The Geological Conditions for the 



Appearance of Life on the Earthy and the 



Problems of Petroleum Genesis 



p. N. KROPOTKIN 

 Geological Institute, U.S.S.R. Academy of Sciences 



THE GEOLOGICAL CONDITIONS AT THE SURFACE OF 



THE EARTH IN THE EARLY STAGES OF ITS DEVELOPMENT 



AND THE PROBLEM OF THE ORIGIN OF LIFE 



All the modern investigations on the origin of life lead to the conclusion that 

 the source of the primary, most primitive forms of life on the Earth was 

 abiogenic organic compounds of the complex hydrocarbon type [1-4]. 



Among the organic material widely distributed in the Earth's crust that could 

 be considered as a source of the primary forms of life, is petroleum or complex 

 hydrocarbons, similar to it in composition. 



Most investigators assume that the Earth's atmosphere originally had no 

 oxygen. Free oxygen appeared later, as a result of the life activity of plants [5]. 

 Evidently, reducing chemical conditions were predominant in the atmosphere 

 at that time. Besides a certain amount of methane, there were probably carbon 

 dioxide, nitrogen, and aqueous vapour in the atmosphere, similar in composition 

 to the present atmosphere of Venus. (It consists of CO 2, No according to 

 Kozyrev, and HoO — according to Lyot, and judging by the reflection of the 

 sun's rays, penetrating the cloud layer of this planet to the reflective surface, 

 which is most probably an ocean surface.) The important, and perhaps even 

 predominant, rôle of carbon dioxide in the atmosphere's composition at the 

 early stages of the Earth's development has been shown by the numerous cal- 

 culations, made by different authors, of the amount of CO2, which is equivalent 

 to the total amount of carbon in mineral coal and in the diffused carbonaceous 

 matter buried in sedimentary rocks. 



Developing in such conditions at the surface of dry land or water basins, the 

 primary living organisms evidendy could neither make use of solar energy (not 

 yet having acquired chlorophyll) nor of the energy which under present condi- 

 tions is freed through oxidation of organic compounds in the atmosphere or in 

 water containing molecular oxygen (for instance, in processes of putrefaction). 

 It would appear that chemical processes, at that time, were of the type now 

 effected by anaerobic bacteria. 



Two types of exothermic reaction accompanied by the emission may be con- 



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