Mud volcanism of the northwestern Caucasus and the oil and gas prospects

Mud Volcanism as One of the Manifestations of Deformation Process

[3] The occurrence of clayey diapirism apparently results from external causes, such as the form of occurrence of clayey formation body producing diapirs and the development of structure formation processes in the adjacent areas. The triggering effect of regional strain state fluctuations is markedly shown by the example of Golubitskiy volcano eruption accompanied by the earthquake intensity of 3 in Temryuk in the summer of 1988. This eruption resulted in the decrease of mud volcanic activity in Kerch-Taman region and the general reduction of the carbon dioxide and methane ratio, which only began to increase a year after the eruption [Yurovskii and Valter, 1991]. Mud cone gases studied in Kerch Peninsula (Nasyrskiy volcano, Bulganakskoye cone hill field, Kerch cone hill) strongly suggest the single reaction of the total body of diapir-forming Maikopian series to the local close discharge in Golubitskiy mud volcano source. Data of hydrogeodeformation observations in Krasnodarskiy Krai corroborate this conclusion as well. Thus strong compression of sedimentary bed rocks in western Ciscaucasia, which was manifested by a sharp rise of underground water, was noted before the above-mentioned eruption of Golubitskiy volcano [Sheremet'yev et al., 1996]. Abrupt change in hydrogeodeformation field also preceded Golubitskiy volcano eruption in 1994. Similar reaction to seismic events in Anatolia was noted in the variation field of gas index in Anatolia (the abovementioned carbon dioxide - methane ratio) for mud volcanoes of Kerch Peninsula [Yurovskiy, 1997].

[4] These facts testify to the reaction of the total diapir-forming Maicopian complex of Kerch-Taman depression as a single body to external effects. Stress in the rock bed is realized by injection of low-viscous clayey mass into relatively more competent overlying beds (viscous inversion [Pil'chin, 1985]). Such realization of the process of clayey diapir formations and consequently of mud volcanoes is apparently characteristic of many areas of their manifestations.

[5] This view point appears to be justified and in our opinion is more preferable than complicated and not convincing mechanisms explaining clayey diapir occurrence and mud volcanism, which results from diapirism, either at the expense of hydrothermal air lift [Kityk and Plotnikov, 1977] or as a result of density inversion at the expense of montmorillonite transformation to illite [Meisner and Tugolesov, 1997].