Stenian

The Stenian Period (/ˈstiːni.ən/ STEE-nee-ən, from Ancient Greek: στενός, romanized: stenós, meaning "narrow") is the final geologic period in the Mesoproterozoic Era and lasted from 1200 Mya to 1000 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The name derives from narrow polymetamorphic belts formed over this period. It is preceded by the Ectasian Period and followed by the Neoproterozoic era and the Tonian period.

Stenian

1200 – 1000 Ma

Pha.

Proterozoic

Archean

Had.

Paleoglobe of Earth during the late Stenian, c. 1040 Ma^{[citation needed]}

Chronology

−1220 —

–

−1200 —

–

−1180 —

–

−1160 —

–

−1140 —

–

−1120 —

–

−1100 —

–

−1080 —

–

−1060 —

–

−1040 —

–

−1020 —

–

−1000 —

–

−980 —

Mesoproterozoic

Np

Ectasian

Stenian

Tonian

←

First appearance of Bangiomorpha pubescens

←

Large-scale mountain-building from continent-continent collision of the Grenvillian orogeny

←

Development of the North American Midcontinent Rift

Events of the Stenian Period
Vertical axis scale: Millions of years ago

Etymology

Name formality

Formal

Usage information

Celestial body

Earth

Regional usage

Global (ICS)

Time scale(s) used

ICS Time Scale

Definition

Chronological unit

Period

Stratigraphic unit

System

Time span formality

Formal

Lower boundary definition

Defined chronometrically

Lower GSSA ratified

1990

Upper boundary definition

Defined chronometrically

Upper GSSA ratified

1990

The supercontinent Rodinia assembled during the Stenian. It would last into the Tonian period before breaking up in the Cryogenian.

This period includes the formation of the Keweenawan Rift at about 1100 Mya.

Fossils of the oldest known sexually reproducing organism, Bangiomorpha pubescens, first appeared in the Stenian.

Stenian

See also

Further reading