Abstract

New data on the structure and formation conditions of the Anabar–Lena sedimentary basin in the Nordvik facies region at the beginning of the Early Jurassic (Hettangian–early Pliensbachian) are presented. Based on a detailed lithofacies analysis, coastal-continental, coastal-marine, and shallow-marine sedimentation conditions were reconstructed. Ichnofacies studies were carried out for the first time: various traces of the vital activity of organisms identified as Scolithos and Cruziana ichnofacies were identified. An analysis of the relationship between individual lithofacies and their associations made it possible to identify a series of different rank cyclites in the section. In the general regressive series, six decameter-scale cyclites corresponding (except the basal, regressive migration regime of cyclogenesis) were established. They are characterized by an asymmetric internal structure, reflecting periods of coastline migration. The reconstructed model of the sedimentary sequence allows one to trace temporal changes in the sedimentation conditions and identify the main events in the sedimentary basin. It is established that the main Early Jurassic evolution phases in the western part of the Anabar–Lena paleobasin are reflected in the structure of the section and are caused by the alternation of transgressive and regressive periods against the background of a gradual attenuation of the regional tectonic activity. The results obtained allow us to significantly refine our understanding of sedimentation evolution in the Anabar–Lena basin. The revealed cyclical nature of the Lower Jurassic sequence can be used for the regional lithostratigraphic correlation.

中文翻译：

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Nordvik相区Anabar-Lena沉积盆地的Hettangian-Pliensbachian早期演化阶段

摘要

提出了侏罗纪早期（Hettangian-Pliensbachian）初期Nordvik相区Anabar-Lena沉积盆地的结构和形成条件的新数据。在详细的岩相分析基础上，重建了沿海大陆，沿海海洋和浅海沉积条件。首次进行了眼相研究：鉴定了被鉴定为Scolithos和Cruziana ichnofacies的生物的各种生命活动的痕迹。对单个岩相及其关联之间的关系进行的分析使得有可能在该断层中识别出一系列不同等级的菱形岩。在一般的回归系列中，建立了六个十米级的单晶石（除回旋作用的基础，回归迁移机制外）。它们的特点是内部结构不对称，反映了海岸线迁移的时期。重建的沉积序列模型可以追踪沉积条件的时间变化并确定沉积盆地的主要事件。已经确定，在Anabar–Lena古生物的西部，侏罗纪早期的主要演化阶段反映在该断面的结构中，并且是由海侵和退回期的交替引起的，其背景是区域构造逐渐衰减。活动。所获得的结果使我们能够极大地加深对阿纳巴－莱纳盆地沉积演化的理解。下侏罗纪层系的揭示的周期性性质可用于区域岩石地层学相关性。