Paleotemperature Analyses of Belemnoidea and Jurassic Paleoclimatology
Paleotemperature Analyses of Belemnoidea and Jurassic Paleoclimatology
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DOI：
10.1086/626744
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发表时间：
1961-05
期刊：
影响因子：
--
通讯作者：
R. Bowen
中科院分区：
文献类型：
--
作者：
R. Bowen
近100个标本的侏罗纪Belemnoidea进行了分析，他们的古温度记录汇编质谱测量。它们来自世界各地，它们的δ值（单位为每密耳的份数）是整个样品的平均值，与标准PDB-1相关。在这一组合中，分析了14个样品在生长过程中的δ变化，即，数据来源于对来自喙部的粉末状碳酸盐的连续增量的检查。这些结果也与PDB-1有关。这样获得的信息与其他调查领域提供的信息进行比较。它表明，在侏罗纪，地球有比现在更大的热带和亚热带，赤道地区贯穿美国和欧洲（这可能比现在更接近）。古地温证实了特提斯海侵和北极海侵。两极的位置仍然不确定，但北极可能位于东亚的某个地方。印度位于温带，离赤道比现在远得多。阿拉斯加和新几内亚在侏罗纪都是冷水区。可以推断，当时的两极比现在要温暖得多，因为Belemnoid证据（从分布在大部分海洋的游泳动物中获得的证据）显示，温度范围比现在小得多，大约为20° C。与约60° C相比。今天Belemnoids显示出明显的季节变化，但这些变化通常涵盖2°-5° C的小范围。因此，尽管侏罗纪是一个极其平静的时期，但季节确实存在。
Almost 100 specimens of Jurassic Belemnoidea were analyzed and their paleotemperature record compiled from mass-spectrometric measurements. They were of world-wide origin, and their δ-values in parts per mil (%0) are averages of whole specimens and are related to the standard PDB-1. Of this assemblage, 14 specimens were analyzed for δ-variation during growth, i.e., data were derived from examination of successive increments of powdered carbonate from the rostra. These results are also related to PDB-1. The information so obtained is compared with that given by other fields of investigation. It is demonstrated that in the Jurassic the earth had larger tropical and semitropical belts than at present, with an equatorial region running through the U.S.A. and Europe (which could have been closer together than they are now). The paleotemperatures confirm the Tethyan and Arctic transgressions in the latter area. The positions of the poles remain uncertain, but the north pole probably occupied a position somewhere in east Asia. India lay in the temperate zone much farther from the equator than at present. Alaska and New Guinea were both cool-water areas in the Jurassic. It may be inferred that the poles were much warmer than at present, since the Belemnoid evidence (obtained from nektonic animals that ranged over most of the seas) shows a temperature range much smaller than that existing now, around 20° C. as compared with about 60° C. today. Well-marked seasonal variations are shown by the Belemnoids, but these usually cover small ranges of the order of 2°-5° C. Thus, although the Jurassic was an extremely equable period, seasons did exist.