Product Code Database
Pannotia (from Greek: , "all", , "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny (650–500 Megaannum), during the Cryogenian period and broke apart 560 Ma with the opening of the Iapetus Ocean, in the late Ediacaran and early Cambrian. Pannotia formed when Laurentia was located adjacent to the two major South American , Amazonian craton and Río de la Plata. The opening of the Iapetus Ocean separated Laurentia from Baltica, Amazonia, and Río de la Plata. A 2022 paper argues that Pannotia never fully existed, reinterpreting the geochronology evidence: "the supposed landmass had begun to break up well before it was fully assembled". However, the assembly of the next supercontinent Pangaea is well established.
The existence of a late Proterozoic supercontinent, much different from Pangaea, was first proposed by based on Paleomagnetism data, and the break-up of this supercontinent around 625–550 Ma was documented by . The reconstruction of Bond et al. is virtually identical to that of and others.
Another term for the supercontinent that is thought to have existed at the end of Neoproterozoic time is "Greater Gondwanaland", suggested by . This term recognizes that the supercontinent of Gondwana, which formed at the end of the Neoproterozoic, was once part of the much larger Neoproterozoic supercontinent.
Pannotia was named by , based on the term "Pannotios" originally proposed by for "the cycle of tectonic activity common to the Gondwana continents that resulted in the formation of the supercontinent."; proposed renaming the older Proterozoic supercontinent (now known as Rodinia) "Kanatia", the St. Lawrence Iroquoian word from which the name Canada is derived, while keeping the name Rodinia for the latter Neoproterozoic supercontinent (now known as Pannotia). Powell, however, objected to this renaming and instead proposed Stump's term for the latter supercontinent.
When Pannotia had formed, Africa was located at the centre surrounded by the rest of Gondwana: South America, Arabia, Madagascar, India, Antarctica, and Australia. Laurentia, which 'escaped' out of Rodinia, Baltica, and Siberia kept the relative positions they had in Rodinia. The Cathaysia and Cimmerian terranes (continental blocks of southern Asia) were located along the northern margins of east Gondwana. The -Cadomian Orogeny terranes (later to become central Europe, Britain, the North American east coast, and Yucatán) were located along the active northern margins of western Gondwana. This orogeny probably extended north into the Ural Mountains margin of Baltica.
Pannotia formed by subduction of exterior oceans (a mechanism called extroversion) over a geoid low, whereas Pangaea formed by subduction of interior oceans (introversion) over a geoid high perhaps caused by and slab avalanche events. The oceanic crust subducted by Pannotia formed within the Mirovia superocean that surrounded Rodinia before its 830–750 Ma break-up and were accreted during the late Proterozoic orogeny that resulted from the assembly of Pannotia.
One of the major of these orogenies was the collision between eastern and western Gondwana or the East African Orogeny. The Trans-Saharan Belt in West Africa is the result of the collision between the East Saharan Shield and the West African Craton when 1200–710 Ma volcanic and arc-related rocks were accreted to the margin of this craton. Between 600 and 500 Ma, two Brazilian interior orogens were highly deformed and metamorphosed between a series of colliding cratons: Amazonian craton, West Africa-São Luís, and São Francisco-Congo craton-Kasai Craton. The material that accreted included, 950–850 Ma, mafic meta-igneous complexes and younger arc-related rocks.
The Iapetus Ocean started to open while Pannotia was being assembled, 200 Ma after the break-up of Rodinia. This opening of the Iapetus and other Cambrian seas coincided with the first steps in the evolution of soft-bodied metazoans, and also made a myriad of habitats available for them; this led to the so-called Cambrian explosion, the rapid evolution of skeletalized metazoans.
originated in the Neoproterozoic and began to diversify before the break-up of Pannotia 600–550 Ma, as evidenced by their ubiquitous presence in the fossil record, and the lack of vicariance patterns in their lineage.
|
|
