摘要
研究Mg/Ca比对生物成因的碳酸盐矿物种类和形态的影响是研究各种含镁方解石形成机理的关键。本文在Mg/Ca摩尔比分别为1、2、4、6和8的条件下进行了为期55d的硫酸盐还原细菌诱导碳酸盐矿物形成的实验,利用X射线衍射仪和扫描电子显微镜研究了Mg/Ca比对碳酸盐矿物种类和形态的影响。实验结果表明:①Mg/Ca比与矿物的种类之间存在密切的关系。在Mg/Ca摩尔比较低(1和2)时仅形成高镁方解石,在Mg/Ca摩尔比为4时,形成的矿物组合为含镁方解石+高镁方解石,在Mg/Ca摩尔比为6和8时,矿物组合为高镁方解石+单水碳钙石+钙白云石;②Mg/Ca比影响矿物的生长速率。Mg/Ca比越高,晶体生长速率越快;③Mg/Ca比明显影响矿物的形态。随着Mg/Ca比的增大,矿物的形态有如下发展规律:哑铃形→花菜状→光球状→刺球状。这些研究结果将有助于探讨制约含镁碳酸盐矿物种类和形态的机制。
The study on the influence of Mg/Ca ratios on different species and shapes of microbial carbonate minerals is a key to the research of the mechanism of various Mg-calcite formations.In this paper,55-days precipitation experiments on sulphate-reducing bacteria are carried out in solutions with Mg/Ca ratios of 1,2,4,6 and 8,respectively.Investigation on the role of Mg/Ca ratios on carbonate species and shapes is conducted by using X-ray diffraction（XRD） and scanning electron microscope（SEM）.The researches on the precipitations at 55 d demonstrate that：① The mineral species are closely related to Mg/Ca ratios.Only high Mg-calcites occur when Mg/Ca ratios are low（1 and 2）.In the Mg/Ca ratio of 4 /1 experiments,Mg-calcite and high Mg-calcites are precipitated.In the Mg/Ca ratios of 6 /1 and 8 /1,following assemblage minerals are precipitated：high Mg-calcites ＋ monohydrocalcite ＋ Ca-dolomite;② Mg/Ca ratios affect the growth rate of precipitations.The growth rate of crystal is faster when the Mg/Ca ratios are higher;③ Mg/Ca ratios obviously affect the morphologies of minerals.As the Mg/Ca ratio increases,the shapes of minerals develop according to the following order：dumbbell→cauliflower→smooth sphere→rough sphere.These investigations are helpful in the exploration of the control mechanism of species and morphologies of Mg-bearing carbonate minerals.
出处
《矿物学报》
CAS
CSCD
北大核心
2010年第1期83-89,共7页
Acta Mineralogica Sinica
基金
国家自然科学基金资助项目(批准号:40573057)
