The Metchosin Igneous Complex is an ophiolite sequence in southwestern British Columbia, Canada, located at the southern end of Vancouver Island. It is the northernmost expression of the Siletzia terrane and consists of three rock units, including a basaltic sequence, a sheeted dike complex and gabbro stocks. [1]
Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term gabbro may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". By rough analogy, gabbro is to basalt as granite is to rhyolite.
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 discontinuous pillow-shaped masses, commonly up to one meter in diameter. They form the upper part of Layer 2 of normal oceanic crust.
Obduction is a geological process whereby denser oceanic crust is scraped off a descending ocean plate at a convergent plate boundary and thrust on top of an adjacent plate. When oceanic and continental plates converge, normally the denser oceanic crust sinks under the continental crust in the process of subduction. Obduction, which is less common, normally occurs in plate collisions at orogenic belts or back-arc basins.
An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks.
Dunite, also known as olivinite, is an intrusive igneous rock of ultramafic composition and with phaneritic (coarse-grained) texture. The mineral assemblage is greater than 90% olivine, with minor amounts of other minerals such as pyroxene, chromite, magnetite, and pyrope. Dunite is the olivine-rich endmember of the peridotite group of mantle-derived rocks.
Race Rocks Ecological Reserve is a BC Parks ecological reserve off the southern tip of Vancouver Island in the Strait of Juan de Fuca in Metchosin, British Columbia, Canada.
The District of Metchosin is a municipality and community in Greater Victoria on the southern tip of Vancouver Island in British Columbia, Canada. It is a coastal community adjacent to the Strait of Juan de Fuca. Metchosin is part of the Western Communities and one of the 13 regional municipalities.
The Lizard complex, Cornwall is generally accepted to represent a preserved example of an exposed ophiolite complex in the United Kingdom. The rocks found in The Lizard area are analogous to those found in such famous areas as the Troodos Mountains, Cyprus and the Semail Ophiolite, Oman.
Harzburgite, an ultramafic, igneous rock, is a variety of peridotite consisting mostly of the two minerals olivine and low-calcium (Ca) pyroxene (enstatite); it is named for occurrences in the Harz Mountains of Germany. It commonly contains a few percent chromium-rich spinel as an accessory mineral. Garnet-bearing harzburgite is much less common, found most commonly as xenoliths in kimberlite.
Trondhjemite is a leucocratic (light-colored) intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites.
Strawberry Mountain Wilderness is a wilderness area of the Strawberry Mountain Range, within Malheur National Forest in the Blue Mountains of east Oregon. The area comprises 69,350 acres (28,060 ha), including mountain peaks and several lakes, and contains more than 125 miles (201 km) of hiking trails. Strawberry Mountain was designated wilderness under the Wilderness Act of 1964, and in 1984 more than doubled in size with the passage of the Oregon Wilderness Act. It is managed by the United States Forest Service.
A sheeted dyke complex, or sheeted dike complex, is a series of sub-parallel intrusions of igneous rock, forming a layer within the oceanic crust. At mid-ocean ridges, dykes are formed when magma beneath areas of tectonic plate divergence travels through a fracture in the earlier formed oceanic crust, feeding the lavas above and cooling below the seafloor forming upright columns of igneous rock. Magma continues to cool, as the existing seafloor moves away from the area of divergence, and additional magma is intruded and cools. In some tectonic settings slices of the oceanic crust are obducted (emplaced) upon continental crust, forming an ophiolite.
Shawnigan Lake is a lake on southern Vancouver Island, located to the west of Saanich Inlet and to the south of the Cowichan Valley region. Its aboriginal name in the Hul'qumi'num language is Showe'luqun.
The Leech River Fault extends across the southern tip of Vancouver Island in British Columbia, Canada, creating the distinctively straight, narrow, and steep-sided valley, occupied by Loss Creek and two reservoirs, that runs from Sombrio Point due east to the Leech River, and then turns southeast to run past Victoria. It is a thrust fault that marks the northernmost exposure of the Crescent Terrane, where basalt of the Metchosin Igneous Complex is dragged under Vancouver Island by the subducting Juan de Fuca Plate. About ten kilometers north the nearly parallel San Juan Fault marks the southern limit of rock of the Wrangellia terrane, which underlies most of Vancouver Island. Between these two northeast-dipping thrust faults are the Leech River Complex and the Pandora Peak Unit. These, along with the Pacific Rim Complex further up the coast, are remnants of the Pacific Rim Terrane which was crushed between Wrangellia and Siletzia. The contact between the bottom of Wrangellia and the top of the subducted PRT continues northwest along the coast as the West Coast Fault, and southeast towards Victoria as the Survey Mountain Fault. The Leach River Fault (LRF) extends off-shore towards Cape Flattery, where the Crescent—Pacific Rim contact continues northwest as the Tofino Fault (TF).
Langford-Juan de Fuca is a provincial electoral district for the Legislative Assembly of British Columbia, Canada that was created in the 2008 redistribution as Juan de Fuca out of the ridings of Malahat-Juan de Fuca and Esquimalt-Metchosin. It was first contested in the 2009 general election, in which New Democrat John Horgan was elected MLA.
The geology of Bosnia & Herzegovina is the study of rocks, minerals, water, landforms and geologic history in the country. The oldest rocks exposed at or near the surface date to the Paleozoic and the Precambrian geologic history of the region remains poorly understood. Complex assemblages of flysch, ophiolite, mélange and igneous plutons together with thick sedimentary units are a defining characteristic of the Dinaric Alps, also known as the Dinaride Mountains, which dominate much of the country's landscape.
The Dun Mountain-Maitai Terrane comprises the Dun Mountain Ophiolite Belt, Maitai Group and Patuki Mélange. The Dun Mountain Ophiolite is an ophiolite of Permian age located in New Zealand's South Island. Prehistorically this ophiolite was quarried by Māori for both metasomatized argillite and pounamu (jade) which was used in the production of tools and jewellery.
The Rocas Verdes ophiolites are a series of greenschists and other rocks constituting ophiolites in Magallanes Region, southernmost Chile. The Rocas Verdes ophiolites represent the continental-oceanic crust that existed in a back-arc basin in the Mesozoic Era as result of extensional tectonics. This back-arc basin then evolved into the Magallanes foreland basin in the Cenozoic Era within the context of the wider Andean orogeny.
The Fidalgo ophiolite or Fidalgo complex is a Jurassic-aged ophiolite sequence located in the San Juan Islands of northwest Washington. The ophiolite complex is a metamorphosed and disrupted ophiolite sequence that contains serpentinized peridotite, layered gabbro, diorite, and plagiogranite, and an overlying sequence of volcanic and sedimentary rocks.