Formations of sequences rich in organic matter in the light of new model of global carbon cycle
The dynamics of photosynthesis is determined by the uneven movement of lithosphere plates. The cyclical nature of the lithosphere plates’ motion determines the cyclicity of the associated factors, namely: carbon cycle, photosynthesis evolution, organic matter accumulation in sedimentary strata, climate changes, and other processes. The formation of rocks rich in organic matter also occurred cyclically; it is associated with the massive mortality of organisms that took place when cycles were changing due to catastrophic alterations in the environment. The key role of photosynthesis in the formation of oil-producing strata allows defining the oil generation interval from Riphean to Paleogene. The lower limit is determined by the time (from the moment of photosynthesis onset) of organic matter accumulation in amount sufficient to provide the dispersed hydrocarbons and allowing to form hydrocarbon accumulations. The oxygen content in the atmosphere at that moment was several percent. From above, oil generation is limited by reaching the environmental compensation point, i. e. such a state of the global carbon cycle, where the amount of carbon produced in photosynthesis becomes equal to the amount of carbon returned to the oxidized inorganic form. The upper limit was reached after Miocene, when the decrease in CO2 concentration has led to the emergence of a new C-4 type of photosynthetic assimilation