The Reykjanes Ridge is a geologically complex ridge. It is a part of the Mid-Atlantic Ridge and is marked by the inclusion of an axial high, axial volcanic ridges, and v-shaped ridges. These are not typical inclusions in the setting of a slow-spreading ridge. Most reports suggest that the reason behind the unique character of the Reykjanes Ridge is because of the mantle plume beneath Iceland. As the plume and ridge interact, there are various geological effects, including the thickening of the crust. This thickening of the crust creates the axial high on which axial volcanic ridges are situated. The involvement of the mantle plume with the ridge system is also a possible method in which v-shaped ridges are produced. However, it is more probable …show more content…
This volcanism is generally attributed to the fact that the island sits directly on top of the Mid-Atlantic Ridge. The Mid-Atlantic Ridge is a divergent plate boundary and it separates the Eurasian and North American Plates. This can be seen in Figure 1. The portion of the Mid-Atlantic Ridge of importance in this paper is seen in the red box in Figure 1. This is known as the Reykjanes Ridge. This ridge includes some of the Southwest portion of Iceland, but mostly deals with the portion of the ridge leading up to Iceland. It is defined as being between Iceland and the Bight Transform Fault near 57°N (Benediktsdóttir et al., 2012). This fault has a fracture zone that extends into crust at least 36 million years old (Reykjanes Ridge Expedition). The Reykjanes Ridge is a slow spreading ridge, with an average spreading rate of about 20 mm/year, and on average trends about 036° with a spreading direction of about 099°. This makes an average spreading obliquity of 28° (Höskuldsson et al., 2007; Searle et al., 1998). The Reykjanes Ridge is the longest oblique spreading ridge in the …show more content…
This ridge lacks and observable transform faults or major (non-transform) lateral offsets of the most recent volcanic centers. The Reykjanes Ridge is instead composed of individual axial volcanic ridges (Höskuldsson et al., 2007). The AVRs form in the axial zones of the ridge and are typically en-echelon in shape. In order to be considered an AVR, the feature must be at least 100 meters above the seafloor, and they are typically between 3 and 15km wide and 5 and 35 km in length (Höskuldsson et al., 2007). AVRs form perpendicular to the spreading direction of the ridge and oblique to the overall orientation of the Reykjanes Ridge (Benediktsdóttir et al., 2012). It is believed that most of the volcanic activity that takes place along the Reykjanes Ridge can be confined to the axial volcanic ridges. The size of an AVR has been suggested to be linked to the strength of the lithosphere (Höskuldsson et al., 2007). According to this, large AVRs would have very strong lithospheres, and small AVRs would have weaker
8.30 Describe the direction of movement of the Pacific plate during the development of the volcanic islands that comprise the
The first deformation event (D1) resulted in folding of volcanic rocks in the Wabigoon and Wawa subprovinces (Hooper and Ojakangas, 1971; Hudleston, 1976; Hudleston et al., 1987; Jirsa et al., 1992) and locally within the Quetico subprovince (Bauer, 1985b). Most D1 folds in the Wawa terrane in MN rarely display axial-planar cleavage, with Bauer (1985b), Hooper and Ojakangas (1971), Hudleston (1976), and Jirsa et al. (1992) having identified cleavage (S1) development locally in the Vermillion greenstone belt (Peterson, 2001). In the Wabigoon terrane, D1 resulted in recumbent folding that overturned the stratigraphic sequence and the first regional schistosity (Poulsen et al., 1980). S1 is generally subparallel to the layering in the metavolcanic and metasedimentary rocks, and a gneissic foliation attributed to D1 is well developed in gneissic domes (Czeck and Poulsen, 2010). Although D1 likely created significant thrust or oblique faulting, direct evidence
All of the volcanic and metasedimentary rocks are metamorphosed, whose grades are extending from greenschist to upper amphibolite, characterized by low-pressure but high-temperature (Isachsen & Bowring, 1994). The influence of basement fracture zone is reflected in the homoclinal and abruptly alternated trends of the volcanic belts, which is more frequently found in the southwestern domain of the province, while north belts show angular patterns (Fyson & Helmstaedt, 1988; Padgham,1992; Padgham & Fyson, 1992). Except for the sharp dips of the volcanics, regional-scale folds, foliations and cleavages over several successions shown in the metasedimentary rocks are studied to understand the deformation and metamorphism (Isachsen & Bowring, 1994). Fyson & Helmstaedt (1988) compare three major types of folds which are ranked by their ages and sizes from oldest, most extensive F0 to minor-sized, cleavage-foliation-associated S3 folds with intermediate type F1 between them and they suggest that the parallel trend and they suggest both foliation and folds are results of syntectonic
The Axial Seamount is an underwater volcano. In the Northeast Pacific, it is actually the most active underwater volcano. The volcano is on top of a divergent plate boundary. This volcano is on the Juan De Fuca ridge and the Pacific Plate. This volcano is one of the best-studied volcanoes along the global mid-ocean ridge (Interactive Oceans).
Anpother factor that can have an impact on the level of hazard posed by a volcano is the type of plate margin on which it occurs. Volcanoes occuring at constructive plate boundaries are usually much less violent than those occuring at destructive plate boundaries. This is because the magma produced by plates moving apart is Basic, and therefoe has a low viscosity, allowing it to flow easily. The lava is produced from a central vent or fissure and erupts regularly but not usually violently. Also,constructive plate boundaries are often found under the sea and create submarine volcanoes, such as along the Mid-Atalntic ridge, so pose few threats to humans. As a result, the hazards posed by volcanoes at constructive plat eboundaries is relatively low. However, the subduction of one plate under another at destrctive plat eboundaries can form an acidic magma chamber, due to the build up of intense heat. Acidic magma is very viscous and resisitant to flow, meaning that there is often a huge build up of pressure, which can result in very violent and dangerous eruptions involving ash and pyroclastic flow. This can pose a a serious hazard. Pyroclastic flowsa are extremely dense, containing toxic gases at very high temperatures, and can move at speeds over 100km/h. The consequences of such an unpredictable hazard can be extremely seruous
It is believed that this volcanic area was caused by a localised hot spot within the Pacific plate. A concentration of radioactive elements inside of the mantle may have caused this hot spot to develop. The hot spot is stationary so as the Pacific plate moves over it a line of volcanoes are made. This is more proof that the Earth’s crust is moving as suggested by Wegener.
The Earth’s outer crust is made up many tectonic plates that move over the surface of the planet. When the plates come collide, volcanoes will form sometime (National Ocean Service). Volcanoes can also form in the middle of a plate, where magma rises upward until it erupts on the sea floor, at what is called a “hot spot” (National Ocean Service). A hot spot is a plume of magma or molten rock that rises from within the Earth then reaches the surface forming underwater volcanoes which may grow tall enough to
The Raton-Clayton volcanic field is about 20 000 km2 in size, and has been active periodically for the past 9 million years. The area is filled with peaks, cones, and lava-capped mesas. The mesas developed as lava flowed into valleys and depressions, cooled off and formed a resistant top layer over sedimentary rocks. As the surrounding rock eroded, the lava protected the underlying stratigraphy from erosion. This caused todays topography, where that which was once the lowest point, is now the highest. There is some disagreement over why the volcanic field is here, one possible cause is that it is near the end of the Jemez Lineament, which has numerous volcanic centers along its reach, possibly
Two plates can separate to split continents apart, to form new oceans, or to enlarge existing oceans by forming new crust in giant rifts in the ocean floor. Plates can converge and collide, forming chains of volcanic islands and deep trenches in the ocean, volcanic mountain belts along coasts, or giant belts of folded mountains between continental masses. These movements and their physical consequences are studied in the branch of geology called plate
To support the theory of continental drift is through topography, surveying the floors of oceans, charts of rock magnetism, and statistics on rock ages (Trefil & Hazen, 2010). At one time scientist believed that the deep ocean floors were flat; accumulating the sediment that progressively wore away from the prehistoric landmasses (Trefil & Hazen, 2010). However, they discovered steep-walled valleys and elevated highlands. This was evidences that just as the continents are transformed and are active, so to is the seafloor (Trefil & Hazen, 2010). The Mid- Atlantic Ridge, positioned in the central part of the Atlantic Ocean, is recorded to be the longest mountain range on this planet. Volcanoes, lava flow, and earthquakes are a source of
The Axial Seamount is an active underwater submarine volcano that is located in the Northeast Pacific Ocean. The purpose of this paper is to research and examine the Axial Seamount and why it is such a natural geological phenomena. The Axial Seamount is the location of the first underwater volcano observatory, the NeMo. The Axial Seamount has had activity in the recent years of 2015, 2011, and 1998.
Magmatism refers to action and movement of magma. Magma is the molten rock that exists within the earth’s mantle, and that is in a state of constant motion resulting from the enormous amount of pressure exerted on it by the overlying layers. The earth’s crust is divided into many plates which are also in a constant state of slow motion against each other. The edges of these plates form weak points at which volcanic activity often occurs. Rifts also form edges that run down to the earth’s mantle. As such, volcanic activities often take place along these rifts. Multiple volcanic features are found along these faults which are evidence of the magmatism. Furthermore, the movement of the plates and the magma along the faults also causes the regular occurrence of earthquakes in these regions. Also, magmatism also plays an important role in the formation of the rifts. However, not all rifts experience magmatism and in some cases, some fault lines are volcanically dormant. This paper shall compare the Great East African Rift with the Rio Grande Rift to identify similarities and differences between these rift systems.
Volcanoes can be found throughout the entire world and are formed when there is a rupture in the mantle of the Earth's crust. This effect allows the output of volcanic lava, ash, and various types of gases. These tectonic plate breaks are normal, the planet Earth is divided into 17 tectonic plates and consistently move against each other forming shifts from low to high intensity. It can cause displacement of earth or water.
The gravitational stress on the volcano flanks develops large-scale on-shore and off-shore sliding, related to the activity of the rift zones. The M=7.2 earthquake at Kilauea on 1975 was probably related to strain accumulated throughout the south flank from dikes intruded in the rift zone (Swanson et al., 1976). However, the earthquake itself resulted from abrupt southward movement of the south flank across the underlying oceanic crust, activating the Hilina-Pali fault system. Such faulting not only provides a means for the flanks to adjust continuously to intrusions, but also generates the stress patterns needed to constrain future dikes to propagate along the rift axis. Therefore, rift intrusion and lateral spreading are major contributors
The new volcanic material welling up into the void, which forms a ribbon of new materials and breaks down its center gradually, when the plates move apart from the axis of the mid-oceanic ridge system. Therefore, every separating plate accretes one half a ribbon of new lithosphere, and, thus, a new surface is added (Pitman, W.C, 2007). The process is continuous, and separation is always happening at the