Sedimentary environments, biota and stratigraphy of the Bajocian–Oxfordian of the northern wing of the Chekurovskaya anticline (Lower Lena River, northern East Siberia)

The article summarizes the new data on the paleontological, litho-, bio- and chemostratigraphic characteristics of the Middle Jurassic section (upper Bajocian–lower Callovian) of the northern wing of the Chekurovskaya anticline (lower reaches of the Lena River, northern East Siberia). New data on the overlying lower Oxfordian deposits are also presented. It has been established that the accumulation of sediments of the uppermost Kelimyar and uppermost Chekurovskii formations occurred mainly in the conditions from the outer zone of the upper sublittoral to the inner zone of the middle sublittoral, while the formation of the greater part of the Chekurovskii Formation is associated with the inner (closest to shore) zone of the upper sublittoral. The Stan-Yuryakh Formation was mainly deposited in the conditions of the outer zone of the upper sublittoral. Beginning from the middle Bathonian, until the onset of the Late Jurassic, three sedimentation pauses are recorded in the marine sedimentation regime in the studied area; ideas about their duration have been adjusted. It was established that the dynamics of biodiversity in the studied shallow-water marine area of the paleobasin was mainly controlled by transgressive-regressive events, which in turn were largely determined by regional tectonic processes. New maps-schemes of the paleogeographic situation for the territory covering the coast of the Laptev Sea for key time slices in the interval of the late Bajocian–Bathonian are proposed.

Middle Jurassic, Upper Jurassic, stratigraphy, lithofacies, biodiversity, bionomic zones, paleotemperatures, paleogeography, Arctic