Abstract In this paper, we use molecular paleothermometry, based on the TEX86 proxy derived from fossilized archaeal lipids, to reconstruct absolute sea surface temperatures (SSTs) for the northwest Tethys Shelf during the late Pliensbachian to early Toarcian (Early Jurassic, ~183 Ma) stages. Our composite record from outcrops in Spain and Italy reveals that tropical SSTs varied between 22 and 32 °C over a ~ 3 Myr time period, including transient temperature excursions of 5–10 °C magnitude with lapse rates of ~0.1 °C/kyr. Changes in reconstructed SSTs covaried with sea level fluctuations and δ18O isotope signatures of marine biocalcifiers, recording recurrent shifts between icehouse and greenhouse states. Parallel trends of reconstructed SST and δ13C isotopes of atmospheric CO2 may reflect storage of isotopically light carbon in cryosphere reservoirs during icehouse phases and release during greenhouse phases. The existence of a labile cryosphere is considered a prerequisite to explain the inferred rapid climate fluctuations and as a reservoir to facilitate pronounced carbon isotope excursions.

中文翻译：

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Toarcian 早期气候扰动的分子古温度测量

摘要 在本文中，我们使用分子古温度测量法，基于源自化石古菌脂质的 TEX86 代理，重建特提斯大陆架在晚 Pliensbachian 到早 Toarcian（早侏罗世，~183 Ma）期间的绝对海面温度（SST）。阶段。我们对西班牙和意大利露头的综合记录显示，热带海温在约 3 Myr 的时间段内在 22 到 32°C 之间变化，包括 5-10°C 量级的瞬态温度偏移，衰减率为约 0.1°C/kyr。重建的 SST 的变化与海平面波动和海洋生物钙化剂的 δ18O 同位素特征共变，记录了冰库和温室状态之间的反复变化。大气 CO2 重建 SST 和 δ13C 同位素的平行趋势可能反映了冰库阶段冰冻圈水库中同位素轻碳的储存和温室阶段的释放。不稳定冰冻圈的存在被认为是解释推断的快速气候波动的先决条件，也是促进碳同位素显着漂移的储库。