“白云石问题”及其实验研究  

“Dolomite Problem”and Experimental Studies of Dolomite Formation

作　　者：张亦凡[1] 马怡飞[1] 姚奇志[2] 钱飞进 王雨晗[1] 李涵[1] 周根陶[1] 

机构地区：[1]中国科学院壳幔物质与环境重点实验室、中国科学技术大学地球和空间科学学院,合肥230026 [2]中国科学技术大学化学与材料科学学院,合肥230026

出　　处：《高校地质学报》2015年第3期395-406,共12页Geological Journal of China Universities

基　　金：国际重点基础研究发展计划资助项目(2014CB846003);国家自然科学基金(41372053);高等学校博士学科点专项科研基金(20133402130007)联合资助

摘　　要："白云石问题"无疑是地质学上最有趣最长久的难题之一。作为一种常见的碳酸盐矿物,白云石在地质历史时期大量发育,却在现代海洋沉积环境中鲜少沉积,并且在实验室模拟海水条件下也几乎无法低温合成。白云石[Ca Mg(CO3)2]不同于Ca2+、Mg2+无序的高镁方解石,具有阳离子有序超结构,空间群为R-3,在地表条件下为热力学稳定相。尽管人们尝试模拟自然界中白云石存在的物理化学条件,但却几乎没有从实验中成功合成有序白云石。在已有的实验室研究中,有序白云石仅能通过高温水热实验形成。这说明白云石的形成极可能是一个动力学控制过程。而近些年被人们广泛接受的白云石微生物成因模式认为微生物活动是低温白云石形成的关键,相关的微生物矿化实验也证实微生物的存在能够促进高镁方解石的形成。对白云石问题的探讨不仅对理解白云岩成因具有重要意义,还能够促进矿物学理论研究发展。此次研究从高温合成实验、低温合成实验、微生物协同沉淀实验等方面综述了有关白云石问题的实验室研究进展,阐明了目前对于白云石问题认识的局限,有助于更好的理解"白云石问题"和其中所包含的矿物学和物理化学问题,乃至于帮助寻找到它的答案。Dolomite problem is undoubtedly one of the most interesting and confusing problems in geology. As a common carbonate mineral, dolomite is abundant in geological history but rarely occurs in modern ocean sediments. It is nearly impossible to precipitate dolomite below 100℃. Dolomite, [CaMg(CO3)2], has a cation ordering structure and its space group is R-3. Additionally, it is thermodynamically stable under the condition of earth's surface. Although researchers tried to mimic physical and chemical conditions of natural environments which can form dolomite, these experiments still can not successfully precipitate ordered dolomite. Fully ordered dolomite can only form in hydrothermal experiments upper 200℃. It seems that the formation of dolomite is a dynamically controlling process. Recently, microbial dolomite model has been widely accepted. In this model, microbial activity is considered as the key of dolomite formation at low temperature. Many microbial mineralization experiments have confirmed that the existence of microorganisms can indeed promote the formation of high-magnesium calcite. Solving“dolomite problem”can not only help understanding the genesis of dolomite, but also promote the development of mineralogy theory. This review summarized current progresses of dolomite synthetic experiments, including experiments at high and low temperatures and microbially induced experiments. We also clarified the limitations of current understanding to“dolomite problem”. Future perspectives were proposed to better understand and finally solve dolomite problem.

关 键 词：白云石问题 低温白云石 动力学控制因素 微生物成因模式 

分 类 号：P588.24[天文地球—岩石学]