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Rodrigues Triple Junction
The Rodrigues Triple Junction (RTJ), also known as the Central Indian ceanTriple Junction (CITJ) is a geologic triple junction in the southern Indian Ocean where three tectonic plates meet: the African Plate, the Indo-Australian Plate, and the Antarctic Plate. The triple junction is named for the island of Rodrigues which lies north-west of it. The RTJ was first recognized in 1971, then described as a stable R-R-R (ridge-ridge-ridge) triple junction based on coarse ship data. Boundaries The boundaries of the three plates which meet at the Rodrigues Triple Junction are all oceanic spreading centers, making it an R-R-R type triple junction. They are: the Central Indian Ridge (CIR, between the African and Indo-Australian plates) with a spreading rate of 50 mm/yr; the Southwest Indian Ridge (SWIR, between the African and Antarctic plates) 16 mm/yr; and the Southeast Indian Ridge (SEIR, between the Indo-Australian and Antarctic plates) 60 mm/yr. The SEIR has the hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Plate
The Indian Plate (or India Plate) is a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian Plate broke away from the other fragments of Gondwana , began moving north and carried Insular India with it. It was once fused with the adjacent Australian Plate to form a single Indo-Australian Plate, and recent studies suggest that India and Australia have been separate plates for at least 3 million years and likely longer. The Indian Plate includes most of modern South Asia (the Indian subcontinent) and a portion of the basin under the Indian Ocean, including parts of South China and western Indonesia, and extending up to but not including Ladakh, Kohistan and Balochistan. Plate movements Until roughly , the Indian Plate formed part of the supercontinent Gondwana together with modern Africa, Australia, Antarctica, and South America. Gondwana broke up as these continents drifted apart at different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galapagos Triple Junction
The Galapagos Triple Junction is a geological area in the eastern Pacific Ocean several hundred miles west of the Galapagos Islands where three tectonic plates - the Cocos Plate, the Nazca Plate and the Pacific Plate - meet. It is an unusual type of triple junction A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can b ... in which the three plates do not meet at a simple intersection. Instead, the junction includes two small microplates, the Galapagos Microplate and the Northern Galapagos Microplate, caught in the junction, turning synchronously with respect to each other and separated by the Hess Deep rift. Introduction The Galapagos Triple Junction (GTJ) is located off the western coast of South America and has been studied for its unique geologic structure of a triple junction. Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaiian–Emperor Seamount Chain
The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about from the Aleutian Trench in the far northwest Pacific to the Kamaʻehuakanaloa Seamount (formerly Lōʻihi), the youngest volcano in the chain, which lies about southeast of the Island of Hawaiʻi. Regions The chain can be divided into three subsections. The first, the Hawaiian archipelago (also known as the ''Windward isles''), consists of the islands comprising the U.S. state of Hawaii. As it is the closest to the hots ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carlsberg Ridge
The Carlsberg Ridge is the northern section of the Central Indian Ridge, a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate, traversing the western regions of the Indian Ocean. The ridge of which the Carlsberg Ridge is a part extends northward from a triple point junction near the island of Rodrigues (the Rodrigues Triple Point) to a junction with the Owen Fracture Zone. The ridge started its northwards propagation in the late Maastrichtian and reached the incipient Arabian Sea in the Eocene. Then it continued to accrete basalt but did not propagate for nearly 30 Ma. Then, in the early Miocene it started to propagate westwards towards the Afar hot spot, opening the Gulf of Aden. The Carlsberg Ridge is seismically active, with a major earthquake being recorded by the U.S. Geological Survey at 7.6 on the moment magnitude scale on July 15, 2003. The submarine ridge was discovered by the Danish research vessel Dana during the '' Carlsberg Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seychelles Microcontinent
The Seychelles Microcontinent is a microcontinent underlying Seychelles in the western Indian Ocean made of Late Precambrian rock. The granite outcrops of the Seychelles Islands in the central Indian Ocean were amongst the earliest examples cited by Alfred Wegener as evidence for his continental drift theory. Ridge–plume interactions have been responsible for separating a thinned continental sliver from a large continent (i.e. India). The granites of the Seychelles Microcontinent were emplaced 750 Ma, during the late Precambrian. Thermally-induced rifting in the Somali Basin and transform rifting along the Davie Fracture Zone began in the late Permian, 225 million years ago. The Gondwana supercontinent began to break up in the Middle Jurassic, about 167 million years ago. At that time, East Gondwana, comprising Antarctica, Madagascar, India, and Australia, began to separate from Africa. East Gondwana then began to separate about 115–120 million years ago when India began to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East African Rift
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of a larger Great Rift Valley that extended north to Asia Minor. A narrow zone, the rift is a developing divergent tectonic plate boundary where the African Plate is in the process of splitting into two tectonic plates, called the Somali Plate and the Nubian Plate, at a rate of 6-7 mm per year. The rift system consists of three microplates, the Victoria Microplate to the north, and the Rovuma and Lwandle microplates to the south. The Victoria Microplate is rotating anti-clockwise with respect to the African plate. Its rotation is caused by the configuration of mechanically weaker and stronger lithospheric regions in the EARS. Extent A series of distinct rift basins, the East African Rift System extends over thousands of kilometers. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somali Plate
The Somali Plate is a minor tectonic plate which straddles the Equator in the Eastern Hemisphere. It is currently in the process of separating from the African Plate along the East African Rift Valley. It is approximately centered on the island of Madagascar and includes about half of the east coast of Africa, from the Gulf of Aden in the north through the East African Rift Valley. The southern boundary with the Nubian-African Plate is a diffuse plate boundary consisting of the Lwandle Plate. Geology The Arabian Plate diverges to the north forming the Gulf of Aden. The Indian Plate, Australian Plate, and Antarctic Plate all diverge from the Somali Plate forming the eastern Indian Ocean. The Somali-Indian boundary spreading ridge is known as the Carlsberg Ridge. The Somali-Australian boundary spreading ridge is known as the Central Indian Ridge. The Somali-Antarctic boundary spreading ridge is known as the Southwest Indian Ridge. The western boundary with the African Plate is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australian Plate
The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when India broke away and began moving north. Australia and Antarctica began rifting and completely separated roughly . The Australian plate later fused with the adjacent Indian Plate beneath the Indian Ocean to form a single Indo-Australian Plate. However, recent studies suggest that the two plates have once again split apart and have been separate plates for at least 3 million years and likely longer. The Australian Plate includes the continent of Australia, including Tasmania, as well as portions of New Guinea, New Zealand and the Indian Ocean basin. Scope The continental crust of this plate covers the whole of Australia, the Gulf of Carpentaria, southern New Guinea, the Arafura Sea, the Coral Sea. The continental crust also includes northwestern N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capricorn Plate
The Capricorn Plate is a proposed minor tectonic plate lying beneath the Indian Ocean basin in the southern and eastern hemispheres. The original theory of plate tectonics as accepted by the scientific community in the 1960s assumed fully rigid plates and relatively narrow, distinct plate boundaries. However, research in the late 20th and early 21st centuries suggests that certain plate junctions are diffuse across several dozen or even hundred kilometres. The Capricorn Plate is a relatively rigid piece of oceanic crust along the far western edge of the former Indo-Australian Plate. The Capricorn Plate was once joined with the Indian Plate and the Australian Plate to form the Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ..., but recent studies suggest that the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material. The magnetic variation (geomagnetic reversals) in successive bands of ocean floor parallel with mid-ocean ridges was important evidence for seafloor spreading, a concept central to the theory of plate tectonics. Measurement Magnetic anomalies are generally a small fraction of the magnetic field. The total field ranges from 25,000 to 65,000 nanoteslas (nT). To measure anomalies, magnetometers need a sensitivity of 10 nT or less. There are three main types of magnetometer used to measure magnetic anomalies: # The fluxgate magnetometer was developed during World War II to detect submarines. It measures the component along a particular axis of the sensor, so it needs to be oriented. On land, it is often oriented vertically, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triple Junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can be described according to the types of plate margin that meet at them (e.g. Fault-Fault-Trench, Ridge-Ridge-Ridge, or abbreviated F-F-T, R-R-R). Of the ten possible types of triple junction only a few are stable through time ('stable' in this context means that the geometrical configuration of the triple junction will not change through geologic time). The meeting of four or more plates is also theoretically possible but junctions will only exist instantaneously. History The first scientific paper detailing the triple junction concept was published in 1969 by Dan McKenzie and W. Jason Morgan. The term had traditionally been used for the intersection of three divergent boundaries or spreading ridges. These three divergent boundaries ideally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
