The Deccan Traps are a large igneous province of west-central India. They are one of the largest volcanic features on Earth,taking the form of a large shield volcano. They consist of many layers of solidified flood basalt that together are more than about 2,000 metres (6,600 ft) thick,cover an area of about 500,000 square kilometres (200,000 sq mi),and have a volume of about 1,000,000 cubic kilometres (200,000 cu mi). Originally,the Deccan Traps may have covered about 1,500,000 square kilometres (600,000 sq mi),with a correspondingly larger original volume. This volume overlies the Archean age Indian Shield,which is likely the lithology the province passed through during eruption. The province is commonly divided into four subprovinces:the main Deccan,the Malwa Plateau,the Mandla Lobe,and the Saurashtran Plateau.
An extinction event is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event,and the data chosen to measure past diversity.
Approximately 251.9 million years ago,the Permian–Triassicextinction event forms the boundary between the Permian and Triassic geologic periods,and with them the Paleozoic and Mesozoic eras. It is Earth's most severe known extinction event,with the extinction of 57% of biological families,83% of genera,81% of marine species and 70% of terrestrial vertebrate species. It is also the greatest known mass extinction of insects. It is the greatest of the "Big Five" mass extinctions of the Phanerozoic. There is evidence for one to three distinct pulses,or phases,of extinction.
The Triassic–Jurassic (Tr-J) extinction event (TJME),often called the end-Triassic extinction,marks the boundary between the Triassic and Jurassic periods,201.4 million years ago. It is one of five major extinction events,profoundly affecting life on land and in the oceans. In the seas,about 23–34% of marine genera disappeared. On land,all archosauromorph reptiles other than crocodylomorphs,dinosaurs,and pterosaurs became extinct;some of the groups which died out were previously abundant,such as aetosaurs,phytosaurs,and rauisuchids. Plants,crocodylomorphs,dinosaurs,pterosaurs and mammals were left largely untouched,allowing the dinosaurs,pterosaurs,and crocodylomorphs to become the dominant land animals for the next 135 million years.
Basalt is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling,fine-grained basalt is chemically equivalent to slow-cooling,coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example,the bulk of the plains of Venus,which cover ~80% of the surface,are basaltic;the lunar maria are plains of flood-basaltic lava flows;and basalt is a common rock on the surface of Mars.
A mantle plume is a proposed mechanism of convection within the Earth's mantle,hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths,a plume is often invoked as the cause of volcanic hotspots,such as Hawaii or Iceland,and large igneous provinces such as the Deccan and Siberian Traps. Some such volcanic regions lie far from tectonic plate boundaries,while others represent unusually large-volume volcanism near plate boundaries.
Bedout,or more specifically the Bedout High,is a geological and geophysical feature centered about 250 km off the northwestern coast of Australia in the Canning and overlying Roebuck basins. Although not obvious from sea floor topography,it is a roughly circular area about 30 km in diameter where older rocks have been uplifted as much as 4 km towards the surface and may mark the centre of a very large buried impact crater up to 250 km in diameter. The Bedout High was penetrated by two petroleum exploration wells in the 1970s and 1980s. It is named after nearby Bedout Island.
The Siberian Traps are a large region of volcanic rock,known as a large igneous province,in Siberia,Russia. The massive eruptive event that formed the traps is one of the largest known volcanic events in the last 500 million years.
A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reaching the surface of the Earth via a mantle plume. Flood basalt provinces such as the Deccan Traps of India are often called traps,after the Swedish word trappa,due to the characteristic stairstep geomorphology of many associated landscapes.
A large igneous province (LIP) is an extremely large accumulation of igneous rocks,including intrusive and extrusive,arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs in the past 500 million years coincide in time with mass extinctions and rapid climatic changes,which has led to numerous hypotheses about causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems.
Wilkes Land crater is an informal term that may apply to two separate cases of conjectured giant impact craters hidden beneath the ice cap of Wilkes Land,East Antarctica. These are distinguished by the names Wilkes Land anomaly and Wilkes Land mascon (mass concentration),based on terms used in their principal published reference sources.
The Emeishan Traps constitute a flood basalt volcanic province,or large igneous province,in south-western China,centred in Sichuan province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Like other volcanic provinces or "traps",the Emeishan Traps are multiple layers of igneous rock laid down by large mantle plume volcanic eruptions. The Emeishan Traps eruptions were serious enough to have global ecological and paleontological impact.
Ocean island basalt (OIB) is a volcanic rock,usually basaltic in composition,erupted in oceans away from tectonic plate boundaries. Although ocean island basaltic magma is mainly erupted as basalt lava,the basaltic magma is sometimes modified by igneous differentiation to produce a range of other volcanic rock types,for example,rhyolite in Iceland,and phonolite and trachyte at the intraplate volcano Fernando de Noronha. Unlike mid-ocean ridge basalts (MORBs),which erupt at spreading centers (divergent plate boundaries),and volcanic arc lavas,which erupt at subduction zones (convergent plate boundaries),ocean island basalts are the result of intraplate volcanism. However,some ocean island basalt locations coincide with plate boundaries like Iceland,which sits on top of a mid-ocean ridge,and Samoa,which is located near a subduction zone.
The Capitanian mass extinction event,also known as the end-Guadalupian extinction event,the Guadalupian-Lopingian boundary mass extinction,the pre-Lopingian crisis,or the Middle Permian extinction,was an extinction event that predated the end-Permian extinction event. The mass extinction occurred during a period of decreased species richness and increased extinction rates near the end of the Middle Permian,also known as the Guadalupian epoch. It is often called the end-Guadalupian extinction event because of its initial recognition between the Guadalupian and Lopingian series;however,more refined stratigraphic study suggests that extinction peaks in many taxonomic groups occurred within the Guadalupian,in the latter half of the Capitanian age. The extinction event has been argued to have begun around 262 million years ago with the Late Guadalupian crisis,though its most intense pulse occurred 259 million years ago in what is known as the Guadalupian-Lopingian boundary event.
Michael R. Rampino is a Geologist and Professor of Biology and Environmental Studies at New York University,known for his scientific contributions on causes of mass extinctions of life. Along with colleagues,he's developed theories about periodic mass extinctions being strongly related to the earth's position in relation to the galaxy. "The solar system and its planets experience cataclysms every time they pass "up" or "down" through the plane of the disk-shaped galaxy." These ~30 million year cyclical breaks are an important factor in evolutionary theory,along with other longer 60-million- and 140-million-year cycles potentially caused by mantle plumes within the planet,opining "The Earth seems to have a pulse," He is also a research consultant at NASA's Goddard Institute for Space Studies (GISS) in New York City.
The Madagascar flood basalt,also known as the Madagascar large igneous province (LIP),is one of the major magmatic events of the Late Cretaceous. They cover a large area of basaltic and rhyolitic lava flows that erupted during an episode of widespread basaltic volcanism during the Cretaceous period. The flood basalts are characterized by lava flows,dykes,sills,and intrusions,and other volcanic features include plugs,scoria,and spatter cones. Tholeiitic basalt constitutes the primary rock type.
Intraplate volcanism is volcanism that takes place away from the margins of tectonic plates. Most volcanic activity takes place on plate margins,and there is broad consensus among geologists that this activity is explained well by the theory of plate tectonics. However,the origins of volcanic activity within plates remains controversial.
Peter H. Barry is an American geochemist who is an associate scientist in the marine chemistry and geochemistry department at the Woods Hole Oceanographic Institution. He uses noble gases and stable isotopes to understand the volatile history and chemical evolution of Earth,including the dynamic processes of subduction,mantle convection and surface volcanism,which control the redistribution of chemical constituents between the crust and mantle reservoirs. Barry’s main research focus has been on high-temperature geochemistry,crust-mantle interactions and the behavior of volatile fluids in the lithosphere. He also studies crustal systems,the origin of high helium deposits,including hydrocarbon formation and transport mechanisms.
