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Variant of Archean.


(Biology) any member of the Archaea, a domain of prokaryotic microorganisms, distinguished from bacteria on molecular phylogenetic grounds and often found in hostile environments, such as volcanic vents and hot springs


(ɑːˈkiːən) or


(Geological Science) of or relating to the highly metamorphosed rocks formed in the early Precambrian era
(Geological Science) the earlier of two divisions of the Precambrian era, during which the earliest forms of life are assumed to have appeared
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.archaean - 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"
References in periodicals archive ?
The drilled part of the Archaean complex (6842-12261 m) is composed of biotite-plagioclase and biotite-amphibole-plagioclase gneisses with high-calcium minerals, gneisses with high-alumina minerals, amphibolites and meta-ultrabasite, pegmatites and granites (Mitrofanov, 1991).
4 billion years old and occurs as a steeply dipping body of rock along the margin of the Wyoming Archaean Province, The exposed stratigraphic thickness of these rock units is around 20K ft.
recA-like genes from three archaean species with putative protein products similar to Rad51 and Dmel proteins of the yeast Saccharomyces cerevisiae.
All of the kimberlites were intruded approximately 390 Ma ago into Proterozoic crystalline rocks, presumed to be underlain by Archaean basement of the Wyoming Province.
These are part of the late Archaean age Kavirondian Group.
The Company s projects are all located in the Archaean Yilgarn Craton in WA, a world class gold province which has been a prolific producer of gold since the late 1880 s and includes the Kalgoorlie Golden Mile deposit which has produced over 50 million ounces of gold since discovery in 1893.
84 km a t ectonic boundary between rock complexes of Archaean and Proterozoic age is located (Kozlovsky, 1987).
The rocks affected by the Panafrican orogenies cover larger outcropping areas than the Archaean and the Lower Proterozoic rocks in Africa.
The genes resemble closely those of other archaea, but subtle differences in their DNA sequences indicate that they belong to new members of the archaean family, say the biologists.
The mineralization is of the hydrothermal alteration type, hosted in a large shear zone in Archaean metamorphosed rocks.
Its titles cover a strike of some 60 km of Archaean greenstone belt 5-15 km wide.
During that ancient terrestrial period, known as the Archaean era, Earth's crust had not yet divided into distinct plates and life forms were extremely primitive.