A PILOT MODEL FOR NEOGENE AND PALEOGENE BIVALVE CENOZONES OF THE NORTHWESTERN PACIFIC

Abstract

By means of taxonomically and geochronologically revised species lists (a total of 793 valid species of bivalve molluscs were considered) from 178 formations (‘Suites’) of Neogene and Paleogene deposits in the Russian Far East and characteristic and index species distinguished on this basis, the molluscan cenozones are established. These allow the construction of a preliminary stratigraphical scheme for the northwestern Pacific (western and eastern Kamchatka, south and north Sakhalin, Koryak 0Upland). The following cenozones are established: 1—extant species; 2—Fortipecten takahashii–Yoldia (Cnesterium) kuluntunensis; 3—Acila (Truncacila) marujamensis–Lucinoma acutilineata; 4—Mya cuneiformis–Acila (Truncacila) gottschei; 5—Mytilus (Tumidimytilus) tichanovitchi–Macoma osakaensis; 6—Megayoldia (Hataiyoldia) tokunagai–Neilonella (Borissia) sakhalinensis; 7—Periploma (Aelga) besshoensis–Yoldia (Yoldia) kovatschensis; 8—Papyridea (Profulvia) harrimani–Ciliatocardium asagaiense; 9—Megayoldia (Portlandella) watasei–Yoldia (Nampiella) takaradaiensis; 10—Nuculana (Saccella) gabbii–Corbula (Cuneocorbula) formosa; 11—Lucina washingtonensis–Nuculana (Saccella) alaeformis. On the basis of bivalve distribution patterns, it is assumed that the boundary between the Neogene and the Paleogene lies at the base of the Kuluven Horizon in western Kamchatka, the base of the lower Nevelisk sub-Horizon in south Sakhalin and at the lower part of the Pakhachin Horizon in eastern Kamchatka and Koryak Upland.