Stikinia, or the Stikine terrane, is a

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

; the largest of the

Canadian Cordillera The Pacific Cordillera, also known as the Western Cordillera or simply The Cordillera, is a top-level physiographic region of Canada, referring mainly to the extensive cordillera system in Western and Northwestern Canada that constitutes the northe ...

. It formed as an independent, intraoceanic

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...

during the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

and

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

. Stikinia forms the bedrock of numerous volcanoes in the southern portion of the

Northern Cordilleran Volcanic Province The Northern Cordilleran Volcanic Province (NCVP), formerly known as the Stikine Volcanic Belt, is a geologic province defined by the occurrence of Miocene to Holocene volcanoes in the Pacific Northwest of North America. This belt of volcanoes ex ...

(NCVP), a

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

geologic province A geologic province is a spatial entity with common geologic attributes. A province may include a single dominant structural element such as a basin or a fold belt, or a number of contiguous related elements. Adjoining provinces may be simila ...

that has its origins in

continental rifting In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben wi ...

Extent

Until recently the Paleozoic rocks that form a non-continuous belt along the western margin of the NCVP (the Stikine assemblage) were only recognized in a restricted area in northern British Columbia, between the

Stikine River The Stikine River is a major river in northern British Columbia (BC), Canada and southeastern Alaska in the United States. It drains a large, remote upland area known as the Stikine Country east of the Coast Mountains. Flowing west and south f ...

and

Taku River The Taku River (Lingít: ''T'aaḵu Héeni'') is a river running from British Columbia, Canada, to the northwestern coast of North America, at Juneau, Alaska. The river basin spreads across . The Taku is a very productive salmon river and its dra ...

areas. In contrast, Mesozoic Stikinia rocks form a near-continuous belt that extends much farther to the north, leading some authors to question the nature of the unexposed Paleozoic basement north of the Taku River area. The following correlations have significant implications for tectonic reconstructions of the northern Cordillera because they suggest that Stikinia's Paleozoic volcanic-sedimentary basement is more widespread than previously thought.

Formation

On the basis of similar rock types and lithologic associations, six new uranium-lead zircon dates, and the common intrusive relationship with 184–195 million year old

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s, the Stikine assemblage is correlated with the

Boundary Ranges The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains. They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian p ...

suite, a metamorphosed Paleozoic volcanic assemblage exposed in the

Tagish Lake Tagish Lake is a lake in Yukon and northern British Columbia, Canada. The lake is more than long and about wide. It has two arms, the Taku Arm in the east which is very long and mostly in British Columbia and Windy Arm in the west, mostly in ...

area, north of the Taku River and south of the Yukon–British Columbia border. The recognition of the Boundary Ranges suite and the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

plutons that intruded it (Tagish Lake suite) as part of Stikinia has implications for the age and character of the Stikinia–Tracy Arm terrane boundary because the Boundary Ranges and Tagish Lake suites form the footwall of a major Middle Jurassic shear zone that carried the continental margin–like rocks of the Tracy Arm terrane in its hanging wall. This correlation also implies that the late Paleozoic basement to the Mesozoic Stikinia arc is not a continental margin assemblage, at least as far north as the British Columbia–Yukon border, and possibly farther. The Boundary Ranges suite, and therefore the Stikine assemblage, are also tentatively correlated with parts of the

Yukon–Tanana Terrane The Yukon–Tanana Terrane (YTT) is a tectonic terrane that extends from central Alaska through central Yukon and into northern British Columbia, Canada and Southeast Alaska, USA. Extending over 2000 km, the YTT is the largest tectonostratigr ...

in Yukon (

Aishihik Lake Aishihik Lake is a lake in southwestern Yukon, Canada. Yukon Electric Corporation operates a 37 megawatt hydroelectric dam at the south end of the lake, where it drains southward into the Aishihik River. A US Air Force base was established near ...

area), parts of the Taku terrane in southeast Alaska, and undivided

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

s in west-central British Columbia. Differences in the isotopic signatures of these rocks may reflect along-strike changes in the character of the basement rocks of the late Paleozoic Stikinia volcanic arc.

References

Notes

Sources

* * {{coord missing, British Columbia Geology of British Columbia Geology of Yukon Paleozoic volcanism Mesozoic volcanism Terranes Volcanic arcs

Extent

Formation

See also

References

Notes

Sources