Middle to Late Jurassic belemnites from the Spiti and Zanskar valleys in the Indian Himalayas were used for stable isotope (δ13C, δ18O) and element (Mg/Ca, Sr/Ca) analyses. Although the Himalayan orogeny deformed and altered a large portion of the collected fossils, cathodoluminescence and scanning electron microscopy in combination with analyses of iron and manganese contents allowed the identification of belemnites believed to still retain their original chemical composition. Results indicate a long-term temperature decrease from the Middle Callovian–Oxfordian to the Tithonian, which is proposed to have been caused by a concomitant drift of eastern Gondwana into higher palaeolatitudes. Reconstructed absolute temperatures depend on the used equation and assumed δ18O value of seawater, but most likely varied between 17.6 °C to 27.6 °C in the Kimmeridgian and Tithonian with average values between 22 °C to 24 °C. This way, temperatures were similar to slightly warmer than today at comparable latitudes. The reconstruction of absolute temperatures for the Middle Callovian–Oxfordian was hindered by a larger number of poorly preserved belemnites representing this time interval.

中文翻译：

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印度喜马拉雅山脉中晚侏罗世箭石稳定同位素（δ13C、δ18O）和元素比（Mg/Ca、Sr/Ca）的首次记录及其古环境重建潜力

来自印度喜马拉雅山脉 Spiti 和 Zanskar 山谷的中至晚侏罗世箭石用于稳定同位素（δ13C、δ18O）和元素（Mg/Ca、Sr/Ca）分析。尽管喜马拉雅造山运动使大部分收集到的化石变形和改变，但阴极发光和扫描电子显微镜结合铁和锰含量的分析，可以识别出据信仍保留其原始化学成分的箭石。结果表明，从中卡洛夫阶 - 牛津阶到提通阶的长期温度下降，被认为是由冈瓦纳东部伴随漂移到更高的古纬度引起的。重建的绝对温度取决于所使用的方程和假设的海水 δ18O 值，但最有可能在 17.6 °C 到 27 °C 之间变化。Kimmeridgian 和 Tithonian 为 6 °C，平均值在 22 °C 到 24 °C 之间。这样，在可比的纬度上，温度类似于比今天略高的温度。代表这一时间间隔的大量保存不佳的箭石阻碍了中卡洛夫阶-牛津阶绝对温度的重建。