Brachiopods of the Carboniferous-Permian Boundary Deposits of the Kubalakh Section (Lower Reaches of the Lena River, Northern Verkhoyanie)

Abstract

The paper presents new data on the vertical distribution of brachiopods in the Carboniferous-Permian boundary deposits (the Kubalakh Formation) of the Kubalakh section (lower reaches of the Lena River). The deposits of the Kubalakh Formation are divided by the valley of the Kubalakh Creek into two outcrops, which are suggested to be considered as subformations. A brachiopod complex Jakutoproductus protoverkhoyanicus Kaschirzew, Verchojania abramovi Makoshin, Verchojania cf. monstrosus (Ganelin), Verchojania sp., Cancrinella? alazeica Zavodowsky, Tornquistia kolymensis Afanasjeva, Tornquistia sp., Rhynoleichus sp., Rhynchopora sp., characteristic of the Jakutoproductus protoverkhoyanicus Zone of the Kygyltasian Horizon of the Verkhoyanie is recognized in the Lower Kubalakh Subformation. A brachiopod complex Jakutoproductus verkhoyanicus (Fredericks), Jakutoproductus crassus Kaschirzew, Waagenoconcha aff. wimani (Fredericks), Orbiculoidea sp., Rhynchopora sp., characteristic of the Jakutoproductus verkhoyanicus Zone of the Khorokytian Horizon of the Verkhoyanie is recognized in the Upper Kubalakh Subformation. Based on the data presented, the Carboniferous-Permian boundary should be drawn within the Kubalakh Formation, rather than at the base of the Tuora-Sis formation, as is was accepted on the basis of the latest Unified Regional Scheme of Permian Deposits in the Verkhoyansk-Okhotsk region.