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__NOTOC__ The Plottier Formation is a geologic formation that outcrops in the Argentine Patagonian provinces of Río Negro and Neuquén. It is the younger of two formations belonging to the Río Neuquén Subgroup within the Neuquén Group, with the oldest rocks dating from the late Coniacian and its youngest maybe from the very start of the Santonian. Formerly that subgroup was treated as a formation, and the Plottier Formation was known as the Plottier Member.〔Sánchez ''et al.'' (2006)〕 A section near the Neuquén City airport, north of the town of Plottier, is the type locality of the Plottier Formation.〔Fossa Mancini ''et al.'' (1938)〕 At its base, this formation grades into the Portezuelo Formation, and it is in turn overlain conformably by the Bajo de la Carpa Formation, a unit of the Río Colorado Subgroup. The Plottier Formation is the smallest formation within the Neuquén Group, with a maximum thickness of only 25 meters. It is differentiated from the underlying Portezuelo Formation primarily by its higher content of argillites (mud deposits) and was deposited under fluvial conditions. In 2006, a detailed lithostratigraphic and paleoecological study of a section of the Plottier Formation was published. This section contained alluvial deposits laid down by what was essentially a low-gradient wandering river throughout the millions of years, but often was of a single-channel type with little meandering.〔Leanza ''et al.'' (2004), Sánchez ''et al.'' (2006)〕 ==Age== Era: Mesozoic Period: Late Cretaceous Faunal stage: late Coniacian – ?early Santonian Absolute Age: ~88 to ~86 mya 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「Plottier Formation」の詳細全文を読む スポンサード リンク
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