Deep structure of the Mt. Karabetov Mud volcano

Abstract

The results of multidisciplinary geological‐geophysical investigations of mud volcanism in the Taman mud-volcanic province are presented. Geophysical data on the internal structure of Mt. Karabetov mud volcano were obtained for the first time, and pathways of fluid migration down to a depth of 15‐25 km were determined. Mud volcanism is a surprising and quite rare natural phenomenon, whose mechanisms had not been fully studied. At present, we can consider that the correlation of mud volcanism with the dynamics of deep fluids and hydrocarbon pools has been established [2, 9]. Intense mud-volcanic activity is observed in the territory of Russia, first of all, on the Taman Peninsula, which is an integral part of the modern evolution of fluid-magmatic systems in the Northern Caucasus [9]. During the last few years, Mt. Karabetov, which is one of the most active mud volcanoes in the Taman region, has been the object of multidisciplinary geological‐geophysical and geochemical investigations [3, 4]. This volcano is characterized by explosive type of eruptions with periodic manifestation of the whole power of this seemingly harmless natural phenomenon. During the field works of the Institute of Physics of the Earth (IPE RAS) in August‐September 2007, a detailed geological-geomorphological mapping of Mt. Karabetov mud volcano was carried out and supplemented by remote sounding data. As a result, it became possible to trace the tectonic deformations of young forms of topography and various manifestations of exogenous geological processes in the study region. Simultaneously, profile geophysical measurements were carried out using the microseismic sounding method [5, 6]. It was shown experimentally and using numerical models that inhomogeneities of the Earth’s crust specifically distort the spectrum of the low-frequency microseismic field. In particular, spectral amplitudes of specific frequency f decrease above highvelocity anomalies at the Earth’s surface and increase above low-velocity anomalies. Frequency f is related to the depth of the anomaly H location and velocity of the fundamental mode of Rayleigh wave V R ( f ) as H = . The low-frequency microseismic field is considered as a superposition of wave packets of fundamental Rayleigh modes with different frequency compositions. The method was used as a principally new technology of microseismic sounding of near-surface (0‐0.5 km) and deep (up to 50 km) structures of the Earth’s crust. The technology was successfully tested in practice on different geological objects in terms of scale and genesis [14].