The study, based on a complex geochemical research, found that the composition of the most chemical elements in mud breccia from the Yuzhno-Sakhalinsky (YSMV) and Pugachevsky (PMV) mud volcanoes (Sakhalin Island), the unique phenomena of endogenous defluidization in the Hokkaido-Sakhalin fold system (alpine-type folding), are comparable to Clarke (C) contents of these elements ( ×C). For Na, Li, Zn and Sn, the ratio between the elemental contentsand their Clarke values (Csample/Clarke value) vary from to xC. | Vietnam Journal of Earth Sciences, 40(1), 56-69, Doi: Vietnam Academy of Science and Technology Vietnam Journal of Earth Sciences (VAST) Geochemical features of Sakhalin Island mud volcanoes Shakirov .*1, Sorochinskaja , Syrbu , Tsoy , Nguyen Hoang2, Le Duc Anh3 1 . Il’ichev Pacific Oceanological Institute (POI), Far Eastern Branch of Russian Academy of Sciences, Vladivostok, Russia 2 Institute of Geological Sciences, VAST, Hanoi, Vietnam 3 Institute of Marine Geology and Geophysics, VAST, Hanoi, Vietnam Received 20 July 2017; Received in revised form 21November 2017; Accepted 28 November 2017 ABSTRACT The study, based on a complex geochemical research, found that the composition of the most chemical elements in mud breccia from the Yuzhno-Sakhalinsky (YSMV) and Pugachevsky (PMV) mud volcanoes (Sakhalin Island), the unique phenomena of endogenous defluidization in the Hokkaido-Sakhalin fold system (alpine-type folding), are comparable to Clarke (C) contents of these elements ( ×C). For Na, Li, Zn and Sn, the ratio between the elemental contentsand their Clarke values (Csample/Clarke value) vary from to xC. But the increased contents of Na and Li are due to the ascending endogenous fluid revealed. Study of the mud breccia chemical composition changes in different explosive activity of YSMV under the seismic activity variations allowed to establish that, when the mud-volcanic gryphons are activated against the background of increase in the temperature of the water-mud mixture and the emission of spontaneous gases, the contents of a number of elements (iron, calcium, manganese, rare earth elements, etc.) are decreased. This is explained by the formation of soluble hydrocarbonate complexes. Daginskie gasgeothermal system (DGHS) trace elements depleted ooze samples were compared with YSMV and PMV samples and exposed that the high ratios of Csample /Clarke values
