Continental fissure eruptions. These are your rocks that lack light-colored minerals. 2. A new method to calculate volcanic susceptibility, i.e. Regional tectonic setting. Komatiite is a rare rock because volcanic material that comes directly from the mantle is not common, although some examples can be found in ancient Archean rocks . Why is felsic lava more viscous? In the following discussion, these three classes are denoted as "mafic", "bimodal-mafic" and "bimodal-felsic" Mafic magma is found at shield and composite volcanoes. Chapters 4 + 5. Methodology for the computation of volcanic susceptibility: An example for mafic and felsic eruptions on Tenerife (Canary Islands) Marti, Joan; Felpeto, Alicia; Abstract. The low viscosity, runny, nature of the lava means it travels in streams far from the source and covers many square miles. Examples include the Noranda, Flin Flon-Snow Lake and Kidd Creek camps (Canada). The average pattern for lava blocks from Upsal Hogback volcano near Fallon, an example of postarc volcanic rocks in western Nevada, has lower Ba/La, La/Nb, and a more within-plate trace-element composition compared to GB volcanic rocks. Noteworthy is that its texture has a medium to coarse feeling. Basalt is a well-known example of a mafic rock. Volcanoes made up of mafic flows are typically shield volcanoes and/or cinder cones. Igneous rock itself is born in volcanic eruptions. YOU MIGHT ALSO LIKE... 35 terms. So mafic/basaltic volcanoes are fairly quiescent. What is Felsic? It is thin and runny. Many parallel mafic and felsic bands are present in this area. Mafic volcanic rock is dark-colored; basalt is a typical mafic rock. Mafic magmas are low in silica and contain more dark, magnesium and iron rich mafic minerals, such as olivine and pyroxene. Shield Volcanoes. This magma has a low viscosity, which allows for gases to escape the volcano, and for the lava flows to erupt calmly and predictably. Mineralization is often associated with the felsic strata. Smallest volcano type Steep-sided mountain formed from pieces of ejected magma … (steep/gentle) 7. Volcanic gases. The flattening of the fragments in the mafic bands suggests that this exposure is in the hinge of a fold. Island of Hawaii: mantle plume. A viscous felsic magma can't flow fast enough to form such droplets, so shatters into volcanic ash that erupts as a hot aerosol. Igneous Rock Quiz. St. Helens. These terms are mafic and felsic. Intermediate eruptions. Since mafic lava flows easily, it can cover very long distances. The word derives from a composite of the chemical symbols for Magnesium (Ma) and Iron (Fe). These are your dark green, brown, red, gray and black igneous rocks. In general, the gradation from felsic to mafic corresponds to an increase in colour index (dark-mineral percentage). 26 terms . Mafic is an acronym for magnesium and ferric, which refers to iron. Mafic magma is found at cinder cone and composite volcanoes. Ultramafic: Nearly 100% dark minerals: Full of very dark minerals. Shield Volcanoes 1. Subduction zones. A. is the only documented example of possible eruption-triggered coolness. Volcano example (Mafic) Hawaii Maune Los Kilolea. McIlvenna Bay is part of the bimodal-mafic subclass of VMS deposits. Example Image: Mafic >40% dark minerals: No quartz or potassium feldspar is found. Intermediate magmas are somewhat more viscous than the mafic magmas. In many mafic-ultramafic volcanic or intrusive systems the magma rises to the lithosphere as a plume. Chapters 4 + 5. Glaciers and Glaciation Lecture Outline. The mafic-ultramafic, bimodal-mafic, and siliciclastic-mafic volcanic … On the opposite side of the rock spectrum are the iron and magnesium rich mafic and ultramafic minerals and rocks. 38 terms. Geology Exam 3. (long/short) 6. The words that describe composition of igneous rocks also describe magma composition. 32 terms. Mafic – 1832 – 2192 degrees Fahrenheit “Mafic” is a term used to describe the densest lava flows. Expert Answer 100% (1 rating) 1) Composite volcano are made up of felsic lava which are very viscous and hold a lot of gas . (A) The late Quaternary Motukorea volcano (also known as Browns Island) in the Auckland Volcanic Field, New Zealand, experienced a range of eruption styles during the course of a single eruption resulting in a hybrid landform, with a scoria cone and rafted cone remnants within an eroded tuff ring surrounded by late-stage lava flows. Felsic is the term used for the rocks rich in the mental feldspar, that contains aluminium and silica at high levels. Give an example of each type. Because of the relative ease of flow, basaltic volcanoes are broad, with gentle slopes. The word "felsic" comes from feldspar and silica. Lava: This is the term used when magma has erupted on the earth’s surface. Felsic rock, like rhyolite or granite, is significantly less dense than mafic rock. (A/B) Show transcribed image text. Bimodal-mafic: hosted by mixed volcanic sequences, typically with greater abundances of mafic than felsic volcanics. In general, the more felsic the magma the greater the volatile content. Mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica. The felsic lava is usually found at 650-750˚ C and is can cause explosive volcanic eruptions. (Mauna Loa, Hawaii/ Mount Fuji, Japn) 9. the spatial probability of vent opening, is presented. Mesa Lava: Made mostly of rhyolitic rock, this lava flow forms a round, biscuit-shaped body. Examples of shield volcanoes are the Hawaiian Islands. As Ni has a moderate partition factor with olivine the Ni-Cu sulfide magma needs to reach the crust with minimum olivine fractionation and sulfide segregation (Barnes and Lightfoot, 2005). Basalt and gabbro are the extrusive and intrusive names for mafic igneous rocks, and peridotite is ultramafic, with komatiite as the fine-grained extrusive equivalent. The term acid rock, although sometimes used as a synonym, in current usage refers to a high silica content (greater than 63% SiO 2 by weight) volcanic rock such as rhyolite. St. Helens in 1980. An example is the eruption of Mt. Iceland: spreading center. It can have some light color to it. Tell me all the three major types of volcanoes; (cinder cones, composite cones and shield volcanoes.) It turns out that mafic lava is high temperature lava because high temperatures are required to melt mafic minerals in the first place. Final Geology Exam Review. Igneous rock is rich in the two metals. Mafic flows erupting beneath water form bulbous masses called pillow lavas. (subduction zones/ hot spot and rift zones) 8. The fine-grained or glassy nature of many volcanic rocks makes a chemical classification such as the felsic-mafic taxonomy very useful in distinguishing the different types. Examples of mafic volcanoes - describe each. Largest type of volcano Gently sloping sides Produced by non-explosive eruptions of mafic magma Examples: mauna kea - Hawaii, Olympus Mons of Mars. Mafic lava (silica-poor; example: basalt) has low viscosity (think ketchup), which allows gas bubbles to easily escape and results in effusive eruptions, where lava pours out of the ground. Coming to the color, the rock typically exists in green or greenish-black appearance. Volcano example (Felsic) Mt. These veins are parallel to layers rich in quartz eyes (Figure 4.15) or fragmental mafic volcanic rocks (Figure 4.16). Magma collects in magma chambers in the crust at 160 kilometers (100 miles) beneath the surface of a volcano. These rocks are also rich in other minerals like oxygen, potassium and sodium. (felsic/ mafic) 2. Mafic (high iron/magnesium content) at <50% silica; Denser at 2.8 - 3.0 g/cm 3; Rocks typically dark in color; Solidifies/melts at high temperatures: 1000-1250 °C; Low viscosity of 10 1-2 Pa s (similar to ketchup) allows flows to travel long distances; Effusive eruptions flows typical (lava seeps out). These minerals are high in magnesium and ferric oxides, and their presence gives mafic rock its characteristic dark colour. Shield volcano. OTHER SETS BY THIS CREATOR. They don't have the stereotypical steep volcanic cone shape. Mafic magmas must be hot - 1270 to 1470 K - to remain liquid. 1. The escape of gases may produce tremendous force in a volcano, producing explosive eruptions. A. are more abundant in felsic lavas than mafic lavas B. are not harmful because most are less dense than air C. killed over 1,700 people at Lake Nyos, Cameroon, Africa, in 1986 Felsic rocks contain much less magnesium and iron, with proportionally more sodium, aluminum, potassium, and especially silicon. 10 terms. Mafic rock is dense, as rocks go. Felsic magmas may be as cool as 1070 K. (very/not very) 3. Volcanic cones or cinder cones result from eruptions that throw out mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. The buildup of these layers form a broad volcano with gently sloping sides called a shield volcano. When gasses escape from the eruption of a fluid mafic magma, a fountain of cinder-sized blobs results. However, some of the examples that fall into this group have a grey color. 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