PALEOCENE FORMATIONS OF HIGH-DENSITY FLOWS OF THE NORTHWEST SKIBA NAPPE OF THE UKRAINIAN CARPATHIANS

Abstract

The aim of the study is to study the formations of high-density paleoflows in the structure of the sand module of the Paleocene Yamnen suite of the Skiba nappe of the Outer Ukrainian Carpathians. Methods. The natural outcrops of the Stryi river basin were studied, where attention was paid to the lithological, mineralogical, petrographic, structural and textural features of the psammite rocks of the Yamnen suite. The results. According to the studies of structural, textural and material features, the lithodynamic types of the psamite module of the Yamnen suite were clarified and distinguished. They belong to coarse-grained (and proximal) turbidites, granites, debrites, formations of liquefied and fluidized flows, underwater landslide deposits. In the upper part of turbidites, granites, deposits of liquefied and fluid flows, spheroidal sand inclusions of three types were noted. Isolated spherical bodies up to 1,5–2,0 m in diameter with spiral-like textures are associated with granites and debrites. The identified spherical inclusions and bodies probably belong to seismites. In addition, individual olistoliths and debris-like conglomerate breccia are observed, which tend towards submarine landslide complexes. The studied lithodynamic types belong to the formations of high-density terrigenous flows, the genesis and transport of which bear signs of high seismic activity. The streams formed underwater channels of the drainage system on the passive edge of the Outer Carpathian Paleogene basin of the studied region in the form of an underwater cone of displacement. The processes that gave rise to isolated lithodynamic types acted almost simultaneously and transformed from dense landslide phenomena with isolated olistoliths to debris, grain, liquefied and fluid flows and low-density turbidite flows with seismites. Flow sediments accumulated in the upper and middle fans, but sometimes reached the lower fan of the drift cone Scientific novelty. The obtained information about the formations of high-density paleoflows of the Yamna suite of the Skiba nappe of the Outer Ukrainian Carpathians will contribute to the further detailing of the Paleocene model of the tectonic-sedimentological development of the Outer Carpathian paleobasin of the Alpine Tethys. Practical value. The psammites of the Yamna world are promising lithological and structural traps for hydrocarbons based on their material and textural features.