| 塔里木盆地巴楚隆起寒武系及奥陶系白云岩类型及形成机理 |
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| 引用本文： | 邵龙义,何宏,彭苏萍,李瑞军.塔里木盆地巴楚隆起寒武系及奥陶系白云岩类型及形成机理[J].古地理学报,2002,4(2):19-30. |
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| 作者姓名： | 邵龙义 何宏 彭苏萍 李瑞军 |
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| 作者单位： | 中国矿业大学(北京校区)资源系，北京 100083 |
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| 基金项目： | 国家杰出青年基金项目 (5 0 0 2 5 4 13)，国家自然科学基金项目 (49872 0 5 3)资助 |
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| 摘 要： | 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侧温等手段，对塔里木盆地巴楚断隆区寒武系和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m(Ca)/m(Mg)平均为3-10，Sr含量高（>300×10-6 ），m(Sr)/m(Ba)>>1，?13C值较高（-1‰-+1‰），18O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，其m(Ca)/m(Mg)较低（1-2），Sr含量中等（100×10-6-200×10-6），m(Sr)/m(Ba) >1，?13C值在-2‰左右，18O值低，在-7‰左右，沉积环境为开阔台地浅滩，为准同生或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m(Ca)/m(Mg)较低（1左右），Sr含量最低（100×10-6左右），m(Sr)/m(Ba) < 1，?13C值最低（-1‰--3‰），?18O值较低（-6‰左右），沉积环境为灰坪、云坪及开阔台地，为准同生或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m(Ca)/m(Mg)较低（1-2），Sr含量低（<100×10-6），m(Sr)/m(Ba)<1，?13C值较高（-1‰-+3‰），18O值较低（-5‰--8‰），沉积环境多为浅滩，为晚期成岩作用阶段埋藏白云化作用形成。
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| 关 键 词： | 塔里木盆地 寒武系及奥陶系 白云岩 白云化作用 |
| 文章编号： | 1671-1505(2002)02-0019-12 |
| 修稿时间： | 2001年8月1日 |
TYPES AND ORIGIN OF DOLOSTONES OF THE CAMBRIAN AND ORDOVICIAN OF BACHU UPLIFT AREA IN TARIM BASIN |
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| Shao Longyi,He Hong,Peng Suping,Li Ruijun.TYPES AND ORIGIN OF DOLOSTONES OF THE CAMBRIAN AND ORDOVICIAN OF BACHU UPLIFT AREA IN TARIM BASIN[J].Journal of Palaeogeography,2002,4(2):19-30. |
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| Authors: | Shao Longyi He Hong Peng Suping Li Ruijun |
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| Institution: | Department of Resource Development Engineering, China University of Mining and Technology, Beijing 100083 |
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| Abstract: | The Cambrian and Ordovician dolostones in the Bachu uplift area of Tarim Basin are investigated by means of stained thin section microscopic identification, cathodoluminescence (CL) microscopic observation, trace element analysis, carbon and oxygen isotope geochemistry, and fluid inclusion analysis. Four types of dolostones have been differentiated. The first one is composed of micritic dolomites which were formed in supratidal dolomitic flats. The micritic dolomites are characterized by the highest m(Ca)/m(Mg) ratios (averagely 3-10), higher Sr contents (>300×10-6) with a m(Sr)/m(Ba) ratio far higher than 1, higher 13C value (ranging over -1‰-+1‰ PDB) and lower 18O values (ranging between -5‰--8‰ PDB), with an origin of penecontemporaneous supratidal sabkha dolomitization. The second one consists of fine crystalline dolomites with a cloudy center and bright rim, which were formed in an opening platform shoal setting. These dolomites have a relatively higher m(Ca)/m(Mg) ratio (ranging over 1-2), a relatively higher Sr content (ranging between100-200×10-6) with m(Sr)/m(Ba) ratios higher than 1, minus 13C value (around -2‰) and 18O value are lower(about -7‰). These dolomites were formed by seepage-reflux dolomitization during the penecontemporaneous or early diagenetic stages. The third one is calcareous dolostones with bright and clean dolomite crystals and calcareous fossil remnants. These dolostones were formed in intertidal lime flat and dolomitic flat, as well as open platform shoal environments. The dolomites are characterized by lower m(Ca)/m(Mg)ratios (about 1), lower Sr contents are (about 100×10-6) with m(Sr)/m(Ba) ratios lower than 1, lowest 13C value (between -1‰--3‰), lower ?18O value (about -6‰). These dolomites were formed by mixing-water dolomitization during the penecontemporaneous or early diagenetic stages. The fourth type is the saccharoidal dolostones with medium to coarse euhedral dolomite crystals. Precursor of this dolostone was formed in open platform shoal environments. The dolomites have lower m(Ca)/m(Mg) ratios (ranging over 1-2), lower Sr contents (< 100×10-6) with lower m(Sr)/m(Ba) ratios (lower than 1), higher 13C values (-1‰-+3‰) and lower ?18O values (-5‰--8‰). This kind of dolomites resulted from the burial dolomitization during the late diagenetic stages. |
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| Keywords: | Tarim Basin Cambrian and Ordovician dolostones dolomitization |
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