Ancient ocean

Paleoceanography The study of the ancient oceans that seeks to reconstruct past environmental condihons by examining chemical and fossil records left in the sediments and polar ice cores. 

The isotopic composition of present day ocean water is more or less constant with 5-values close to 0%c. The isotopic composition of ancient ocean water is less well constrained, but stiU should not be removed from 0 by more than 1 or 2%c. Many volcanogenic massive sulfide deposits are formed in submarine environments from heated oceanic waters. This concept gains support from the recently observed hydrothermal systems at ocean ridges, where measured isotopic compositions of fluids are only slightly modified relative to 0%c. 8 0 and 5D-values of vent fluids are best understood in terms of sea water interaction with the ocean crust (Shanks 2001). 

Assuming that the H- and O-isotope compositions and temperatures of ancient ocean waters are comparable to present day values, the isotopic composition of ancient meteoric waters may have been governed by relations similar to those existing presently. However, given the local complexities, the application of this relation-... 

He postulated that the determination of temperatures of the ancient oceans should be possible, in principle, by measuring the 0 content of fossil shell calcite. The first paleotemperature scale was introduced by McCrea (1950). Subsequently, this scale has been refined several times. Through experiments which compare the actual growth temperatures of foraminifera with calculated isotope temperatures Erez and Luz (1983) determined the following temperature equation ... 

Thiemens MH, Heidenreich JE (1983) The mass independent fractionation of oxygen - A novel isotope effect and its cosmochemical implications. Science 219 1073-1075 Thiemens MH, Jackson T, Zipf EC, Erdman PW, van Egmond C (1995) Carbon dioxide and oxygen isotope anomalies in the mesophere and stratosphere. Science 270 969-972 Thode HG, Monster J (1964) The sulfur isotope abundances in evaporites and in ancient oceans. In Vinogradov AP (ed) Proc Geochem Conf Commemorating the Centenary of V I Vernadsku s Birth, vol 2, 630 p... 

Horner DS, Heil , Happe T, Embley TM (2002) Iron hydrogenases - ancient enzymes in modern eukaryotes. Trends Biochem Sci 27 148-153 Hrdy I, Hirt RP, Dolezal P, Bardonova L, Foster PG, Tachezy J, Embley TM (2004) Trichomonas hydrogenosomes contain the NADH dehydrogenase module of mitochondrial complex I. Nature 432 618-622 Hurtgen MT (2003) Ancient oceans and oxygen. Nature 423 592-593 Javaux EJ, Knoll AH, Walter MR (2001) Morphological and ecological complexity in early eukaryotic ecosystems. Nature 412 66-69... 

Many of the ore deposits found on the continents are the result of ancient oceans. Tin is found in offshore deposits, such as in Indonesia, in Cornwall (Saint Ives Bay), and Phuket Island off the west coast of the Malay Peninsula. 

Sodium compounds are important largely because they are inexpensive and soluble in water. Sodium chloride is readily mined as rock salt, which is a deposit of sodium chloride left as ancient oceans evaporated and it is also obtained from the evaporation of brine from present-day seas and salt lakes (Fig. 14.19). Sodium chloride is used in large quantities in the electrolytic production of chlorine and sodium hydroxide from brine. 

Veizer J. (1985) Carbonates and ancient oceans Isotopic and chemical record on time scales of 107 - 109 years. In The Carbon Cycle and Atmospheric CO2 Natural Variations, Archean to Present (eds. E.T. Sundquist and W.S. Broecker), pp. 595-601. Geophys. Monographs, Washington, D.C. 

For ancient chemogenic cherts, including cherts from the BIF of Gunflint, Ontario, and Biwabik, Minnesota, Perry (1967) established a functional relationship between the of silica and the time of deposition. On this basis it was concluded that the waters of the ancient ocean were depleted in the heavy oxygen isotope, and that the 5 0 value was about — 10 to — 12%o for the Proterozoic and up to — 18%o for the Archean (compared to the oxygen of recent ocean water, SMOW standard). 

Head J. W., Hiesinger H., Ivonov M. A., Kreslavsky M. A., Pratt S., and Thompson B. J. (1999) Possible ancient oceans on Mars evidence from Mars orbiter laser altimeter data. Science 286, 2134-2137. 

Hofmann A. W. and White W. M. (1982) Mantle plumes from ancient oceanic crust. Earth Planet. Sci. Lett. 57, 421-436. 

Coleman R. G. (1977) Ophiolites Ancient Oceanic Lithosphere . Springer, Heidelberg, Berlin, New York. 

Jacob D. E., Bizinis M., and Salters V. J. M. (2002) Lu-Hf isotope systematics of subducted ancient oceanic crust Roberts Victor eclogites. Geochim. Cosmochim. Acta Spec. Suppl.) 66S1, A360. 

MacGregor I. D. and Manton W. I. (1986) Roberts Victor Eclogites ancient oceanic crust. J. Geophys. Res. 91, 14063-14079. 

Despite this progress our knowledge of the ancient oceans is miniscule compared to our knowledge of the modern ocean. Even the... 

Holmden C. and Muehlenbachs K. (1993) The 0/ 0 ratio of 2-biUion-year-old seawater inferred from ancient oceanic crust. Science 259, 1733—1736. 

Wright J., Schrader H., and Holser W. T. (1987) Paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite. Geochim. Cosmochim. Acta 51, 631-644. 

Godderis Y. and Veizer J. (2000) Tectonic control of chemical and isotopic composition of ancient oceans the impact of continental growth. Am. J. Sci. 300, 434-461. 

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