The Mesoproterozoic Era is a

geologic Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

era An era is a span of time. Era or ERA may also refer to: * Era (geology), a subdivision of geologic time * Calendar era Education * Academy of European Law (German: '), an international law school * ERA School, in Melbourne, Australia * E ...

that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the

Paleoproterozoic The Paleoproterozoic Era (also spelled Palaeoproterozoic) is the first of the three sub-divisions ( eras) of the Proterozoic eon, and also the longest era of the Earth's geological history, spanning from (2.5–1.6 Ga). It is further sub ...

), 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.

Major events and characteristics

The major events of this era are the breakup of the Columbia supercontinent, the formation of the

Rodinia Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago (Ga) and broke up 750–633 million years ago (Ma). wer ...

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...

, and the evolution of

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

. This era is marked by the further development of continental plates and

plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

. The supercontinent of Columbia broke up between 1500 and 1350 million years ago, 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 subsequent

Neoproterozoic The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...

. These tectonic events were accompanied by numerous

orogenies Orogeny () is a mountain-building process that takes place at a convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involv ...

(episodes of

mountain building Mountain formation occurs due to a variety of geological processes associated with large-scale movements of the Earth's crust (List of tectonic plates, tectonic plates). Fold (geology), Folding, Fault (geology), faulting, Volcano, volcanic acti ...

) that included the

Kibaran orogeny The Kibaran orogeny is a term that has been used for a series of orogenic events, in what is now Africa, that began in the Mesoproterozoic, around 1400 Ma and continued until around 1000 Ma when the supercontinent Rodinia was assembled. The term " ...

in Africa; the

Late Ruker orogeny The Late Ruker orogeny, also known as the Nimrod orogeny, was a mountain building event around 1 billion years ago in the Proterozoic. Large portions of West Antarctica were added to the continent during this event. The orogeny was marked by subs ...

in Antarctica; the Gothian and Sveconorwegian orogenies in Europe; and the Picuris and Grenville orogenies in North America. The era saw the development of sexual reproduction, which greatly increased the complexity of life to come and signified the start of development of true

multicellular organisms A multicellular organism is an organism that consists of more than one cell, unlike unicellular organisms. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and pa ...

. Though the biota of the era was once thought to be exclusively microbial, recent finds have shown multicellular life did exist during the Mesoproterozoic. This era was also the high point of the

stromatolites Stromatolites ( ) or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria) ...

before they declined in the

Subdivisions

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. The Mesoproterozoic is presently divided into the

Calymmian The Calymmian Period (from , meaning "cover") is the first geologic period in the Mesoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The peri ...

(1600 to 1400 Mya) and the

Ectasian The Ectasian Period (from , meaning "extension") is the second geologic period in the Mesoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. Geol ...

(1400 to 1200 Mya), and the

Stenian The Stenian Period ( , from , meaning "narrow") is the final geologic period in the Mesoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The name ...

(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. The time period from 1780 Ma to 850 Ma, an unofficial period based on

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

rather than

chronometry Chronometry or horology () is the science studying the measurement of time and timekeeping. Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. ''Hor ...

, named the Rodinian, is described in the geological timescale review 2012 edited by Gradstein et al., but , this has not yet been officially adopted by the

International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to global cooperation in the field of geology. As of 2023, it represents more than 1 million geoscientists around the world. About Fo ...

(IUGS).

References

External links

Mesoproterozoic (chronostratigraphy scale)
{{Authority control Geological eras

Major events and characteristics

Subdivisions

See also

References

External links