Ore Genesis

General. Emphasized in this section are sulfide ore bodies and natural solutions which are normally not radioactive. Uranium deposits are not included because they generally do not contain common lead and few data are yet available on other sorts of deposits, such as iron ore and gold. The bearing of lead isotopes on genesis of sulfide ore bodies is considered. 

Magmatogenic Ores. Ores in which the isotopic composition of ore lead is the same as that in the presumably related igneous source at the time of crystallization are good candidates for a magmatogenic origin. Data for this fingerprint are available in support of this mechanism. These ores are usually isotopically uniform with Pb/ Pb 19.5 and Pb/ Pb 39. Examples (Fig. 22) are the ores at Butte, Montana (Doe et al., 1968), Bingham Canyon, Utah (Stacey et al., 1968), and the Nelson batholith, British Columbia (Reynolds, 1967). It must be 

Deposits of Metamorphic Origin in Much Older Rocks. Lead isotope data clearly support a metamorphic origin for some deposits of this kind although well-documented studies are few for this little-emphasized category. In order to have a good isotopic solution, the metamorphism 

Lateral Secretion Through Much Older Rocks. Many important stratiform ores, such as those of the Mississippi Valley type, do not have any close association with either volcanism or metamorphism. (Some lead isotope data are summarized in Table 23, Fig. 24.) These ores are characterized by isotopic heterogeneity, as first shown by Nier (1938) and Nier et al (1941). The lead isotope data nicely fit a lateral secretion 

Kind of ratio 206p, /204pb 207p, 204pj, 208p, /204pj, pgf (no. of samples) 

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Kajiwara, Y. (1970a) Syngenetic features of the Kuroko ore from the Shakanai mine. In Tatsumi, T. (ed.), Volcanism and Ore Genesis. Tokyo U. Tokyo Press, pp. 197-206. 

Sawkins, F.J. (1982) The formation of Kuroko-type deposits viewed within the broader context of ore genesis theory. Mining Geology, 32, 25-34. 

From the perspective of ore genesis, these results seem disappointing in light of the fluid s high degree of supersaturation. Shanks and Bischoff (1977), for example, estimate that about 60 mg of sphalerite alone precipitate from each kg of ore fluid feeding the Atlantis II deep. The reaction to form chalcocite,... 

Xiaoqing Z. Zhonggang W. 2002. Gold occurrence and ore genesis, Yata micro-disseminated gold deposit, Guizhou, Southwest China. Chinese Journal of Geochemistry, 21, 370-373. 

Ghosh, S., Thorpe, R.I., Ghosh, A.K. 1999. Lead and sulphur isotope geochemistry of galena from Sargipali sulphide deposit, Sundergarh, Orissa -Implications for ore genesis. Indian Journal of Earth Science, 26, 1-12. 

Loftus-Hills, G Solomon, M. 1967. Cobalt, Niokel and Selenium in sulphides as indicators of ore genesis. Mlnerallum Deposita, 2, 228-242. 

In as much as water is the dominant constituent of ore-forming fluids, knowledge of its origin is fundamental to any theory of ore genesis. There are two ways for determining 5D- and 5 0-values of ore fluids ... 

The concept of juvenile water has influenced early discussions about ore genesis tremendously. The terms juvenile water and magmatic water have been used synonymously sometimes, but they are not exactly the same. Juvenile water originates from degassing of the mantle and has never existed as surface water. Magmatic water is a non-genetic term and simply means a water that has equilibrated with a magma. 

Yaroshchuk, M.A. and Onopriyenko, V.L., 1973. New data on the mineralogy and conditions of deposition of the cherty iron-formations of the sixth and seventh horizons of the Central Krivoy Rog. In Geokhimiya i rudoobrazovaniye (Geochemistry and Ore Genesis). Izd. Naukova Dumka, Kiev, 2 31-38 (in Russian). 

The final case of surficial ore genesis dealt with here involves the transport of physically disaggregated residuum from physically and chemically weathered materials by wind and water, resulting in placers, mineral deposits formed at the Earth s surface by mechanical... 

Han T.-M. (1982) Iron formations of Precambrian age hematite-magnetite relationships in some Proterozoic iron deposits—a microscopic observation. In Ore Genesis— The State of the Art (eds. G. C. Amstutz, A. E. Goresy, G. Frenzel, C. Kluth, G. Moh, A. Wauschkuhn, and R. A. Zimmermann). Springer, Berlin, pp. 451-459. 

Goldhaber M. B., Church S. E., Doe B. R., Aleinikoff J. N., Brannon J. C., PodosekF. A., MosierE.L., Taylor C. D., and Gent C. A. (1995) Lead and sulfur isotope investigation of Paleozoic sedimentary rocks from the southern Midcontinent of the United States implications for paleohydrology and ore genesis of the Southeast Missouri lead belts. Econ. Geol. 90(7), 1875-1910. 

Krauskopf, K.B., 1964. The possible role of volatile metal compounds in ore genesis. Econ Geol., 59 22-45. 

Saxby, J.D., 1976. The significance of organic matter in ore genesis. In K.H. Wolf (Editor), Handbook of Strata-bound and Stratiform Ore Deposits, Vol. 1. Elsevier, Amsterdam, pp. 111—133. 

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