Archean


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Related to Archean: archaean, Proterozoic

Ar·che·an

also Ar·chae·an  (är-kē′ən)
adj.
1. Of, relating to, or being the older of the two divisions of Precambrian time, from about 3.8 to 2.5 billion years ago, marked by an atmosphere with little free oxygen, the formation of the first rocks and oceans, and the development of unicellular life. See Table at geologic time.
2. Of, relating to, or being the oldest known rocks, those of the Precambrian Eon, that are predominantly igneous in composition.
n.
The Archean Eon. Also called Archeozoic.

[From Greek arkhaios, ancient; see archaic.]

Archean

(ɑːˈkiːən)
adj
(Geological Science) a variant spelling (esp US) of Archaean

Ar•che•an

(ɑrˈki ən)

adj.
of or pertaining to rocks of the Archeozoic portion of the Precambrian Era.
[1870–75]

Ar·che·an

(är-kē′ən)
The earlier of the two divisions of the Precambrian Eon, from about 3.8 to 2.5 billion years ago. During this time, the Earth had an atmosphere with little free oxygen, and the first single-celled life appeared. See Chart at geologic time.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.Archean - the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life
Precambrian, Precambrian aeon, Precambrian eon, Precambrian period - the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago
Adj.1.archean - of or relating to the earliest known rocks formed during the Precambrian Eon
geology - a science that deals with the history of the earth as recorded in rocks
early - at or near the beginning of a period of time or course of events or before the usual or expected time; "early morning"; "an early warning"; "early diagnosis"; "an early death"; "took early retirement"; "an early spring"; "early varieties of peas and tomatoes mature before most standard varieties"
Translations
References in periodicals archive ?
Lavigne has developed expertise in gold mineralization systems through project work and consulting assignments in SE Asia, Colombia, Peru, Mexico, the western USA, and Archean terrains in eastern and northern Canada.
Exploration during the 2014-2017 period had identified mineralized intrusions corresponding to units of the Eastern Gabbro which had intruded the Archean footwall along the eastern and northern margins of the Coldwell Complex.
Hope Bay is an 80 km by 20 km Archean greenstone belt located in Nunavut, Canada.
Some Archean VMS deposits may be transitional to volcanic-associated iron formation.
Bonterra is a gold exploration company with assets in the Archean greenstone belts in the Canadian Shield.
According to the company, the campaign will initially focus on Archean lode style gold mineralisation in the area where earlier broad spaced rock chip sampling has returned results including 66.0g/t gold and 18.45g/t gold.
"We were targeting cobalt-nickel-silver mineralization in the shallow Archean rocks when we encountered the kimberlitic material.
The strata outcropping in the section comprise of Xuzhuang, Zhangxia, Gushan, Changshan and Fengshan formations, having an angular unconformable contact with the underlying Archean metamorphic rocks and parallel unconformable contact with the overlying Ordovician Yeli Formation.
Previous research studies have put average temperatures during the Archean era, 4 to 2.5 billion years ago, as low as minus 25 degrees Celsius.
To find out, Catling's graduate student Joshua Krissansen-Totton led a study that examined the Earth's atmosphere in three stages of its existence: The Archean (4 billion to 2.5 billion years ago), the Proterozoic (2.5 billion to 541 million years ago) and the Phanerozoic (541 million years ago to the present).
This study aims to identify the role of Archean seismicity along the Cadillac-Larder Lake Fault (CLLF) on gold deposition in the Abitibi greenstone belt, Quebec, Canada.
Chennai, which included a meeting with the chairman of Archean