Ancient continental margins and comparative analysis of their oil-and-gas bearing

Abstract

Analysis of peculiarities in the distribution of hydrocarbon accumulations within the basins of Phanerozoic continental margins, which had completed their evolution, and complicated peripheral regions of ancient Laurasian and Gondwanian platforms nowadays, has enabled us to reveal certain regularities related to two stages in the evolution of sedimentary basins. The first stage of evolution of sedimentary basins (period of existence of the continental margin proper) is related to large accumulations of fluid and gaseous hydrocarbons in the margins of continents belonging to the Laurasian megablock; for the margins of continents belonging to Gondwana, this period was reflected in the formation of large gas accumulation only (in the Permian). At the second stage of sedimentary basin evolution, large oil and gas accumulations were formed in areas associated with fore deeps, which were laid in the boundary of the Gondwanian platforms and fold belts. In comparison, in fore deeps that emerged in the marginal parts of Laurasian platforms, less significant accumulations of fluid and gaseous hydrocarbons were found (Table 1). The results of comparative analysis in oil-and-gas bearing basins located in the margins of the Laurasian and Gondwanian megablocks would help in purposeful exploratory works for oil and gas.