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采用染色薄片鉴定、阴极发光显微镜观察、微量元素分析、碳氧稳定同位素测定及包体测温等手段 ,对塔里木盆地巴楚隆起寒武系及奥陶系白云岩的特征及成因进行了研究 ,共划分出四种类型的白云岩 :①泥粉晶白云岩 ,其w(Ca) /w(Mg)平均为 3— 10 ,Sr含量高 (>30 0× 10 - 6 ) ,w(Sr) /w(Ba) >>1,δ13C值较高 (- 1‰— + 1‰ ) ,δ18O值较低 (- 5‰— - 8‰ ) ,沉积环境为潮上带云坪 ,为准同生作用阶段潮上萨布哈白云化作用形成。②含雾心亮边白云石的细晶白云岩 ,w(Ca) /w(Mg)较低 (1— 2 ) ,Sr含量中等 (10 0× 10 - 6 — 2 0 0× 10 - 6 ) ,w(Sr) /w(Ba) >1,δ13C值在 - 2‰左右 ,δ18O值低 ,在 - 7‰左右 ,沉积环境为开阔台地浅滩 ,为早期成岩作用阶段回流渗透白云化作用形成。③含明亮白云石晶体及钙质残余的钙质白云岩 ,其w(Ca) /w(Mg)较低 (1左右 ) ,Sr含量最低 (10 0× 10 - 6左右 ) ,w(Sr) /w(Ba) <1,δ13C值最低 (- 1‰— - 3‰ ) ,δ18O值较低 (- 6‰左右 ) ,沉积环境为灰坪、云坪及开阔台地 ,为早期成岩作用阶段混合水白云化作用形成。④砂糖状白云岩 ,其w(Ca) /w(Mg)较低 (1— 2 ) ,Sr含量低 (<10 0× 10 - 6 ) ,w(Sr) /w(Ba) <1,δ13C值较高 (- 1‰— + 3‰ ) ,δ18O值较低(- 5‰— - 8‰ ) ,?
The characteristics and genesis of the Cambrian and Ordovician dolomites of the Bachu uplift in the Tarim Basin have been studied by means of the identification of stained flakes, the observation of cathodoluminescence microscopy, the analysis of trace elements, the determination of carbon and oxygen stable isotopes and the temperature measurement of the inclusions. Four types of dolomite are divided into four categories: (1) the dolomite dolomite has an average w / (Mg) of 3-10, a high Sr content (> 30 0 × 10-6) / Ba (Ba) >> 1, δ13C value is higher (-1 ‰ - + 1 ‰), δ18O value is lower (-5 ‰ - -8 ‰), and the depositional environment is tidal flat The role of stage Sassafras dolomitization formation. (2) The wurtzite margin dolomite fine crystalline dolomite has lower w (Ca) / w (Mg) and (1-2) Sr with medium (10 0 × 10 -6 -2 0 0 × 10 -6) (Ba)> 1, δ13C value is around -2 ‰, δ18O value is low, and around-7 ‰, the sedimentary environment is open platform platform, which is formed by reflux infiltration and dolomitization in the early diagenetic stage. (3) The calcareous dolomite with bright dolomite crystals and calcareous dolomite has the lowest content of w (Ca) / w (about 1), the lowest content of Sr (about 10 × 10 - 6), w (Sr) (Ba) <1, the lowest δ13C value (-1 ‰ - -3 ‰), the lower δ18O value (-6 ‰), and the depositional environment is the gray level, cloud level and open platform. Water white cloud formation. (4) The granulated dolomite with low w (Ca) / w (Mg), low Sr (<10 0 × 10-6), w (Sr) / w (-1 ‰ - + 3 ‰), δ18O values are lower (-5 ‰ - -8 ‰)