SESSION I. DISCUSSION 111 



N. M. Galaktionova (U.S.S.R.): 



The Cojiîent of Bituminous Material in Sedimentary and Metamorphic 

 Rocks of the Crystalline Foundation 



(Based on the results of a study of the cores of test borings in the central regions 

 of the Russian platform) 



The theory of the origin of life on the Earth, postulates that, for a long time before 

 the appearance of Ufe on the surface of the planet there accumulated a large quantity of 

 organic substances which had been formed abiogenically. 



This hypothesis is based on the well-known syntheses of organic from inorganic sub- 

 stances eflfected under technological conditions, the presence of hydrocarbon compounds 

 in some meteorites (which have been formed under conditions unsuitable to life), the 

 frequently observed presence of hydrocarbon radicals in the spectra of stars and the 

 existence of hydrocarbons in the atmospheres of some planets. From these facts it follows 

 that the abiogenic synthesis of organic compounds is widely distributed in nature. 



In this connection it would be very significant if we could find, on our own planet, 

 organic substances of abiogenic origin formed a long time ago, before the appearance of 

 life on the Earth. 



Hydrocarbons of various origins have now been found in the crust of the Earth both 

 in rocks of the sedimentary complex, starting with the most ancient Precambrian rocks 

 and ending with recent deposits, and also in the rocks of the crystalHne foundation. 



The elucidation of the origin of the hydrocarbons found in the crust of the Earth is 

 sometimes extremely complicated and requires special precautions to avoid confusion of 

 products of abiogenic synthesis with those of more recent biogenic origin. 



The solution of such problems has been substantially helped by the new geochemical 

 data which have been obtained by the systematic and many-sided investigation of the 

 cores of test borings. 



The study of the section made by a bore, beginning with the superficial layers of 

 the sedimentary complex and ending with the formations of the crystalline foimdation, 

 provides the possibiUty of using geological and geochemical methods to clarify the origin 

 of the bitimiinous substances found in the cores. 



With this object we shall consider some new material which has been obtained by 

 studying the cores of 40 test bores which were driven into the extensive territory of the 

 central regions of the Russian platform, occupying an area of about 1000 km longitudinally 

 and 1200 km latitudinally. As a result of studying the sections brought up by the test 

 bores, the following facts have been estabUshed. 



1. The depth at which the foundation Ues is not the same in all parts of the Russian 

 platform (minimum observation 845 m, maximvmi 1950 m). 



2. Bituminous substances were found both in rocks of the sedimentary Palaeozoic 

 complex, and in plagioclase gneisses — rocks of the crystalline foundation, untouched 

 by superficial weathering processes. It has been shown that the reUef of the crystalline 

 foundation is compUcated by intensive, tectonic disturbances expressed as cleavages of 

 the foundation into blocks which are displaced in relation to one another. The constitution 

 of the sections, seen as a whole, gives an intelUgible picture of lack of uniformity in both 

 the qualitative and quantitative distribution of bituminous substances horizontally and 

 vertically. Thus, in the metamorphic rocks of the crystalHne foundation, composed 

 mainly of gneisses, the concentration of bituminous substances varies from nothing to 

 some thousandths of I'^o- It is very important to note that the quaUtative composition of 

 the bituminous substances of the rocks of the foundation differs from that of the 

 bitviminous substances contained in formations of the sedimentary strata covering the 

 foundation. 



As concerns the sandstones and clays of the Precambrian sedimentary strata which lie 

 direcüy upon the crystaUine foimdation, it would seem that bituminous substances are, 

 as a rule, absent from them. 



In the dolomites and anhydrites of the Devonian beds which cover the Precambrian 

 rocks, bituminous substances are present in concentrations which may reach as high 

 as some tenths of i % . 



Tracing the distribution of bituminous substances further in the rocks of the Devonian 

 period, we notice that the content of bituminous substances corresponding to a particular 



