Temperatures and oxygen isotopic composition of Phanerozoic oceans
Temperatures and oxygen isotopic composition of Phanerozoic oceans
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DOI：
10.1016/j.earscirev.2015.03.008
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发表时间：
2015-07
影响因子：
12.1
通讯作者：
J. Veizer;A. Prokoph
中科院分区：
文献类型：
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作者：
J. Veizer;A. Prokoph
古代海洋的温度是了解我们星球气候历史的一个重要制约因素。经典的氧同位素古温度计在化石贝壳上，而在应用于年轻的时候非常熟练（新生代）部分的地质记录，被认为只能产生不可靠的结果，为中生代的“深时间”，因为经验充分记录的长期趋势，以更负的δ 18 O值随着年龄的增加是由沉积后重结晶过程产生的，或者，如果是主要的，意味着生态上不适宜的早期炎热海洋。在这里，我们提供了几乎覆盖整个古生代的58，532个低镁方解石海贝壳的δ 18 O测量结果的汇编，认为约-6 ‰的长期下降是主要的，提出它反映了海水氧同位素组成的变化，并定义了古海水δ 18 O的新基线趋势;后者为化石标本的环境温度计算提供了一个新的模板。由此产生的化石分类群（有孔虫，腕足动物，箭石和双壳类）的模式模仿他们的现代同行的温度范围和模式。这一概念框架使现实主义的概念应用于化石的环境栖息地温度，并为我们提供了一个早该解释的“深时间”地质历史的工具。
The temperature of ancient oceans is an important constraint for understanding the climate history of our planet. The classical oxygen isotope paleothermometry on fossil shells, while very proficient when applied to the younger (Cenozoic) portion of the geologic record, is believed to yield only unreliable results for the Phanerozoic “deep time”, either because the empirically well documented secular trend to more negative δ18O values with increasing age was generated by post-depositional recrystallization processes or, if primary, implies ecologically unpalatable hot early oceans. Here we present a compilation of δ18O measurements for 58,532 low-Mg calcite marine shells that cover almost the entire Phanerozoic eon, argue that the secular decline of about − 6‰ is primary, propose that it reflects the changing oxygen isotopic composition of sea water, and define a new baseline trend for δ18O of paleo-sea water; the latter providing a new template for calculation of ambient habitat temperatures of fossil specimens. The resulting pattern for fossil taxa (foraminifera, brachiopods, belemnites and bivalves) mimics their modern counterparts in temperature ranges and modes. This conceptual framework enables application of actualistic concepts to ambient habitat temperatures of fossils and provides us with a long overdue tool for interpretation of “deep time” geologic history.