Tectonic realms

Table 10.3. Summary of recycling rates and half-lives for major global tectonic realms. (After Veizer, 1988.)... 

Tectonic Realms Steady-State Since 4500 x 106 y Ago "Preferred" or Logistic Growth Model Theoretical Half-L (T50) x 10 y... 

GLOBAL TECTONIC REALMS AND THEIR RECYCLING RATES... 

The concept of global tectonics (Dietz, 1961 Hess, 1962 Morgan, 1968 Le Pichon et al., 1973) combined the earlier proposals of continental drift and seafloor spreading into a unified theory of terrestrial dynamics. It introduced the notion of continual generation and destruction of oceanic crust and implied similar consequences for other tectonic realms. 

Global Tectonic Realms and their Recycling Rates... 

Figure 5 Preservation probabilities for major global tectonic realms. AMB = active margin basins, OB = oceanic intraplate basins, OC = oceanic crust, PMB = passive margin basins, lOB = immature orogenic belts. Rates were derived on the assumption that all deviations from the ideal pattern of the type I age distributions were a consequence of the poor quaUty of the available database (after Veizer, 1988b).

As already pointed out in Figure 7, the relative proportion of carbonate rocks within the continental realm generally decreases in the course of the Phanerozoic, and the Mesozoic and Cenozoic deficiency of carbonates was attributed to a tectonic cause, the ubiquity of transient immature tectonic settings. Another reason is the general northward drift of continents, which resulted in a progressive decline in the shelf areas that fell within the confines of the tropical climatic belt... 

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