Abstract：The siliceous and dolomitic rocks of the Permian Fengcheng are the most significant oil source rocks in the Junggar Basin. However,there is a debate on the origin of dolomitic and siliceous rocks. Base on the core observation and geochemical analyses including major elements,trace elements and silica isotopes,a more detailed study was made on the origin of siliceous rock. The results indicate the SiO2 content of siliceous rocks ranges from 55.15% to 85.61%,which indicates the rocks are not purely siliceous and contain a relatively high content of salt minerals formed in an alkaline lake and minerals formed in hydrothermal fluids. The siliceous rock is mainly distributed around the hydrothermal vents and usually interbedded with dolomitic rocks. Boron is enriched in siliceous rock,ranging from 90×10-6 to 10 000×10-6 with an average of 680×10-6,which might be related to the searlesite and reflect an alkaline lake depositional environment the Sr/Ba of siliceous is larger than 1,and the Th/U and Sm/Nd values range from 0.62 to 2.06 and 0.20 to 0.24,respectively. REE distribution pattern of siliceous rock shows Eu negative anomaly and Ce negative anomaly or weak positive anomaly and significant enrichment in LREE. The δ30Si values range from 0.39‰ to 1.88‰. Trace elements and δ30Si values are different from typical hydrothermal siliceous origin. Both geological occurrence and geochemical characteristics of siliceous rocks indicate that the siliceous rocks of Members 2 and 3 of Fengcheng Formation are formed in an alkaline lacustrine involves hydrothermal activities. The formation of siliceous rock is controlled by many factors,such as the location of hydrothermal vents,the hydrothermal exhalative period and the temperature of each hydrothermal vents. During the hydrothermal exhalative period,the hydrothermal fluids mix with the alkali lake water to form the siliceous rocks that contain salt and dolomite. The sedimentary environment of siliceous rocks is a relatively closed environment with high salinity and alkaline reduction. During the intermittent stage between hydrothermal exhalative activity,the dolomite rocks containing salt minerals are the major products.
Gao Yuan,Wang Guo-Zhi,Li Na. Geochemical features and origin of siliceous rocks of the Permian Fengcheng Formation in the northwestern margin of Junggar Basin[J]. JOPC, 2019, 21(4): 647-660.
[1] 陈宝赟,李荣西,刘海青,张艳妮,刘淑文. 2014. 陕西南郑马元铅锌矿区灯影组白云岩地球化学特征. 矿物岩石地球化学通报, 33(2): 193-200. [Chen B Y,Li R X,Liu H Q,Zhang Y N,Liu S W.2014. Geochemical characteristics of Dengying dolomite in the Mayuan Lead-zinc Orefield,Nanzheng,Shaanxi.Bulletin of Mineralogy,Petrology and Geochemistry, 33(2): 193-200] [2] 常海亮,郑荣才,郭春利,文华国. 2016. 准噶尔盆地西北缘风城组喷流岩稀土元素地球化学特征. 地质论评, 62(3): 551-568. [Chang H L,Zheng R C,Guo C L,Wen H G.2016. Characteristics of rare earth elements of exhalative rock in Fengcheng Formation,northwestern margin of Junggar Basin. Georeview, 62(3): 551-568] [3] 邓碧平,刘显凡,朱建军,卢秋霞,赵普峰,楚亚婷,李春辉. 2014. 壳幔混染成矿机制的稀有气体同位素及硅同位素证据: 以滇西富碱斑岩型多金属矿区为例. 吉林大学学报(地球科学版), 44(6): 1856-1866. [Deng B P,Liu X F,Zhu J J,Lu Q X,Zhao P F,Chu Y T,Li C H.2014. Noble gas isotope and silicon isotope evidences of crust-mantle mixing ore-formation mechanism: Examplified by the Alkali-Rich porphyry polymetallic deposits in Western Yunnan,China. Journal of Jilin University: Earth Science Edition, 44(6): 1856-1868] [4] 冯建伟,戴俊生,嫣继华,黄立良,王军. 2009. 准噶尔盆地乌—夏前陆冲断带构造活动—沉积响应. 沉积学报, 27(3): 494-502. [Feng J W,Dai J S,Yan J H,Huang L L,Wang J.2009. Sedimentary response to Permian structural movements in Wuxia Foreland Thrust Belt of Junggar Basin.Acta Sedmentologica Sinica, 27(3): 494-502] [5] 冯有良,张义杰,王瑞菊,张光亚,吴卫安. 2011. 准噶尔盆地西北缘风城组白云岩成因及油气富集因素. 石油勘探与开发, 38(6): 685-692. [Feng Y L,Zhang Y J,Wang R J,Zhang G Y,Wu W A.2011. Dolomites genesis and hydrocarbon enrichment of the Fengcheng Formation in the northwestern margin of Junggar Basin. Petroleum Exploration and Development, 38(6): 685-692] [6] 付伟,周永章,杨志军,何俊国,张澄博,杨海生. 2004. 湘中南二叠系孤峰组硅质岩的成因属性及其地球动力学指示意义. 矿物岩石地球化学通报, 23(1): 292-300. [Fu W,Zhou Y Z,Yang Z J,He J G,Zhang C B,Yang H S.2004. Petrogenesis of the bedded chert from the Gufeng Formation and its implications to Early Permian geodynamic background in South China.Bulletin of Mineralogy,Petrology and Geochemistry, 23(1): 292-300] [7] 黄华,王国芝,王英军,龙国徽,陈园园. 2013. 江南造山带内二叠系硅质岩的地球化学特征及其地质意义. 矿物岩石地球化学通报, 32(5): 567-573. [Huang H,Wang G Z,Wang Y J,Long G H,Chen Y Y.2013. Geochemical characteristics of the Permian chert in the Jiangnan Orogenic Belt and its geological implications.Bulletin of Mineralogy,Petrology and Geochemistry, 32(5): 567-573] [8] 蒋宜勤,文华国,祁利琪,张锡新,李云. 2012. 准噶尔盆地乌尔禾地区二叠系风城组盐类矿物和成因分析. 矿物岩石, 32(2): 105-114. [Jiang Y Q,Wen H G,Qi L Q,Zhang X X,Li Y.2012. Salt minerals and their genesis of the Permian Fengcheng Formation in Urho Area,Junggar Basin. Mineral Petrology, 32(2): 105-114] [9] 林良彪,陈洪德,朱利东. 2010. 川东茅口组硅质岩地球化学特征及成因. 地质学报, 84(4): 500-507. [Lin L B,Chen H D,Zhu L D.2010. The origin and geochemical characteristics of Maokou Formation silicalites in the eastern Sichuan Basin.Acta Geologica Sinica, 84(4): 500-507] [10] 柳益群,焦鑫,李红,袁明生,Yang Wan,周小虎,梁浩,周鼎武,郑朝阳,孙芹,汪双双. 2011. 新疆三塘湖跃进沟二叠系地幔热液喷流型原生白云岩. 中国科学: 地球科学, 41(12): 1862-1871. [Liu Y Q,Jiao X,Li H,Yuan M S,Yang W,Zhou X H,Liang H,Zhou D W,Zheng C Y,Sun Q,Wang S S.2011. Primary dolostone formation related to mantle-originated exhalative hydrothermal activities,Permian Yuejingou section,Santanghu area,Xinjiang,NW China. Science China: Earth Science, 41(12): 1862-1871] [11] 刘英俊,曹励明,李兆麟. 1984. 元素地球化学. 北京: 科学出版社,422-428. [Liu Y J,Cao L M,Li Z L.1984. Geochemistry of Element. Beijing: Science Press,422-428] [12] 牛海青,陈世悦,张鹏,鄢继华. 2009. 准噶尔盆地乌—夏地区二叠系储集层特征及影响因素分析. 古地理学报, 11(4): 425-434. [Niu H Q,Chen S Y,Zhang P,Yan J H.2009. Analysis of the Perm ian reservoir characteristics and controlling factors inWuxia area,Junggar Basin. Journal of Palaeogeography(Chinese Edition), 11(4): 425-434] [13] 彭军,田景春,伊海生,夏文杰. 2000. 扬子板块东南大陆边缘晚前寒武纪热水沉积作用. 沉积学报, 18(1): 107-113. [Peng J,Tian J C,Yi H S,Xia W J.2000. The Late Precambrian hot water sedimentation of the southeast Yangtze Plate Continental margin. Acta Sedmentologica Sinica, 18(1): 107-113] [14] 秦志军,陈丽华,李玉文,王婷婷,曹剑. 2016. 准噶尔盆地玛湖凹陷下二叠统风城组碱湖古沉积背景. 新疆石油地质, 37(1): 1-6. [Qin Z J,Chen L H,Li Y W,Wang T T,Cao J.2016. Paleo-Sedimentary setting of the Lower Permian Fengcheng Alkali Lake in Mahu Sag,Junggar Basin. Xinjiang Petroleum Geology, 37(1): 1-6] [15] 孙玉善. 1994. 中国西部地区首次发现硅硼钠石. 石油与天然气地质, 15(3): 264-265. [Sun Y S.1994. First discovery of reedmergnerite in western China.Oil & Gas Geology, 15(3): 264-265] [16] 田云涛,冯庆来,李琴. 2007. 桂西南柳桥地区上二叠统大隆组层状硅质岩成因和沉积环境. 沉积学报, 25(5): 671-677. [Tian Y T,Feng Q L,Li Q.2007. The petrogenesis and sedimentary environment of the bedded cherts from Upper Permian Dalong Formation,Southwest Guangxi. Acta Sedmentologica Sinica, 25(5): 671-677] [17] 王津津,胡煜昭,韩润生. 2011. 贵州晴隆锑矿田微量元素地球化学特征及其对成矿流体的指示意义. 矿物学报, 31(3): 571-577. [Wang J J,Hu Y Z,Han R S.2011. Geochemical characteristics and its implications of trace elements in Qinglong antimony deposit,Guizhou Province,China. Acta Mineralogica Sinica, 31(3): 571-577] [18] 薛晶晶,孙靖,朱筱敏,刘巍,朱世发. 2012. 准噶尔盆地二叠系风城组白云岩储层特征及成因机理分析. 现代地质, 26(4): 755-761. [Xue J J,Sun J,Zhu X M,Liu W,Zhu S F.2012. Characteristics and formation mechanism for dolomite reservoir of Permian Fengcheng Formation in Junggar Basin. Geoscience, 26(4): 755-761] [19] 杨建民,张招崇. 1999. 硅质岩岩石化学研究方法及其在“镜铁山式”铁矿床中的应用. 岩石矿物学杂志, 18(2): 108-120. [Yang J M,Zhang Z C.1999. The petrochemical research method for silicalite and its application to the Jingtieshan Type iron desposits. Acta Petrologica Et Mineralogica, 18(2): 108-120] [20] 杨瑞东,张传林,罗新荣,田敬全,包亚范,宋果奇. 2006. 新疆库鲁克塔格地区早寒武世硅质岩地球化学特征及其意义. 地质学报, 80(4): 598-605. [Yang R D,Zhang C L,Luo X R,Tian J Q,Bao Y F,Song G Q.2006. Geochemical characteristics of Early Cambrian cherts in Quruqtagh,Xinjiang,West China. Acta Geologica Sinica, 80(4): 598-605] [21] 姚通,李厚民,杨秀清,李立兴,陈靖,张进友,刘明军. 2014. 辽冀地区条带状铁建造地球化学特征: Ⅱ.稀土元素特征. 岩石学报, 30(5): 1239-1252. [Yao T,Li H M,Yang X Q,Li L X,Chen J,Zhang J Y,Liu M J.2014. Geochemical characteristics of Banded Iron Formations in Liaoning-eastern Hebei area: Ⅱ. Characteristics of rare earth elements. Acta Petrologica Sinica, 30(5): 1239-1252] [22] 余宽宏,操应长,邱隆伟,孙沛沛,杨勇强,曲长胜,万敏. 2016. 噶尔盆地玛湖凹陷下二叠统风城组含碱层段韵律特征及成因. 古地理学报, 18(6): 1012-1027. [Yu K H,Cao Y C,Qiu L W,Sun P P,Yang Y Q,Qu C S, Wan M.2016. Characteristics of alkaline layer cycles and origin of the Lower Permian Fengcheng ormation in Mahu sag,Junggar Basin. Journal of Palaeogeography(Chinese Edition), 18(6): 1012-1027] [23] 张亚冠,杜远生,徐亚军,余文超,黄虎,焦良轩. 2015. 湘中震旦纪—寒武纪之交硅质岩地球化学特征及成因环境研究. 地质论评, 61(3): 499-510. [Zhang Y G,Du Y S,Xu Y J,Yu W C,Huang H,Jiao L X.2015. Geochemical characteristics of siliceous rocks during the transition from Sinian(Ediacaran) to Cambrian in Central Hunan and its implication for genesis and sedimentary environment. Geological Review, 61(3): 499-510] [24] 郑荣才,文华国,李云,常海亮. 2018. 甘肃酒西盆地青西凹陷下白垩统下沟组湖相喷流岩物质组分与结构构造. 古地理学报, 20(1): 1-17. [Zheng R C,Wen H G,Li Y,Chang H L.2018. Compositions and texture of lacustrine exhalative rocks from the Lower Cretaceous Xiagou Formation in Qingxi sag of Jiuxi Basin,Gansu. Journal of Palaeogeography(Chinese Edition), 20(1): 1-17] [25] 周洁,胡凯. 2008. 贵州遵义下寒武统黑色页岩镍钼多金属矿床的形态硫特征及成矿模式. 资源调查与环境, 29(2): 87-91. [Zhou J,Hu K.2008. Characteristics of sulphur species and ore genesismodel of Ni-Mo polymetallic deposit in the Lower Cambrian black shale in Zunyi,Guizhou Province. Resources Survey & Environment, 29(2): 87-91] [26] 周永章. 1990. 广西丹池盆地热水成因的硅质岩的沉积地球化学特征. 沉积学报, 8(3): 75-83. [Zhou Y Z.1990. Geochemical characteristics of siliceous rocks orig-inated from a fossi-hydrothermal system in the upper Devonian strata,Guangxi,South China. Acta Sedimentlogica Sinica,(3): 75-83] [27] 周永章,何俊国,杨志军,付伟,杨小强,张澄博,杨海生. 2004. 华南热水沉积硅质岩建造及其成矿效应. 地学前缘, 11(2): 373-377. [Zhou Y Z,He J G,Yang Z J,Fu W,Yang X Q,Zhang C B,Yang H S.2004. Hydrothermally sedimentary formations and related mineralization in South China. Earth Science Frontiers, 11(2): 373-377] [28] 朱世发,朱筱敏,刘英辉,陈相亦,王俊怀,王小军,马爱钰. 2014. 准噶尔盆地西北缘北东段下二叠统风城组白云质岩岩石学和岩石地球化学特征. 地质论评, 60(5): 1113-1122. [Zhu S F,Zhu X M,Liu Y H,Chen X Y,Wang J H,Wang X J,Ma A Y.2014. Petrological and geochemical features of dolomitic rocks in the Lower Permian Fengcheng Formation in Wuerhe-Xiazijie Area,Junggar Basin. Geological Review, 60(5): 1113-1122] [29] Bau M,Dulski P.1996. Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations,Transvaal Supergroup,South Africa. Precambrian Research, 79(1): 37-55. [30] Chen D Z,Qing H R.2006. Hydrothermal venting and basin evolution(Devonian,South China): Constraints from rare earth element geochemistry of chert. Sedimentary Geology, 183: 203-216. [31] Duarte C M,Prairie Y T,Montes C,Cole J J,Striegl R.2008. CO2 emissions from saline lakes: A global estimate of a surprisingly large flux.Journal of Geophysical Research Biogeosiciences,113(G4). [32] Herzig P M.1988. Hydrothermal silica chimney field in the Galapages Spreading Centerat 86W. Earth and Planet Science Letter, 89(1): 281-320. [33] Hesse R.1989. Silica diagenesis: Origin of inorganic and replacement cherts. Earth-Science Reviews, 26: 253-284. [34] Kametaka M,Takebe M,Nagai H.2005. Sedimentary environments of the Middle Permian phosphorite chert complex from the northeastern Yangtze platform,China;the Gufeng Formation: A continental shelf radiolarian chert.Sedimentary Geology, 174: 197-222. [35] Klinkhammer G P,Elderfield H,Edmond J M,Mitra A.1994. Geochemical implications of rare earth element patterns in hydrothermal fluids from mid-ocean ridges.Geochimica et Cosmochimica Acta, 58(23): 5105-5113. [36] Masao K,Masamichi T.2005. Sedimentary environments of the Middle Permian phosphorite-chert complex from the northeastern Yangtze platform,China;the Gufeng Formation: A continental shelf radiolarian chert. Sedimentary Geology, 174(3-4): 197-222. [37] Maxchig V,Gundlach H,Moller P.1982. Some geochemical indicators for discrimination between diagenetic and hydrothermal metalliferous ediments. Mar Geol, 50(3): 241-256. [38] Morad S, Felitsyn S.2001. Identification of primary Ce-anomaly signatures in fossil biogenic apatite: Implication for the Cambrian oceanic anoxia and phosphogenesis. Sedimentary Geology, 143(3-4): 259-264. [39] Murray R W, Buchholtz ten Bringk M R, Gerlach D C, Russ G P, Jones D.1992. Rare earth, major, and trace element composition of Monterey and DSDP chert and associated host sediment: Assessing the influence of chemical fractionation during diagenesis. Geochimica et Cosmochimica Acta, 56(7): 2657-2671. [40] Murray R W.1994. Chemical criteria to identify the depositional environment of chert: General principles and applications.Sedimentary Geology, 90(3-4): 213-232. [41] Qiu Z,Wang Q C.2011. Geochemical evidence for submarine hydrothermal origin of the Middle-Upper Permian chert in Laibin of Guangxi,China. Science in China: Earth Science, 54(7): 1011-1023. [42] Rona P A.1987. Criteria for recognition of hydrother malmineral deposits in ocean crus.Teconomic Geology, 73(2): 135-160. [43] Taylor S R,Mclennan S M.1985. The continental crust: Its composition and evolution.Oxford: Blackwell,1-328. [44] Yamamoto K.1987. Geochemical characteristics and depositional environments of cherts and associated rocks from the Franciscan and Shimanto Terranes. Sedimentary Geology, 52(1-2): 65-108. [45] Yao L B,Gao Z M,Yang Z S.2002. Origin of seleniferous cherts in Yutangba Se deposit,Southwest Enshi,Hubei Province. Science in China: Series D, 45(8): 741-754. [46] Zhou Y Z. Chown E H,Guha J.1994. Hydothermal origin of Precambrian bedded chertat Gusui,Guangdong,China: Petrologic and geochemical evidence. Sedimentology, 41(3): 605-619.
