Phanerozoic time scale

Darnley, a. G. Uranium-thorium-lead age determinations with respect to the Phanerozoic time-scale, pp. 73—86. In The Phanerozoic time-scale. 548 p, Geol. Soc. London Quart. J. 120, Suppl., (1964). 

Golonka, J. and Kiessling, W. (2002) Phanerozoic time scale and definition of time slices. Phanerozoic Reef Patterns. SEPM Special Publication, 72 11-20. 

Like the concept of steady state described in Section 8.09.2.2, the concept of abrupt change requires the context of a particular timescale and frame of reference. In Section 8.09.3, we described examples of abrupt change in the context of the Late Quaternary ice-core record. Abrupt changes in the context of the Phanerozoic rock record might be viewed as leisurely transitions from the perspective of Quaternary time-scales. A formal treatment of abmpt change is beyond the scope of this chapter. However, we describe two examples that seem to qualify as abrupt changes in the carbon cycle by any definition. 

Figure 7.2. A) Contrasting scales of continental margin and intracratonic margin associated carbonate platforms. B) The distribution of epicontinental (long lines) and cratonic-based (short lines) platform margins during different times in the Phanerozoic. (Based on James and Mountjoy, 1983 After Moore, 1989.)...

The Neoproterozoic interval witnessed supercontinent formation and breakup and profound global-scale glaciations that persisted for perhaps millions of years (Knoll 1991). It therefore is not surprising that this interval experienced substantial isotopic excursions reminiscent of those during the Paleoproterozoic (Fig. 10). Eukaryotic lineages that would lead directly to plants and animals had developed by this time. It is generally believed that the events associated with tectonics, climate and the biogeochemical cycles played important roles in the enormous diversification of plant and animal life at the dawn of the Phanerozoic Eon. 

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