Great Unconformity

The Great Unconformity shows us that Rodinia cracked and continents eroded, sending calcium, molybdenum, and phosphate into the oceans (800-550 million years ago). 

After the Second Great Oxidation Event had done most of its work, the planet reached a stable threshold of oxygen levels, near today s, with oxygen present from the air to the deep sea. While surface ocean oxygen increased 10 times, deep ocean oxygen increased a million times. A hundred million years later, after the events of the Great Unconformity, the Cambrian Explosion exploded. Ifwe scale the history of life... 

The Cambrian fossils adopt countless shapes and sizes, but they are mostly three members of the geological Big Six calcium, oxygen, and silicon. After the Great Unconformity, microfossils increasingly developed defensive spikes made from calcium, silicon, and oxygen. Later, after the Cambrian Explosion, life used calcium even more. For example, sponges changed their skeletons from spindly calcium lace to thick calcium layers. 

The tan layers on top are 525-million-year-old Cambrian Tapeats sandstone. .. Dissolved rocks brought more elements into the ocean,. .. S. E. Peters and R. R. Gaines. Formation of the Great Unconformity as a trigger for the Cambrian explosion. 2012. Nature 484(7394), p. 363. DOI 10.1038/naturel0969. 

Fig. 5. Example of a stratigraphic trap. This unconformity represents the condition where upward movement of oil has been halted by the impermeable cap rock laid clown across tine cutoff (possibly by water or wind erosion) surfaces of the lower beds. This type of reservoir is found in the great East Texas field...

Davies, P.J., 1974. Sub surface solution unconformities at Heron Island, Great Barrier Reef. Proceedings of the Second International Symposium on Coral Reefs, Vol. 2, pp. 573—578. 

The identification of such dia- or catagenetic barriers is of great importance in the search for traps as the accumulation of hydrocarbons may have taken place below a more pronounced barrier located above the unconformity. 

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