Abstract

Analysis of the distribution of ostracods from the Armkhi Formation (Callovian) of the Tsudakhar section (Central Dagestan) enabled the identification of a stratigraphic sequence of six assemblages determined by paleoecological conditions and the first ostracod-based biostratigraphic zonation of the Callovian of Dagestan. Beds with Pleurocythere khapissovi and the Neurocythere cruciata intermedia Zone of the European ostracod scales were identified in the middle Callovian; this facilitated the interregional correlation for ostracods. Paleoecological analysis demonstrated the formation of the lower part of the section (beds with P. khapissovi and the N. cruciata intermedia Zone) in the coastal zone of the upper subtidal with normal marine salinity, good aeration, and low sedimentation rates. Sediments of the upper part of the section (paleoecological intervals with Schuleridea translucida–Cytherella perennis and with C. perennis) accumulated in the lower zone of the upper subtidal with a high sedimentation rate, high (and constantly increasing) eutrophication, and lowered pH values. Analysis of the paleogeographic distribution of the species studied revealed the connections of the Caucasus Sea to Western and Eastern Europe and to Central Asia.

中文翻译：

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达吉斯坦中部Callovian兽足：生物地层学，古生态学和色学

摘要

对Tsudakhar断面（中达吉斯坦中部）Armkhi组（Callovian）中的兽脚类动物的分布进行分析，可以识别由古生态条件和达吉斯坦Callovian的第一个基于兽人类生物地带划分的6个组合的地层序列。在中部Callovian上发现了欧洲原产兽类鳞片的Pleurocythere khapissovi和neurocythere cruciata intermedia Zone床。这促进了成龙的区域间相关性。古生态学分析表明，该断层下部（含P. khapissovi的床）的形成和潮间带N. cruciata中间区），盐度正常，通气性好，沉降率低。该断面上部的沉积物（半透明Schuleridea translucida–Cytherella perennis和C. perennis的古生态区间）堆积在上潮下层的下部，沉积速率高，富营养化程度高（且不断增加），pH值降低。对所研究物种的古地理分布进行分析后发现，高加索海与西欧，东欧和中亚的联系。