Polar climates during the early Cretaceous greenhouse world: Evidence from clumped isotope thermometry of belemnites
Polar climates during the early Cretaceous greenhouse world: Evidence from clumped isotope thermometry of belemnites
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白垩纪早期温室世界的极地气候：来自箭石聚集同位素测温的证据
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Passey
中科院分区：
文献类型：
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作者：
G. Price;B. Passey
在这里，我们使用碳酸盐聚集同位素测温法确定从化石软体动物（射箭石）获得的亚北极海洋温度，这种方法基于碳酸盐矿物晶格中 13C 和 18O“聚集”成彼此的键。根据这些分析，我们推断亚北极白垩纪早期的海洋温度范围为 10-20°C。这些温暖的亚北极温度比目前 60-65 N 的夏季平均水温要高，并且与具有浅（平坦）纬度温度梯度的较温暖的“温室”世界一致。我们的综合温度和 18O-碳酸盐数据表明海水 18O 值具有显着的现代特征，因为它们与现代高纬度海水相似，但比模拟白垩纪海水更积极。我们确定了一个较冷的晚凡兰吉阶区间，其温度与极地地区一致，比冰点高几度，并且也与 18O 海水值的增加相一致。因此，我们找到了极地冰不太可能出现以及极地冰可能出现的时间间隔的证据。这两种情景都支持这样的观点：在温室间隔期间，极地气候总体温暖但充满活力，期间夹杂着短暂的冰生长期。
Here we determine sub-Arctic marine temperatures obtained from fossil mollusks (belemnites) using carbonate clumped-isotope thermometry, an approach based on the ‘clumping’ of 13C and 18O in the carbonate mineral lattice into bonds with each other. From these analyses we infer sub-Arctic early Cretaceous marine temperatures ranging from of 10‐20 C. These warm sub-Arctic temperatures are warmer than present mean summer water temperatures at 60-65 N and are consistent with a warmer ’greenhouse’ world featuring a shallow (equable) latitudinal temperature gradient. Our combined temperature and 18O-carbonate data imply seawater 18O values that have a remarkably modern character in that they are similar to modern high latitude seawater but more positive that modelled Cretaceous seawater. We identify a cooler Late Valanginian interval with temperatures consistent with polar regions a few degrees above freezing and are also coincident with increased 18O seawater values. Thus we find evidence of intervals when polar ice was unlikely, and also when polar ice was plausible. Both scenarios support the view of generally warm but dynamic polar climates during greenhouse intervals that were punctuated by minor periods of ice growth.