Stable isotope differences among morphotypes of Neogloboquadrina pachyderma (Ehrenberg): implications for high-latitude palaeoceanographic studies
Stable isotope differences among morphotypes of Neogloboquadrina pachyderma (Ehrenberg): implications for high-latitude palaeoceanographic studies
复制标题
Neogloboquadrina pachyderma (Ehrenberg) 形态类型之间的稳定同位素差异：对高纬度古海洋学研究的影响
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
N. Healy
中科院分区：
文献类型：
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作者：
N. Healy
总结
浮游有孔虫的稳定同位素组成在解释过去的海洋学和环境条件中起着至关重要的作用，因此准确了解影响其同位素组成的因素是必不可少的。为了提高高纬度浮游有孔虫Neogloboquadrina pachyderma的古海洋学应用价值，本研究定量描述了其形状和氧、碳同位素变异性。8200余份N.对来自北大西洋和南印度洋表层沉积物的36个重力和活塞岩心顶部的厚皮进行了数字化，并通过封闭形式的傅立叶级数进行了分析。形态学结果在别处详细介绍，并在本研究中用于选择标本进行同位素分析。这种重要的高纬度珊瑚的形态变异之间存在着显著的同位素差异。随着测试形状变得更五边形和更少方形，样本中的氧和碳同位素变得耗尽。同位素差异既不能归因于测试增厚，也不能归因于尺寸或盘绕方向。这一观察结果具有重要的意义，在使用这种矿物作为高纬度古海洋学调查的示踪剂。特别是，未来的同位素调查利用这个物种应分析单一的形式，以便明确解释古海洋学信号。
SUMMARY
The stable isotopic composition of planktonic foraminifera plays a paramount role in interpretations of past oceanographic and environmental conditions; thus an accurate understanding of the factors which influence their isotopic composition is essential. In order to increase the palaeoceanographic utility of the high-latitude planktonic foraminifera Neogloboquadrina pachyderma, its shape and oxygen and carbon isotopic variability are quantitatively described in this study. Over 8200 specimens of N. pachyderma from 36 gravity and piston core tops from surface sediments of the North Atlantic and southern Indian Oceans were digitized and analysed via Fourier series in closed form. The morphological results are presented in detail elsewhere and are utilized in this study to select specimens for isotopic analyses. Significant isotopic differences exist between morphological variants of this important high-latitude speaes. Specimens become depleted in both oxygen and carbon isotopes as the test shape becomes more pentagonal and less quadrate. The isotopic differences cannot be attributed to test thickening nor to size or coiling direction. This observation has important implications in the use of this speaes as a tracer in high-latitude palaeoceanographic investigations. In particular, future isotopic investigations utilizing this species should analyse single forms to allow for clear interpretation of palaeoceanographic signals.