Siberian Traps

Coordinates: 67°N 90°E / 67°N 90°E / 67; 90 Coordinates: 67°N 90°E / 67°N 90°E / 67; 90 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 known volcanic events in the last 500 million years. The eruptions continued for roughly two million years and spanned the P–T boundary, or the Permian–Triassic boundary, which occurred between 251 to 250 million years ago. Large volumes of basaltic lava covered a large expanse of Siberia in a flood basalt event. Today, the area is covered by about 7 million km2 (3 million sq mi) of basaltic rock, with a volume of around 4 million km3 (1 million cu mi). The source of the Siberian Traps basaltic rock has been attributed to a mantle plume, which rose until it impacted against the bottom of the Earth's crust, producing volcanic eruptions through the Siberian Craton. It has been suggested that, as the Earth's lithospheric plates moved over the mantle plume (the Iceland plume), the plume produced the Siberian Traps in the Permian and Triassic periods, later going on to produce volcanic activity on the floor of the Arctic Ocean in the Jurassic and Cretaceous, and then generating volcanic activity in Iceland. Other plate tectonic causes have also been suggested. Another possible cause may be the impact that formed the Wilkes Land crater in Antarctica, which is estimated to have occurred around the same time and been nearly antipodal to the traps. The main source of rock in this formation is basalt, but both mafic and felsic rocks are present, so this formation is officially called a Flood Basalt Province. The inclusion of mafic and felsic rock indicates multiple other eruptions that occurred and coincided with the one-million-year-long eruption that created the majority of the basaltic layers. The traps are divided into sections based on their chemical, stratigraphical, and petrographical composition. One of the major questions is whether the Siberian Traps were directly responsible for the Permian–Triassic mass extinction event that occurred 250 million years ago, or if they were themselves caused by some other, larger event, such as an asteroid impact. A recent hypothesis put forward is that the volcanism triggered the growth of Methanosarcina, a microbe that then spewed enormous amounts of methane into Earth's atmosphere, ultimately altering the Earth's carbon cycle based on observations such as a significant increase of inorganic carbon reservoirs in marine environments. This extinction event, also called the Great Dying, affected all life on Earth, and is estimated to have killed about 95% of all species living at the time. Some of the disastrous events that impacted the Earth continued to repeat themselves on Earth five to six million years after the initial extinction occurred. Over time a small portion of the life that survived the extinction was able to repopulate and expand starting with low trophic levels (local communities) until the higher trophic levels (large habitats) were able to be re-established. Calculations of sea water temperature from δ18O measurements indicate that at the peak of the extinction, the Earth underwent lethally hot global warming, in which equatorial ocean temperatures exceeded 40 °C (104 °F). It took roughly eight to nine million years for any diverse ecosystem to be re-established; however, new classes of animals were established after the extinction that did not exist beforehand. Palaeontological evidence further indicates that the global distribution of tetrapods vanished, with very rare exceptions in the region of Pangaea that is today Utah, between latitudes bounded by approximately 40°S to 30°N. The tetrapod gap of equatorial Pangaea coincides with an end-Permian to Middle Triassic global 'coal gap' that indicates the loss of peat swamps. Peat formation, a product of high plant productivity, was reestablished only in the Anisian stage of the Triassic, and even then only in high southern latitudes, although gymnosperm forests appeared earlier (in the Early Spathian), but again only in northern and southern higher latitudes. In equatorial Pangaea, the establishment of conifer-dominated forests was not until the end of the Spathian, and the first coals at these latitudes did not appear until the Carnian, around 15 million years after their end-Permian disappearance. These signals suggest equatorial temperatures exceeded their thermal tolerance for many marine vertebrates at least during two thermal maxima, whereas terrestrial equatorial temperatures were sufficiently severe to suppress plant and animal abundance during most of the Early Triassic.