Proterozoic

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Proterozoic

[¦präd·ə·rə¦zō·ik]
(geology)
Geologic time between the Archean and Paleozoic eras, that is, from 2500 million to 550 million years ago. Also known as Algonkian.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
These Late Proterozoic ages span from 1000 - 1100 Ma (Karunjhar grey granite) to 700-800 Ma (pink and other granites).
These sediments form a down-faulted portion of the Quamby Conglomerate of Middle Proterozoic age. Gold appears to occur predominantly within the coarser sediments in association with water-worn, coarse, detrital hematite and ilmenite.Previous workers have suggested that the gold mineralisation is a fossil placer deposit.Host sediments strike north-easterly and have a northerly dip varying from 25 to 45 degrees.The pit trends sub-parallel to the western bounding fault to the Quamby Conglomerate and almost at right angles to the strike of the host stratigraphy.
This mapping identified a NE-SW trending package of Archaean to Proterozoic age quartzitic metasediment, gneiss and amphibolite, as well as numerous itabirite units containing millimetre to centimetre bands of magnetite.
The latest isotopic studies have confirmed the Proterozoic ages of Estonian granulites.