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Panthalassa (Greek πᾶν "all" and θάλασσα "ocean"〔(【引用サイトリンク】url=http://www.etymonline.com/index.php?term=Panthalassa&allowed_in_frame=0 )〕), also known as the Panthalassic Ocean, was the vast global ancestral Pacific ocean that surrounded the supercontinent Pangaea, during the late Paleozoic and the early Mesozoic eras. It included the Pacific Ocean to the west and north and the Tethys Ocean to the southeast. It became the Pacific Ocean, following the closing of the Tethys basin and the breakup of Pangaea, which created the Atlantic, Arctic, and Indian Ocean basins. The Panthalassic is often called the Paleo-Pacific ("old Pacific") because the Pacific Ocean developed from it in the Mesozoic to the present. In the map shown here, the Earth's equator was a line that roughly crossed the spot where Spain, Casablanca (Morocco) and Boston (U.S.) met. South of that line, the land mass is referred to as Gondwana. North of the line, it is referred to as Laurasia. In the map, the Panthalassa Ocean is depicted as an empty ocean. Plate tectonic studies〔 have argued that during the Paleozoic and Mesozoic small fragments, or terranes (currently preserved at the North American and Asian margins), were drifting across the ocean plate until they accreted at the surrounding continental margins. ==Formation== By 900 million years ago (in the early Neoproterozoic) a triple junction formed as the supercontinent Rodinia started to rift apart. Between about 800 million and 700 million years ago Rodinia split in half in a significant rifting event which opened up the Panthalassic Ocean to the west of Laurentia, a continent that became North America. In western Laurentia (North America), a tectonic episode that preceded this rifting produced failed rifts that harbored large depositional basins in Western Laurentia. The global ocean of Mirovia, an ocean that surrounded Rodinia, started to shrink as the Pan-African ocean and Panthalassa expanded. Between 650 million and 550 million years ago, another supercontinent started to form: Pannotia, which was shaped like a "V". Inside the "V" was Panthalassa, outside of the "V" were the Pan-African Ocean and remnants of the Mirovia Ocean. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Panthalassa」の詳細全文を読む スポンサード リンク
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