Abstract The shell δ18O of young modern Aequipecten opercularis from the southern North Sea provides an essentially faithful record of seasonal variation in seafloor temperature. In this well-mixed setting, A. opercularis shell δ18O also serves as a proxy for seasonal variation in surface temperature. Individuals from less agitated (e.g. deeper) settings in a warm climate would not be expected to record the full seasonal range in surface temperature because of thermal stratification in summer. Such circumstances have been invoked to explain cool isotopic summer temperatures from early Pliocene A. opercularis of eastern England. Support for a sub-thermocline setting derives from high-amplitude variation in microgrowth-increment size, which resembles the pattern in sub-thermocline A. opercularis from the southern Mediterranean Sea. Here, we present isotope and increment profiles from further sub-thermocline individuals, live-collected from a location in the Adriatic Sea for which we provide modelled values of expected shell δ18O. We also present data from supra-thermocline shells from the English Channel and French Mediterranean coast. The great majority of sub-thermocline A. opercularis show high-amplitude variation in increment size, and winter and summer δ18O values are generally quite close to expectation. However, the relatively warm summer conditions of 2015 are not recorded, in most cases due to a break in growth, perhaps caused by hypoxia. The supra-thermocline shells show subdued increment variation and yield isotopic winter and summer temperatures quite close to the local directly measured values. A. opercularis shells therefore provide a fairly good isotopic record of ambient temperature (if not always of relatively warm summer conditions below the thermocline) and their hydrographic setting can be determined from increment data. Early Pliocene examples from eastern England can be interpreted as having lived in a setting below the thermocline, with a higher seasonal range in surface temperature than now in the adjacent southern North Sea.

中文翻译：

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亚温跃层 Aequipecten opercularis (Mollusca:Bivalvia) 的生长增量特征和同位素 (δ18O) 温度记录：来自现代亚得里亚海形态的证据以及对英格兰东部上新世早期例子的应用

摘要 来自北海南部的年轻现代 Aequipecten opercularis 的贝壳 δ18O 为海底温度的季节性变化提供了基本真实的记录。在这种混合良好的环境中，A. opercularis shell δ18O 也可以作为表面温度季节性变化的代表。由于夏季的热分层，来自温暖气候中较不激动（例如更深）环境的个体预计不会记录表面温度的整个季节性范围。这种情况已被用来解释英格兰东部上新世早期 A. opercularis 的凉爽同位素夏季温度。对亚温跃层环境的支持源于微生长增量大小的高幅度变化，这类似于来自地中海南部的亚温跃层 A. opercularis 的模式。这里，我们提供了更多亚温跃层个体的同位素和增量分布，这些个体是从亚得里亚海的一个位置现场采集的，我们提供了预期壳 δ18O 的模型值。我们还提供了来自英吉利海峡和法国地中海沿岸的超温跃层贝壳的数据。绝大多数亚温跃层 A. opercularis 的增量大小呈现高幅度变化，冬季和夏季 δ18O 值普遍接近预期。然而，没有记录到 2015 年相对温暖的夏季条件，在大多数情况下是由于生长中断，可能是缺氧引起的。超温跃层壳显示出减弱的增量变化，产生的同位素冬季和夏季温度与当地直接测量值非常接近。一种。因此，鳃盖壳提供了相当好的环境温度同位素记录（如果并非总是在温跃层以下相对温暖的夏季条件下），它们的水文环境可以从增量数据中确定。来自英格兰东部的上新世早期例子可以解释为生活在温跃层以下的环境中，表面温度的季节性范围比现在相邻的北海南部更高。