Accretion history of the Trans-Hudson Orogen in Manitoba and Saskatchewan from paleomagnetism

2005 ◽  
Vol 42 (4) ◽  
pp. 723-740 ◽  
Author(s):  
David TA Symons ◽  
Michael J Harris

Lithoprobe's sponsorship has led to the acquisition of paleomagnetic data from ~20 units throughout the Paleoproterozoic Trans-Hudson Orogen (THO) of Saskatchewan and Manitoba, essentially the first such data for the region. Discussed summarily in this paper, they provide an initial framework for the THO's tectonic evolution. They show that the Archean Hearne and Superior cratons were at subtropical and subpolar paleolatitudes, respectively, at ~1875 Ma, with the Lynn Lake – LaRonge arc midway between them in the Manikewan Ocean. By ~1855 Ma, this ocean was still ~5500 ± 700 km wide, and its seafloor was subducting northwestward under the Hearne craton and pericratonic Peter Lake domain margin with the coeval development of an Andean-type continental magmatic arc, the Wathaman–Chipewyan batholith. Between ~1855 and ~1810 Ma, coalescing apparent polar wander path (APWP) segments record closing of the ocean at a rate of ~12 cm/a, trapping and accreting the several separate intervening terranes (Flin Flon, Hanson Lake, Lynn Lake – LaRonge, Rottenstone, and presumably also other THO terranes). From ~1815 to ~1775 Ma, the assembled terranes drifted as a coherent craton, yielding a stillstand and hairpin in the APWP.


1985 ◽  
Vol 22 (3) ◽  
pp. 452-463 ◽  
Author(s):  
B. R. Watters ◽  
R. L. Armstrong

Two whole-rock suites of metavolcanic rocks from separate volcanic belts of the Churchill Province in northern Saskatchewan have been dated by Rb–Sr. Samples from the Amisk Group of the Flin Flon – Snow Lake domain provide an isochron date of 1784 ± 44 Ma; suites from the Waddy Lake and Devil Lake areas of the La Ronge (–Lynn Lake) domain yield isochron dates of 1814 ± 26 and 1854 ± 100 Ma, respectively. All are regarded as minima for, but close approximations to, emplacement ages. The maximum crustal age of any suite cannot greatly exceed 1850 Ma.Previous Rb–Sr and U–Pb isotopic dates together with these new determinations confirm the contemporaneous existence of two volcanic arcs, active during the late Aphebian (1875–1784 Ma) in the Churchill Province.Low initial 87Sr/86Sr ratios (0.7017–0.7022) are consistent with a petrochemically inferred subduction-related origin for the volcanic rocks with no closed-system reworking of Archean crust, and a linear evolution of 87Sr/86Sr ratio in the magmatic-arc mantle source region from 4.55 Ga to the present.



2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Toshitsugu Yamazaki ◽  
Shun Chiyonobu ◽  
Osamu Ishizuka ◽  
Fumisato Tajima ◽  
Naoki Uto ◽  
...  

AbstractReconstructing the history of Philippine Sea (PHS) plate motion is important for better understanding of the tectonics of the surrounding plates. It is generally considered that the PHS plate migrated northward since Eocene, but its rotation has not been constrained well; some reconstructions incorporated a large clockwise rotation but others did not. This is mainly because the difficulty of collecting oriented rocks from the mostly submerged PHS plate hindered establishing an apparent polar wander path. In this study, we conducted a paleomagnetic study of oriented cores taken using an ROV-based coring apparatus from the Hyuga Seamount on the northern part of the Kyushu-Palau Ridge, a remnant arc in the stable interior of the PHS plate. Stepwise thermal and alternating-field demagnetizations were applied to specimens taken successively from two ~ 30 cm long limestone cores of middle to late Oligocene age, and characteristic remanent magnetization directions could be isolated. Declination and inclination of D = 51.5° and I = 39.8°, respectively, were obtained as the mean of the two cores. The easterly-deflected declination means ~ 50° clockwise rotation of the PHS plate since middle to late Oligocene. In addition, ~ 5° latitudinal change of the site is estimated from the mean inclination. The result implies that the Kyushu-Palau Ridge was located to the southwest of the present position in middle to late Oligocene, and that PHS plate rotation as well as the Shikoku and Parece Vela Basin spreading contributed to the eastward migration of the Izu-Ogasawara (Bonin) Arc to the current position.



1991 ◽  
Vol 28 (12) ◽  
pp. 1931-1938 ◽  
Author(s):  
D. T. A. Symons

The Wathaman (Wathaman–Chipewyan) batholith is an 1854 ± 11 Ma, northeast-trending, homogenous, felsic pluton that is over 900 km long. It is thought to be a magmatic arc, with the Archean Hearne craton on its northwestern side as the hinterland and the remains of the Early Proterozoic Manikewan oceanic crust of the Trans-Hudson orogen on its southeastern side. Alternating-field and thermal step demagnetization methods isolate an A remanence component with a mean direction of D = 134.6°, I = 54.1° (α95 = 3.5°, k = 94, N = 19). Isothermal remanent magnetization tests confirm that this A magnetization component is preserved in pseudosingle to multidomain magnetite and in hematite. Contact tests with intruded older rocks of the Peter Lake domain, with younger crosscutting mafic dikes and with younger crosscutting shear zones, indicate that A is a primary remanence. Its pole position of 67°W, 9°N (dp = 3°, dm = 5°) confirms that it was formed along the margin of the Slave–Rae–Hearne craton, supporting tectonic models that it records a suture zone. It also indicates that the LaRonge – Lynn Lake domain, Flin Flon domain, and Superior Province were translated relatively northwestward into the suture by at least 11 ± 11°, 27 ± 12°, and 49° ± 16°, respectively, as the Manikewan Ocean closed.



Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 604
Author(s):  
Evgeny V. Vetrov ◽  
Johan De Grave ◽  
Natalia I. Vetrova ◽  
Fedor I. Zhimulev ◽  
Simon Nachtergaele ◽  
...  

The West Siberian Basin (WSB) is one of the largest intracratonic Meso-Cenozoic basins in the world. Its evolution has been studied over the recent decades; however, some fundamental questions regarding the tectonic evolution of the WSB remain unresolved or unconfirmed by analytical data. A complete understanding of the evolution of the WSB during the Mesozoic and Cenozoic eras requires insights into the cooling history of the basement rocks as determined by low-temperature thermochronometry. We presented an apatite fission track (AFT) thermochronology study on the exposed parts of the WSB basement in order to distinguish tectonic activation episodes in an absolute timeframe. AFT dating of thirteen basement samples mainly yielded Cretaceous cooling ages and mean track lengths varied between 12.8 and 14.5 μm. Thermal history modeling based on the AFT data demonstrates several Mesozoic and Cenozoic intracontinental tectonic reactivation episodes affected the WSB basement. We interpreted the episodes of tectonic activity accompanied by the WSB basement exhumation as a far-field effect from tectonic processes acting on the southern and eastern boundaries of Eurasia during the Mesozoic–Cenozoic eras.



Sign in / Sign up

Export Citation Format

Share Document