Eruptive history of the Mount Meager Volcanic Complex

The Mosaic Assemblage is a rock unit of the

Pacific Ranges , photo = Mount Garibaldi (50997016501).jpg , photo_size = 280px , photo_caption = Mount Garibaldi massif as seen from Squamish , map = , map_image = South BC-NW USA-relief PacificRanges.png , m ...

of the

Coast Mountains The Coast Mountains (french: La chaîne Côtière) are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia ...

in southwestern

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 ...

. It is the namesake of Mosaic Glacier, which is drained by Mosaic Creek. This

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

formed 140,000 to less than 90,000 years ago when

porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all ...

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...

augite Augite is a common rock-forming pyroxene mineral with formula . The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees. Characteristics Augite is a solid solution in the pyroxene group. ...

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

and

trachybasalt Trachybasalt is a volcanic rock with a composition between trachyte and basalt. It resembles basalt but has a high content of alkali metal oxides. Minerals in trachybasalt include alkali feldspar, calcic plagioclase, olivine, clinopyroxene and li ...

was erupted in valleys and on mountain ridges. These

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...

s form

scoria Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''G ...

ceous lava flows,

breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...

volcanic bomb A volcanic bomb or lava bomb is a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. Because volcanic bombs cool after they l ...

s and

pillow lava Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of disconti ...

s. The location of the Mosaic Assemblage is sparse, being present just north of the

Lillooet River The Lillooet River is a major river of the southern Coast Mountains of British Columbia. It begins at Silt Lake, on the southern edge of the Lillooet Crown Icecap about 80 kilometres northwest of Pemberton and about 85 kilometres northwest of W ...

, south of and in upper

Meager Creek Meager Creek is a creek in the southern Pacific Ranges of the Coast Mountains in British Columbia, Canada. It flows northeast into the Lillooet River approximately northwest of the village of Pemberton and is adjacent to the Upper Lillooet Pro ...

and between Job Creek and Mosaic Creek. Because these four areas are well apart, each area probably has its own volcanic vents. Small patches of the Mosaic Assemblage overlie

The Devastator Assemblage The Devastator Assemblage is a geological formation comprising a portion of the Mount Meager massif in southwestern British Columbia, Canada. It is named after Devastator Peak (also known as The Devastator), the lowest and southernmost subsidiary p ...

and form minor portions of the

Mount Meager massif The Mount Meager massif is a group of volcanic peaks in the of the Coast Mountains in southwestern British Columbia, Canada. Part of the Cascade Volcanic Arc of western North America, it is located north of Vancouver at the northern end of the ...

References

External links

* {{coord missing, British Columbia Mount Meager massif Volcanism of British Columbia Geologic formations of British Columbia Pleistocene volcanism Basalt formations Pleistocene British Columbia

See also

References

External links