中文摘要：

为探讨内蒙古乌素图地区蛇纹石化大理岩的成因,采用显微镜和扫描电镜观察、能谱分析、X射线衍射分析和全岩分析等方法对其进行了岩相学、矿物学和地球化学特征的研究。结果显示,乌素图地区蛇纹石化大理岩主要以方解石和白云石为主,含少量蛇纹石,其中蛇纹石以利蛇纹石为主要类型,含少量叶蛇纹石和纤蛇纹石,蛇纹石呈鳞片状交代了原先为透镜化粒状假象或压扁条带状的橄榄石。蛇纹石化大理岩富含CaO、MgO和LOI,Ca/Mg离子比值为0.97~1.68;富集V、Ni、Sr、Ba等大离子亲石元素,亏损Nb、Ta、U、Th等高场强元素;ΣREE为9.55~12.99μg/g,Ce元素在球粒陨石和北美页岩标准化后都明显亏损,Eu元素在球粒陨石标准化后为亏损,北美页岩标准化后为富集。研究表明,乌素图地区蛇纹石化大理岩原岩为陆表海相沉积型白云岩,受陆源物质影响小,其沉积环境比较稳定。

英文摘要：

In order to probe the genesis of the serpentinized marble in the Wusutu region of Inner Mongolia, its petro- graphical, mineralogical and geochemical characteristics have been studied in this paper by using microscope, scanning e- lectron microscopy （ SEM ） , energy dispersive spectrum （EDS） , X-ray diffraction （XRD） , and whole rock analysis. Results show that the serpentinized marble in Wusutu area is mainly composed of calcite and dolomite, with minor serpen- tine, including major lizardite and trace antigorite and chrysotile. The serpentine occurred as scaly aggregates replaced the originally lensoid granular or flattening banded olivines. The serpentinized marble samples have high contents of CaO, MgO and LOI, with Ca/Mg mole ratios varying from 0.97 to 1.68.They are rich in large ion lithophile elements such as V, Ni, Sr, Ba and depleted in high field strength elements such as Nb, Ta, U, Th, with the ∑ REE varying from 9.55 μg/g to 12.99 μg/g. They have obvious negative Ce anomalies in both the chondrite standardized and the North A- merican shale standardized REE patterns. However, they have negative Eu anomaly in the ebondrite standardized REE pat- terns, but positive Eu anomaly in the North America shale standardized REE patterns. It is believed that the protolith of the serpentinized marble was epicontinental marine dolomite, which was deposited in relatively stable environment with lit- tle involvement of terrigenous materials.