The Emeishan Traps constitute a

flood basalt A flood basalt (or plateau 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 reac ...

volcanic province, or

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

, in south-western China, centred in

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of t ...

province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Like other

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plat ...

provinces or " traps", the Emeishan Traps are multiple layers of

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

laid down by large

mantle plume 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 hot ...

volcanic eruptions. The Emeishan Traps eruptions were serious enough to have global

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

and

paleontological Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

impact. It is named for Emeishan, a mountain in Sichuan.

Etymology

The term "

trap A trap is a mechanical device used to capture or restrain an animal for purposes such as hunting, pest control, or ecological research. Trap or TRAP may also refer to: Art and entertainment Films and television * ''Trap'' (2015 film), Fil ...

" has been used in

geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...

since 1785–1795 for such

rock formation A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term ''rock formation'' can also refer to specific sedime ...

s. It is derived from the Swedish word for stairs ("trappa") and refers to the step-like hills forming the landscape of the region.

Formation and development

The eruptions that produced the Emeishan Traps began 265 million years ago (Ma) or earlier. The main eruptive period is between 262 and 261 Ma, and the volcanism activities end 259 Ma. In volume, the Emeishan Traps are dwarfed by the massive

Siberian Traps The Siberian Traps (russian: Сибирские траппы, Sibirskiye trappy) is 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 ...

, which occurred, in terms of the

geological time scale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochro ...

, not long after, at approximately 252 Ma. The Emeishan

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

s covers an area of more than 250,000 km² with thicknesses ranging from several hundred meters up to 5.5 km (the average flood basalt thickness throughout the entire region is estimated to be around 700 m), but the Emeishan traps may have initially covered an area as much as 500,000 km². Thus the entire volume of the Emeishan basalts is estimated to be 300,000 km³. Evidence suggests that the initial volcanism of the central Emeishan Traps occurred in a deep submarine environment without any significant prevolcanic uplift. The Emeishan Traps are associated with the end-

Capitanian mass extinction event The Capitanian mass extinction event, also known as the end-Guadalupian extinction event or the pre-Lopingian crisis was an extinction event that predated the end-Permian extinction event and occurred around 260 million years ago during a period ...

, the extinction of

animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...

and

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

life that occurred at the end of the

Capitanian In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between and million years ago. It was preceded by ...

stage of the Guadalupian

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided ...

of the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...

period. Limestone within the traps show the extinction to occur immediately below the first eruptive unit, with the mass extinction marked at the onset of explosive Emeishan volcanism. The formation of volcaniclastics suggest violent phreatomagmatic-style eruptions. The synchrony between the Emeishan Traps and the

end-Guadalupian extinction The Capitanian mass extinction event, also known as the end-Guadalupian extinction event or the pre-Lopingian crisis was an extinction event that predated the end-Permian extinction event and occurred around 260 million years ago during a period ...

has been taken to support the argument of

Vincent Courtillot Vincent E. Courtillot (born 6 March 1948) is an emeritus French geophysicist, prominent among the researchers who are critical of the hypothesis that impact events are a primary cause of mass extinction of life forms on the Earth. He is known for ...

and others that volcanism is the main driver of mass extinctions.

References

;Citations: ;Bibliography: * * * * Koeberl, Christian, and Francisca C. Martinez-Ruiz, eds. (2003) ''Impact Markers in the Stratigraphic Record.'' New York, Springer-Verlag. * Yuen, David A., Shinegoru Maruyama, Shun-Ichiro Karato, and Brian F. Windley, eds. (2007) ''Superplumes: Beyond Plate Tectonics.'' New York, Springer-Verlag.

External links

Age of the Emeishan Flood Magmatism and Relations to Permian-Triassic Boundary Events.

- "Re-evaluating plume-induced uplift in the Emeishan large igneous province"
Science
- "Volcanism, Mass Extinction, and Carbon Isotope Fluctuations in the Middle Permian of China" {{Large igneous provinces Large igneous provinces Permian volcanism Geography of Sichuan Volcanism of China

Etymology

Formation and development

See also

References

External links