The Taltson Magmatic Zone (TMZ) is a north-trending belt of

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth during the Arc ...

Paleoproterozoic The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Ga), is the first of the three sub-divisions ( eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's ...

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

basement

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

, amphibolite

supracrustal Supracrustal rocks (''supra'' (Latin for "above")) are rocks that were deposited on the existing basement rocks of the crust, hence the name. They may be further metamorphosed from both sedimentary and volcanic rocks. The oldest minerals on Ear ...

gneissic rock and Paleoproterozoic

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

tic rocks in the Canadian Shield, extending from

Northern Alberta Northern Alberta is a geographic region located in the Canadian province of Alberta. An informally defined cultural region, the boundaries of Northern Alberta are not fixed. Under some schemes, the region encompasses everything north of the cen ...

to the southwestern Northwest Territories. The TMZ basement is 3.2–3.0 Ga and the Rutledge River supracrustal gneisses 2.13–2.09 Ga years old and were intruded by magmatic rocks around 1.99–1.92 Ga. The long exposed part of the TMZ in Northern Alberta and the Northwest Territories is bounded by the

Great Slave Lake Great Slave Lake (french: Grand lac des Esclaves), known traditionally as Tıdeè in Tłı̨chǫ Yatıì (Dogrib), Tinde’e in Wıìlıìdeh Yatii / Tetsǫ́t’ıné Yatıé (Dogrib / Chipewyan), Tu Nedhé in Dëne Sųłıné Yatıé (Chi ...

shear zone to the north and by the subsurface

Snowbird Tectonic Zone The Snowbird Tectonic Zone (STZ) is a geological structure in the western Canadian Shield which forms a geophysical boundary between the Hearne Craton and the south-west arm of the Rae Craton. It is enigmatic and has been interpreted as a Prote ...

to the south. TMZ is an Andean-type continental

magmatic arc Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

and an orogenic belt between the subsurface

Buffalo Head Terrane The Buffalo Head Terrane (BHT) is a terrane in the western Canadian Shield in northern Alberta. It is covered by of Devonian and Cretaceous sediments and its centre is intruded by the 88–86 Ma kimberlites of the diamondiferous Buffalo Head ...

on the west and the Archean Churchill Province on the east. It is also the southern continuation of the Thelon Magmatic Zone, an orogenic belt between the Slave and Churchill cratons. The northern TMZ is divided by major faults and can be subdivided into two main terranes: an eastern gneiss framework and the TMZ batholiths in the west. The exposed basement in northern Alberta is composed of banded gneissic rocks, predominantly 2.4–2.1 Ga metaplutonic gneissic rock, but it also contains amphibolitic gneiss and paragneiss. This basement also contains slices of Archean gneissic rock up to 3.73 Ga-old; an age similar to those of the Hearne and Rae cratons (also known as the Western Churchill Province), which can indicate that TMZ represents the recycling of parts of this province. The U–Pb ages and the isotopic composition of TMZ and the

(west of TMZ), including the

Buffalo Head Hills kimberlite field The Buffalo Head Hills kimberlite field is a group of kimberlitic volcanic pipes or diatremes in north-central Alberta, Canada. As of 2011, 41 kimberlite pipes, of which 28 are diamondiferous, had been identified in the field. They were emplaced ...

, are identical. It is possible that these two domains represent a single Paleoproterozoic block. This block is composed mostly of contribution from depleted mantle sources but with contribution from the Churchill Province. TMZ basement rock together with the Buffalo Head terrane can represent the earliest Paleoproterzoic magmatism, pre-dating the break-up of the Churchill Province and the Taltson–Thelon orogeny.

References

; Notes ; Sources * * * * {{Refend Volcanism of Alberta Volcanism of the Northwest Territories Volcanic arcs Paleoproterozoic volcanism

See also

References