胶结壳有孔虫对长石的选择性利用

Selective Utilization of Feldspars by Agglutinated Foraminifera

文章采用扫描电镜、红外光谱、拉曼光谱、粒度分析等方法对浙江台州大港湾滨海沉积物中的胶结壳有孔虫亚洲波斯基砂虫(Polskiammina asiatica)和抱球砂抱球虫(Ammoglobigerina globigeriniformis)的壳壁进行了分析。结果表明,两种有孔虫壳壁具有相似的物质组成,主要包括矿物颗粒、有机外膜、有机内壁衬层、覆盖矿物的有机膜和连接矿物的丝状有机质。构筑壳壁的矿物主要有石英、长石和高岭石,有机物主要为酸性糖蛋白和脂肪。两种有孔虫倾向于选取沉积物中粒径较小的矿物,矿物粒径分布范围较小。壳壁中长石集中分布于有孔虫中心和外壁,很少出现于房室之间的隔板中。分析认为,壳壁曲率和矿物成分制约了长石的特异性分布,而长石的特异性分布有利于提高壳壁稳定性和有孔虫对能量及营养元素的获取。

This study used multiple analysis methods,such as scanning electron spectroscopy,Fourier transform infrared spectroscopy,Raman spectroscopy,and particle size analysis to investigate the tests of agglutinated foraminifera,Polskiammina asiatica and Ammoglobigerina globigeriniformis,which were separated from the coastal sediments of the Dagang Bay,Taizhou,China.Results show that P.asiatica and A.globigeriniformis are similar in components,including mineral particles,organic membrane on the external surface of tests,organic lining on the internal surface of tests,organic membrane on the surface of minerals,and filaments which are used for connecting minerals.Quartz,microcline,and kaolinite are dominant minerals in the tests.Organic components in the tests are mainly acidic glycoproteins and lipids.Both foraminifera tend to select small sized particles which are within a narrow size range to construct their tests.Microcline particles in the tests are distributed mainly in the center of the tests and the outer wall.Few feldspar particles are observed in the clapboard of the chambers.The specific distribution of feldspars in the tests of foraminifer is probably by the curvatures of the tests and the chemical compositions of the feldspars.It is indicated that the specific distribution of feldspars would help the foraminifera with the stability of tests and access to energy as well as nutrient elements.