Palynofacies analysis, sedimentology and hydrocarbon potential of the Menilite Beds (Oligocene) in the Slovakian and Romanian Outer Carpathians

Abstract

The sed i men tary or ganic mat ter (SOM) as sem blages and sedimentology of the Menilite Beds from the Dukla, Grybów and Vrancea units in the Slovakian and Ro ma nian Outer Carpathians are de scribed. Qual i ta tive and quan ti ta tive anal y ses of the SOM help as cer tain depositional con di tions, while the ther mal ma tu rity of the or ganic mat ter stud ied is es ti mated uti liz ing the Spore Col our In dex and UV light ex ci ta tion tech niques. The sed i men tary or ganic par ti cles were grouped into ten SOM cat ego ries: ma rine palynomorphs (dinoflagellate cysts), sporomorphs (saccate and non-saccate, pol len and spores), fresh wa ter al gae (Botryococcus sp., and other fresh wa ter microplankton), phytoclasts (cu ti cles, trans lu cent wood, opaque wood), resin and amor phous or ganic mat ter (AOM). All sam ples are dom i nated by AOM. The pres ence of Botryococcus sp., Pediastrum sp., Pterospermella sp. and Campenia sp., in some sam ples points to de po si tion un der hyposaline con di tions. It is in terpreted that the fresh wa ter in flux in duced wa ter col umn strat i fi ca tion in the ba sin, lead ing to the de vel op ment of dysoxic to anoxic bot tom-wa ter con di tions that en hanced the pres er va tion of AOM. Kerogen anal y sis in UV light and eval u a tion us ing the Spore Col our In dex dem on strated dif fer ent ther mal mat u ra tion pat terns from the Slovakian (post-ma ture) and Ro ma nian (im ma ture) sec tions. In te grated palynofacies anal y sis (no ta bly, the pres ence of fresh wa ter al gae) and sedimentological obser va tions (e.g., hummocky cross-strat i fi ca tion) lead to the con clu sion that the de po si tion of the Menilite Beds in the Vrancea Unit (Ro ma nia) was rel a tively prox i mal to the shore line, above storm wave base, whereas the Slovakian units (Dukla and Grybów) were de pos ited in a more dis tal set ting.