Production of mud-grade carbonates by marine fish: Crystalline products and their sedimentary significance
Production of mud-grade carbonates by marine fish: Crystalline products and their sedimentary significance
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海鱼生产泥级碳酸盐：结晶产物及其沉积意义
DOI：
10.1111/j.1365-3091.2012.01339.x
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发表时间：
2012
期刊：
影响因子：
3.5
通讯作者：
SALTER M
中科院分区：
文献类型：
--
作者：
SALTER M
最近的研究表明，海洋硬骨鱼通过肠道内的初级沉淀，是泥质的丰富来源，主要是高镁方解石、碳酸盐沉淀物。以前记载的结晶产品具有多种形态，其中许多在热带浅海环境中是独一无二的，并且镁含量范围很广(从18到39 摩尔%碳酸镁)。这项研究利用扫描电子显微镜、能量色散X射线光谱、X射线衍射和液体离子色谱，对更广泛的鱼氨酸官能团(涵盖巴哈马常见的21种不同鱼种)产生的晶型进行了更广泛和更广泛的形态、矿物学和化学表征。几种以前没有在鱼源碳酸盐中描述的晶体形态被记录在案，化学成分被发现比以前报道的更加多变：除了含有>；18 摩尔%碳酸镁的高镁方解石外，还发现了镁含量较低的高镁方解石和低镁方解石。从扩展的物种范围来看，鱼源碳酸盐中的碳酸镁含量在Ca0.5到>； 40 μ%之间，颗粒长度在0.1到>；50 μm之间(单个晶体通常为<；2 mol m)。在许多物种的沉淀物中也不同程度地发现了无定形的碳酸镁(含有可检测到的CaCO3Of；2 摩尔%)。主要矿物学和碳酸镁含量随生产物种和晶体形态(本身是物种相关变量)而不同。鉴于这些碳酸盐的颗粒非常小，而且往往含有很高的碳酸镁，因此对它们的保存潜力产生了有趣的问题。因此，不同物种产生的碳酸盐可能遵循不同的排泄后保存途径的程度被考虑在内。
Recent work has established that marine teleost (bony) fish represent a prolific source of mud grade, mainly high‐Mg calcite, carbonate sediment by means of primary precipitation within the intestine. Previously documented crystalline products display a diverse array of morphologies, many unique in shallow tropical marine settings, and have a wide range of magnesium contents (from 18 to 39 mol% MgCO3). This study utilizes scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction and liquid ion chromatography to provide a more extensive and expansive morphological, mineralogical and chemical characterization of the crystalline forms produced by a wider range of piscine functional groups (covering 21 different fish species common in The Bahamas). Several crystal morphologies not previously described in fish‐derived carbonates are documented, and chemical composition is found to be more variable than previously reported: in addition to high‐Mg calcites with >18 mol% MgCO3, high‐Mg calcites with lower MgCO3contents and low‐Mg calcites are identified. From the expanded species range, MgCO3content in fish‐derived carbonates ranges fromca0˙5 to > 40 mol%, and particle length is in the range 0˙1 to >50 μm (typically <2 μm for individual crystals). Amorphous Mg‐carbonates (with detectable CaCO3of <2 mol%) are also found to varying extent in the precipitates of many species. Dominant mineralogy and MgCO3content varies with producing species and crystal morphology (itself a species‐dependent variable). Given the very small grain size and often high MgCO3contents of these carbonates, interesting questions arise about their preservation potential. Thus, the extent to which carbonates produced by different species may follow different post‐excretion preservation pathways is considered.