Место издания: Florence , Год издания: 2004

The Siberian Platform was subject to the catastrophic manifestation of trap magmatism at the Permian/Triassic boundary. During a short time interval (about 0.6 million years), nearly 1.2 million km3 of high-temperature basic magma have been erupted here, of which no less than 0.4 km3 were accounted for by igneous bodies intruded into sedimentary rocks in the range from the Upper Riphean to Upper Permian. Mass intrusion of trap bodies into the sedimentary cover of the Lena-Tunguska petroleum province made a significant impact on the fuel minerals contained in the cover. Strong and nonuniform heating of the sedimentary rocks by intrusions was the major factor responsible for transformation of Permian brown coals into hard coals within the wide range of metamorphism, the anthracites inclusive. At the same time, mass emissions of methane and carbon dioxide into atmosphere occurred, representing a global ecological event. The distribution of coals of different quality directly depends on the amount and thickness of intrusive bodies in the coal measure.Intense and nonuniform heating of sedimentary rocks stimulated the processes of interaction of the matrix with fluids contained in it, including oil and gas. When rocks were heated above 5000 C, hydrocarbons completely decomposed. At lower temperatures, a part of liquid hydrocarbons transformed into gaseous state, the remainder being enriched in heavy fractions. The concentration of brines rose at the expense of solution of solid phase, which, in turn, underwent qualitative changes. Hydrocarbon pools occurring in the sulfate-carbonate matrix were enriched in hydrogen sulphide and carbon dioxide, and oils became sulfurous. Pools in the terrigenous matrix became free of sulfur, which transformed into hydrogen sulphide and sulphide form.Intrusive bodies were responsible for the formation of new unconventional hydrocarbon migration pathways and partial, in some cases, complete transformation of earlier formed pools. The position of the main zone of oil formation has also changed, affecting the processes of oil and gas generation processes in the province.The catastrophic manifestation of magmatism at the Paleozoic/Mesozoic boundary was largely responsible for the present-day pattern of distribution and quality of the fuel minerals in the western part of the Siberian Platform.