We present the first Sr-isotope data on benthic, semi-pelagic and pelagic invertebrates from 10 biostratigraphical zones of Lower Cretaceous deposits in the Caucasus. We provide a ⁸⁷Sr/⁸⁶Sr record for the Lower Cretaceous of the Caucasus that represents a first step towards refining the sequence of palaeoenvironmental events in the late Barremian–early Albian interval in this region. Integration of data from the Caucasus and Middle Volga regions reveals two local minima events in the Sr-isotope record for the Aptian-lower Albian interval. The first decrease in ⁸⁷Sr/⁸⁶Sr to 0.70733–0.70738 (the early Aptian event) was recognized from limited material from the Volgensis-Schilovkensis Zone in the Ulyanovsk Middle Volga region. A second decrease in ⁸⁷Sr/⁸⁶Sr (the late Aptian event), was more pronounced than the first, and occurred within the Abichi, Nolani and Jacobi zones in the Caucasus, where the ⁸⁷Sr/⁸⁶Sr ratio fell to 0.70720–0.70723, 0.70720–0.70723 and 0.70721, respectively. The combined ⁸⁷Sr/⁸⁶Sr, δ¹⁸O, δ¹³C and redox records of the Caucasus, Ulyanovsk Middle Volga region and western Europe suggest that the ⁸⁷Sr/⁸⁶Sr decreases in the early and late Aptian times were initiated by sea-floor hydrothermal (basaltic volcanism) activity; associated palaeoenvironmental events include (1) an increase in temperature, (2) the development of anoxia (OAE-1a and OAE-b, respectively), (3) transgression and (4) a decrease in bio-productivity.

我们提出了高加索地区下白垩统沉积物的10个生物地层带底栖，半上层和上层无脊椎动物的第一个Sr同位素数据。我们提供了高加索下白垩纪的⁸⁷ Sr / ⁸⁶ Sr记录，这是朝着完善该地区晚Barremian-Albian早间期古环境事件的顺序迈出的第一步。来自高加索地区和伏尔加河中部地区的数据整合显示，在阿普特一低阿比安区间的Sr同位素记录中出现了两个局部极小事件。第一次降低⁸⁷ Sr / ⁸⁶从Ulyanovsk中伏尔加河地区的Volgensis-Schilovkensis地区有限的物质中可以识别出Sr达到0.70733-0.70738（早期Aptian事件）。⁸⁷ Sr / ⁸⁶ Sr的第二次下降（后期的Aptian事件）比第一次更明显，发生在高加索地区的Abichi，Nolani和Jacobi地区，那里的⁸⁷ Sr / ⁸⁶ Sr比率降至0.70720-0.70723 ，分别为0.70720–0.70723和0.70721。将合并的⁸⁷ SR / ⁸⁶的Sr，δ ¹⁸ O，δ ^13个高加索，扬诺夫斯克中东伏尔加区域和西欧的C和氧化还原记录表明，⁸⁷ SR / ⁸⁶在Aptian早期和晚期，Sr的降低是由海底热液（玄武质火山活动）引起的。相关的古环境事件包括：（1）温度升高；（2）缺氧的发生（分别为OAE-1a和OAE-b）；（3）越境行为；（4）生物生产力降低。