TheMesoproterozoic Era[4] is ageologicera that occurred from1,600 to 1,000 million years ago. The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (thePaleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, although their arrangement on the Earth's surface was different.
This era is marked by the further development of continental plates andplate tectonics. The supercontinent of Columbia broke up between 1500 and 1350 million years ago,[5] and the fragments reassembled into the supercontinent of Rodinia around 1100 to 900 million years ago, on the time boundary between the Mesoproterozoic and the subsequentNeoproterozoic.[7] These tectonic events were accompanied by numerousorogenies (episodes ofmountain building) that included theKibaran orogeny in Africa;[8] theLate Ruker orogeny in Antarctica;[9] theGothian[10] andSveconorwegian orogenies in Europe;[11] and thePicuris andGrenville orogenies in North America.[12]
The era saw the development of sexual reproduction, which greatly increased the complexity of life to come and signified the start of development of truemulticellular organisms.[6][13] Though the biota of the era was once thought to be exclusively microbial, recent finds have shown multicellular life did exist during the Mesoproterozoic.[14][6] This era was also the high point of thestromatolites before they declined in theNeoproterozoic.[15]
The subdivisions of the Mesoproterozoic are arbitrary divisions based on time. They are not geostratigraphic or biostratigraphic units. The decision to base the Precambrian time scale on radiometric dating reflects the sparse nature of the fossil record, and Precambrian subdivisions of geologic time roughly reflect major tectonic cycles. It is possible that future revisions to the time scale will reflect more "natural" boundaries based on correlative geologic events.[16]
The Mesoproterozoic is presently divided into theCalymmian (1600 to 1400 Mya) and theEctasian (1400 to 1200 Mya), and theStenian (1200 to 1000 Mya). The Calymmian and Ectasian were characterized by stabilization and expansion of cratonic covers and the Stenian by formation of orogenic belts.[16]
The time period from 1780 Ma to 850 Ma, an unofficial period based onstratigraphy rather thanchronometry, named theRodinian, is described in the geological timescale review 2012 edited by Gradstein et al.,[17] but as of February 2017[update], this has not yet been officially adopted by theInternational Union of Geological Sciences (IUGS).
^Andesson, Jenny; Bingen, Bernard; Cornell, David; Johansson, Leif; Möller, Charlotte (2008). "The Sveconorwegian orogen of southern Scandinavia: setting, petrology and geochronology of polymetamorphic high-grade terranes".33 IGC excursion No 51, August 2 – 5.
^Troppenz, Uwe-Michael; Littkowski, Sven (3 May 2019)."The Mesoproterozoic – no "boring billion""(PDF).Iranian Journal of Earth Sciences.11 (4):239–243. Retrieved25 November 2022.
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