Recent culture studies of living coccolithophores have established a biogeochemical framework for the use of the geochemical compositions of their calcite biominerals as proxies in palaeoceanography. Yet, questions remain regarding the transferability of such experimental data to fossil coccoliths. Here we analysed the carbon and oxygen isotopic composition of Miocene coccoliths to assess the suitability of such data for reconstructing the past environment. We found that the oxygen isotopic compositions of the relatively small Noelaerhabdaceae coccoliths gathered in the 3–5 μm fractions appear to be a suitable material to derive temperatures after a correction for a constant vital offset of 0.8‰. The interpretation of the isotopic signal of the relatively large Coccolithales coccoliths (5–8 μm fractions) is more complex, but supports results from cultures. The expression of the carbon and oxygen vital effect in coccoliths appears to be limited during the so-called Miocene Climate Optimum (MCO), a period of relatively elevated atmospheric pCO₂. Subsequently, during the Miocene Climatic Transition (MCT; ~14 Ma), which saw a decline in pCO₂, large carbon and oxygen vital effects were expressed in coccolith calcite. This phenomenon predates the postulated “Late Miocene Threshold” by approximately 4 Ma, and cannot be reconciled as a temporally-synchronous nor localised feature. Furthermore, we observed a statistically significant correlation between the oxygen and carbon offsets of the small relative to large coccoliths (hence, the vital effect per se) that is likely linked to variations in atmospheric CO₂. This biogeochemical correlation further supports a forcing of the environment on the cellular physiology (growth rate and utilisation of intracellular carbon) and ultimately the magnitude of isotopic vital effects in fossil coccoliths.

活球藻的生物最近的文化研究已经建立了一个生物地球化学框架，以利用其方解石生物矿物的地球化学成分作为古海洋学的代理。然而，关于这些实验数据向化石cococoliths的可转移​​性仍然存在疑问。在这里，我们分析了中新世蛇床的碳氧同位素组成，以评估此类数据对重建过去环境的适用性。我们发现，聚集在3–5μm馏分中的相对较小的Noelaerhabdaceae球藻的氧同位素组成似乎是一种合适的材料，可以将温度常数校正为0.8‰后进行校正。相对较大的球藻（5–8μm馏分）的同位素信号的解释更为复杂，但支持来自文化的结果。在所谓的中新世气候最适期（MCO）期间，大气中的pCO相对升高，在球墨石中碳和氧的重要作用的表达似乎受到限制。₂。随后，在中新世气候转变（MCT；〜14 Ma）期间，pCO ₂下降，椰壳石方解石中表现出较大的碳和氧的重要作用。该现象比假定的“中新世晚期阈值”早了约4 Ma，因此无法作为时间同步特征或局部特征进行协调。此外，我们观察到较小的相对于较大的可可石的氧气和碳偏移之间的统计显着相关性（因此，本身的生命效应）很可能与大气中CO _2的变化有关。。这种生物地球化学的相关性进一步支持了环境对细胞生理的强迫作用（生长速率和细胞内碳的利用），并最终支持了化石可可石中同位素至关重要的作用。