Geochemical characteristics and paleoceanic environment analysis of black shale in Doushantuo Formation in northeastern Sichuan Basin
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摘要:
下震旦统陡山沱组页岩是四川盆地震旦系成藏的主要烃源岩，是近年来海相古老地层天然气勘探的重点层位。根据川东北城口地区白包溪、柿坪两个剖面的46件样品的有机地球化学(总有机碳、岩石热解、干酪根碳同位素)和元素地球化学(主微量元素、稀土元素)特征，分析了陡二段和陡四段烃源岩的地球化学特征与沉积环境的变化情况。结果表明，该地区陡山沱组页岩有机质丰度高，总有机碳(TOC)含量在0.19 %~20.38 % (均值4.76 %)，有机质类型为Ⅰ型干酪根，成熟度已达到过成熟；黑色页岩较高的δEu异常值与异常富集V、Mn、Mo、Ba和U微量元素，揭示了该时期强烈的热液作用；稀土元素配分模式与氧化还原指标识别出川东北地区陡二段沉积时期水体在缺氧－贫氧－硫化的水体条件下反复波动，陡四段水体环境则由贫氧演变为缺氧－硫化环境，总体盆地环境水体连通性较强，沉积速率较高，上升流携带热液来源的营养元素造成了生产力的繁盛，促进了有机质页岩的形成。
Abstract:The shale in Doushantuo Formation is the main source rock of the Ediacaran in Sichuan Basin and the major hydrocarbon source layer of the ancient marine strata for natural gas exploration in recent years. Forty-six samples were collected from two outcrops(Baibaoxi and Shiping)in Chengkou county in northeastern Sichuan Basin.We analyzed the change of the sedimentary environment of the Member Ⅱ and Ⅳ of Doushantuo Formation in terms of their organic geochemical characteristics(total organic carbon, rock pyrolysis, kerogen carbon isotopes)and element geochemical characteristics(major elements, trace elements and rare earth elements).Results show that the shale of Doushantuo Formation in northeastern Sichuan Basin exhibit a high abundance of organic matter, with TOC content ranging from 0.19 % to 20.38 % (mean value is 4.76 %). The dominant type of organic matter is type Ⅰ kerogen, and it has reached over-maturity stage. High δEu anomalies and abnormally richness in V, Mn, Mo, Ba and U elements of the black shale revealed strong hydrothermal action during this period. The distribution pattern of rare earth elements and various redox indexes indicated that the redox fluctuates repeatedly under the conditions of anaerobic-anoxic-sulfidic environment during the depositional period of the Member Ⅱ. The water environment of Member Ⅳ changed from anoxic to anaerobic-sulfidic environment. In general, the water connectivity of the basin is strong, the depositional rate is relative high. The nutrients carried by upwelling from hydrothermal sources proliferate productivity, which promotes the formation of organic shale.
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图 3 川东北地区陡山沱组有机地球化学特征
Figure 3. Organic geochemical characteristics of Doushantuo Formation in the northeastern Sichuan Basin
图 4 震旦系陡山沱组页岩微量元素富集程度
Figure 4. Trace elements enrichment of source rocks in Doushantuo Formation
图 5 震旦系陡山沱组页岩黑色页岩PAAS标准化REE配分模式
Figure 5. PAAS-normalized REE patterns of Ediacaran black shale of Doushantuo Formation
图 8 陡山沱组页岩K2O/Al2O3和Ga/Rb交汇图
Figure 8. Crossplot of K2O/Al2O3 and Ga/Rb of shale in Doushantuo Formation
图 9 川东北地区震旦系陡山沱组水体局限性判识
Figure 9. Discrimination map for hydrographically restricted settings of the Edicaran Doushantuo Formation in northeastern Sichuan Basin
图 10 U、V含量与Th、Al含量之间的相关性分析
Figure 10. Correlation analysis between the content of U and V and content of Th and Al
图 11 川东北地区陡二段、陡四段时期古环境参数
Figure 11. Paleo-environmental parameters of the Member Ⅱ and Ⅳ of Doushantuo Formation in northeastern Sichuan Basin
图 12 川东北地区震旦系陡山沱组沉积时期有机质富集模式
Figure 12. Sedimentary models of Ediacaran Doushantuo Formation in northeastern Sichuan Basin
表 1 川东北地区震旦系陡山沱组水体氧化还原条件判识指标
Table 1. Criteria for identifying redox conditions in water bodies of Ediacaran Doushantuo Formation in northeastern Sichuan Basin
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[1] 魏国齐, 王志宏, 李剑, 等. 四川盆地震旦系、寒武系烃源岩特征、资源潜力与勘探方向[J]. 天然气地球科学, 2017, 28(1): 1-13. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201701001.htmWEI Guoqi, WANG Zhihong, LI Jian, et al. Characteristics of source rocks, resource potential and exploration direction of Sinian and Cambrian in Sichuan Basin[J]. Natural Gas Geoscience, 2017, 28(1): 1-13. https://www.cnki.com.cn/Article/CJFDTOTAL-TDKX201701001.htm [2] LI C, SHI W, CHENG M, et al. The redox structure of Ediacaran and early Cambrian Oceans and its controls[J]. Science Bulletin, 2020, 65(24): 2141-2149. doi: 10.1016/j.scib.2020.09.023 [3] XIAO D, CAO J, LUO B, et al. Neoproterozoic postglacial paleoenvironment and hydrocarbon potential: a review and new insights from the Doushantuo Formation Sichuan Basin, China[J]. Earth-Science Reviews, 2021, 212: 103453. doi: 10.1016/j.earscirev.2020.103453 [4] JIANG G Q, KENNEDY M J, CHRISTIE-BLICK N. Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates[J]. Nature, 2003, 426(6968): 822-826. doi: 10.1038/nature02201 [5] 朱光有, 赵坤, 李婷婷, 等. 中国华南陡山沱组烃源岩的形成机制与分布预测[J]. 地质学报, 2021, 95(8): 2553-2574. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE202108019.htmZHU Guangyou, ZHAO Kun, LI Tingting, et al. Formation mechanism and distribution prediction of source rocksin the Ediacaran Doushantuo Formation, South China[J]. Acta Geologica Sinica, 2021, 95(8): 2553-2574. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE202108019.htm [6] 张道亮, 杨帅杰, 王伟锋, 等. 川东北—鄂西地区下震旦统陡山沱组烃源岩特征及形成环境[J]. 石油实验地质, 2019, 41(6): 821-830. https://www.cnki.com.cn/Article/CJFDTOTAL-SYSD201906006.htmZHANG Daoliang, YANG Shuaijie, WANG Weifeng, et al. Source rock characteristics and depositional environment of Lower Sinian Doushantuo Formation in northeastern Sichuan and western Hubei[J]. Petroleum Geology & Experiment, 2019, 41(6): 821-830. https://www.cnki.com.cn/Article/CJFDTOTAL-SYSD201906006.htm [7] 王宁. 震旦系－寒武系页岩有机质生源和沉积环境的地球化学响应: 以上扬子区为例[D]. 北京: 中国石油大学(北京), 2020.WANG Ning. Geochemical response of biological source and sedimentary environment of Sinian-Cambrian shale [D]. Beijing: China University of Petroleum(Beijing), 2020. [8] 王文之, 肖文摇, 和源, 等. 四川盆地震旦系陡山沱组烃源岩地球化学特征与有机质富集机制[J]. 高校地质学报, 2019, 25(6): 860-870. https://www.cnki.com.cn/Article/CJFDTOTAL-GXDX201906006.htmWANG Wenzhi, XIAO Wenyao, HE Yuan, et al. Geochemical characteristics of the sinian Doushantuo Formation source rocks of the Sichuan Basin: implications for the organic matter accumulation[J]. Geological Journal of China Universities, 2019, 25(6): 860-870. https://www.cnki.com.cn/Article/CJFDTOTAL-GXDX201906006.htm [9] 王剑, 肖洒, 杜秋定, 等. 四川盆地东北部地区陡山沱组黑色页岩古海洋环境与有机质富集机制[J]. 天然气工业, 2023, 43(4): 76-92. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG202304017.htmWANG Jian, XIAO Sa, DU Qiuding, et al. Paleomarine environment and organic matter enrichment mechanism of Doushantuo black shale in the northeastern Sichuan Basin[J]. Natural Gas Industry, 2023, 43(4): 76-92. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG202304017.htm [10] 张旋. 鄂西地区及其邻区下震旦统陡山沱组黑色页岩特征研究[D]. 成都: 成都理工大学, 2013.ZHANG Xuan. The study of the features of the black shale of the lower sinian Doushantuo formation in western Hubei and adjacent area[D]. Chengdu: Chengdu University of Technology, 2013. [11] 汪正江, 汪泽成, 余谦, 等. 川东北新元古代克拉通裂陷的厘定及其深层油气意义[J]. 沉积与特提斯地质, 2021, 41(3): 361-375. https://www.cnki.com.cn/Article/CJFDTOTAL-TTSD202103001.htmWANG Zhengjiang, WANG Zecheng, YU Qian, et al. Reconfirmation of Neoproterozoic intra-cratonic rift in northeast Sichuan Basin and its significance of deep oil and gas[J]. Sedimentary Geology and Tethyan Geology, 2021, 41(3): 361-375. https://www.cnki.com.cn/Article/CJFDTOTAL-TTSD202103001.htm [12] 汪泽成, 刘静江, 姜华, 等. 中—上扬子地区震旦纪陡山沱组沉积期岩相古地理及勘探意义[J]. 石油勘探与开发, 2019, 46(1): 39-51. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201901004.htmWANG Zecheng, LIU Jingjiang, JIANG Hua, et al. Lithofacies paleogeography and exploration significance of Sinian Doushantuo depositional stage in the middle-Upper Yangtze Region, Sichuan Basin, SW China[J]. Petroleum Exploration and Development, 2019, 46(1): 39-51. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201901004.htm [13] 黄籍中. 干酪根的稳定碳同位素分类依据[J]. 地质地球化学, 1988, 16(3): 66-68. https://www.cnki.com.cn/Article/CJFDTOTAL-DZDQ198803016.htmHUANG Jizhong. Classification basis of stable carbon isotope of kerogen[J]. Geology-geochemistry, 1988, 16(3): 66-68. https://www.cnki.com.cn/Article/CJFDTOTAL-DZDQ198803016.htm [14] TAYLOR S R, MCLENNAN S M, MCCULLOCH M T. Geochemistry of loess, continental crustal composition and crustal model ages[J]. Geochimica et Cosmochimica Acta, 1983, 47(11): 1897-1905. doi: 10.1016/0016-7037(83)90206-5 [15] 李娟, 于炳松, 郭峰. 黔北地区下寒武统底部黑色页岩沉积环境条件与源区构造背景分析[J]. 沉积学报, 2013, 31(1): 20-31. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB201301004.htmLI Juan, YU Bingsong, GUO Feng. Depositional setting and tectonic background analysis on lower Cambrian black shales in the north of Guizhou Province[J]. Acta Sedimentologica Sinica, 2013, 31(1): 20-31. https://www.cnki.com.cn/Article/CJFDTOTAL-CJXB201301004.htm [16] ROSER B P, KORSCH R J. Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio[J]. The Journal of Geology, 1986, 94(5): 635-650. doi: 10.1086/629071 [17] HUANG B J, TIAN H, WILKINS R W T, et al. Geochemical characteristics, palaeoenvironment and formation model of Eocene organic-rich shales in the Beibuwan Basin, South China Sea[J]. Marine and Petroleum Geology, 2013, 48: 77-89. doi: 10.1016/j.marpetgeo.2013.07.012 [18] 王立成, 刘成林, 张华. 华南地块震旦纪晚期一早寒武世古大陆位置暨灯影组蒸发岩成钾条件分析[J]. 地球学报, 2013, 34(5): 585-593. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB201305010.htmWANG Licheng, LIU Chenglin, ZHANG Hua. Tectonic and sedimentary settings of evaporites in the Dengying formation, South China Block: implications for the potential of Potash formation[J]. Acta Geoscientica Sinica, 2013, 34(5): 585-593. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB201305010.htm [19] CHOI J H, HARIYA Y. Geochemistry and depositional environment of Mn oxide deposits in the Tokoro Belt, northeastern Hokkaido, Japan[J]. Economic Geology, 1992, 87(5): 1265-1274. doi: 10.2113/gsecongeo.87.5.1265 [20] DOUVILLE E, BIENVENU P, CHARLOU J L, et al. Yttrium and rare earth elements in fluids from various deep-sea hydrothermal systems[J]. Geochimica et Cosmochimica Acta, 1999, 63(5): 627-643. doi: 10.1016/S0016-7037(99)00024-1 [21] LIU Q Y, ZHU D Y, JIN Z J, et al. Influence of volcanic activities on redox chemistry changes linked to the enhancement of the ancient Sinian source rocks in the Yangtze craton[J]. Precambrian Research, 2019, 327: 1-13. doi: 10.1016/j.precamres.2019.02.017 [22] NESBITT H W, YOUNG G M, MCLENNAN S M, et al. Effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments, with implications for provenance studies[J]. Journal of Geology, 1996, 104(5): 525-542. doi: 10.1086/629850 [23] ZHANG S H, LI H Y, JIANG G Q, et al. New paleomagnetic results from the Ediacaran Doushantuo Formation in South China and their paleogeographic implications[J]. Precambrian Research, 2015, 259: 130-142. doi: 10.1016/j.precamres.2014.09.018 [24] TENGER, LIU W H, XU Y C, et al. Comprehensive geochemical identification of highly evolved marine hydrocarbon source rocks: organic matter, paleoenvironment and development of effective hydrocarbon source rocks[J]. Chinese Journal of Geochemistry, 2006, 25(4): 333-340. doi: 10.1007/s11631-006-0332-4 [25] ALGEO T J, TRIBOVILLARD N. Environmental analysis of paleoceanographic systems based on molybdenum-uranium covariation[J]. Chemical Geology, 2009, 268(3/4): 211-225. [26] TRIBOVILLARD N, ALGEO T J, BAUDIN F, et al. Analysis of marine environmental conditions based onmolybdenum-uranium covariation—applications to Mesozoic paleoceanography[J]. Chemical Geology, 2012, 324/325: 46-58. doi: 10.1016/j.chemgeo.2011.09.009 [27] SWEERE T, VAN DEN BOORN S, DICKSON A J, et al. Definition of new trace-metal proxies for the controls on organic matter enrichment in marine sediments based on Mn, Co, Mo and Cd concentrations[J]. Chemical Geology, 2016, 441: 235-245. doi: 10.1016/j.chemgeo.2016.08.028 [28] JONES B, MANNING D A C. Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones[J]. Chemical Geology, 1994, 111(1/2/3/4): 111-129. [29] MURRAY R W. Chemical criteria to identify the depositional environment of chert: general principles and applications[J]. Sedimentary Geology, 1994, 90(3): 213-232. [30] WINDLEY B F. The continental crust: its composition and evolution[J]. Physics of the Earth and Planetary Interiors, 1986, 42(3): 196-197. doi: 10.1016/0031-9201(86)90093-2 [31] JIANG G Q, KAUFMAN A J, CHRISTIE-BLICK N, et al. Carbon isotope variability across the Ediacaran Yangtze platform in South China: implications for a large surface-to-deep ocean δ13C gradient[J]. Earth and Planetary Science Letters, 2007, 261(1/2): 303-320. [32] 杨爱华, 朱茂炎, 张俊明, 等. 扬子板块埃迪卡拉系(震旦系)陡山沱组层序地层划分与对比[J]. 古地理学报, 2015, 17(1): 1-20. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201501001.htmYANG Aihua, ZHU Maoyan, ZHANG Junming, et al. Sequence stratigraphic subdivision and correlation of the Ediacaran(Sinian)Doushantuo Formation of Yangtze Plate, South China[J]. Journal of Palaeogeography, 2015, 17(1): 1-20. https://www.cnki.com.cn/Article/CJFDTOTAL-GDLX201501001.htm [33] 李智武, 冉波, 肖斌, 等. 四川盆地北缘震旦纪—早寒武世隆-坳格局及其油气勘探意义[J]. 地学前缘, 2019, 26(1): 59-85. https://www.cnki.com.cn/Article/CJFDTOTAL-DXQY201901008.htmLI Zhiwu, RAN Bo, XIAO Bin, et al. Sinian to Early Cambrian uplift-depression framework along the northern margin of the Sichuan Basin, central China and its implications for hydrocarbon exploration[J]. Earth Science Frontiers, 2019, 26(1): 59-85. https://www.cnki.com.cn/Article/CJFDTOTAL-DXQY201901008.htm -
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