8/28/2019 1643

Allibashi (The Permian-Triassic boundary) geosite

There are few places in the world where we can go back in time and observing history of the planet Earth and its landmark event. One of these places is Alli-bashi located in west of Aras geopark and could take us back to 252 million years ago. The Paleozoic-Mesozoic boundary is characterized by one of the most significant events throughout the Earth's history that was the mass extinction of the most biological species on the planet. Continuity of the sedimentary sequence in this area that preserved the story of Late Permian could evaluate only when we know that the sedimentary sequence of the earth includes stratigraphic gaps more than record and the stratigraphic column of the most parts in the world have missing strata.

Mass extinction occurred in Permian-Triassic boundary made it one the most important events in the Earth's history which wind up Paleozoic Period and incepted new Period named Mesozoic. The sedimentary rocks contain this timeline a little have preserved in the outcrops. Little Caucasus and Alli-bashi mountains are among the few places where the Permian-Triassic boundary is observable that scientifically has very important implications.

Since its emersion, the life on the Earth has undergone five major mass extinctions, among which Permian end extinction was the largest, leading to significant changes on the earth. Occurring 252 Mya, has extinct 96% of all marine species, and 70% of land vertebrates. Approximately 99% of all the species emerged from the beginning life on the planet now have extinct forever.

Because of End Permian Extinction, lasting a few million years- and not suddenly- most of the species has extinct, therefore it took a long time before life find its diversity again. Presumably, it occurred due to long-lasting vast volcanic eruptions together with poisoned gases in atmosphere which resulted in suffocation of living creatures as well as global warming. It appears that if there were no tropical plants in that time to absorb and consume the large volume of carbon dioxide released from the vast volcanism, the life would never come back to our planet. What potentially happened to planet Venus.

In the Late Permian, Aras geopark area was a part of Paleo-Tethys sea floor in the northern edge of Central Iran micro-plate; about 5000 km south of the present day location and below the equator. Transition from Permian to Triassic, in this area, is continuous there and the sedimentary bed specifying the boundary in the Alli-bashi area, with a thickness about one meter, is a mudstone between red limestone bed with paratirolites ammonite and a limestone bed with worm trace from Triassic Elika formation on the top.