Oxygen and strontium isotopes from fossil shark teeth: Environmental and ecological implications for Late Palaeozoic European basins
Oxygen and strontium isotopes from fossil shark teeth: Environmental and ecological implications for Late Palaeozoic European basins
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DOI：
10.1016/j.chemgeo.2013.01.022
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发表时间：
2013-03-29
期刊：
影响因子：
3.9
通讯作者：
Berner, Ulrich
中科院分区：
文献类型：
--
作者：
Fischer, Jan;Schneider, Joerg W.;Berner, Ulrich
晚古生代化石鲨鱼遗迹在海相和非海相沉积中都有发现，因此其古生态学存在争议。氧和锶同位素组成的生物氟磷灰石在179牙齿，鳞片和刺主要是hybodontid（Lissodus）和xenacanthiform（Orthacanthus，Xenacanthus，Bohemiacanthus，Triodus）鲨鱼从不同的晚石炭世（莫斯科）到早二叠世（Artinskian）盆地的欧洲被用来作为生态示踪剂，以破译调查类群的溯河或专性淡水生活方式。在不同的盆地中，不同鲨鱼牙齿的δ O-18（P）值范围为11.7 - 20.2 ppm，波希米亚地块的平均值为16.9 +/- 0.5 ppm，德国东部为16.2 +/- 0.8 ppm，德国西南部为18.2 +/- 1.0 ppm，西班牙中南部为18.5 +/- 0.7 ppm，撒丁岛为17.6 +/- 0.4 ppm，法国中部为16.6 +/- 0.5 ppm。相对于同期海洋环境的鲨鱼牙齿，来自盆地的牙齿三角洲O-18（P）值大多减少了千分之1-5。共存类群的氧同位素特征不显示系统的差异，排除栖息地的影响，为不同的鲨鱼群体。然而，Puertollano和Saar-Nahe的δ O-18（P）值明显较高，这可能是由于温暖干燥的气候和盆地中充足的停留时间导致古湖泊环境中环境水O-18的显著蒸发富集。牙齿的锶同位素组成在0.70824和0.71216之间变化，平均值为0.71031。这些Sr-87/Sr-86比值与其地层年龄的海水Sr-87/Sr-86记录相比，总是更具放射性。总体而言，调查的牙齿样品产生低三角洲O-18（P）和高Sr-87/Sr-86值偏离生物磷灰石值预期为同期的海洋脊椎动物和典型的淡水环境。这表明，在晚古生代欧洲盆地的各种化石鲨鱼类群完全适应淡水的生活方式。(C)2013爱思唯尔有限公司版权所有。
Fossil shark remains occur in both marine and nonmarine Late Palaeozoic deposits, therefore their palaeoecology is controversial. The oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth, scales and spines predominantly of hybodontid (Lissodus) and xenacanthiform (Orthacanthus, Xenacanthus, Bohemiacanthus, Triodus) sharks from various Late Carboniferous (Moscovian) to Early Permian (Artinskian) basins of Europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa. The delta O-18(P) values of the different shark teeth range from 11.7 to 20.2 parts per thousand within the different basins with mean values of 16.9 +/- 0.5 parts per thousand for the Bohemian Massif, 16.2 +/- 0.8 parts per thousand for eastern Germany, 18.2 +/- 1.0 parts per thousand for southwestern Germany, 18.5 +/- 0.7 parts per thousand for southern-central Spain, 17.6 +/- 0.4 parts per thousand for Sardinia, and 16.6 +/- 0.5 parts per thousand VSMOW for the French Massif Central. The tooth delta O-18(P) values from the basins are mostly depleted by 1-5 parts per thousand relative to those of shark teeth from contemporaneous marine settings. Oxygen isotope signatures of co-occurring taxa do not show systematic differences excluding habitat effects for different shark groups. However, distinctly higher delta O-18(P) values from Puertollano and Saar-Nahe can be attributed to significant evaporative enrichment in O-18 of the ambient water in the ancient lacustrine environments due to a warm and dry climate and sufficient residence time in the basins. The strontium isotopic composition of the teeth varies between 0.70824 and 0.71216 with a mean value of 0.71031. These Sr-87/Sr-86 ratios are always more radiogenic in comparison to the Sr-87/Sr-86 record of seawater of their stratigraphic age. Overall, the investigated tooth samples yield low delta O-18(P) and high Sr-87/Sr-86 values deviating from bioapatite values expected for contemporaneous marine vertebrates and typical for freshwater settings. This indicates a fully freshwater adapted lifestyle for a variety of fossil shark taxa in Late Palaeozoic European basins. (C) 2013 Elsevier B.V. All rights reserved.