东海钙质生物骨屑的矿物学特征

通过电镜、电子探针和X射线等项分析,对东海沉积物中的有孔虫、腹足类、双壳类、苔藓、珊瑚、海胆等骨屑进行了矿物学研究,确定了矿物成分与生物属种的关系,并基于有孔虫壳体化学成分将壳体分为均质壳和异质壳,生物碳酸盐中镁主要富集在方解石及镁方解石中,锶在方解石和镁方解石中的分配系数(D)相似,为0.11—0.14;在文石质骨屑中D=1.09-1.20。碳氧同位素组成与生物属种有明显关系。据一些有孔虫壳体氧同位素偏差值计算的水温来看,本次测定的有孔虫属种的骨屑不能作为理想的骨屑温度计。

THE MINERAIOGIC FEATURE OF CAICIC BIOGENIC DETRITUS OF THE EAST CHINA SEA

The skeletal mineralogy of the foraminifera, gastropods, bivalve, bryzoan, coral, and echinozoan in the sediments of the East China Sea has beed researched. The relationship between mineral composition and biogenic genus has been determined by SEM, EPMA and XRD. Based on their chemical components the foram tests may be divided into two types: homogeneous and heterogeneous. The latter could also be distinguished into the subtypes of high-Mg internal layer and High-Mg external layer. The XRD data of the biogenic skeleton are different from the standard curves of calcitedolomite because of the heterogen -eity of the mineral component of skeleton. The concentrations of elements Mg and Sr in the biogenic carbonate are related to the mineral type.Mg is concentrated in calcite and High-Mg calcite(HMC). The distribution coefficient(D) of Sr is similar both in calcite and HMC, i. e.D = 0. 11-1. 14; but the D in aragonite skeleton is equals to 0. 11 -1.2, and D=1.09-1.2 in aragonite coral skeleton. The carbon and oxygen isotopic constituents in the carbonate skeleton are obviously controlled by the biogenic genus. According to the temperature values calculated from the deviation of oxygen isotope of some tests, the foram genus by study are not considered as an ideal sclerothermometer.