Archean

Olson, J. S. In The Carbon Cycle and Atmospheric CO2 Natural Variations Archean to Present Sundquist, E. T. Broecker, W. S., Eds. Geophysical Monograph 32 American Geophysical Union Washington DC, 1985 pp. 377-396. 

Archean 3.8 Gyr Origin of life prokaryotes flourish. Photosynthetic cells liberate oxygen, O2 first appears in the atmosphere... 

Barret, J.J., Faraick, W. and Jarvis, I. (1988) Rare-earth element geochemistry of some Archean iron formations north of Lake Superior, Ontario. Can. J. Earth Sci., 25, 570-586. 

Des Marais, D.J. (1985) Carbon exchange between the mantle and crust, and its effect upon the atmosphere Today compared to Archean time. In Sundquist, E.T. and Broecker, W.S. (eds.), The Carbon Cycle and Atmosphere CO2 Natural Variations Archean to Present. Washington, D.C. Am. Geophysical Union, pp. 602-611. 

Barth MG, Foley SF, Horn 1 (2002) Partial melting in Archean subduction zones constraints from experimentally determined trace element partition coefficients between eclogitic minerals and tonahtic melts under upper mantle conditions. Precamb Res 113 323-340... 

Olafsson M, Eggler DH (1983) Phase relations of amphibole, amphibole-carbonate, and phlogopite-carbonate peridohte petrologic constraints on the asthenosphere. Earth Planet Sci Lett 64 305-315 Olson P, Schubert G, Anderson C, Goldman P (1988) Plume formahon and lithosphere erosion a comparison of laboratory and numerical experiments. J Geophys Res 93 15065-15084 Pearson DG, Shirey SB, Carlson RW, Boyd FR, Nixon PH (1995) Stabilisahon of Archean lithospheric manhe A Re-Os isotope isotope study of peridohte xenoliths. Earth Planet Sci Lett 134 341-357... 

Thiel K, Vorwerk R, Saager R, Stupp HD (1983) U fission tracks and U-series diseqttilibria as a means to study recent mobilization of ttranittm in archean pyritic conglomerates. Earth Planet Sci Lett 65 249-262... 

Walker ICG, Klein C, Schidlowski M, Schopf 1W, Stevenson DJ, Walter MR (1983) Environmental Evolution of the Archean-Early Proterozoic Earth. In Schopf 1W (Ed.) Earth s Earliest Biosphere Its Origin and Evolution. Princeton University Press, Princeton pp 260-290 Weinberg S (1977) The First Three Minutes. A Modern View of the Origin of the Universe. Basic Books, New York... 

Canfield, D.E., Habicht, K.S. and Thamdrup, B. (2000). The Archean sulphur cycle and the early history of atmospheric oxygen. Science, 288, 658-661... 

Among the oldest rocks on Earth are those on Isua, an island off the coast of Greenland they are 3.8 Gyr old, formed some 0.7 Gyr after accretion of the Earth. The rocks mark the beginning of the Archean period of geological time. The Isua rocks suggest that there was an extensive hydrosphere at this time, with erosion, transportation and deposition of minerals from water solution. The oldest lunar rocks, however, record an earlier high-temperature event - the Earth-Moon capture event. 

Crowflight Minerals Inc. The ore deposit consists of Aphebian ultramafic sills intruded into Archean gneisses (Wardrop 2008). Rougher tails were produced from lock cycle testing of bulked drill core samples. 

Fig.1. Geology of the Lac Cinquante region shows Archean (green rocks) and ProterozOc rocks (yellow, grey, brown, and pink) separated by an unconformity (dashed line). The location of the two major zones of mineralization, the main zone and south zone, documented by Miller et al. (1987) are noted on the map.

Bulk rock geochemistry of the Lac Cinquante deposit shows that the Archean volcanic rocks (both the mafic volcanic flows and the bimodal volcanic suite) are dominantly tholeiitic high-Fe basalts and basaltic andesites. The alternating felsic units in the bimodal suite are dacitic and rhyolitic in composition (Fig. 2). 

The Dumas Formation is uncomformably overlying the Archean Superior Province. It hosts metasediments and intercalated iron formations, as well as peridotite and gabbro bodies, which were identified and separated with the help of both Band ratio and Principal Component Analysis. 

Another similar origin deposit is Lac des files in Canada. This complex is apparently contrary to a somewhat general rule in that of intrusion and is regarded as Archean age and may be therefore intruded prior to the Kenora origin into a technically unstable environment. 

Table 5.23. Pb isotope composition of Archean granites from Zimbabwe (courtesy...

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