塔里木盆地中央隆起区上寒武统—下奥陶统白云岩地球化学特征及白云石化流体演化规律<sup>*</sup>

黄擎宇, 刘伟, 张艳秋, 石书缘, 王坤. (2016)塔里木盆地中央隆起区上寒武统—下奥陶统白云岩地球化学特征及白云石化流体演化规律^* [J]. 古地理学报, 18(4): 661-676
Huang Qingyu, Liu Wei, Zhang Yanqiu, Shi Shuyuan, Wang Kun. (2016)Geochemistry and evolution of dolomitizing fluids of the Upper Cambrian-Lower Ordovician dolostones in Central Uplift, Tarim Basin[J]. Journal Of Palaeogeography, 18(4): 661-676. DOI:10.7605/gdlxb.2016.04.049 复制到剪切板

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塔里木盆地中央隆起区上寒武统—下奥陶统白云岩地球化学特征及白云石化流体演化规律^*

黄擎宇¹, 刘伟¹, 张艳秋², 石书缘¹, 王坤¹

1 中国石油勘探开发研究院,北京 100083

2 中国石油塔里木油田公司勘探开发研究院,新疆库尔勒 841000

第一作者简介黄擎宇,男,1984年生,中国石油勘探开发研究院博士后,主要从事碳酸盐岩储集层地质学方面的研究。E-mail: qingyuh08@163.com。

收稿日期:2015-07-06

基金:*国家科技重大专项(编号:2011ZX05004)和中国石油天然气股份有限公司重大科技专项(编号:2014E-3201)共同资助

摘要

以详细的岩石学研究为基础,综合利用碳、氧、锶同位素等地球化学资料,深入分析了塔里木盆地中央隆起区上寒武统—下奥陶统白云石化流体演化规律以及白云岩成因机制。结果表明,上寒武统白云岩主要由泥晶—粉晶白云岩、微生物白云岩和(残余)颗粒白云岩等原始结构保留较好的白云岩构成,其 C、 Sr同位素与同期海水相近, O同位素值偏正,属于同生 /准同生期与轻微蒸发海水有关的白云石化的产物;下奥陶统白云岩以细晶自形—半自形白云石为主,原始结构保留差,其 C、 Sr同位素与同期海水近似,但 O同位素值略微偏负,主要为浅埋藏期白云石化的产物。部分早期白云岩在中—深埋藏过程中受埋藏重结晶和构造—热液白云石化的影响,形成细晶—粗晶他形白云岩和缝洞鞍形白云石充填物,该阶段白云石化流体主要来自于地层内封存的海源流体、深部热液以及蒸发岩层间热卤水,多期多源流体的共同作用导致该类白云岩具有较宽的 Sr同位素组成和明显负偏的 O同位素值。总体上,研究区白云岩具有早期形成(近地表到浅埋藏期大规模交代)、中期加强(中—深埋藏期部分重结晶)、晚期改造(热液局部调整)的整体演化趋势。

关键词: 塔里木盆地; 上寒武统—下奥陶统; 白云岩; 地球化学; 白云石化流体

中图分类号:P588.24⁺5 文献标志码:A 文章编号:1671-1505(2016)04-0661-16

Geochemistry and evolution of dolomitizing fluids of the Upper Cambrian-Lower Ordovician dolostones in Central Uplift, Tarim Basin

Huang Qingyu¹, Liu Wei¹, Zhang Yanqiu², Shi Shuyuan¹, Wang Kun¹

1 Research Institution of Petroleum Exploration & Development,PetroChina,Beijing 100083

2 Institute of Petroleum Exploration and Development,Tarim Oilfield Company,PetroChina,Korla 841000,Xinjiang

About the first author Huang Qingyu,born in 1984,is a postdoctoral fellow in Research Institution of Petroleum Exploration & Development,PetroChina. He is mainly engaged in reservoir geology of carbonate rocks. E-mail: qingyuh08@163.com.

Fund:[Co-funded by the National Science and Technology Major Project(No.2011ZX05004)and PetroChina Science and Technology Major Project(No.2014E-3201)]

Abstract

Based on the detailed petrology study as well as isotope data ( δ¹³C, δ¹⁸O and⁸⁷Sr/⁸⁶Sr),the evolution of dolomitizing fluids and genetic mechanism of the Upper Cambrian-Lower Ordovician dolostones are investigated in the Central Uplift,Tarim Basin.The results indicate that:The Upper Cambrian dolostones are composed of micritic dolostones,microbial dolostones and(relict)grainy dolostones with well-preserved precursor lithologic fabric. These dolostones have similar δ¹³C values and⁸⁷Sr/⁸⁶Sr ratios to the coeval seawater and slightly higher δ¹⁸O values,suggesting that the dolomitization occurred during the penecontemporaneous period and the dolomitizing fluid was associated with the slightly evaporitic seawater. The Lower Ordovician dolostones are mainly comprised of fine-crystalline,planar-euhedral to subhedral dolomites. Poor-preserved precursor texture,similar δ¹³C values and⁸⁷Sr/⁸⁶Sr ratios to the coeval seawater as well as slightly depleted δ¹⁸O values of the dolostone indicated the dolomitization occurred during shallow burial. Some of the dolostones formed in early stage could be altered to fine-coarse crystalline,nonplanar-anhedral dolostones and rift-cavity-filling saddle dolostone cements through recrystallization and tectonically controlled hydrothermal dolomitization during medium to deep burial. The dolomitizing fluids of the burial dolomitization were derived from remnant seawater preserved in the formations,deep mantle hydrothermal fluids and hot brine water in the underlying Middle Cambrian evaporate rocks. These dolostones formed during burial have wide range of⁸⁷Sr/⁸⁶Sr ratios and obviously more negative δ¹⁸O values due to the combined impact of multi-stage and multi-source diagenetic fluids. Generally,these dolostones in the study area formed in multiple stages of dolomitization with the tendency of forming in early period(large scale replacement during near-surface and shallow burial),being mature in middle diagenetic stage (partly recrystallization during medium-deep burial)and modified in late diagenetic stage(partial adjustment of hydrothermal fluid).

Key words: Tarim Basin; Upper Cambrian-Lower Ordovician; dolostone; geochemistry; dolomitizing fluids

Show Figures

质量平衡计算表明, 大范围的白云石化作用以及块状白云岩的形成均需要较高的水岩比率(Machel, 2004), 因此反演白云石化流体特征是解决白云岩成因的关键之一。通常, 白云石化流体可以是正常海水(Saller, 1984; Hood et al., 2011)、经过蒸发浓缩或改造的海水(Adams and Rhodes, 1960; Jones et al., 2002; Sena et al., 2014)、大气淡水与海水形成的混合水(Humphrey, 1988; Li et al., 2013)、地层水以及来自深部的热液(Qing and Mountjoy, 1994; Davies and Jr. Smith, 2006; Diehl et al., 2010; Haeri-Ardakani et al., 2013)等。不同来源或不同运移方式的白云石化流体不仅代表了白云石化模式的差异, 同时也对白云岩储集层质量具有重要影响, 加强对白云石化流体性质及其演化规律的详细研究, 对于解决白云岩成因以及预测有利储集层十分必要。

塔里木盆地上寒武统— 下奥陶统发育一套厚达千米的白云岩层系, 是油气勘探的重要接替领域。前人对该套白云岩的成因进行了大量研究, 普遍认为其成因与埋藏白云石化有关(钱一雄和尤东华, 2006; 吴仕强等, 2008; 胡明毅等, 2011; 赵文智等, 2012), 流体主要来自于蒸发海水、海水与大气水的混合水、地层封存海水、岩浆热液等(张学丰等, 2008; 陈永权等, 2010; 张静和罗平, 2010; 邢凤存等, 2011; 乔占峰等, 2012; Dong et al., 2013; 张德民等, 2013)。但由于上寒武统— 下奥陶统中缺乏蒸发岩层系, 很难用传统的超咸海水回流模式来解释; 同时对野外露头剖面的详细解剖发现, 这些白云岩很可能在早— 中成岩期已经形成(郑剑锋等, 2013), 而且埋藏环境相对封闭的成岩系统与白云石化作用需要大量流体通过的事实之间的矛盾(Warren, 2000; Ehrenberg et al., 2012), 也促使研究者不得不重新审视该套巨厚白云岩体的成因机制。另外, 塔里木盆地属于典型的叠合盆地, 受多期次构造活动驱动的不同性质、不同来源的成岩流体, 势必会对早期形成的白云岩进行调整和改造, 因此其成因很难用单一模式来解释, 更可能是多种白云石化流体叠加改造、共同作用的结果。鉴于此, 作者综合利用岩心、薄片、阴极发光以及碳、氧、锶同位素数据等多种资料, 在详细的岩相学研究基础上, 对塔里木盆地中央隆起区上寒武统— 下奥陶统不同类型白云岩的地球化学特征进行系统分析, 反演白云石化流体性质及特征, 同时结合研究区的沉积、构造演化背景对白云石化流体的演化规律进行了梳理, 从而为白云岩的成因解释以及白云岩储集层研究提供更多依据。

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	图1 塔里木盆地上寒武统— 下奥陶统沉积相平面图Fig.1 Sedimentary facies map of the Upper Cambrian-Lower Ordovician in Tarim Basin

1 区域地质背景

塔里木盆地位于中国西北部, 是一个由造山带环绕的大型陆内叠合盆地, 面积达56× 10⁴, km², 其北缘和西缘为天山造山带, 南边为西昆仑造山带, 东南缘为阿尔金造山带(任建业等, 2011)。根据盆地构造属性以及基底起伏特征, 可将塔里木盆地分为塔北隆起、中央隆起、东南隆起、库车坳陷、北部坳陷、塔西南坳陷、东南坳陷等“ 三隆四坳” 的构造格局。本文研究的区域主要分布在中央隆起区, 钻井及地震资料显示:晚寒武世到早奥陶世早期, 该区沉积环境较为稳定, 总体上具有“ 西台东盆” 的古地理格局( 图 1), 其中塔西台地相区呈现出宽缓的“ 陆表海” 特征, 发育了大套浅水碳酸盐沉积物。白云岩主要发育在该套厚层碳酸盐岩的中部和下部, 层位上包括寒武系丘里塔格组(∈ ₃q)、下奥陶统蓬莱坝组(O₁p)和鹰山组(O_1-2y)( 图 2)。

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	图2 塔里木盆地上寒武统— 下奥陶统地层柱状图Fig.2 Stratigraphic column of the Upper Cambrian-Lower Ordovician in Tarim Basin

2 样品采集与测试

选取研究区钻遇上寒武统— 下奥陶统白云岩的方1、和4、康2、巴探5、中15、中19、中4和城探1等20余口钻井岩心进行详细观察并取样, 将所采集样品制备岩石薄片并保留配对副样。利用显微镜和阴极发光对薄片样品进行微观观察, 识别出不同产状、不同结构类型的白云岩和白云石充填物, 在薄片上对需要分析的样品位置进行圈定, 然后利用微钻对副样上的相同位置实施微区取样, 分别进行碳— 氧同位素、锶同位素分析。其中, 阴极发光在中国石油勘探开发研究院实验中心完成, 所用仪器为英国CITL公司生产的CL8200 MK5阴极发光仪, 工作环境为束电压15, kV; 束电流320, μ A。碳— 氧同位素分析在核工业北京地质研究院分析中心完成, 测试仪器为MAT-253质谱仪, 测试方法为常规的磷酸法, 分析误差± 0.005%。锶同位素在成都理工大学同位素实验室完成, 测试仪器为MAT-261质谱仪, 检测依据为美国国家标准局标样NBS987, 分析误差为0.002%。

3 结果与讨论

3.1 白云岩岩石学特征

塔里木盆地上寒武统— 下奥陶统白云岩类型多样, 本次研究中根据产状的差异将其划分为基质白云岩和缝洞充填白云石两大类( 表 1), 其中基质白云岩主要包括泥晶— 粉晶白云岩、微生物白云岩、(残余)颗粒白云岩、细晶自形/半自形白云岩和细晶— 粗晶他形白云岩; 缝洞充填白云石以中晶— 粗晶鞍形白云石为主。

表1 塔里木盆地中央隆起区上寒武统— 下奥陶统白云岩岩石类型 Table1 Petrographic characteristics of the Upper Cambrian-Lower Ordovician dolostones in Central Uplift, Tarim Basin

a— 浅灰白色细晶自形— 半自形白云岩, 具“ 砂糖状” 结构, 可见生物扰动痕迹(箭头), Z19井, 鹰山组, 5526.0, m; b— 细晶自形— 半自形白云岩镜下特征, 平面— 自形晶为主, 晶体边缘环带发育, H4井, 蓬莱坝组, 4478.9, m; c— 细晶自形— 半自形白云岩, 晶间孔发育, 可见残余颗粒结构(箭头), Z19井, 鹰山组, 5526.0, m; d— 细晶自形白云岩阴极发光特征, Z19井, 鹰山组, 5527.7, m; e— 灰质细— 中晶他形白云岩, 白云石沿缝合线发育, Z19井, 鹰山组, 5616.5, m; f— 细晶— 中晶他形白云岩, 晶体自形程度差, 多为曲面— 他形晶, 晶间孔匮乏, GC8井, 丘里塔格组, 6734.15, m; g— 细晶— 中晶他形白云岩, 残留部分鲕粒结构(箭头), 说明晚期白云石化作用对早期白云岩强烈改造, CT1井, 丘里塔格组, 6879.32, m; h— 细晶— 粗晶他形白云岩具明显波状消光特征, 正交偏光, GC8井, 丘里塔格组, 6737.3, m; i— 细晶— 粗晶他形白云岩阴极发光特征, GC8井, 丘里塔格组, 6734.7, m

1)泥晶— 粉晶白云岩深灰— 灰褐色, 薄层— 中层状产出, 晶体细小( 图 3-a), 半自形— 他形晶为主, 局部可见似鸟眼构造及藻纹层结构。主要分布在水体能量较低的潟湖或滩间海中, 总体含量较少, 占研究区所有白云岩的5%~10%。

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	图3 塔里木盆地中央隆起区泥— 粉晶白云岩、微生物白云岩、(残余)颗粒白云岩特征Fig.3 Characteristics of micritic dolostones, microbial dolostones and(relict) grainy dolostones in Central Uplift, Tarim Basin

2)微生物白云岩岩心上可见微生物结构, 包括凝块石、叠层石、枝状石、核形石等(罗平等, 2013; 宋金民等, 2014), 其中凝块结构最为常见( > 图 3-b), 并伴生窗格状构造。镜下观察, 凝块呈不规则斑状特征, 内部为泥晶结构, 凝块间为亮晶白云石胶结物( 图 3-c), 发育残余格架孔或溶蚀孔。部分凝块重结晶明显, 破坏原岩结构( 图 3-d)。沉积环境为潮下浅水带, 盆地西北缘露头区可见微生物礁。层位上主要见于丘里塔格组中, 占所有白云岩的15%~25%。

3)(残余)颗粒白云岩岩心上通常为灰色、浅灰色或灰白色, 粒屑结构特征明显( 图 3-e), 颗粒主要由砂屑、藻砂屑、鲕粒、团块和少量生屑构成, 颗粒间为微晶基质或亮晶胶结物半充填、全充填。阴极发光测试显示, 该类白云岩整体以发暗红色光为主, 其中颗粒部分的发光性较粒间胶结物弱一些, 但总体差别不大( 图 3-f)。该类白云岩主要分布在水体能力较高的台内滩或台缘丘滩体中, 纵向上多出现在向上变浅序列的中上部。在丘里塔格组和蓬莱坝组中常见, 占所有白云岩的20%~30%。

4)细晶自形— 半自形白云岩岩心上通常为浅灰色或灰白色、呈中层状或透镜状产出, 具有砂糖状特征( 图 4-a)。镜下观察, 平均晶粒大小为0.05~0.25, mm, 自形— 半自形为主, 具平直的晶面特征, 雾心亮边常见( 图 4-b), 晶粒之间相互支撑呈网络状, 保留大量晶间孔。部分样品中还可见残余的砂屑幻影( 图 4-c), 推测其前驱沉积物为能量相对较高的浅滩相沉积物(如亮晶砂屑灰岩)。阴极发光下显均匀的中等亮度红色光到暗红色光( 图 4-d)。该类白云岩主要分布在下奥陶统, 如塔中地区鹰山组中下部以及巴楚隆起蓬莱坝组, 寒武系中出现频率相对较少, 占所有白云岩的10%~15%。

5)细晶— 粗晶他形白云岩该类白云岩通常有2种产出方式: 一种与低幅度压溶缝合线相伴生( 图 4-e), 呈斑状或不规则条带状产出; 另一种则为块状或厚层状纯白云岩。镜下观察, 这类白云岩以中晶到粗晶(0.25~2.0, mm)为主, 细晶次之。白云石自形程度差, 多曲面— 他形晶, 晶粒之间呈凹凸甚至缝合线状接触( 图 4-f), 原始结构破坏明显, 仅个别样品可见未被完全改造的颗粒或残余颗粒幻影( 图 4-g)。部分样品发育不规则环带, 晶间孔发育程度低, 正交偏光下显波状消光特征( 图 4-h); 该类白云岩整体显极暗红色光或基本不发光特征, 局部可见暗红色斑块, 可能受重结晶影响( 图 4-i)。细晶— 粗晶他形白云岩分布较广, 占所有白云岩的30%~40%。

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	图4 塔里木盆地中央隆起区白云岩特征Fig 4 Characteristics of dolostones in Central Uplift , Tarim Basin

6)缝洞鞍形白云石充填物岩心上观察, 缝洞中充填的鞍形白云石多为乳白色或浅灰白色( 图 5-a); 镜下观察, 该类白云石具有明ra显弯曲的、阶梯状的晶面边界特征, 正交偏光下多具波状消光特征( 图 5-b, 5-c); 通常与萤石、重晶石、自生石英、硬石膏以及巨晶方解石等矿物相伴生。阴极发光下, 鞍形白云石充填物发光性较弱, 整体以暗红色为主, 与细晶— 粗晶他形基质白云岩发光性类似, 部分样品边缘见明暗相间的环带( 图 5-d), 可能预示其形成过程中流体性质多变或是多期热液活动作用的结果。

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	图5 塔里木盆地中央隆起区缝洞充填白云石特征Fig.5 Characteristics of rift￣cavity￣filling dolomite in Central Uplift, Tarim Basin

3.2 地球化学特征

3.2.1 碳— 氧同位素特征塔里木盆地上寒武统— 下奥陶统各类白云岩以及缝洞充填白云石的C、O同位素组成见表2和图6。

表2 塔里木盆地中央隆起区各类白云岩及缝洞充填物氧、碳、锶同位素值 Table2 Oxygen, carbon and strontium isotopic values of each type of dolostone in Central Uplift, Tarim Basin

样号	深度/m	层位	岩石类型	岩性特征	δ ¹³C/‰ , PDB	δ ¹⁸O/‰ , PDB	⁸⁷Sr/⁸⁶Sr
Z19	5613.48	O_1-2y	灰岩	微亮晶球粒灰岩	-1.4	-8.8	0.708 231
Z15	5564.13	O_1-2y		泥晶灰岩	-1.6	-8.4
Z3	5496.37	O_1p		泥晶灰岩	-1.4	-7.4
Z19	5479.95	O_1-2y	泥晶— 粉晶白云岩	粉晶白云岩	-1.0	-3.2	0.708 382
BT5	4741.94	∈ ₃_q		泥晶白云岩	-0.8	-5.9
GL3-2	6236.80	O_1p		纹层状微晶— 粉晶白云石	-0.3	-5.1	0.708 358
GL3-3	6235.70	O_1p		微晶白云石	-0.2	-5.3	0.708 362
H4-27	4358.90	∈ ₃_q		粉晶白云岩	-2.0	-4.6	0.709 002
BT5	4741.83	∈ ₃_q	微生物白云岩	叠层石白云岩(富藻层)	-0.7	-5.7	0.708 171
H4-32	4352.10	∈ ₃_q		凝块石白云岩(溶孔发育)	-1.8	-6.3
H4-20	4352.90	∈ ₃_q		叠层石白云岩(富屑层)	-1.8	-4.4	0.708 982
H4-30	4353.10	∈ ₃_q		凝块石白云岩	-1.7	-5.7
H4-29	4358.20	∈ ₃_q		凝块石白云岩	-2.1	-5.1
H4-28	4358.80	∈ ₃_q		叠层石白云岩	-2.1	-4.6
H4-24	4814.70	∈ ₃_q		叠层石白云岩	-1.6	-6.6
H4-10	4924.40	∈ ₃_q		凝块石白云岩(局部重结晶)	-1.6	-7.4	0.709 056
H4-7	4925.00	∈ ₃_q		凝块石白云岩(局部重结晶)	-1.5	-6.7	0.709 236
H4-8	4925.10	∈ ₃_q		凝块石白云岩(局部重结晶)	-1.6	-6.7	0.709 226
BT5	4741.95	∈ ₃_q	(残余) 颗粒白云岩	残余鲕粒白云岩	-0.7	-5.6	0.708 217
BT5	4741.40	∈ ₃_q		残余砂屑白云岩	-0.8	-4.7
BT5	4739.43	∈ ₃_q		砂屑白云岩	-0.8	-5.4
H4-23	4817.60	∈ ₃_q		残余鲕粒白云岩	-1.5	-6.1	0.709 092
H4-22	4819.40	∈ ₃_q		鲕粒白云岩	-1.6	-6.8
H4-12	4924.30	∈ ₃_q		残余藻砂屑白云岩	-1.7	-7.6	0.709 117
GL1	6456.75	O_1p	细晶自形— 半自形白云岩	粉晶— 细晶自形— 半自形白云岩	-1.7	-5.8	0.708 345
Z19	5527.75	O_1-2y		细晶自形白云岩	-0.1	-4.5
Z19	5529.03	O_1-2y		细晶自形白云岩	-0.4	-5.2	0.708 602
Z19	5529.50	O_1-2y		细晶自形(环带)白云岩	-0.7	-6.5	0.708 445
Z19	5549.55	O_1-2y		细晶自形(环带)白云岩	-0.1	-6.6	0.708 379
H4-25	4479.50	∈ ₃_q		细晶自形— 半自形白云岩	-1.6	-6.3	0.708 692
Z13	5972.08	O_1-2y		粉晶— 细晶、半自形白云岩	-1.9	-7.0	0.708 526
Z19	5544.65	O_1-2y	细晶— 粗晶、他形白云岩	溶孔细晶、半自形— 他形白云岩	-0.5	-9.5	0.709 584
Z19	5520.50	O_1-2y		溶孔细晶他形白云岩	-0.5	-10.7	0.714 287
Z19	5523.80	O_1-2y		溶孔中晶— 细晶他形白云岩(见萤石)	-0.5	-9.0	0.708 276
Z19	5549.70	O_1-2y		细晶他形白云岩	-0.8	-8.6	0.707 993
Z19	5550.31	O_1-2y		溶孔中晶— 细晶他形白云岩	-0.5	-9.6	0.707 813
Z19	5553.60	O_1-2y		溶孔中晶— 细晶他形白云岩(见萤石)	-0.7	-10.0	0.707 487
Z19	5613.48	O_1-2y		细晶他形白云岩	-0.1	-9.5	0.708 231
Z3	4630.57	O_1p		中晶— 粗晶他形白云岩	-1.3	-7.6	0.707 881
Z4	5817.07	O_1p		中晶— 粗晶他形白云岩	-1.6	-7.2	0.710 705
H4-33	4352.10	∈ ₃_q		角砾状细晶— 中晶他形白云岩	-2.0	-8.4
H4-31	4353.10	∈ ₃_q		中晶— 粗晶他形白云岩	-2.1	-9.4	0.709 121
H4-15	4477.90	∈ ₃_q		中晶— 细晶他形白云岩	-1.3	-7.6	0.709 084
H4-13	4479.30	∈ ₃_q		中晶他形白云岩	-1.6	-8.3	0.709 275
CT1-8	6927.34	∈ ₃_q	细晶— 粗晶、他形白云岩	细晶— 中晶他形白云岩	-0.6	-9.2
CT1-12	6879.03	∈ ₃_q		粉— 细晶、半自形— 他形白云岩	-0.4	-8.8
CT1-10	6927.02	∈ ₃_q		细晶他形白云岩	-0.4	-9.5
CT1-9	6610.51	∈ ₃_q		中晶— 粗晶他形白云岩	-0.5	-10.5
GC8-3	6734.70	∈ ₃_q		中晶他形白云岩	-0.8	-10.1	0.708 977
GC8-2	6737.20	∈ ₃_q		粗晶他形白云岩	-0.4	-10.8
Z4	4-Vsd	∈ ₃_q	鞍形白云石充填物	鞍形白云石充填孔洞	-2.3	-7.9	0.709 605
Z4	6-VeinSd	∈ ₃_q		鞍形白云石充填裂缝	-2.4	-8.9
Z4	1-VeinSd	∈ ₃_q		鞍形白云石充填裂缝	-1.7	-7.3	0.708 922
Tong1	3176.70	∈ ₃_q		鞍形白云石充填裂缝	-1.5	-8.4	0.711 248
Tong1	3176.50	∈ ₃_q		鞍形白云石充填孔洞	-2.1	-8.8	0.708 323
BT5	4741.49	∈ ₃_q		鞍形白云石充填裂缝	-1.7	-7.2	0.707 296
BT5	4740.75	∈ ₃_q		鞍形白云石充填裂缝	-1.1	-7.1	0.719 213
H4-11	4924.30	∈ ₃_q		鞍形白云石充填缝洞	-2.9	-16.6	0.709 914
H4-9	4924.40	∈ ₃_q		鞍形白云石充填裂缝	-2.7	-16.8	0.710 009
CT1-1	6926.04	∈ ₃_q		鞍形白云石充填裂缝	-1.2	-8.0
CT1-2	6925.97	∈ ₃_q		鞍形白云石充填裂缝	-1.0	-9.3
CT1-3	6927.34	∈ ₃_q		鞍形白云石充填裂缝	-1.1	-8.2
CT1-7	6876.63	∈ ₃_q		鞍形白云石充填溶洞	-1.1	-9.2	0.709 253
CT1-11	6876.60	∈ ₃_q		鞍形白云石充填溶洞	-0.5	-9.8	0.709 608
CT1-6	6879.18	∈ ₃_q		鞍形白云石充填溶洞	-0.8	-9.3
CT1-5	6927.02	∈ ₃_q		鞍形白云石充填溶洞	-0.8	-9.1	0.709 399
Z4	6-VCal	∈ ₃_q	方解石充填物	溶孔内方解石充填物	-4.4	-11.7	0.709 732
Z4	1-VeinCal	∈ ₃_q		裂缝内方解石充填物	-3.4	-9.6	0.709 894
Z4	3-VeinCal	∈ ₃_q		裂缝内方解石充填物	-2.9	-8.9	0.710 175
BT5	4740.75	∈ ₃_q		孔洞内方解石充填物	-1.1	-9.2	0.719 402
GC8-1	6737.05	∈ ₃_q		裂缝内方解石充填物	-1.6	-12.8	0.710 38
CT1-4	6927.02	∈ ₃_q		溶孔内方解石充填物	-2.9	-12.4
H4-19	4477.50	∈ ₃_q		溶孔内方解石充填物	-3.2	-10.9
H4-18	4477.65	∈ ₃_q		裂缝内方解石充填物	-3.2	-11.3	0.709 087
H4-17	4477.90	∈ ₃_q		裂缝内方解石充填物	-2.9	-10.6	0.709 121
H4-26	4477.95	∈ ₃_q		裂缝内方解石充填物	-3.1	-13.0

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	图6 塔里木盆地中央隆起区各类白云岩碳— 氧同位素交会图Fig.6 Cross-plot of oxygen and carbon isotope values for each type of dolostones in Central Uplift, Tarim Basin

总体上, 研究区大部分基质白云岩的δ ¹³C值变化不明显, 均分布于同时期海相方解石的碳同位素(-2.0‰ ~0‰ PDB)范围内(Veizer et al., 1999); 也与本次研究中所测试的泥晶灰岩的碳同位素值一致。说明这些基质白云岩多为交代成因, 大部分碳均继承自原始灰岩(Land, 1985), 外部有机碳参与不明显。

氧同位素方面, 研究区灰岩 δ ¹⁸O 值(-8.8‰ ~-7.4‰ )与Veizer等(1999)(Veizer et al., 1999)所确定的晚寒武世— 早奥陶世海相方解石的氧同位素组成(-9.5‰ ~-7.5‰ )类似, 因此可以认为从当时海水中直接沉淀的方解石的 δ ¹⁸O 分布范围为-9.5‰ ~-7.5‰ 。由于从相同流体中形成的方解石和白云石的氧同位素之间存在1.5‰ ~3.5‰ 的分馏(Major et al., 1992), 取其平均值2.5‰ , 可得出从晚寒武世— 早奥陶世海水中形成的白云石的氧同位素范围为-7.0‰ ~-5.0‰ 。研究区泥晶— 粉晶白云岩、微生物白云岩、颗粒白云岩和细晶自形— 半自形白云岩的 δ ¹⁸O 值大多分布在晚寒武世— 早奥陶世海相白云石的 δ ¹⁸O 值范围内( 图 6), 说明形成这些白云岩的流体与同期海水有关。特别地, 部分样品具有略高于同时期海相白云石的 δ ¹⁸O 值, 预示着这些海水可能经历了轻微的蒸发作用。

细晶— 粗晶他形白云岩的O同位素分布范围较宽, 但总体上具有负向漂移的趋势。较高的形成温度或贫¹⁸O成岩流体(如大气淡水)的混入都可能造成氧同位素值降低。一般由大气淡水和海水混合而形成的白云岩多具较低的δ ¹³C值, 且其O-C同位素具明显的协变性(Meyers et al., 1997; Li et al., 2013), 但这种现象在研究区并未出现; 另外, 结合对该类白云岩中包裹体均一温度的测试发现(胡明毅等, 2011; 黄擎宇等, 2014), 形成该类白云岩的流体通常都具有高温、高盐度的特征; 因此, 导致细晶— 粗晶他形白云岩氧同位素值负向漂移的原因主要与高温有关, 例如持续增加的埋深或是热液的参与。

大部分鞍形白云石充填物的O同位素组成与细晶— 粗晶他形白云岩明显重叠, 说明两者的成岩流体相似或是具有很强的继承性; 少量具有极低 δ ¹⁸O 值的样品可能与其具有更高的形成温度或是云化流体性质的差异有关。

3.2.2 锶同位素特征由于锶同位素在地质历史时期的海水中具有长期独特的变化规律, 加之它不像氧、碳同位素那样因温度、压力和微生物作用而分馏, 因而成为近年来研究碳酸盐沉积和成岩作用最常用的手段之一(Palmer and Edmond, 1989; Jiang et al., 2001; 黄思静等, 2009)。

研究区内, 大部分保留原始结构的白云岩(泥晶— 粉晶白云岩、微生物白云岩、颗粒白云岩)和晶粒白云岩中的细晶自形— 半自形白云岩的锶同位素组成, 与同时期海水 ⁸⁷Sr/⁸⁶Sr 值(0.7080~0.7092)相当(Denison et al., 1998; Veizer et al., 1999)( 图 7), 同样说明形成这几类白云岩的成岩流体与海水密切相关, 其他流体参与不明显。

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	图7 塔里木盆地中央隆起区各类白云岩Sr同位素分布图Fig.7 Diagram showing Sr isotope values for each type of dolostones in Central Uplift, Tarim Basin

细晶— 粗晶他形白云岩和鞍形白云石充填物的锶同位素值范围较宽( 图 6), 既有与同时期海水值接近的样品, 也有大量高 ⁸⁷Sr/⁸⁶Sr 值的样品(> 0.7092)和少量低值样品(< 0.7080)。较宽的锶同位素值范围预示其云化流体的复杂性和多源性:

1)与同时期海水Sr同位素值相近样品的成因应该与地层中封存的海源流体有关, 即在埋藏过程中还未有大量其他流体混入的阶段已形成; 亦可能是重结晶作用的结果, 即细晶— 粗晶他形白云岩中的锶同位素组成主要继承自早期形成的白云岩。

2)少量 ⁸⁷Sr/⁸⁶Sr 值明显低于当时海水值样品的存在, 指示了贫 ⁸⁷Sr 幔源锶的混入(成岩蚀变和采样过程中的污染将导致 ⁸⁷Sr/⁸⁶Sr 值升高)(Banner, 1995; Machel, 2000; 刘存革等, 2008; Dong et al., 2013), 说明深部幔源热液体参与到了白云石化过程中, 特别是当这种幔源贫 ⁸⁷Sr 热流体沿基底断裂快速上涌、且未在前寒武系或下寒武统碎屑岩中长距离运移时, 所形成的白云岩就具有较低的 ⁸⁷Sr/⁸⁶Sr 值。

3)大部分具有较高 ⁸⁷Sr/⁸⁶Sr 值的样品可能与盆地深部来源的、幔源贫 ⁸⁷Sr 热流体流经前寒武系或下寒武统碎屑岩输导层后吸附了大量放射性成因 ⁸⁷Sr 而导致其 ⁸⁷Sr/⁸⁶Sr 值变高有关。国内外已有不少这类白云岩的实例, 特别是受构造控制的热液白云岩中, 许多具有高Sr同位素值的鞍形白云石均被认为是深部热流体流经了古老的碎屑岩地层或结晶基底后而富集 ⁸⁷Sr 的结果(Qing and Mountjoy, 1992; Cai et al., 2001; Green and Mountjoy, 2005; Katz et al., 2006)。另外, 中下寒武统蒸发岩中的地层热卤水也可提供过量的 ⁸⁷Sr。由于中下寒武统沉积时海平面极低, 膏盐岩及泥岩大量发育, 吸附大量放射性成因锶, 导致地层水中的 ⁸⁷Sr/⁸⁶Sr 值普遍增高。如果这种具有高锶同位素值的蒸发岩层间热卤水, 在地热对流或构造挤压的驱动下向上运移, 也会造成上寒武统— 下奥陶统白云岩的 ⁸⁷Sr/⁸⁶Sr 值升高。

总体上, 细晶— 粗晶他形白云岩和鞍形白云石充填物较宽的Sr同位素组成是多种成岩流体共同作用的结果, 包括孔隙中封存的海源流体、深部热液以及蒸发岩层间热卤水等。

3.3 白云岩形成机制

3.3.1 上寒武统白云岩对于上寒武统白云岩而言, 其岩石类型主要为泥晶— 粉晶白云岩、微生物白云岩和(残余)颗粒白云岩等。这些白云岩往往具有成层性, 且晶粒细小、原岩结构保留较好, 推测其形成时为近地表低温成岩环境, 同时白云石化流体供应充足, 白云石成核点多, 部分具微生物结构的白云岩很可能是微生物调制作用的结果(胡文瑄等, 2014)。与同期海水值相近的 ⁸⁷Sr/⁸⁶Sr 组成和略微偏正的 δ ¹⁸O 值, 说明白云石化流体与轻微蒸发海水有关( 图 8)。由于晚寒武世研究区为一宽缓的陆表海台地, 海平面长期处于较低位置, 受东部台缘带阻隔以及盆地当时位于赤道附近(Huang et al., 2000)、气候炎热的影响, 台内海水盐度升高、密度增大, 有利于形成轻微蒸发或中等盐度的海水。虽然这类海水并未达到膏岩沉淀的盐度, 但近年来不少研究认为, 这种经历了轻微蒸发作用的海水同样具备大规模白云石化的能力(Whitaker and Smart, 1990; Sun, 1994; Qing et al., 2001; 潘立银等, 2012), 而且早期开放成岩环境中云化流体供给充足, 有助于形成大面积层状展布的白云岩体, 因此上寒武统白云岩主要是同生/准同生期与轻微蒸发海水有关的白云石化的产物。

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	图8 塔里木盆地中央隆起区各类白云岩Sr-O同位素交会图Fig.8 Cross-plot of oxygen and strontium isotope values for each type of dolostones in Central Uplift, Tarim Basin

3.3.2 下奥陶统白云岩对于下奥陶统白云岩而言, 其岩石学特征与上寒武统有一定差别, 主要的白云岩类型为细晶自形— 半自形白云岩, 晶粒相对较大, 原岩结构保存差, 交代作用明显, 部分样品可见残余颗粒幻影( 图 4-c), 说明其形成时灰质沉积物普遍经历了早成岩作用, 因此白云石化时间要晚于上寒武统白云岩。该类白云岩的Sr同位素组成与同期海水接近, O同位素值相比上寒武统原始结构保留的白云岩具有负向漂移的趋势( 图 8), 可能是埋藏增温所致。由于早奥陶世研究区沉积环境由半局限台地向开阔台地转变(乔占峰等, 2012), 海水受限程度降低, 盐度趋于正常, 因此沉积期海水的白云石化能力降低, 白云石成核点减少, 但随着埋深相对增加, 逐步升高的地层温度有助于克服白云石形成的动力学障碍(Machel, 2004), 进而形成大量晶粒相对较粗的、具明显交代特征的白云岩, 因此下奥陶统白云岩主要与浅埋藏期白云石化作用有关。

3.3.3 埋藏阶段的调整改造上寒武统— 下奥陶统早期形成的白云岩, 在漫长的埋藏过程中经历了不同程度的调整改造, 主要体现在如下2个方面。

一是埋藏条件下较高的成岩温度, 可导致白云石过度生长以及晶体曲面化(Sibley and Gregg, 1987), 从而形成大量细晶— 粗晶他形白云岩。由于中— 深埋藏阶段镁离子供给相对有限, 因此很难大规模交代灰岩, 但根据该类白云岩在薄片中呈双峰态分布的粒度特征( 图 4-f)、残余颗粒结构( 图 4-g)以及斑状的阴极发光( 图 4-i)认为, 细晶— 粗晶他形白云岩很可能是早期白云岩在埋藏阶段重结晶作用的结果(Wendte et al., 1998; Fu et al., 2006)。另外, 该阶段外部流体混入有限, 因此所形成白云岩的 ⁸⁷Sr/⁸⁶Sr 值基本保留沉积期海水特征, 而 δ ¹⁸O 值则受温度升高的影响逐步降低, 总体呈现出O同位素变轻而Sr同位素基本不变的地球化学特征( 图 8)。

另一方面, 受多期构造活动与岩浆热事件影响, 该套白云岩地层内发育大量与构造— 热液作用有关的缝洞鞍形白云石充填物, 同时围岩也不同程度地受到改造。由于热流体性质及运移机制的不同, 所形成的热液白云岩/石在地化组成方面也有明显差异:例如当深部幔源贫 ⁸⁷Sr 热流体沿断裂系统快速上涌时可形成 ⁸⁷Sr/⁸⁶Sr 值和 δ ¹⁸O 值均较低的缝洞白云石; 而当这种幔源热液流体与前寒武系碎屑岩交换充分时或是与其他富 ⁸⁷Sr 流体(如蒸发岩层间热卤水)混合时, 形成的缝洞白云石就具有较高的 ⁸⁷Sr/⁸⁶Sr 值和较低的 δ ¹⁸O 值( 图 8)。因此受热液改造的白云岩/石, 往往具有明显负偏的O同位素值和较宽的Sr同位素组成。

3.4 白云石化模式及流体演化规律

根据塔里木盆地中央隆起区上寒武统— 下奥陶统白云岩岩石学、地球化学特征以及沉积、构造演化背景, 建立了相应的白云石化模式( 图 9)。

晚寒武世研究区为半局限台地相, 海平面长期处于较低位置, 台地内海水循环受限, 大量中等盐度的海水在密度差以及海平面变化的驱动下发生回流(Qing et al., 2001; 袁鑫鹏和刘建波, 2012), 沉积物在同生/准同生期已经白云石化, 并能够较好地保留原始结构; 早奥陶世, 研究区沉积环境由半局限台地向开阔台地转化, 海水盐度逐步趋于正常, 同生/准同生期白云石化减少, 大部分白云岩形成于浅埋藏阶段, 残余地层中的海水构成云化流体的主要来源。

中— 深埋藏阶段:该阶段的白云石化模式通常有“ 埋藏压实及页岩失水模式” (Machel and Anderson, 1989)、“ 构造挤压水流模式(Qing and Mountjoy, 1994; Gasparrini et al., 2006)、“ 地形驱动水流模式” (Garven and Freeze, 1984; Yao and Demicco, 1997)以及“ 热对流模式” (Evans and Nunn, 1989; Morrow, 1998)等。由于研究区上寒武统— 下奥陶统缺乏大量泥岩, 因此埋藏压实模式并不适用; 构造挤压和地形驱动水流的流动速率缓慢且活动时间较短(Buschkuehle and Machel, 2002; Machel and Buschkuehle, 2008), 影响范围有限。对于研究区白云岩而言, 其形成机制更可能与热对流有关( 图 9), 特别是该套地层缺乏有效隔水夹层(如泥岩或蒸发岩)的先天条件, 可使盆地内封存的海源地层水发生热对流或深循环(Bjø rlykke et al., 1988; 黄思静等, 2006), 从而使白云石化作用持续进行。

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	图9 塔里木盆地中央隆起区主要的白云石化模式图Fig.9 Main models of dolomitization in Central Uplift, Tarim Basin

构造— 热液活动阶段:该阶段的白云石化受构造活动的差异而具有不同的作用机制, 例如巴— 麦地区多发育盖层滑脱型逆冲断裂, 部分断层沿中寒武统膏盐层滑脱(任建业等, 2011; 邬光辉等, 2012), 热流体可能主要来自于蒸发岩层间热卤水; 而塔中地区由于基底走滑断裂以及海西晚期岩浆活动的影响(Dong et al., 2013; 杨圣彬等, 2013), 热流体则主要来源于深部, 而且这种热流体向上运移的过程中极易与其他地层流体(如残余地层水、蒸发岩层间热卤水)相混合, 从而导致该期白云岩/石多变的地球化学特征。

4 结论

1)上寒武统白云岩主要由泥晶— 粉晶白云岩、微生物白云岩和(残余)颗粒白云岩等原始结构保留较好的白云岩构成, 其C、Sr同位素与同期海水相近, O同位素值偏正, 属于同生/准同生期与轻微蒸发海水有关的白云石化的产物; 下奥陶统白云岩以细晶自形— 半自形白云岩为主, 原始结构保留差, 其C、Sr同位素与同期海水近似, O同位素值略微偏负, 主要为浅埋藏期白云石化的产物。

2)部分早期白云岩在中— 深埋藏过程中受埋藏重结晶和构造— 热液白云石化的影响, 形成细— 粗晶他形白云岩和缝洞鞍形白云石充填物, 其Sr同位素值受多期多源流体的共同影响而具有较宽的分布范围, O同位素值则由于高温影响而明显负偏。

3)研究区上寒武统— 下奥陶统白云岩具有早期形成(近地表到浅埋藏期大规模交代)、中期加强(中埋藏期部分重结晶)、晚期改造(构造— 热液作用期进一步调整改造)的总体变化趋势。其中早期白云石化流体以轻微蒸发的海水为主, 埋藏阶段白云石化的流体主要为地层中封存的海源流体, 而构造— 热液白云石化流体则主要来自于深部热液、蒸发岩层间热卤水以及其混合。

(责任编辑郑秀娟)

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2010

0.0

陈永权, 周新源, 杨海军. 2010. 塔里木盆地塔中地区上寒武统3种截面特征白云岩的岩石地球化学特征与成因研究. 沉积学报, 28(2): 209-218.

[Chen Y

, Zhou Y

, Yang H

2010. Geochemical research and genesis of dolostones with different crystal characteristics occurring in the Upper Cambrian, centeral area of Tarim Basin. Acta Sedimentologica Sinica, 28(2), 209-218]

In Tarim basin occurs a large amount of dolostone strata, in which contains plenty of good reservoir. In this paper, petrology and geochemistry methods were attempted to reveal the genesis of dolostones with different crystal characteristics and the subjects were the dolostones of the upper Cambrian in the centeral area of Tarim basin. According to the petrology, the studied dolostones can be divided into “Cloudy center with bright rim” type of euhedral dolomite (CBED),“clean and light” type of euhedral dolomite(CLED) and “dirty section” type of euhedral/subhedral dolomite (DED or DSD). The geochmical results show that the Mg/Ca of CBED,DSD and DED vary in 0.760.93, of the three types, the Mg/Ca value of DSD is the highest, which indicates DSD might have been on the highest evolving stage; There is a considerable coincidence between CBED and CLED, with Ca enriched in rim and Mg enriched in core, which indicates the meteoric water had taken part in at the late crystal stage. The order degrees of CBED, DED and DSD are 0.51, 0.6, 0.69 respectively, which suggests that the crystal speed of CBED is fast and the DSD might have been affected by thermal alternation resulting in the high order degree and high evolving stage. The Rb, Th, Ti enriched characteristics and the right inclined PAASnomalized REE patterns suggest that the CBED, DED and DSD might have derived Mg from evaporated seawater. The δ13C and δ18O values of CBED, DED and DSD range in -2.5‰-1.0‰ and -8.3‰ -5.4‰ respectively, and the δ18O values of CBED are lower than those of DED or DSD, which coincides with the joining of the meteoric water. The 87Sr/86Sr varies in 0.708 8350.709 204, coincident with paleoseawater. Therefore, conclusions were reached: 1) the crystallization of CBED can be divided into two stage, center stage and rim stage, of which the dolomitization fluid are evaporated seawater and mixed seawater and meteoric water, respectively; 2) CLED is results of mixed water dolomitization, however the different proportion of seawater and meteoric water lead to different composition of dolomite in core and rim; 3) DED and DSD are results of dolomitization by evaporated seawater, of which DSD had suffered thermal alternation, which may result in the higher order degree, higher 87Sr/86Sr values and higher evolving stage. 

Tarim Oil Field Company Exploration and Development Research Institute, CNPC, Korla, Xinjiang 841000

塔里木盆地寒武系白云岩分布范围广，厚度大，是非常重要的油气储层。研究以塔中地区上寒武统白云岩为对象，试图通过岩石学与地球化学分析方法探讨白云岩的成因问题。塔中地区上寒武统白云岩可划分为雾心亮边型自形粒状细晶白云岩、洁净明亮型自形粒状粗晶白云岩、截面污浊型自形（他形）粒状白云岩；岩石学分析表明，雾心亮边型白云岩可能为两世代交代产物，洁净明亮与截面污浊型白云岩为单世代交代产物。雾心亮边型白云岩与截面污浊型白云岩的Mg/Ca摩尔比变化在在0.76～0.93之间，截面污浊型他形粒状白云岩Mg/Ca比平均值最高，指示其演化程度较高；雾心亮边型白云岩与洁净明亮型白云岩皆表现出核部富Mg、边部富Ca特征，指示亮边部分云化流体中大气水的含量更高。雾心亮边型白云岩、截面污浊型自形粒状白云岩与截面污浊型他形粒状白云岩平均有序度值分别为0.51、0.6、0.69，指示了雾心亮边型白云岩交代速度较快，截面污浊型他形粒状白云岩由于受到了热作用导致其具有高的有序度与演化程度。雾心亮边型白云岩与截面污浊型白云岩富集Rb、Th、Ti等元素，稀土元素配分模式呈平缓右倾特征，体现了蒸发海水特征；雾心亮边型白云岩与截面污浊型白云岩的δ13C值变化为-2.5‰～-1.0‰，δ18O值变化为-8.3‰～-5.4‰，指示了白云岩形成于低温环境，交代流体为蒸发海水，同时雾心亮边型白云岩低δ18O特征反映了大气水的参与；雾心亮边型白云岩与截面污浊型白云岩87Sr/86Sr比值变化在0.708 835～0.709 204，与古海水一致。因此，雾心亮边型白云岩为两世代交代产物，第一世代交代雾心，交代流体以蒸发海水为主，第二世代为亮边，交代流体以海水与大气水混合为主；洁净明亮型白云岩为由海水与大气淡水组成的混合水云化的产物，只是核部交代期混合水中海水比例高，边部交代期混合水中大气水混合比例高；截面污浊型则由蒸发海水交代形成，他形粒状结构白云岩为自形粒状白云岩经热改造而成，导致了其具有较高的有序度与87Sr/86Sr比值。

... 陈永权等,2010 ...

2011

0.0

胡明毅, 胡忠贵, 李思田, 王延奇. 2011. 塔中地区奥陶系白云岩岩石地球化学特征及成因机理分析. 地质学报, 85(12): 2060-2069.

[Hu M

, Hu Z

, Li S

, Wang Y

2011. Geochemical characteristics and genetic mechanism of the Ordovician dolostone in the Tazhong Area, Tarim Basin. Acta Geologica Sinica, 85(12): 2060-2069]

The dolomite of the Ordovician in Tazhong area are widely distributed，which has a large thickness and is one of the most important reservoirs in Tarim basin. According to the size of the structure of the dolomite crystal and the original sedimentary features，six kinds of dolomite types are found: mud - fine silty dolostone，algal dolomite，dolomite particles， coarse dolomite，medium - coarse crystalline dolomite，mottled dolomite. The mud - fine silty dolostone and algal dolostone preserve the original sedimentary. The study of geochemical characteristics of Ordovician dolomite shows: high carbon and oxygen isotopes，the index of salinity is higher than normal sea water，high Sr and Na，with relatively low Fe and Mg，the characteristics of REE are similar，they are interpretated of the production of the penecontemporaneous dolomitation. Crystalline dolostone and coarse dolostone particles with a crystal is relatively large，with a clear replacement of the structure (such as fog light side of heart structure and ring structure) features.By the geochemical characteristics of rare elements，the carbon and oxygen isotopes turn to the negative of offset and the index of salinity is low with the development of the diagenetic.The low of the Sr and Na，and the high of the Fe and the Mn，the ∑REE is changed very big， REE distribution patterns and Ce， Eu anomaly similar to be interpreted as a buried phase of the role of the product of dolomite，and may have been affecte by the tectonic hydrothermal liquid in the process of dolomite. Based on the study of the mechanism of the origin of the dolostone，the different dolomitation models are established to adapt to the actual case in the Tazhong area.

塔中地区奥陶系统白云岩分布广泛，厚度大，是该区重要的储层之一。根据白云石晶体结构大小、原始沉积特征保存情况，将该区白云岩分为泥晶-微晶白云岩、藻纹层白云岩、颗粒白云岩、粗粉晶-细晶白云岩、中晶-粗晶白云岩、斑状白云岩等6种类型。泥晶-微晶白云岩、藻纹层白云岩保留了其原岩沉积特征，地球化学特征表现为：碳、氧同位素偏高，盐度指数略高于正常海水，微量元素锶、钠含量高和铁、锰含量低，稀土元素特征大体相似，将其解释为准同生白云岩化作用产物。结晶白云岩和颗粒白云岩具有晶体相对粗大、具明显的交代结构（如雾心亮边结构和环带构造）特点，地球化学特征表现为：碳、氧同位素具有随着成岩作用加强依次向负值偏移，盐度指数逐渐降低的特点，微量元素锶、钠含量低和铁、锰含量高，稀土元素总量变化较大，REE配分模式和Ce、Eu异常相似，将其解释为埋藏阶段白云岩化作用的产物，并且在白云岩化过程中可能叠加有构造热液作用的影响。在白云岩成因机理分析的基础上，建立了适合研究区发育的各种白云岩类型的白云岩化作用模式。

... 胡明毅等,2011 ...

... 另外,结合对该类白云岩中包裹体均一温度的测试发现(胡明毅等,2011 ...

2014

0.0

胡文瑄, 朱井泉, 王小林, 由雪莲, 何凯. 2014. 塔里木盆地柯坪地区寒武系微生物白云岩特征、成因及意义. 石油与天然气地质, 35(6): 860-869.

[Hu W

, Zhu J

, Wang X

, You X

, He

2014. Characteristics, origin and geological implications of the Cambrian microbial dolomite in Keping area, Tarim Basin. Oil & Gas Geology, 35(6): 860-869]

Reefal (biohermal) carbonate rocks are important petroleum reservoirs. In Tarim Basin, the occurrences of reefal facies in the Ordovician sequences have been well documented, whereas that in the Cambrian strata have been rarely reported. In this study, the occurrences of stromatolite dolomite and reefal dolomite in the Cambrian Qiulitage Formation at Keping area, Tarim Basin were reported. Based on careful field observations, the micro-structures of these microbial dolomite were investigated by using conventional microscope and scanning electron microscope (SEM). It is suggested that the microbial reefs formed in shallow subtidal environment where the water was turbulent, the deposition rate was relatively high and the platform was relatively open. In contrast, the stromatolite dolomites were developed in tidal flat-intertidal facies. Nanoscale spherical dolomite formed nanocrystal aggregats including dumbbell and chain-like structures. In addition, tubular and sheet-like aggregates were suggested to be in close association with the mineralization of extracellular polymeric substances (EPS). All the above nanostructures resemble the morphology observed in microbial culture experiments. These evidences support the conclusion that microbial mediation might have played an important role in the formation of the Cambrian dolomite. During the formation of microbially mediated dolomite, sulfate reducing bacteria did not play an important role because no pyrite was observed, then SO 4 2- may not serve as an important kinetic inhibitor for the precipitation of dolomite. Thus it is proposed that the hydration of Mg 2+ should be emphasized in the future study on the origin of dolomite.

1. School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China; 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 3. School of Ocean Sciences, China University of Geosciences, Beijing 100083, China; 4. Henan Institute of Geological Survey, Zhengzhou, Henan 450001, China

生物礁(丘)碳酸盐岩是重要的油气储层.塔里木盆地关于生物礁的报道主要集中在奥陶系,而在寒武系中却少有发现.通过柯坪地区上寒武统丘里塔格下亚群中的叠层石白云岩和凝块石(礁)白云岩的野外产出特征和微观结构构造分析,认为凝块石白云岩主要形成于潮下带水动力条件较强的沉积环境,而叠层石白云岩则形成于潮坪-潮间水动力相对稳定的沉积环境.叠层石白云岩中发育纳米级球形颗粒及其组成的哑铃状、链状结构,并发育管状-片状结构.上述特殊的结构在成分上均为白云石,与微生物培养实验中沉淀的白云石在形态上基本一致,说明微生物调制作用是研究区寒武系白云岩重要的成因模式之一.丘里塔格下亚群中未见任何蒸发岩和黄铁矿,说明叠层石白云岩形成流体盐度未达到沉淀石膏的临界点,白云石沉淀流体中含有SO 4 2- ,并且未发生明显的细菌硫还原作用.因此,前人提出的SO 4 2- 抑制白云石沉淀的作用可能被夸大,结合白云岩成因研究新进展,认为白云石成因机理研究应更多考虑Mg 2+ 的水合作用.此外,对叠层石白云岩和凝块石白云岩的储集特征初步研究发现,其有可能成为天然气的潜在储层,值得引起重视.

... 这些白云岩往往具有成层性,且晶粒细小、原岩结构保留较好,推测其形成时为近地表低温成岩环境,同时白云石化流体供应充足,白云石成核点多,部分具微生物结构的白云岩很可能是微生物调制作用的结果(胡文瑄等,2014) ...

2014

0.0

黄擎宇, 张哨楠, 叶宁, 李映涛. 2014. 玉北地区下奥陶统白云岩岩石学、地球化学特征及成因. 石油与天然气地质, 35(3): 391-400.

[Huang Q

, Zhang S

, Ye

, Li Y

2014. Petrologic, geochemical characteristics and origin of the Lower Ordovician dolomite in Yubei area. Oil & Gas Geology, 35(3): 391-400]

The petrologic,geochemical characteristics and origin of the Lower Ordovician dolomite in Yubei area were investigated through the analysis of the cores,thin-sections,SEM,cathode luminescence,trace element,C-O isotope and microthermometry of fluid inclusions.The following results were obtained.Matrix dolomites are of two types:fine crystalline,euhedral-subhedral dolomite and fine to coarse crystalline,anhedral dolomite with saddle fillings.The origin of dolomite is closely related to crystal texture(nonplanar anhedral,planar euhedral/subhedral)instead of crystal size.The fine crystalline,euhedral-subhedral dolomite has high Sr and low Fe-Mn content,and C and O isotope composition similar to that of seawater in Early Ordovician.So this type of dolomite was overall the product of low-temperature dolomitization associated with the Ordovician seawater during the early stage of shallow burial.In contrast,the fine to coarse crystalline,anhedral dolomite has low Sr,relatively high Fe and Mn content and more negative O isotope value.And its fluid inclusion microthermometry result suggests that it has high homogenization temperature and salinity.Combined with the regional tectonic background,it is believed that this type of dolomite was primarily the product of high-temperature dolomitization during late stage of shallow burial to moderate burial,and was locally transformed by hydrothermal fluids from marine-sourced saline water in formation.Moreover,there are two stages of saddle dolomite fillings:one is coeval with the matrix dolomite of hydrothermal dolomitization origin and the other may be associated with the thermal fluid post-magmatic activity during the Permian.

1. School of Energy Resources, Chengdu University of Technology, Chengdu, Sichuan 610059, China; 2. School of Resources and Environment, Southwest Petroleum University, Chengdu, Sichuan 610050, China

通过岩心、薄片、扫描电镜、阴极发光、微量元素、同位素和包裹体测温等分析手段，对玉北地区下奥陶统白云岩岩石学特征、地球化学特征及成因进行研究。结果表明，该区白云岩主要由细晶、自形-半自形白云岩和细-粗晶、它形白云岩以及鞍形白云石充填物构成。白云岩的晶粒大小并不反映成因，反而是晶体结构特征（曲面-它形晶和平面-自形、半自形晶）与成因关系密切。细晶、自形-半自形白云岩具有高Sr、低Fe、Mn含量的特征以及与早奥陶世海水相似的O和C同位素组成，总体属于浅埋藏早期与海水有关的低温白云石化作用的产物。细-粗晶、它形白云岩的Sr含量较低而Fe和Mn含量相对较高，O同位素值明显偏负，包裹体测温结果显示部分样品具有较高的均一温度和盐度值，结合区域构造演化背景，认为该类白云岩以浅埋藏晚期到中埋藏阶段的高温白云石化为主，局部受热液改造，云化流体主要来自于地层中封存的海源卤水。鞍形白云石充填物有两期，一期与热液成因的基质白云岩形成时期相近，另一期则可能与二叠纪的岩浆期后热液有关。

... 黄擎宇等,2014),形成该类白云岩的流体通常都具有高温、高盐度的特征 ...

2006

0.0

黄思静, Qing

Hairuo

, 裴昌蓉, 胡作维, 吴素娟, 孙治雷. 2006. 川东三叠系飞仙关组白云岩锶含量、锶同位素组成与白云石化流体. 岩石学报, 22(8): 2123-2132.

[Huang S

, Qing H

, Pei C

, Hu Z

, Wu S

, Sun Z

2006. Strontium concentration, isotope composition and dolomitization fluids in the Feixianguan Formation of Triassic, Eastern Sichuan of China. Acta Petrologica Sinica, 22(8): 2123-2132]

川东飞仙关组白云岩包括微晶白云岩、具原始结构的粒屑白云岩和结晶白云岩等3种主要的结构类型，其中结晶白云岩是重要的天然气储集岩。根据白云岩的锶含量和锶同位素组成，结合相关岩石学和地球化学资料，本文研究了白云石化过程中锶的迁移和相应的同位素变化。三种类型白云岩具有类似的锶含量，但其^87Sr/^86Sr比值均不同程度地高于同期海水值，锶在白云石和方解石（或文石）中分配系数的差别是影响白云石化过程中白云石锶含量最为重要的因素。不同流体中锶的混合方程计算表明：如果白云石化流体是大气淡水和海水的混合流体，则结晶白云岩的白云石化流体相当于94％的大气淡水和6％的海水混合，具原始结构的粒屑白云岩的白云石化流体相当于81％的大气淡水和19％的海水混合，微晶白云岩的白云石化流体相当于92％的大气淡水和8％的海水混合。但极低的锰含量、相对较高的锶含量和包裹体均一化温度等资料均不支持有94％的大气淡水参与了结晶白云岩的白云石化作用，其白云石化流体应是埋藏成岩过程中囚禁的近同期、但是非同期的海源流体，其来源可能与埋藏成岩过程中该时间段蒸发盐的溶解有关。锰含量、锶含量、^87Sr/^86Sr比值都表明具原始结构的粒屑白云岩和微晶白云岩的白云石化过程都存在大气淡水的介入，微晶白云岩的白云石化可能与潮坪环境的蒸发泵机理有关；具原始结构的粒屑白云岩的白云石化可能与混合水白云石化作用有关，这类白云岩分布于向上浅滩化旋回滩体的顶部，这是埋藏前或浅埋藏阶段大气淡水与海水混合白云石化作用最容易发生地带。

... 黄思静等,2006),从而使白云石化作用持续进行 ...

2009

0.0

... 黄思静等,2009) ...

2008

0.0

... 刘存革等,2008 ...

2013

0.0

罗平, 王石, 李朋威, 宋金民, 金廷福, 王果谦, 杨式升. 2013. 微生物碳酸盐岩油气储集层研究现状与展望. 沉积学报, 31(5): 807-823.

[Luo

, Wang

, Li P

, Song J

, Jin T

, Wang G

, Yang S

2013. Review and prospectives of microbial carbonate reservoirs. Acta Sedimentologica Sinica, 31(5): 807-823]

Microbial carbonates are important oil & gas reservoir rocks, as well as the main rock types in China old strata. Microbial carbonates can be divided into stromatolites, thrombolite，dendrolite and other two types. The reservoir pore systems are closely related to microbialite sedimentary process, and mostly affected by structures and textures of microbialites. Framework and fenestral vugs are the main types of reservoir space. From Middle-Neo Proterozoic to Mesozoic, microbial carbonates reservoirs are discovered globally in various oil & gas fields, so that their petroleum resource potential is great.The researches on rock types,litofacies texture, depositional models and favorable facies zones of microbial reservoir, are well worth deep study in future.

Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083

微生物碳酸盐岩是一种重要的油气储集岩。在中国古老深埋碳酸盐岩地层中它们是主要的岩石类型。微生物碳酸盐岩通常可划分为叠层石、凝块石、树枝石、均一石和核形石等五种类型。储层孔隙系统与微生物岩的沉积结构和构造密切相关，窗格孔（洞）和格架孔（洞）是主要储集空间类型。全球中新元古界至中生界都发现了以微生物碳酸盐岩为储层的油气田，资源潜力巨大。微生物岩储层的岩石类型、沉积构造、相序结构、沉积模式和储层有利相带尚有许多不明晰之处，是今后进一步深化研究的重点方向。

... 2)微生物白云岩岩心上可见微生物结构,包括凝块石、叠层石、枝状石、核形石等(罗平等,2013 ...

2012

0.0

潘立银, 刘占国, 李昌, 寿建峰, 张建勇, 张杰, 沈安江, 周进高, 郑兴平. 2012. 四川盆地东部下三叠统飞仙关组白云岩化作用及其与储集层发育的关系. 古地理学报, 14(2): 176-186.

[Pan L

, Liu Z

, Li

, Shou J

, Zhang J

, Zhang

, Shen A

, Zhou J

, Zheng X

2012. Dolomitization and its relationship with reservoir development of the Lower Triassic Feixianguan Formation in eastern Sichuan Basin. Journal of Palaeogeography(Chinese Edition), 14(2): 176-186]

Gas reservoirs of the Lower Triassic Feixianguan Formation in eastern Sichuan Basin are mostly dolostones，which are distributed in the platform margin around Kaijiang-Liangping Basin. Petrographic and geochemical evidences indicate multiple dolomitization events，and the most significant one of which was triggered penecontemporaneously by reflux of evaporative seawater. Dolostones formed in early periods had undergone various degree of recrystallization during burial，which resulted in the complex rock textures. Pore of the Feixianguan Formation dolostones is predominantly intergranular and/or oomoldic(or intragranular)，which is inherited from the precursor limestones rather than creating during dolomitization.These kinds of pore are well preserved in dolostones，owing to early dolomitization and the resistance of dolomites to compaction.

1 PetroChina Hangzhou Research Institute of Geology，Hangzhou 310023，Zhejiang 2 Key Laboratory of Carbonate Reservoir，CNPC， Hangzhou 310023，Zhejiang

四川盆地东部下三叠统飞仙关组鲕滩相储集层多为白云岩，主要分布于环开江—梁平盆地的台地边缘相带。岩石学和地球化学特征表明，飞仙关组鲕滩相储集层经历了多期白云岩化作用，其中最重要的一期发生于成岩早期近地表环境，由蒸发海水回流引起，形成的粉晶交代白云石构成了现今白云岩的主体。飞仙关组早期白云岩经历了不同程度的埋藏重结晶作用，形成了不同的岩石结构类型。飞仙关组白云岩的孔隙多为原岩中继承而来，白云岩化作用对储集层发育的意义并非创造孔隙，而是保存已有的孔隙。由于白云岩化作用发生的时间早以及白云岩的抗压溶性质，原生（鲕）粒间孔以及早期大气淡水溶蚀作用形成的鲕模孔/粒内溶孔可以在很大程度上保存下来，构成了现今鲕滩相储集层的主要储集空间。

... 潘立银等,2012),而且早期开放成岩环境中云化流体供给充足,有助于形成大面积层状展布的白云岩体,因此上寒武统白云岩主要是同生/准同生期与轻微蒸发海水有关的白云石化的产物 ...

2006

0.0

... 前人对该套白云岩的成因进行了大量研究,普遍认为其成因与埋藏白云石化有关(钱一雄和尤东华,2006 ...

2012

0.0

乔占峰, 沈安江, 郑剑锋, 胡杰, 吴兴宁, 陆俊明. 2012. 塔里木盆地下奥陶统白云岩类型及其成因. 古地理学报, 14(1): 21-32.

[Qiao Z

, Shen A

, Zheng J

, Hu

, Wu X

, Lu J

2012. Classification and origin of the Lower Ordovician dolostone in Tarim Basin. Journal of Palaeogeography(Chinese Edition), 14(1): 21-32]

Dolostone of the Lower Ordovician in the Tarim Basin is the most practical exploration target.In this paper，based on the Early Ordovician of tectonic，sedimentary，and palaeoclimate setting of the Tarim Basin，considering the former classifications of dolostone according to the structure，the Lower Ordovician dolostone of the Tarim Basin according to the development and occurrence has been classified as: scattered dolomite in limestone，mottled dolomite in limestone，bedded dolostone，and dolostone related to faults，and the content of dolomite in strata decreases upward.Four dolostones have different features of lithology and occurrence，and they can occur superposably.Features of lithology，geochemistry and occurrence of scattered，mottled dolomite in limestone have revealed their origin of shallow burial dolomitization，and bedded dolostone and dolostone related to faults are formed during moderate-deep burial dolomitization.Their origin and occurrence diversity are controlled by the changes of seawater level，seawater property，and burial environment.Dolostone related to faults，which constitutes important reservoirs，appear to be related closely to the faults in origin and/or in occurrence.Furthermore，it is concluded that the burial dolomitization failed to exert the constructive effects on the formation of dolostone reservoir，while the dissolution caused by migration of fluids in late periods is the main origin.

1 PetroChina Hangzhou Research Institute of Geology，Hangzhou 310023，Zhejiang 2 Key Laboratory of Carbonate Reservoir，CNPC， Hangzhou 310023，Zhejiang 3 PetroChina Tarim Oilfield Company，Kurler 841000， Xinjiang

下奥陶统白云岩是塔里木盆地最现实的重点勘探领域。文中在分析塔里木盆地早奥陶世构造、沉积及古气候等地质背景的基础上，以前人对白云岩的结构分类为基础，从白云岩发育产状出发，将塔里木盆地下奥陶统白云岩划分为灰岩中零散白云石、灰岩中斑状白云石、层状白云岩和沿断裂分布白云岩4类，白云石含量层位上自下而上具有总体减少的趋势。各类白云岩在岩石学特征和发育分布上具有较为明显的差异，局部可重叠出现。灰岩中零散白云石和斑状白云石的岩石学和地球化学及发育分布特征均反映其主要由浅埋藏白云石化作用形成；层状白云岩和沿断裂分布白云岩形成于中深埋藏白云石化作用；各类白云岩的产状特征差异受控于沉积期海平面变化、海水性质及埋藏条件等因素。沿断裂分布白云岩的形成和分布与断裂密切相关，是重要的储集岩石类型。白云岩储集层的形成主要是后期改造的结果，埋藏白云石化作用并未对大规模白云岩储集层的形成起到建设性作用，伴生或后期流体再运移导致的溶蚀作用为其主要成因。

... 乔占峰等,2012 ...

... 由于早奥陶世研究区沉积环境由半局限台地向开阔台地转变(乔占峰等,2012),海水受限程度降低,盐度趋于正常,因此沉积期海水的白云石化能力降低,白云石成核点减少,但随着埋深相对增加,逐步升高的地层温度有助于克服白云石形成的动力学障碍(Machel,2004),进而形成大量晶粒相对较粗的、具明显交代特征的白云岩,因此下奥陶统白云岩主要与浅埋藏期白云石化作用有关 ...

2011

0.0

任建业, 张俊霞, 阳怀忠, 胡德胜, 李朋, 张云鹏. 2011. 塔里木盆地中央隆起带断裂系统分析. 岩石学报, 27(1): 219-230.

[Ren J

, Zhang J

, Yang H

, Hu D

, Li

, Zhang Y

2011. Analysis of fault systems in the Central uplift, Tarim Basin. Acta Petrologica Sinica, 27(1): 219-230]

Based on interpretation of seismic profiles, the structural styles, distribution and deformation characteristics of main fault systems in different periods in the Central uplift of Tarim Basin have been analysed in details. Our research will help for establishing links between development of Central uplift belt fault systems and peripheral orogenic belt evolution, and clarifing the dynamic background of the fault systems development. Moreover, a new classification of fault deformation style in the Central uplift of Tarim Basin is presented in this paper. Two sets of regional decollement structures are identified in the southern flank of Bachu uplift, in which the shallow Serikbuya-Mazhatage decollement fault system, the leading fault of the present southwestern Tarim foreland thrust system, thrusted onto the southern flank of Bachu uplift. We found a set of huge arc-shaped foreland thrust fault system protruding northwestward in the middle-east of Tanggubas depression and the east of Tazhong uplift. The thrust fault system is bounded by Che'erchen fault in the southeastern Tarim Basin and mainly occurred in the end of Late Ordovician. The leading faults of the thrust fault system are characterized by cover-bed decollement and thrusting, and cut northwest trending faults, such as Tazhong I fault belt, Tazhong 10 fault belt, Tazhong 2 fault belt and Tazhong 22 fault belt which were formed in the Late Early Ordovician and are featured by basement-involved style. Integrated with the significant tectonic events adjacent orogenic belts, these fault systems in Tarim Basin can be classified into three sets with respect to the West Kunlun orogenic belt, South Tianshan orogenic belt and Altyn orogenic belt respectively.

[Ren JianYe] China Univ Geosci, Minist Educ, Key Lab Tecton & Petr Resources, Wuhan 430074, Peoples R China.;[Ren JianYe] Minist Educ, Struct Res Ctr Oil & Gas Bearing Basin, Wuhan 430074, Peoples R China.;[Zhang JunXia] China Univ Geosci, Sch Econ & Management, Wuhan 430074, Peoples R China.;[Yang HuaiZhong; Hu DeSheng; Li Peng; Zhang YunPeng] China Univ Geosci, Fac Earth Resources, Wuhan 430074, Peoples R China.

本文以地震剖面解释为基础,深入分析塔里木盆地中央隆起带主要断裂带的构造样式和变形特征,确定不同时期断裂系统的分布规律,并试图建立中央隆起带断裂系统发育与周缘造山带演化之间的联系,进而阐明其发育的动力学背景。论文提出了塔里木盆地中央隆起带断裂构造变形样式分类体系;在巴楚隆起的南部边缘,识别出两套区域性的盖层滑脱构造系统,其中浅层色力布亚-玛扎塔格滑脱冲断层逆冲到巴楚南部边缘之上,并构成了现今塔西南前陆冲断系的锋缘断裂;发现了分布在塘古巴斯坳陷的中东部和塔中隆起东部的、规模巨大的、向北西方向凸出的弧形逆冲断裂系统。该弧形逆冲断裂系统的东南部以车尔臣断裂为界,主要形成于晚奥陶世末期,锋缘断裂以盖层滑脱逆冲为特征,与早奥陶世末期发育的、呈NW向展布的塔中Ⅰ号断裂带、塔中10号断裂带、塔中2号断裂带和塔中22号断裂带等构成的基底卷入式逆冲断裂形成明显的交切关系;论文将周缘造山带的重大构造运动事件与塔里木盆地内部不同时期发育的断裂系统相对比,在塔里木盆地内划分出分别与西昆仑造山带、阿尔金造山带和南天山造山带相关的三套断裂系统。

... 10⁴,km²,其北缘和西缘为天山造山带,南边为西昆仑造山带,东南缘为阿尔金造山带(任建业等,2011) ...

... 麦地区多发育盖层滑脱型逆冲断裂,部分断层沿中寒武统膏盐层滑脱(任建业等,2011 ...

2014

0.0

... 宋金民等,2014),其中凝块结构最为常见( >图 3-b),并伴生窗格状构造 ...

2012

0.0

邬光辉, 杨海军, 屈泰来, 李浩武, 罗春树, 李本亮. 2012. 塔里木盆地塔中隆起断裂系统特征及其对海相碳酸盐岩油气的控制作用. 岩石学报, 28(3): 793-805.

[Wu G

, Yang H

, Qu T

, Li H

, Luo C

, Li B

2012. The fault system characteristics and its controlling roles on marine carbonate hydrocarbon in the Central uplift, Tarim basin. Acta Petrologica Sinica, 28(3): 793-805]

Based on the analysis of 3D seismic date and regional geology data, lots of NW and NWW trending compression faults and NE trending strike-slip faults, but with less extensional faults, are identified in the Central uplift of the Tarim craton, which has the main characters of diversity of styles, multiple epochs and inheritance of evolution, and segmentation along strike. Most of the compression faults are detachment thrusts slipped in Middle Cambrian salt layer but not basement involved as previous cognition, which formed in the end of Early Ordovician with 4 kinds of fault styles, and had transpression effects and segmentation along the fault belt. Many strike-slip faults are discovered in the northern slope of the Central uplift by the 3D seismic data in recent years. There were tulip flower structure, upstanding structure and positive flower structure in profiles, and en echelon structure, feathered structure, brush structure, and so on, converged to southwest in plane. NE-trending sinistral strike-slip faults were developed by the intensive three stages of oblique collision from the south Tarim plate boundary in Silurian, Middle Devonian and Late Permian. The fault system, mostly distributed in Palaeozoic, can be divided into 3 types and 3 levels and 4 groups of orientation, which controlled the structure framework and shape of the Central uplift with layering in vertical and the zoning from north to south and blocking from west to east. The fault system of the Central uplift undergone 4 stages with 9 periods’ evolution: extensive extension-weak compression stage in Neoproterozoic, local weak extension period in Cambrian to Early Ordovician-powerful thrusting period in Middle-Late Ordovician, strike-slip fault developed stage in Silurian-Middle Devonian, and partly inherited faulting stage in Carboniferous-Early Triassic. It is obvious that the fault system played important roles in the hydrocarbon accumulation of Lower Palaeozoic marine carbonate in the Central uplift. It is not only the oil and gas composite accumulation in vertical, but also the favorable reservoirs and enriching hydrocarbon controlled by faults. Different type and stage faults had varied effects which caused the segmentation of hydrocarbon distribution along the fault belt. The migration-accumulation system consisted by hydrocarbon source fault and adjacent reservoir controlled the fluid orderly distribution.

结合新三维地震与区域地质资料研究,塔里木克拉通中部的塔中隆起挤压断裂与走滑断裂发育,张性断裂欠发育,断裂系统具有构造样式的多样性、形成演化的多期性、构造发育的继承性及平面展布的区段性。新资料表明挤压断裂缺少基底卷入型,多在中寒武统盐膏层滑脱,主要发育4种断裂样式,形成于早奥陶世末,多具有扭压作用与分段性。塔中隆起北斜坡新发现一系列北东向左旋走滑断裂带,剖面上以负花状构造、直立型构造、正花状构造为主,平面上发育向西南方向收敛的雁列构造、羽状构造、帚状构造等;塔中地区经历志留纪晚期、中泥盆世、晚二叠世等三期走滑断裂作用,东南方向强烈斜向挤压作用是走滑断裂形成的动力机制。塔中隆起断裂主要分布在下古生界,三类、三级、四组方向断裂控制了塔中隆起纵向分层、南北分带、东西分块的构造格局。塔中隆起经历新元古代强伸展-弱挤压的断裂发育阶段、寒武纪-奥陶纪局部弱伸展-强挤压逆冲断裂发育阶段、志留纪-中泥盆世走滑断裂发育阶段、石炭纪-早三叠世局部断裂继承性发育阶段等4阶段9期的差异发育演化史。塔中隆起断裂对下古生界海相碳酸盐岩油气分布控制作用明显,断裂控制了油气的纵向复式聚集,断裂带储层发育、油气富集;不同时期、不同类型断裂控油作用有差异性,断裂带横向上的变化造成油气分布的区段性;油气源断裂与储层组成的运聚体系内具有流体分布的有序性。

... 邬光辉等,2012),热流体可能主要来自于蒸发岩层间热卤水 ...

2008

0.0

吴仕强, 朱井泉, 王国学, 胡文瑄, 张军涛, 王小林. 2008. 塔里木盆地寒武—奥陶系白云岩结构构造类型及其形成机理. 岩石学报, 24(6): 1390-1400.

[Wu S

, Zhu J

, Wang G

, Hu W

, Zhang J

, Wang X

2008. Types and origin of Cambrian-Ordovician dolomites in Tarim basin. Acta Petrologica Sinica, 24(6): 1390-1400]

塔里木盆地寒武-奥陶系白云岩度大、分布广,是重要的油气储集层.根据岩石学研究并结合地球化学特征将其分为4类,其特点如下:(1)泥晶-粉晶白云岩,白云石晶体小、晶形差,有序度在4类中最低(0.73);Na、K、Sr含量在4类中最高;δ13C值及Z值较高,分别为-0.94‰、122.3;Fe、Mn含量较低;阴极发光为亮桔红色;常呈纹层状,具暴露及成化标志.这些特征表明其结晶较快,形成环境蒸发强烈、盐度较高、氧化性较强,是在萨布哈环境中由浓缩海水发生白云石化所形成.(2)藻纹层白云岩,白云石晶体小,晶形较好,有序度较高(0.85);藻纹层基本保留了其原始微细结构;Na、K、Sr含量较低:δC值在4类中最高,平均为-0.50‰;含有较多黄铁矿.这些特征说明其可能形成于成岩作用的稍早期阶段且其成因与藻类活动密切相关,成岩环境盐度较低,可能是在藻类作用下,由富藻层浓集的镁与残留海水在浅埋藏环境中共同作用所形成.(3)雾心亮边白云岩,白云石普遍具雾心亮边结构,雾心含少量包裹体及灰质残余,亮边则少见或无;阴极发光下,雾心发亮桔黄色光,亮边发光暗或不发光;局部见此类白云石;呈星散状分布于亮晶颗粒灰岩或泥晶灰岩中;白云石晶体较大,晶形较好.此类白云岩的δ13C及Z值在4类中最低,K、Na、Sr、Fe含量相对较低,Mn含量最高;有序度较高,均值为0.83.这些特征表明此类白云岩中白云石的雾心可能是在早期浅埋藏环境中,由富镁孔隙水交代周围灰质所形成;亮边则形成于埋藏较深的环境,其所需镁可能来源于粘土矿物的转化.(4)重结晶白云岩:白云石晶体粗大且污浊,接触紧密;局部见白云石晶体具环带结构,局部见颗粒幻影结构;阴极发光较暗;Fe含量在4类中最高,Mn含量较高;有序度最高,平均为0.95;包裹体均一温度平均为110.2℃.这些特征表明其可能是在还原性较强的深埋藏环境中,由早期形成的白云岩经较强的重结晶作用所形成.

... 吴仕强等,2008 ...

2011

0.0

邢凤存, 张文淮, 李思田. 2011. 热流体对深埋白云岩储集性影响及其油气勘探意义: 塔里木盆地柯坪露头区研究. 岩石学报, 27(1): 266-276.

[Xing F

, Zhang W

, Li S

2011. Influence of hot fluids on reservoir property of deep buried dolomite strata and its significance for petroleum exploration: A case study of Keping outcrop in Tarim Basin. Acta Petrologica Sinica, 27(1): 266-276]

Whether deep buried dolomite can form effective reservoirs is the main challenge for petroleum exploration in deep area of Tarim Basin. The cores sampled from Tashen-1 well at the burial-depth of >8000m have revealed that the dolomites are well-developed with vuggy zones, have high porosity and permealbity favorable for forming effective petroleum reservoirs, and revealing the existence of effective dolomite reservoirs in deep part. It has been confirmed vuggy zones are of hot fluid origin. However, the detailed characteristics of vuggy zones including their origin and their distribution in strata need to be disclosed by further studies. Based on field outcrop observation as well as experimental analyses, it was found that solution pores similar with those in Tashen-1 well are widely spread in Upper Sinian and Lower Ordovician dolomite ( which have experienced deep-buried conditions) in Keping area. It was also found that primary saline water inclusions of vug-filling quartz, automorphic dolomite and calcite have homogenization temperature of up to 368 degrees C, 314 degrees C and 303 degrees C respectively, which are much higher than normal formation temperature range (120 similar to 240 degrees C) of corresponding host strata at the maximum burial depth of about 6000m. The salinity of inclusions is respectively 3. 39% similar to 9. 86% NaCleqv, 1. 05% similar to 18. 13% NaCleqv and 4.34% similar to 9. 98% NaCleqv. Moreover, a variety of hydrothermal mineral associations related to pyrite, fluorite, barite, quartz, siderite, dalarnite and saddle dolomite are identified in dolomite samples. In the inclusions of these hydrothermal minerals, CO(2), H(2)S, hydrocarbon gases which may dissolve dolomite are also recognized. It was proposed that dolomite strata in Keping outcrop area experienced large-scaled abnormal hot fluid activities which might be related to extensive magmatic activities in deep part of the basin. It created abundant pore space types, such as bedding dissolution, differential dissolution, cooling fissure and dissolution-slump belt caused by hot fluid. Pore types are mainly characterized by combined type of solution enhanced fracture and vug. Hot fluid activity is mainly controlled by structural fractures and stratigraphical boundary. In this study area, the modification of hot fluid to dolomite reservoirs is mainly represented by the coexistence of constructive and destructive effects, and it is characterized by constructive effect.

[Xing FengCun; Zhang WenHuai; Li SiTian] China Univ Geosci, Beijing 100083, Peoples R China.

深埋条件下白云岩能否形成有效储层是塔里木盆地深层油气勘探面临的主要挑战之一,塔深1井大于8000m深度白云岩岩芯仍具有多孔洞带发育,并具有形成储层的孔渗性,揭示了深部白云岩有效储层的存在。研究证实,该类孔洞的形成与热流体活动相关,但其在地层中分布的特征和广泛性有待揭示。通过野外露头观察及室内测试分析,在柯坪地区经历过深埋条件的上震旦统-下奥陶统白云岩中发现了与塔深1井相似的溶蚀孔洞的普遍存在现象。孔洞内充填的石英、自形白云石以及方解石矿物原生盐水溶液包裹体均一温度依次可达到368℃、314℃和303℃,远高于相应地层最大埋深(约6000m)条件下推测的正常地层温度范围(120~240℃),盐度分布范围依次为3.39%~9.86% NaCleqv、1.05%~18.13% NaCleqv和4.34%~9.98% NaCleqv。同时,研究也发现了黄铁矿、萤石、重晶石、石英、菱铁矿、毒砂和鞍形白云石等热流体相关矿物组合,并在相应流体包裹体内发现了CO 2 、H 2 S和烃类气体等对白云岩具有溶蚀性的气体存在。综合以上测试成果,证实柯坪露头区白云岩地层内存在大规模的异常热流体活动,推断可能与盆地深部大规模岩浆热事件相关。研究揭示热流体活动产生了顺层溶蚀、冷缩裂缝、差异性溶蚀以及热流体再作用的大型溶塌等多种孔隙空间结构,孔隙类型主要为缝-洞复合型。揭示热流体溶蚀改造作用主要受构造裂缝和地层界面等因素控制,其对白云岩地层孔隙空间的改造主要表现为建设性与破坏性共存,研究区则以建设性为主。

... 邢凤存等,2011 ...

2013

0.0

杨圣彬, 刘军, 李慧莉, 张仲培, 李婧婧. 2013. 塔中北围斜区北东向走滑断裂特征及其控油作用. 石油与天然气地质, 34(6): 797-802.

[Yang S

, Liu

, Li H

, Zhang Z

, Li J

2013. Characteristics of the NE-trending strike-slip fault system and its control on oil accumulation in north peri-cline area of the Tazhong paleouplift. Oil & Gas Geology, 34(6): 797-802]

A series of strike-slip faults occurr in north peri-cline area of the Tazhong Uplift in the Tarim Basin.The structural styles include flower structure,parallel high-steep fault,en-echelon structure etc.In the Middle Caledonian, the Tazhong-Ⅰ fault and the southern boundary fault were most active,and the NE-trending tear faults were formed because of the differential movement of NW-trending overthrust nappe or sliding block.In the Late Caledonian,the Tazhong uplift experienced strong oblique compression from the SE direction,which was the dynamic mechanism for the formation of strike-slip faults.This resulted in right-lateral strike-slip on the basis of basement weak zone.NE-trending strike-slip faults were formed in the tectonic setting of intraplate transpressional nature,and were connected with the NW-trending thrust fault.In the Late Caledonian to Early Hercynian,faults were developed in inheritance along the Middle Caledonian tear faults,and were characterized by multistage activities.The strike-slip faults not only greatly modified carbonate reservoirs,but also controlled the development of structural trap in the Paleozoic clasitc rocks.In addition,they also acted as important pathways of hydrocarbon migration.

1. Exploration & Production Research Institute, SINOPEC, Beijing 100083, China; 2. Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China

塔里木盆地塔中北围斜区发育一系列北东走向的走滑断裂，主要发育花状构造、平行高陡断裂带、雁列构造等多种构造样式。加里东中期塔中Ⅰ号断裂、南缘断裂活动剧烈，北西向的逆掩岩片或滑动块体中由于差异运动而形成了北东走向的撕裂断层-调节断层。加里东末期塔中地区受到东南向强烈斜向挤压作用是走滑断裂形成的动力机制，在基底薄弱带的基础上，塔中地区发生了右旋走滑特征。在这种板内挤压转换构造背景下，形成了一些连接北西向逆冲断层的北东向走滑断裂。加里东晚期—海西早期断裂基本上沿着加里东中期的调节断层带的基础上继承发育，具有多期活动的特征。走滑断裂对碳酸盐岩储集层具有强烈的改造作用，还控制了古生界碎屑岩构造圈闭的发育，并作为重要的油气运移通道。

... 杨圣彬等,2013),热流体则主要来源于深部,而且这种热流体向上运移的过程中极易与其他地层流体(如残余地层水、蒸发岩层间热卤水)相混合,从而导致该期白云岩/石多变的地球化学特征 ...

2012

0.0

袁鑫鹏, 刘建波. 2012. 回流渗透模式白云岩研究历史与进展. 古地理学报, 14(2): 219-228.

[Yuan X

, Liu J

2012. Research history and progress on reflux seepage dolostone. Journal of Palaeogeography(Chinese Edition), 14(2): 219-228]

Reflux seepage dolostones were widely distributed in the geological records and considered to be potential high-quality reservoirs of applicable value.Recent studies on the reflux model of dolomitization highlight its advances and controversies.This paper briefly covers the research history and progress of the brine reflux model and its application.The source of magnesium，the fluid-flow mechanism and the ancient characteristics of rocks in this model are particularly summarized.Some new researches such as penesaline dolomitization by reflux seepage provide a new impetus to revisit the primary model.

1 School of Earth and Space Sciences，Peking University，Beijing 100871 2 Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education，Peking University,Beijing 100871 3 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu

回流渗透白云岩化是一类重要的白云岩化模式，其应用广泛，成岩储集性良好，具有重要的研究意义。近年来，国内外对回流渗透模式白云岩的研究不断深入，取得了许多新的进展。作者从回流渗透模式的研究历史出发，详细讨论了其发展和应用现状，总结了该模式下白云岩的Mg来源、水文模式和沉积岩石学特征，并着重讨论了中等盐度下的回流渗透白云岩化等新的研究和应用，指出大规模的回流渗透白云岩化作用可在中等盐度的条件下形成，其强度往往受控于海平面变化。

... 袁鑫鹏和刘建波,2012),沉积物在同生/准同生期已经白云石化,并能够较好地保留原始结构 ...

2013

0.0

张德民, 鲍志东, 潘文庆, 郝雁, 陈敏. 2013. 塔里木盆地下古生界白云岩类型及成因. 古地理学报, 15(5): 693-706.

[Zhang D

, Bao Z

, Pan W

, Hao

, Chen

2013. Type and origin of the Lower Paleozoic dolostones in Tarim Basin. Journal of Palaeogeography(Chinese Edition), 15(5): 693-706]

There was a huge exploration potential in the Lower Paleozoic dolostones of Tarim Basin. In a combination of former classification schemes and based on the analysis of tectonic evolution and sedimentary background, the Lower Paleozoic dolostone was classified into two types (penecontemporaneous dolostones and post-penecontemporaneous dolostones) according to its forming time. Furthermore, more detailed subtypes were divided through combining the data of cores, thin sections, cathodoluminescence(CL), scanning electron microscope(SEM) and stable isotopes (δ 13 , C and δ 18 , O). And penecontemporaneous dolostones could be divided into three subtypes, including penecontemporaneous dolostones in supratidal flat environments, penecontemporaneous dolostones in lagoons, and microbial dolostones. The former two subtypes were dolomitized by evaporating seawater in arid environment and complete dumbbell-like dolomite was firstly found in gypsum moldic pore, which expanded the existence area of the microbial dolomite. While post-penecontemporaneous dolostones could be divided into three subtypes: shallow burial dolostones, middle-deep burial dolostones and hydrothermal dolomites. Shallow burial dolostones were dolomitized by adjusting|pore water and infiltrating reflux of brine. Middle-deep burial dolostones were occurred in middle-deep burial. The hydrothermal dolomites|were dolomitized by hydrothermal fluids along faults/fractures.

1 College of Geosciences, China University of Petroleum(Beijing), Beijing 102249 2 State Key Laboratory for Petroleum Resource and Prospecting, China University of Petroleum(Beijing), Beijing 102249 3 Research Institute of Petroleum Exploration and Development, Tarim Oilfield Company, PetroChina, Korla 841000, Xinjiang 4 Sinopec Overseas Oil & Gas Ltd. , Beijing 100029

塔里木盆地下古生界白云岩勘探潜力巨大。在下古生界构造演化、沉积背景分析的基础上, 结合前人的白云岩分类方案, 首先根据形成时期将塔里木盆地下古生界白云岩分为准同生白云岩和准同生后白云岩两大类。在此基础上, 综合运用岩心、薄片、阴极发光、扫描电镜、碳氧稳定同位素资料, 对上述两类白云岩进一步细分。其中准同生白云岩, 可进一步分为云坪型准同生白云岩、潟湖型准同生白云岩与微生物白云岩, 云坪型、潟湖型准同生白云岩是在准同生阶段由蒸发泵白云化形成的；本次研究首次在膏模孔内发现完整哑铃状白云石, 拓宽了微生物白云岩的存在范围。准同生后白云岩包括浅埋藏白云岩、中—深埋藏白云岩和热液白云岩3类, 浅埋藏白云岩由调整白云化及渗透回流白云化形成；中—深埋藏白云岩主要为埋藏白云化的产物；热液白云岩由沿断裂或裂缝的热液白云化所形成。

... 张德民等,2013) ...

2010

0.0

张静, 罗平. 2010. 塔里木盆地奥陶系孔隙型白云岩储集层成因. 石油实验地质, 32(5): 470-474, 503

[Zhang

, Luo

2010. Genesis of Ordovician matrix-porosity dolomite reservoir in the Tarim Basin. Petroleum Geology and Experiment, 32(5): 470-474, 503]

There is a large quantity of deeply buried dolomite with well-developed matrix porosity in the Lower Ordovician of the Tarim Basin which can be quality reservoir.The development of this kind of dolomite is facies-controlled and the initial rock is grainstone of grain bank facies,according to the analyses of cores,thin sections and cathodeluminescence.The dolomite formed under burial condition which is the product of burial dolomitization,based on the study of petrology,trace element,degree of order and homogenization temperature of the dolomite.It is predicted from the trace element,rare earth element and Sr isotope that the dolomitizing fluid is modified seawater which may be related to Mg 2+ -bearing seawater in Cambrian evaporative platform.Permian volcanic activity is supposed to be the driving force of dolomitization over the entire platform and the burial dolomite in the Lower Ordovician formed by means of the replacement of overlying limestone by underlying Mg 2+ -bearing seawater in Cambrian evaporative platform through thermal convection.

State Key Laboratory of Enhanced Oil Recovery, Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China

塔里木盆地下奥陶统存在大量基质孔隙发育的深埋白云岩,是一类优质储层。岩心、薄片观察和阴极发光分析表明该类白云岩的发育具有明显的相控特征,以滩相颗粒灰岩为原岩。岩石学特征和微量元素、有序度及包裹体均一温度特征研究表明,该类白云岩形成于埋藏环境中,属埋藏白云石化作用的产物。由微量元素、稀土元素及锶同位素特征判断白云石化流体为受改造的海水,很可能与深部封存的蒸发台地相海水有关。推断塔里木盆地二叠纪大规模火山活动是台地相区白云石化作用的主要驱动机制,寒武系蒸发台地中富含镁离子的海水在广泛的热作用驱动下交代其上覆灰岩而形成白云岩。

... 张静和罗平,2010 ...

2008

0.0

... 赵文智等,2012),流体主要来自于蒸发海水、海水与大气水的混合水、地层封存海水、岩浆热液等(张学丰等,2008 ...

2012

0.0

赵文智, 沈安江, 胡素云, 潘文庆, 郑剑锋, 乔占峰. 2012. 塔里木盆地寒武—奥陶系白云岩储集层类型与分布特征. 岩石学报, 28(3): 758-768.

[Zhao W

, Shen A

, Hu S

, Pan W

, Zheng J

, Qiao Z

2012. Types and distributional features of Cambrian-Ordovician dolostone reservoirs in Tarim Basin, northwestern China. Acta Petrologica Sinica, 28(3): 758-768]

The Cambrian-Ordovician dolostones are important reservoirs for oil & gas accumulations in the Tarim Basin, northwestern China, four types of which are recognized: ① tidal flat dolostone or sabkha dolostone, which is dominated by dolomicrite with relatively well developed gypsum-dissolution and interbreccia porosities and was deposited in intertidal to supratidal evaporitic environments. The dolomite show linear correlation of MgO and CaO, low Mg/Ca ratios, high ∑REE with none to dull cathodoluminescene. 87 Sr/ 86 Sr ratios range from 0.7085~0.7100 and are slightly higher than those of the contemporaneous seawater. The reservoir occurs mainly in Middle-Lower Cambrian and is mainly controlled by sedimentary facies; ② evaporitic platform dolomite or seepage-reflux dolostone, which is characterized by reef mound and grainstone fabrics being selectively dolomitized with well developed moldic, gypsum-dissolved and intergranular porosities, shows the wide range of Mg/Ca values, δ 13 C and δ 18 O with the values of higher than 2 ‰ and -4 ‰, respectively, and bright red cathodoluminescene. The reservoir occurs mainly in the part of evaporitic platform or lagoon close to platform margin; ③ burial dolostone, composed of fine to coarse-crystalline dolomites with well developed inter-crystalline (dissolved) pores, shows relatively negative δ 18 O with a range from -5‰~-10‰ (PDB), higher 87 Sr/ 86 Sr ratios ranging from 0.7090 to 0.7110, and dark brown and purple cathodoluminescene. The development of this kind of reservoir was controlled mainly by diagenetic facies, however, tends to be related to the sedimentary facies, because platform margin and inner platform reef and shoal and other open systems with fractures are propitious to the burial dolomitization; ④ hydrothermal dolostone, characterized by crystallized dolomite modified by hydrothermal fluid and significantly negative δ 18 O values less than -9‰ (PDB), bright red cathodoluminescene, positive Eu abnormity of REE with homogenization temperatures of fluid inclusions 5 to 20℃ higher than the surrounding strata and irregularly developed enlarged intergranular pores and dissolved vugs and caverns. Hydrothermal dolostone is commonly accompanied by barite, fluorite, pyrite and other hydrothermal minerals. The reservoir occurs mainly along the deep-seated faults under the unconformities. The scale and distribution for the four types of dolostones are different, but they can be predicted using integrated methods. The distribution of burial and hydrothermal dolostones is constrained by both initial depositional facies and diagenetic fluid source. Sabkha dolostone or tidal flat dolostone are variable in scale but can be predicted with the reconstruction of sedimentary environment, diagenetic facies analysis and seismic inversion interpretation.

塔里木盆地寒武-奥陶系白云岩是台盆区最重要的储层之一,发育4种类型:①潮坪白云岩。以含膏泥晶白云岩为主,石膏溶孔及白云岩砾间孔发育,发育于潮间-潮上坪蒸发环境。白云石表现为MgO-CaO呈线性正相关、低Mg/Ca值及高∑REE值、锶同位素值分布在0.7085~0.7100之间,略高于同期海水值0.7090、阴极发光不发光或暗色光。储层分布主要受沉积相控制,发育于中下寒武统地层;②蒸发台地白云岩。以藻丘及颗粒灰岩选择性白云石化为特征,发育铸模孔、膏溶孔和残留粒间孔,白云石Mg/Ca值变化范围大、 δ 13 C、 δ 18 O值相对偏正、分别大于2‰和-4‰、阴极发光发较亮红光。储层主要发育于台内靠近台缘一侧;③埋藏白云岩。发育细晶、中晶及粗晶白云岩,以晶间孔及晶间溶孔为主, δ 18 O值偏负在-5‰~-10‰(PDB)之间, 87 Sr/ 86 Sr值相对较大,为0.7090~0.7110,阴极发光以发暗棕褐色、紫色光为主。埋藏白云岩储层发育主要受成岩相控制,但也表现出与沉积相具有相关性,这是因为物性好的台缘、台内礁滩体及有裂缝沟通构成的开放体系更有利于埋藏白云石化作用发生;④热液白云岩。以受热液改造的结晶白云岩为特征,往往伴生热液矿物,白云石 δ 18 O值异常偏负、一般小于-9‰(PDB)、阴极发光多发明亮红光、稀土元素标准化配分曲线中Eu出现正异常、出现高于地层背景值的异常高温包裹体;主要发育在具有上覆隔挡层的不整合面之下地层及大断裂发育带附近。上述四类白云岩在规模与分布上有不同,但都可预测。埋藏和热液白云岩规模较大,受原始沉积相带和成岩流体来源双重约束。潮坪和蒸发台地白云岩规模可变性较大,可由沉积环境重建,结合成岩相研究预测评价。

... 赵文智等,2012),流体主要来自于蒸发海水、海水与大气水的混合水、地层封存海水、岩浆热液等(张学丰等,2008 ...

2013

0.0

郑剑锋, 沈安江, 乔占峰, 倪新锋. 2013. 塔里木盆地下奥陶统蓬莱坝组白云岩成因及储集层主控因素分析: 以巴楚大班塔格剖面为例. 岩石学报, 29(9): 3223-3232.

[Zheng J

, Shen A

, Qiao Z

, Ni X

2013. Genesis of dolomite and main controlling factors of reservoir in Penglaiba Formation of Lower Ordovician, Tarim Basin: A case study of Dabantage outcrop in Bachu area. Acta Petrologica Sinica, 29(9): 3223-3232]

Dolomite reservoir is a potentially important exploration field in Cambrian-Lower Ordovician of Tarim Basin, but because of deeply buried and low exploration and research degree, the current understanding unable to meet the needs of the exploration, especially the main controlling factors and distribution rules of dolomite reservoir. This paper takes the dolomite reservoir in Penglaiba Formation of Dabantage outcrop in Bachu area as an example, measured 9 section, collected 195 samples and studied the characteristics of thin sections, physical properties and geochemistry systematically, and gets tow new understanding. Firstly, powder dolomite, fine dolomite, medium dolomite and coarse dolomite are the four dolomite types in research area, the dolomitization took place in the shallow-medium burial phase, the dolomitization fluid is mainly sea water, and some dolomites influenced by hydrothermal. The size of crystals is associated with the size of structure and pore space of protolith. Secondly, the distribution of pores has stratification and cyclicity, the pores mainly occur in the top of upward shallowing sequences, and their formation is relate to exposure. The main carrier of pores is fine-coarse dolomite, the pores are mainly from the pores of original rock or their readjustment, and just a few pores are from burial solution. It is different from conventional opinion which is pores are mainly formed by dolomitization, and this opinion is of a great significance for guiding the prediction of dolomite reservoir in Tarim Basin.

寒武系-下奥陶统白云岩是塔里木盆地非常重要的勘探接替领域,但由于白云岩埋藏深度大,勘探和研究程度低,目前的认识程度无法满足勘探的需求,尤其是白云岩储层成因和分布的认识。本文以巴楚地区大班塔格剖面蓬莱组白云岩的精细解剖为例,测制解剖剖面9条,采集样品195块,系统的开展了岩石薄片、物性及地球化学特征分析,取得了两个方面的新的认识。1)是塔里木盆地蓬莱坝组发育粉晶、细晶、中晶和粗晶四种白云岩,主要形成于早-中埋藏期与海源流体有关的白云石化作用中,局部受到热液改造,其晶粒大小与原岩结构的粗细及孔隙空间的大小有关,原岩结构粗,形成的白云石晶粒就粗,原岩孔隙空间大,白云石晶粒就大。2)是白云岩储层的分布具成层性和旋回性,孔隙发育段总体位于向上变浅旋回的顶部,与高频旋回的暴露面有关,其载体以细-粗晶白云岩为主,孔隙主体来自原岩孔隙的继承和再调整,少量来自埋藏(热液)溶蚀作用,而并不是传统观点所认为的白云石化作用建造孔隙,这一认识对塔里木盆地深层白云岩有效储层预测具重要的指导意义。

... 中成岩期已经形成(郑剑锋等,2013),而且埋藏环境相对封闭的成岩系统与白云石化作用需要大量流体通过的事实之间的矛盾(Warren,2000 ...

1960

0.0

... , 2011)、经过蒸发浓缩或改造的海水(Adams and Rhodes,1960 ...

1995

0.0

... 2)少量 ⁸⁷Sr/⁸⁶Sr 值明显低于当时海水值样品的存在,指示了贫 ⁸⁷Sr 幔源锶的混入(成岩蚀变和采样过程中的污染将导致 ⁸⁷Sr/⁸⁶Sr 值升高)(Banner,1995 ...

1988

0.0

... 对于研究区白云岩而言,其形成机制更可能与热对流有关( 图 9),特别是该套地层缺乏有效隔水夹层(如泥岩或蒸发岩)的先天条件,可使盆地内封存的海源地层水发生热对流或深循环(Bj#cod#x000f8 ...

2002

0.0

... 构造挤压和地形驱动水流的流动速率缓慢且活动时间较短(Buschkuehle and Machel,2002 ...

2001

0.0

... Cai et al ...

2006

0.0

1998

0.0

... 7092)相当(Denison et al ...

2010

0.0

... Diehl et al ...

2013

0.0

... Dong et al ...

... 而塔中地区由于基底走滑断裂以及海西晚期岩浆活动的影响(Dong et al ...

2012

0.0

... Ehrenberg et al ...

1989

0.0

... (Evans and Nunn,1989 ...

2006

0.0

... Fu et al ...

1984

0.0

... (Garven and Freeze,1984 ...

2006

0.0

... Gasparrini et al ...

2005

0.0

... Green and Mountjoy,2005 ...

2013

0.0

... Haeri-Ardakani et al ...

2011

0.0

... Hood et al ...

2000

0.0

... 由于晚寒武世研究区为一宽缓的陆表海台地,海平面长期处于较低位置,受东部台缘带阻隔以及盆地当时位于赤道附近(Huang et al ...

1988

0.0

... , 2014)、大气淡水与海水形成的混合水(Humphrey,1988 ...

2001

0.0

... Jiang et al ...

2002

0.0

... Jones et al ...

2006

0.0

... Katz et al ...

1985

0.0

... 说明这些基质白云岩多为交代成因,大部分碳均继承自原始灰岩(Land,1985),外部有机碳参与不明显 ...

2013

0.0

... Li et al ...

2000

0.0

... Machel,2000 ...

2004

0.0

... 质量平衡计算表明,大范围的白云石化作用以及块状白云岩的形成均需要较高的水岩比率(Machel,2004),因此反演白云石化流体特征是解决白云岩成因的关键之一 ...

1989

0.0

... (Machel and Anderson,1989)、#cod#x0201c ...

2008

0.0

... Machel and Buschkuehle,2008),影响范围有限 ...

1992

0.0

... 的分馏(Major et al ...

1997

0.0

... ¹³C值,且其O-C同位素具明显的协变性(Meyers et al ...

1998

0.0

... Morrow,1998)等 ...

1989

0.0

... 2 锶同位素特征由于锶同位素在地质历史时期的海水中具有长期独特的变化规律,加之它不像氧、碳同位素那样因温度、压力和微生物作用而分馏,因而成为近年来研究碳酸盐沉积和成岩作用最常用的手段之一(Palmer and Edmond,1989 ...

2001

0.0

... Qing et al ...

... 晚寒武世研究区为半局限台地相,海平面长期处于较低位置,台地内海水循环受限,大量中等盐度的海水在密度差以及海平面变化的驱动下发生回流(Qing et al ...

1992

0.0

... 国内外已有不少这类白云岩的实例,特别是受构造控制的热液白云岩中,许多具有高Sr同位素值的鞍形白云石均被认为是深部热流体流经了古老的碎屑岩地层或结晶基底后而富集 ⁸⁷Sr 的结果(Qing and Mountjoy,1992 ...

1994

0.0

... , 2013)、地层水以及来自深部的热液(Qing and Mountjoy,1994 ...

... 构造挤压水流模式(Qing and Mountjoy,1994 ...

1984

0.0

... 通常,白云石化流体可以是正常海水(Saller,1984 ...

2014

0.0

... Sena et al ...

1987

0.0

... 一是埋藏条件下较高的成岩温度,可导致白云石过度生长以及晶体曲面化(Sibley and Gregg,1987),从而形成大量细晶#cod#x02014 ...

1994

0.0

... Sun,1994 ...

1999

0.0

... PDB)范围内(Veizer et al ...

... )与Veizer等(1999)(Veizer et al ...

... Veizer et al ...

2000

0.0

... 中成岩期已经形成(郑剑锋等,2013),而且埋藏环境相对封闭的成岩系统与白云石化作用需要大量流体通过的事实之间的矛盾(Warren,2000 ...

1998

0.0

... 粗晶他形白云岩很可能是早期白云岩在埋藏阶段重结晶作用的结果(Wendte et al ...

1990

0.0

... 虽然这类海水并未达到膏岩沉淀的盐度,但近年来不少研究认为,这种经历了轻微蒸发作用的海水同样具备大规模白云石化的能力(Whitaker and Smart,1990 ...

1997

0.0

... Yao and Demicco,1997)以及#cod#x0201c ...