The First Data on Carbon Isotope Stratigraphy of the Asselian and Sakmarian Stages of the Lower Permian in Northern Verkhoyanie

Abstract

Changes in the values of δ¹³С_оrg in the lower part of the Permian deposits, obtained in the Kuba-lakh Section of the lower reaches of the Lena River and integrated with biostratigraphic data are detected in northeastern Russia for the first time. A comparison with isotope-carbon trends identified in the Asselian and Sakmarian stages of the Southern Urals is proposed. Based on the established sequence of negative shifts of the carbon isotope composition of organic matter, a conclusion is made that the Carboniferous–Permian boundary in the Kubalakh Section is located at the 80 m thick gap in section. The first data independent of the biostratigraphic and paleontological records are obtained on the Late Asselian age of the Tuora-Sis Formation beds containing the Bulunites ammonoid association, the stage assignment of which has been debated for many decades. The chronostratigraphic indefinite interval between the Asselian and Samarian stages is significantly reduced to the upper parts of the Jakutoproductus lenensis Beds. The data obtained indicate that the continuation of the work on the chemostratigraphy of stable carbon isotopes has good prospects for substantiating the division into stages and the interregional correlation of the Lower Permian deposits in Verkhoyanie.