Prospects for the discovery of natural hydrogen in the Voronezh anteclise

Abstract

Introduction: The study considers important issues relating to the prospects for the discovery of deposits of natural hydrogen in the Voronezh anteclise. A brief review of the history of research and fundamental and applied problems related to the manifestations of "golden" hydrogen, as well as its role as an ideal energy carrier is presented. General information is provided about the structure of the Voronezh anteclise (VA), which is the largest segment of the East European Platform and, at the same time, a structure with very important prospects for hydrogen. Based on global experience, the relevant sections provide a comprehensive analysis of mineragenic factors for the control and localization of natural hydrogen for such structures. Natural hydrogen localisation factors: The most important factor is the surface of the Precambrian basement, which has been studied based on geophysical data, drilling, and exploited quarries. The surface is a giant arch, gently sloping in the central part and deepening towards the periphery, and is emphasized by the presence of weathering crusts of varying degrees of preservation. The arches are surrounded by a system of depressions and aulacogens, which is generally favourable for the formation of gas emanations. The presence of ultramafic and basic rocks distributed at different structural and age levels is an additional factor in the localization of natural hydrogen. The role of ultrabasic and basic rocks is ambivalent. First, they are products of mantle origin, and their transport to the surface facilitates degassing. Secondly, they compose covers and subtabular bodies, which can reliably block the paths of gas transportation. From this point of view, bodies of the trap formation of the Novogolsk complex and Upper Devonian basalt covers are the most promising. The lithological factor it is especially expressed for the Phanerozoic cover, in which rocks favourable for the conservation of natural hydrogen are ubiquitous - clays, limestones and dolomites, as well as evaporites. Natural gas transportation systems: Four orders of such systems of different ages are distinguished. The first order includes the Losevo suture zone of the Sarmatia and Volga-Ural paleocontinents, which was formed due to the closure of the Paleoproterozoic ocean (the maximum number of circumments was noted above this zone). The Tim-Yastrebovka and Belgorod-Mikhailovka Paleoproterozoic rift structures are assigned to the second order, within which deposits of ferruginous quartzites are recorded. Systems of the first and second orders "worked" for a long time over the interval of 2.5–2.0 billion years. Third-order systems (depressions and aulacogens surrounding the VCM) were formed in the Upper Proterozoic, and their activity continued until the Upper Paleozoic. The structures laid down in the Upper Devonian are assigned to the fourth order. The interface between the Precambrian and the Phanerozoic cover plays a special role as a gas transport system. Structural traps and drainage zones: The nonconformity surface of the Precambrian and Phanerozoic is a transport system and the main megatrap, however it is "leaky" due to the many circumments through which a significant part of hydrogen is lost. In this regard, the most promising are the positive structures of the second and third orders associated with depressions, which complicate the periphery of the anteclise arch. In addition, the bottom parts of the bodies of the Novogolsk complex and covers of Devonian dolerites and basaltoids are of primary interest. Circumments, their morphological features and accompanying phenomena: The general characteristics of surface ring and oval subsiding structures, their possible genetic nature and role in hydrogen degassing are provided. The phenomena accompanying circumments include: "whitening" of chernozems, desertification and increasing concentrations of noble metals, primarily platinum group elements (PGE). Conclusions: An analysis of the mineragenic factors that control the transport and accumulation of natural hydrogen within the EA shows a very high potential for the considered structure.