Constraints of authigenic carbonates on trace elements (Sr, Mg) of lacustrine ostracod shells in paleoenvironment reconstruction and its mechanism
Constraints of authigenic carbonates on trace elements (Sr, Mg) of lacustrine ostracod shells in paleoenvironment reconstruction and its mechanism
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DOI：
10.1007/s11430-008-0043-2
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
Guanguan Hu;Zhangdong Jin;Fei Zhang
中科院分区：
文献类型：
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作者：
Guanguan Hu;Zhangdong Jin;Fei Zhang
对云南河庆盆地上部岩心（15 ~ 55 m）保存的2种介形虫壳进行了Mg/Ca和Sr/Ca的摩尔比测定。通过对比Mg/Ca和Sr/Ca的摩尔比值，并将其与沉积物中Sr浓度进行比较，我们认为：(1)介形虫中Mg/Ca和Sr/Ca的摩尔比值变化反映了其环境水组成和生态的变化；(2)在体系中没有文石沉淀的情况下，Sr/Ca摩尔比对盐度变化的线性响应好于Mg/Ca摩尔比，否则两者之间不存在线性关系；(3)摩尔Sr/Ca比值主要受盐度和自生碳酸盐沉淀控制，而摩尔Mg/Ca比值受盐度和温度控制。事实上，介形虫在温度作用下的生长速率控制着壳中Mg/Ca的波动。在此基础上，今后应进一步关注自生矿物沉淀过程对介形虫壳中微量元素的约束，以及生物碳酸盐中微量元素与系统沉积物组成的相关性，并在体外实验中进一步研究。
Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest China. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracodprimoreflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in futurein vitroexperiments.