Origin of dolomite in Middle Permian Qixia Formation in northwestern Sichuan Basin: a case study of Chejiaba section
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摘要: 以岩石学观察为基础,结合稳定同位素与团簇同位素分析,探讨了川西北地区中二叠统栖霞组白云岩形成机理。川西北车家坝剖面白云岩集中发育于栖霞组上段,可识别出基质白云石与白云石胶结物2种不同类型的白云石。基质白云岩呈灰白色,与灰岩接触界线截然,呈指状交错接触;白云石胶结物呈乳白色,局限分布于溶蚀孔洞的边缘。镜下可进一步划分为3种类型基质白云石,即漂浮状细晶直面自形—半自形基质白云石(Md1)、细—中晶直面自形—半自形基质白云石(Md2)、中—粗晶它形曲面基质白云石(Md3),以及一种鞍形白云石胶结物(Sd)。Md1沿缝合线呈漂浮状分布于灰泥基质中,可能为浅埋藏环境下压溶作用的产物。Md2与Md3具有与宿主灰岩相似的δ13C、δ18O和87Sr/86Sr同位素特征,指示白云石化流体主要来源于二叠纪同期海水,而相对较高的成岩温度说明受二叠纪末大规模火山活动的影响显著。鞍形白云石及其后的方解石胶结物具有明显偏负的δ18O值和放射性87Sr/86Sr值,说明它们形成于高温外源富放射性锶的白云石化流体中,可能为来自或穿过碎屑岩地层的深部热流体。川西北地区栖霞组白云岩的形成受原始沉积相与断裂活动的双重控制,热流体的注入使原始滩相地层发生白云石化作用,形成大量溶洞与晶间溶孔,对储层的改造起到了积极的建设性作用。Abstract: This study focuses on the origin of dolomite within the Middle Permian Qixia Formation in the northwestern Sichuan Basin by the approaches of petrographic examination and stable isotopic as well as clumped isotopic analysis. Two types of dolomite (matrix dolomite and dolomite cement) in the upper part of the Qixia Formation at the Chejiaba (CJB) section were classified. The gray matrix dolomite shows a clear inter-finger contact with limestone, while the milky white dolomite cement lines the edges of dissolved pores. Microscopic examination revealed three types of matrix dolomite including floating fine crystalline, planar-e(s) matrix dolomite (Md1); fine to medium crystalline, planar-e(s) matrix dolomite (Md2); and medium to coarse crystalline, planar-a matrix dolomite (Md3), along with saddle dolomite cement (Sd). The presence of Md1 dolomites along stylolites suggests they were formed due to pressure dissolution during shallow burial. The similar isotopic signatures of Md2 and Md3 with the host limestone indicate that the dolomitizing fluids likely originated from Permian seawater. However, elevated diagenetic temperatures suggest an influence from the Late Permian volcanic activity. The Sd dolomite and subsequent calcite cementation with negative δ18O values and radioactive 87Sr/86Sr ratios point to formation in high-temperature, externally-derived, radio-genic strontium-rich dolomitizing fluids, possibly from deep-seated thermal fluids within siliciclastic strata. The formation of dolomite in the Qixia Formation of the northwestern Sichuan Basin was influenced by both original sedimentary facies and faulting activities. The influx of hydrothermal fluids triggered widespread dolomitization, resulting in the creation of numerous dissolved and inter-crystalline pores, which played a beneficial role in reservoir development.
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Key words:
- hydrothermal fluid /
- stable isotope /
- clumped isotope /
- dolomite /
- Qixia Formation /
- middle Permian /
- northwestern Sichuan Basin
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图 1 川西北地区地质背景
a.车家坝剖面大地构造位置(改自邓小亮等[17]);b.车家坝剖面地层柱状图。
Figure 1. Geological settings of northwestern Sichuan Basin
图 2 川西北地区K2井埋藏热史及古热流趋势
红色为栖霞组;据DONG等[11]。
Figure 2. Burial history and paleoheat flow distribution of well K2 in northwestern Sichuan Basin
图 3 川西北地区车家坝剖面栖霞组下段宿主灰岩岩石学特征
a.灰色中层粒泥灰岩与深灰色泥灰岩互层;b.泥灰岩中生物定向性排列;c.粒泥灰岩中单体珊瑚原始结构保存良好,被沥青浸染的微裂缝发育;d.粒泥灰岩镜下特征,单偏光;e.泥灰岩中生屑定向性排列,微裂缝与缝合线大量发育并被沥青充填,正交偏光;f.生屑颗粒中世代方解石胶结物,并被缝合线切割,正交偏光;g.生屑颗粒丰富,颗粒间灰泥支撑,灰泥基质与生屑颗粒发极暗红色光;h.泥灰岩阴极发光特征与粒泥灰岩相似,发极暗红色光。
Figure 3. Petrology characteristics of host limestone in lower part of Qixia Formation, Chejiaba section, northwestern Sichuan Basin
图 4 川西北地区车家坝剖面栖霞组Md1白云石宏、微观特征
a.灰岩与白云岩呈指状交错接触,局部含有残留的原始灰岩(黄色圈);b.孔洞被沥青与鞍形白云石充填(黄色箭头);c.Md1间呈点—线接触或漂浮状分布,雾心亮边特征明显,正交偏光;d.为图c中的红框放大部位,Md1沿缝合线发育,正交偏光;e.自形程度相对较差的Md1晶体间呈晶簇状分布,单偏光;f.Md1发环带状红光。
Figure 4. Macro- and microscopic characteristics of Md1 dolomite of Qixia Formation in Chejiaba section, northwestern Sichuan Basin
图 6 川西北地区车家坝剖面栖霞组Md3与缝洞充填物(Sd与Cc)的岩石学特征
a.Md3晶面弯曲、浑浊,晶体间呈镶嵌状接触,溶蚀孔发育,单偏光;b.Md3具明显波状消光特征,正交偏光;c.溶蚀孔洞被鞍形白云石与方解石完全充填,鞍形白云石被沥青浸染,单偏光;d.图c的正交偏光特征;e.Md3、Sd与Cc共生关系,单偏光;f.Sd发红光,Cc不发光,Md3发暗红光—不发光。
Figure 6. Petrographic characteristics of Md3 dolomite and subsequent fracture and vug fillings (Sd and Cc) of Qixia Formation in Chejiaba section, northwestern Sichuan Basin
表 1 川西北地区车家坝剖面与K2井栖霞组不同类型碳酸盐岩地球化学分析测试结果
Table 1. Geochemical analytical results of different types of carbonates from Qixia Formation in Chejiaba section and well K2, northwestern Sichuan Basin
样品号 测试类型 δ13CVPDB/‰ δ18OVPDB/‰ Δ47/‰ TΔ47 /℃ 87Sr/86Sr CJB-01 宿主灰岩 2.89 -5.02 CJB-17 宿主灰岩 2.84 -4.66 CJB-48 宿主灰岩 2.97 -8.25 0.595 7 52.3 0.707 6 CJB-60 宿主灰岩 0.57 -7.87 0.593 3 53.0 0.707 5 CJB-105 宿主灰岩 2.49 -7.45 CJB-60 Md1 1.45 -8.20 CJB-105 Md1 3.14 -4.77 0.707 2 CJB-67 Md2 2.81 -7.18 0.549 9 65.5 0.707 6 CJB-72 Md2 2.79 -7.71 CJB-56 Md2 2.52 -7.84 0.707 5 CJB-97 Md2 2.69 -6.69 CJB-87 Md2 2.68 -6.66 0.562 5 61.7 0.707 4 CJB-58 Md3 2.70 -6.39 CJB-76 Md3 2.46 -7.80 0.707 5 CJB-80 Md3 2.58 -6.72 0.707 4 CJB-92 Md3 2.30 -6.78 0.515 3 76.6 0.707 4 CJB-99 Md3 2.79 -7.11 K2-22 Sd 1.01 -16.35 0.709 8 K2-11 Sd 1.03 -14.18 0.709 7 CJB-59 Cc -1.71 -11.55 0.708 9 CJB-92 Cc -5.48 -15.49 0.569 2 59.7 0.708 7 注:K2-22、K2-11鞍形白云石数据来源于PAN等[30]。 -
[1] WARREN J. Dolomite: occurrence, evolution and economically important associations[J]. Earth-Science Reviews, 2000, 52(1/3): 1-81. [2] HARDIE L A. Dolomitization; a critical view of some current views[J]. Journal of Sedimentary Research, 1987, 57(1): 166-183. doi: 10.1306/212F8AD5-2B24-11D7-8648000102C1865D [3] JINGHWA HSÜ K. Chapter 4 chemistry of dolomite formation[J]. Developments in Sedimentology, 1967, 9: 169-191. [4] LAND L S. Failure to precipitate dolomite at 25 ℃ from dilute solution despite 1000-fold oversaturation after 32 years[J]. Aquatic Geochemistry, 1998, 4(3): 361-368. [5] FAIRBRIDGE R W. The dolomite question[M]//LE BLANC R J, BREEDING J G. Regional aspects of carbonate deposition. Tulsa: SEPM, 1957, 5: 125-178. [6] 董翼昕. 四川盆地中二叠统白云岩成因机理研究[D]. 成都: 成都理工大学, 2020.DONG Yixin. Genetic mechanism of the Middle Permian dolomite in the Sichuan Basin[D]. Chengdu: Chengdu University of Technology, 2020. [7] 胡安平, 潘立银, 郝毅, 等. 四川盆地二叠系栖霞组、茅口组白云岩储层特征、成因和分布[J]. 海相油气地质, 2018, 23(2): 39-52. https://www.cnki.com.cn/Article/CJFDTOTAL-HXYQ201802006.htmHU Anping, PAN Liyin, HAO Yi, et al. Origin, characteristics and distribution of dolostone reservoir in Qixia Formation and Maokou Formation, Sichuan Basin, China[J]. Marine Origin Petroleum Geology, 2018, 23(2): 39-52. https://www.cnki.com.cn/Article/CJFDTOTAL-HXYQ201802006.htm [8] 张荫本. 四川盆地二迭系中的白云岩化[J]. 石油学报, 1982, 3(1): 29-33. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB198201006.htmZHANG Yinben. Dolomitization in Permian rocks in Sichuan Basin[J]. Acta Petrolei Sinica, 1982, 3(1): 29-33. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB198201006.htm [9] 何幼斌, 冯增昭. 四川盆地及其周缘下二叠统细—粗晶自云岩成因探讨[J]. 江汉石油学院学报, 1996, 18(4): 15-20. https://www.cnki.com.cn/Article/CJFDTOTAL-JHSX604.002.htmHE Youbin, FENG Zengzhao. Origin of fine- to coarse-grained dolostones of Lower Permian in Sichuan Basin and its peripheral regions[J]. Journal of Jianghan Petroleum Institute, 1996, 18(4): 15-20. https://www.cnki.com.cn/Article/CJFDTOTAL-JHSX604.002.htm [10] 金振奎, 冯增昭. 滇东—川西下二叠统白云岩的形成机理: 玄武岩淋滤白云化[J]. 沉积学报, 1999, 17(3): 383-389. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB199903007.htmJIN Zhenkui, FENG Zengzhao. Origin of dolostones of the Lower Permian in East Yunnan-West Sichuan: dolomitization through leaching of basalts[J]. Acta Sedimentologica Sinica, 1999, 17(3): 383-389. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB199903007.htm [11] DONG Yixin, CHEN Hongde, WANG Jiuyuan, et al. Thermal convection dolomitization induced by the Emeishan Large Igneous Province[J]. Marine and Petroleum Geology, 2020, 116: 104308. [12] LI Pingping, ZOU Huayao, HAO Fang, et al. Using clumped isotopes to determine the origin of the Middle Permian Qixia Formation dolostone, NW Sichuan Basin, China[J]. Marine and Petroleum Geology, 2020, 122: 104660. [13] LIN Pan, PENG Jun, ZHANG Lianjin, et al. Characteristics of multiple dolomitizing fluids and the genetic mechanism of dolomite formation in the Permian Qixia Formation, NW Sichuan Basin[J]. Journal of Petroleum Science and Engineering, 2022, 208: 109749. [14] QUAN Li, WANG Guangwei, ZHANG Ya, et al. Early dolomitization and subsequent hydrothermal modification of the Middle Permian Qixia Formation carbonate in the northwest Sichuan Basin[J]. Geoenergy Science and Engineering, 2023, 221: 211384. [15] XU Wenli, ZHOU Gang, WAN Cixuan, et al. Geochemical characteristics and fluid properties of the Qixia Formation dolomites of the Middle Permian in the Shuangyushi block, NW Sichuan Basin, China[J]. Frontiers in Earth Science, 2022, 10: 904932. [16] 何登发, 李德生, 张国伟, 等. 四川多旋回叠合盆地的形成与演化[J]. 地质科学, 2011, 46(3): 589-606. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKX201103001.htmHE Dengfa, LI Desheng, ZHANG Guowei, et al. Formation and evolution of multi-cycle superposed Sichuan Basin, China[J]. Chinese Journal of Geology, 2011, 46(3): 589-606. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKX201103001.htm [17] 邓小亮, 林良彪, 余瑜, 等. 川西北剑阁地区栖霞组地球化学特征及古环境意义[J]. 成都理工大学学报(自然科学版), 2020, 47(2): 198-209. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG202002008.htmDENG Xiaoliang, LIN Liangbiao, YU Yu, et al. Geochemical characteristics and palaeoenvironmental significance of Qixia Formation in Jiange area, Sichuan, China[J]. Journal of Chengdu University of Technology (Science & Technology Edition), 2020, 47(2): 198-209. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG202002008.htm [18] 袁庆东, 李本亮, 刘海涛, 等. 川西北地区构造演化阶段及岩相古地理[J]. 大庆石油学院学报, 2010, 34(6): 42-52. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSY201006010.htmYUAN Qingdong, LI Benliang, LIU Haitao, et al. The tectonics evolution and lithofacies palaeogeography in the northwest of the Sichuan Basin[J]. Journal of Daqing Petroleum Institute, 2010, 34(6): 42-52. https://www.cnki.com.cn/Article/CJFDTOTAL-DQSY201006010.htm [19] 韦恒叶, 陈代钊. 鄂西—湘西北地区二叠纪栖霞期岩相古地理[J]. 古地理学报, 2011, 13(5): 551-562. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201105015.htmWEI Hengye, CHEN Daizhao. Lithofacies palaeogeography of the Qixia Age of Permian in western Hubei-northwestern Hunan provinces[J]. Journal of Palaeogeography, 2011, 13(5): 551-562. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201105015.htm [20] YAN Jiaxin, CARLSON E H. Nodular celestite in the Chihsia Formation (Middle Permian) of South China[J]. Sedimentology, 2003, 50(2): 265-278. [21] WEI Hengye, CHEN Daizhao, WANG Jianguo, et al. Organic accumulation in the Lower Chihsia Formation (Middle Permian) of South China: constraints from pyrite morphology and multiple geochemical proxies[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2012, 353-355: 73-86. [22] JERRAM D A, WIDDOWSON M, WIGNALL P B, et al. Submarine palaeoenvironments during Emeishan flood basalt volcanism, SW China: implications for plume-lithosphere interaction during the Capitanian, Middle Permian ('end Guadalupian') extinction event[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016, 441: 65-73. [23] 朱传庆, 徐明, 袁玉松, 等. 峨眉山玄武岩喷发在四川盆地的地热学响应[J]. 科学通报, 2010, 55(6): 474-482. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB201006016.htmZHU Chuanqing, XU Ming, YUAN Yusong, et al. Palaeogeothermal response and record of the effusing of Emeishan basalts in the Sichuan Basin[J]. Chinese Science Bulletin, 2010, 55(10): 949-956. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB201006016.htm [24] 康玉柱, 王宗秀, 李会军, 等. 四川盆地构造体系控油作用研究[M]. 北京: 地质出版社, 2012: 12-44.KANG Yuzhu, WANG Zongxiu, LI Huijun, et al. The study on oil control of tectonic system in Sichuan Basin[M]. Beijing: Geology Press, 2012: 12-44. [25] 王旭, 崔琳琳, 翟吉璇, 等. 陆生蜗牛壳体碳酸盐团簇同位素组成及其古气候意义[J]. 第四纪研究, 2021, 41(4): 893-902. https://www.cnki.com.cn/Article/CJFDTOTAL-DSJJ202104002.htmWANG Xu, CUI Linlin, ZHAI Jixuan, et al. Clumped isotopes in land snail shell carbonate and its significance for paleoclimate study[J]. Quaternary Sciences, 2021, 41(4): 893-902. https://www.cnki.com.cn/Article/CJFDTOTAL-DSJJ202104002.htm [26] 岳姣姣, 肖举乐, 王旭, 等. 湖泊自生碳酸盐团簇同位素分析与区域古温度定量重建: 以内蒙古达里湖为例[J]. 中国科学(地球科学), 2021, 51(3): 411-425. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK202103007.htmYUE Jiaojiao, XIAO Jule, WANG Xu, et al. Clumped isotope analysis of lacustrine endogenic carbonates and implications for paleo-temperature reconstruction: a case study from Dali Lake[J]. Science China Earth Sciences, 2021, 64(2): 294-306. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK202103007.htm [27] DENNIS K J, AFFEK H P, PASSEY B H, et al. Defining an absolute reference frame for 'clumped' isotope studies of CO2[J]. Geochimica et Cosmochimica Acta, 2011, 75(22): 7117-7131. [28] 王丹, 陈代钊, 杨长春, 等. 埋藏环境白云石结构类型[J]. 沉积学报, 2010, 28(1): 17-25. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB201001004.htmWANG Dan, CHEN Daizhao, YANG Changchun, et al. Classification of texture in burial dolomite[J]. Acta Sedimentologica Sinica, 2010, 28(1): 17-25. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB201001004.htm [29] SIBLEY D F, GREGG J M. Classification of dolomite rock textures[J]. Journal of sedimentary Research, 1987, 57(6): 967-975. [30] PAN Liyin, SHEN Anjiang, ZHAO Jianxin, et al. LA-ICP-MS U-Pb geochronology and clumped isotope constraints on the formation and evolution of an ancient dolomite reservoir: the Middle Permian of northwest Sichuan Basin (SW China)[J]. Sedimentary Geology, 2020, 407: 105728. [31] BUGGISCH W, WANG Xiangdong, ALEKSEEV A S, et al. Carboniferous-Permian carbon isotope stratigraphy of successions from China (Yangtze platform), USA (Kansas) and Russia (Moscow Basin and Urals)[J]. Palaegeography, Palaeoclimatology, Palaeoecology, 2011, 301(1/4): 18-38. [32] KORTE C, JASPER T, KOZUR H W, et al. δ18O and δ13C of Permian brachiopods: a record of seawater evolution and continental glaciation[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2005, 224(4): 333-351. [33] VEIZER J, ALA D, AZMY K, et al. 87Sr/86Sr, δ13C and δ18O evolution of Phanerozoic seawater[J]. Chemical Geology, 1999, 161(1/3): 59-88. [34] MACHEL H G. Concepts and models of dolomitization: a critical reappraisal[J]. Geological Society, London, Special Publications, 2004, 235(1): 7-63. [35] COMPTON J, HARRIS C, THOMPSON S. Pleistocene dolomite from the Namibian Shelf: high 87Sr/86Sr and δ18O values indicate an evaporative, mixed-water origin[J]. Journal of Sedimentary Research, 2001, 71(5): 800-808. [36] 黄思静. 碳酸盐岩的成岩作用[M]. 北京: 地质出版社, 2010.HUANG Sijing. Carbonate diagenesis[M]. Beijing: Geology Press, 2010. [37] BANNER J L, KAUFMAN J. The isotopic record of ocean chemistry and diagenesis preserved in non-luminescent brachiopods from Mississippian carbonate rocks, Illinois and Missouri[J]. Geological Society of America Bulletin, 1994, 106(8): 1074-1082. [38] 王一刚, 余晓锋, 杨雨, 等. 流体包裹体在建立四川盆地古地温剖面研究中的应用[J]. 地球科学(中国地质大学学报), 1998, 23(3): 69-72. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX803.016.htmWANG Yigang, YU Xiaofeng, YANG Yu, et al. Applications of fluid inclusions in the study of paleo-geotemperature in Sichuan Basin[J]. Earth Science(Journal of China University of Geosciences), 1998, 23(3): 69-72. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX803.016.htm [39] HENKES G A, PASSEY B H, GROSSMAN E L, et al. Temperature limits for preservation of primary calcite clumped isotope paleotemperatures[J]. Geochimica et Cosmochimica Acta, 2014, 139: 362-382. [40] 韩月卿, 张军涛, 何治亮, 等. 川西中二叠统栖霞组白云岩特征与成因[J]. 石油与天然气地质, 2023, 44(1): 75-88. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202301006.htmHAN Yueqing, ZHANG Juntao, HE Zhiliang, et al. Characteristics and genesis of the Middle Permian Qixia Formation dolostone in western Sichuan Basin[J]. Oil & Gas Geology, 2023, 44(1): 75-88. https://www.cnki.com.cn/Article/CJFDTOTAL-SYYT202301006.htm [41] 刘树根, 罗志立, 庞家黎, 等. 四川盆地西部的峨眉地裂运动及找气新领域[J]. 成都地质学院学报, 1991, 18(1): 83-90. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199101015.htmLIU Shugen, LUO Zhili, PANG Jiali, et al. The Emei taphrogenesis and the new regions for searching gas in the western part of Sichuan Basin[J]. Journal of Chengdu College of Geology, 1991, 18(1): 83-90. https://www.cnki.com.cn/Article/CJFDTOTAL-CDLG199101015.htm [42] DONG Shaofeng, CHEN Daizhao, ZHOU Xiqiang, et al. Tectonically driven dolomitization of Cambrian to Lower Ordovician carbonates of the Quruqtagh area, north-eastern flank of Tarim Basin, north-west China[J]. Sedimentology, 2017, 64(4): 1079-1106. [43] KOESHIDAYATULLAH A, CORLETT H, STACEY J, et al. Origin and evolution of fault-controlled hydrothermal dolomitization fronts: a new insight[J]. Earth and Planetary Science Letters, 2020, 541: 116291.