FIRST FIND OF PLANKTONIC FORAMINIFERA IN DANIAN DEPOSITS OF THE KHATYR BASIN (NORTHEASTERN USSR)

Abstract

The Khatyr Basin, located in the eastern part of the Koryak highland, is bordered on the northwest by Cenozoic fold structures and opens to the southeast into the Aleutian Basin of the Bering Sea. The present study discusses the core from borehole KK-1, drilled in the Khayidin River valley in the western part of the Khatyr Basin (Kaygytkinskaya exploration area). The absence of the species Globigerina eugubina in the Khatyr complex and the presence of Globorotalia trinidadensis suggest that the planktic foraminifera-bearing deposits of the Khatyr Basin are slightly older than those from the top of the Kotsuhiro Formation, which contains the zone species of the lower zone of the Danian Stage, i.e., Globigerina eugubina. The deposits of the Danian Stage in borehole KK-1 are overlain in the interval of 495 to 62 meters by deposits with rich benthic foraminiferan complexes of the upper Eocene. Deposits of late Paleocene and early or middle Eocene age are, in all likelihood, either partially or entirely lacking in that part of the Khatyr Basin.