Environmental stress in the northern Tethys during the Paleogene: a review of foraminiferal and geochemical records from the Polish Outer Carpathians

Barbara OLSZEWSKA, Andrzej SZYDŁO
2017 Geological Quarterly  
Olszewska, B., Szyd³o, A., 2017. En vi ron men tal stress in the north ern Tethys dur ing the Paleogene: a re view of foraminiferal and geo chem i cal re cords from the Pol ish Outer Carpathians. Geo log i cal Quar terly, 61 (3) : 682-695, doi: 10.7306/gq.1369 Dur ing the Paleogene, the area of the north ern Tethys was con trolled by a tur bid ity sys tem stim u lated by di a strophic and geodynamic pro cesses. These fac tors con trib uted to the dis per sion and rapid ox y gen a tion of or
more » ... en a tion of or ganic de bris. Its ac cu mu lation was a con se quence of stag nant bot tom wa ter con di tions that pe ri od i cally oc curred in the ba sin. In these pe ri ods, in tense de com po si tion in ten si fied by hy dro ther mal and diagenetic pro cesses was as so ci ated with ox y gen con sump tion and the release of green house gases, which led to hypoxia and acid i fi ca tion. These phe nom ena in ten si fied by ther mal and den sity strat i fi ca tion had a ma jor im pact on the struc ture, evo lu tion and dis tri bu tion of biota. Stress as so ci ated with rap idly chang ing con di tions in duced by sed i men tary pro cess and upwelling re sulted in the dom i nance of forms that col o nized most sed i ments (Glomospira, Ammodiscus, Recurvoides, Rzehakina) and sur face wa ters (Guembelitria, Chiloguembelina, Globanomalina, Globigerina, Cassigerinella, Catapsydrax). At the time, foraminifera were lim ited to low-di ver si fied eutrophic as sem blages or were mainly re placed by si li ceous phytoplankton (radio lar ians and di a toms). Geo chem i cal data con firm that en vi ron men tal cri ses in the Paleogene ba sin took place un der chang ing ther mal con di tions that re flect global events (KTBE, PTME, EEOC and TTE). Ther mal stress fa vour ing the for ma tion of cer tain min er als or rocks oc ca sion ally oc curred dur ing the Paleocene to Eocene (sid er ite, phos phates) and dom i nated in the Early Oligocene (sil ica).
doi:10.7306/gq.1369 fatcat:xjm7v7oxh5dgbhklxzajdbnmoa