The influence of gas-fluid processes on the formation of both the rocks of the Visean terrigenous oil and gas bearing complex of the Timan-Pechora province and hydrocarbon deposits in them is considered. It was established that siderite concretions of the Lower Carboniferous terrigenous strata are siderite bacteriolites formed in the back-arc basin with normal marine fauna and occurrence of gasfluid seepage in the bottom sediment. The formation of pyrophyllite in terrigenous rocks of the

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... margin of the sedimentation basin can also be associated with post-volcanic hydrothermal or metasomatic processes.