Harding Iceland spar: A new δ18O−δ13C carbonate standard for hydrothermal minerals

Fish otoliths are aragonitic accretions located within the inner ear of teleost fish. The acellular nature of otoliths, along with taxon-specific shapes, chronological growth increments, and abundance in the fossil record suggest that the stable isotope chemistry of these structures may be unique recorders of environmental conditions experienced by fish in both modern and ancient water masses. To assess the factors determining δ13C and δ18O fractionation in fish otoliths, we reared Atlantic croaker (Micropogonias undulatus) larvae under controlled environmental conditions. Metabolic effects apparently generated large isotopic disequilibria in the δ13C values of M. undulatus otoliths. We found evidence of a negative regression between δ13C-carbonate-δ13Cwater (δ13C) and temperature: δ13C = −1.78 − 0.18 T°C However, this relationship was aliased to a degree by a positive correlation between δ13C and somatic growth and otolith precipitation rates. Oxygen isotopes were deposited close to equilibrium with the ambient water. The relationship between temperature and the 18O/16O fractionation factor (α) was determined empirically to be: 1000 ln α = 18.56(103T K−1) − 32.54 The fractionation factor was not affected by either otolith precipitation or fish growth rates. Reconstruction of water temperature histories should, therefore, be possible from the δ18O values of M. undulatus otoliths with a precision of 1°C, providing the δ18O of the ambient water can be estimated.

δ18O

δ15N

Equilibrium fractionation

10.1016/s0016-7037(97)00141-5

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Carbon Oxygen Isotope Analysis and Its Significance of Carbonate in the Zhaogezhuang Section of Early Ordovician in Tangshan, North China

地球科学学刊：英文版 (2013)

Zhenhong Yang Ning Zhang Jinxiu

在早奥陶纪 Zhaogezhuang () Tangshan 的节() ，诺思中国， Yeli () 形成由一个全部第三顺序的序列组成，与外形从内部斜面把站台和开放水兵限制了为中间、平的外部斜面。Liangjiashan () 形成被 highstand 系统道(HST ) 与谷物浅的主要内部的斜面和泻湖外形统治。在整个岩石的碳酸盐期间分析碳和氧同位素从 7.110.76 在 Yeli 形成范围揭示 13C 价值(PDB ) 与在 2.98 点的吝啬的价值，当 18O 珍视时，在 6.12 点与吝啬的价值 9.094.65 变化。在 1.150.3 的 Liangjiashan 形成范围的 13C 价值，和 0.57 的吝啬的价值；18O 价值是 8.767.48，并且吝啬的价值是 8.06。在 Yeli 形成的 13C 价值减少，但是在 Liangjiashan 形成的底部，价值稳定地增加。在中间上面的形成，在 01.00 之间有一个扩大变化。在学习的节的 13C 趋势类似于当代的节的，除了它有低得多的 13C 价值和一次更否定的旅行之外。在 13C 变化和海面升降的事件之间的关联，以及沉积外形，显示在 Tangshan 区域，碳同位素进化能是到发育营养正常促进剂 sea/oligotrophic 海的过程的 attributabled， seafloor 浅水里的调停有机体的氧化和在最大的泛滥以后的器官的减小。在碳同位素内容的变化被地区性的相对的海水平变化首先影响。比作另外的同时代的数据，唐 shan 区域的早奥陶纪严重地也在 18O 被弄空，与 18O，样品珍视的所有低于 5，除了有 -4.65 的价值的一件样品。与有 5.5 的 18O 价值(降雪) 的古老的海水，描出是合理的不到 37 畨湡的温度吗？？

δ18O

Oxygen-18

Isotope Analysis

Carbon fibers

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