmatic age of 2882 ± 2 Ma with 3051 ± 6 Ma inheritance. Ages of syntectonic dykes show that asymmetric refolding of these gneisses occurred between 2717 ± 2 and about 2713 ± 1 Ma. Subsequent regional vertical flattening and horizontal extension are dated at 2708 ± 2 Ma by syntectonic tonalite sheets. These events are broadly coeval with deposition of orogenic sediments in the Warclub Group and a first stage of regional folding (age brackets of 2716–2709 Ma) in the Lake of the Woods greenstone belt to the south. A second stage of folding and regional faulting in the greenstone belt occurred about 2695 ± 4 Ma and is approximately coeval with open upright folding in the Winnipeg River subprovince. These observations are consistent with overthrusting and collapse of a Mesoarchean continental terrane by a juvenile Neoarchean arc terrane over the time span 2717–2695 Ma.

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.

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