DOLERITE BODIES IN VENDIAN AND CAMBRIAN OF THE YURUBCHENSKAYA AREA

N. V. Melnikov

About 100 wells are drilled within the Yurubchenskaya area, each one uncovers 2-5 dolerite bodies, concentrated in three stratigraphic data: in the Katanga or Soba formations of Upper Vendian, in the saliferous Usolye Formation of the Cambrian lowermosts and in the Angara Formation, in the Upper Belsk, Upper Litvintsevskaya saliferous subformations of the Lower Cambrian uppermosts – Middle Cambrian lowermosts. Dolerite intrusions in Upper Vendian and the Usolye Formation of the Cambrian lowermosts penetrated into uncovered vesicles of sedimentary strata (“passive” intrusion). In the Upper Belsk – Upper Litvintsevskaya subformations intrusions themselves parted host sedimentary strata (“active” intrusion). The intrusion process was accompanied by washing and removal of salts from enclosing salt-bearing members, disruption of carbonate members and formation of xenoliths at sites of sharp increase of intrusion thicknesses.

Key words: Yurubchenskaya area, Upper Vendian, Usolye Formation, Upper Belsk and Upper Litvintsevskaya subformations, Cambrian, dolerite intrusions, wash out of salts, xenoliths. 

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