Carbon rock cycles

Carbon. Most of the Earth s supply of carbon is stored in carbonate rocks in the Hthosphere. Normally the circulation rate for Hthospheric carbon is slow compared with that of carbon between the atmosphere and biosphere. The carbon cycle has received much attention in recent years as a result of research into the possible relation between increased atmospheric carbon dioxide concentration, most of which is produced by combustion of fossil fuel, and the "greenhouse effect," or global warming. Extensive research has been done on the rate at which carbon dioxide might be converted to cellulose and other photosyntheticaHy produced organic compounds by various forms of natural and cultivated plants. Estimates also have been made of the rate at which carbon dioxide is released to soil under optimum conditions by various kinds of plant cover, such as temperature-zone deciduous forests, cultivated farm crops, prairie grassland, and desert vegetation. 

Kempe, S. (1979b). Carbon in the rock cycle. In "The Global Carbon Cycle" (B. Bolin, E. T. Degens, S. Kempe and P. Ketner, eds), pp. 343-377. Wiley, New York. 

Linkages between the global carbon and crustal rock cycles. 

As the rock cycle continues, the calcium silicate minerals are eventually uplifted onto land where they imdergo chemical weathering. This reaction involves acid hydrolysis driven by carbonic acid. The latter is derived from the dissolution of the magmatic CO2 in rainwater ... 

To begin the discussion, we will present briefly a view of the modern carbon cycle, with emphasis on processes, fluxes, reservoirs, and the "CO2 problem". In Chapter 4 we introduced this "problem" here it is developed further. We will then investigate the rock cycle and the sedimentary cycles of those elements most intimately involved with carbon. Weathering processes and source minerals, basalt-seawater reactions, and present-day sinks and oceanic balances of Ca, Mg, and C will be emphasized. The modern cycles of organic carbon, phosphorus, nitrogen, sulfur, and strontium are presented, and in Chapter 10 linked to those of Ca, Mg, and inorganic C. In conclusion in Chapter 10, aspects of the historical geochemistry of the carbon cycle are discussed, and tied to the evolution of Earth s surface environment. 

In the last two decades, a great deal of progress has been made in the modeling of the carbon cycle and of parameters related to the formation of carbonate rocks. These models attempt to show quantitatively the interrelated mass relationships... 

Hay W.W. (1985) Potential errors in estimates of carbonate rock accumulating through geologic time. In The Carbon Cycle and Atmospheric CO2 Natural Variations Archean to Present (eds. E.T. Sundquist and W.S. Broecker), pp. 573-584. Geophysical Monograph 32, American Geophysical Union, Washington, D.C. 

The two dominant exogenic reservoirs of carbon are carbonate rocks and organic matter in sediments. They are linked in the carbon cycle via atmospheric CO2 and the carbon species dissolved in the hydrosphere. The for the total... 

The overall cycling rates of carbon have always depended upon geothermal forces that cause volcanic CO2 exhalation and carbonate uplift, independently of life processes. The hydrosphere s carbonate buffer system kept the oceans at near saturation, with respect to CaC03, at all times (Holland, 1972). Rates of deposition and accumulation of carbonate rocks per unit of geological time have also been within the range of fluctuation observed for the Phanerozoic (Garrels et al., 1976). The form of carbonate deposits, however, was certainly different in the Precambrian from those of today, i.e. it was a predominantly chemical precipitate, rather than biogenic skeletal carbonate (Monty, 1973). 

On geological time scales, CO2 cycles between rocks, often by way of the ocean and atmosphere. The rock reservoirs include the mantle, continental carbonates, carbon in reduced form mostly in continental shales, and carbon (mostly carbonate) in or on the sea floor. The small volatile reservoir (ocean plus atmosphere) cycles through carbonate rock in a hundred thousand to a million years. Over longer periods free CO2 is dynamically controlled by processes that form carbonates at low temperatures and processes that decompose carbonates at high temperatures by (Urey) reactions of the form... 

Kempe S. (1979) Carbon in the rock cycle. In The Global Carbon Cycle (ed. Bolin B., Degens E.T., Kempe S., Ketner P.) SCOPE Rep. No. 13, 343-77. Chichester Wiley. 

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