扬子地台北缘震旦系灯影组地球化学特征及其对热水沉积暗示
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摘要
震旦系灯影组在扬子地台北缘广泛分布,其岩性主要为白云岩、硅质白云岩和少量硅质岩。为探讨灯影组沉积时期的氧化还原状态并对热水沉积作用的暗示,分析了白云岩、硅质白云岩和硅质岩的微量稀土元素特征。结果表明,这3类岩石均呈现负的Ce异常,其V/Cr>2、Ni/Co>5、V/(V+Ni)为0.6~0.84,表明灯影组沉积于弱氧化的浅水碳酸盐岩台地环境。另外,白云岩、硅质白云岩具有明显的正Eu异常、U/Th>1,与海水稀土元素分布特征相比,其Ce负异常和轻稀土亏损程度明显减弱。上述特征及前人对灯影组硅质岩的Si-O同位素温度的计算结果表明,灯影组沉积时期有海底热水的混合。晚元古代晚期震旦纪扬子北缘处于裂谷构造环境,在由裂谷活跃期向平静期演化的过程中,其表现形式也由活跃的火山活动转化为热水喷流事件。灯影组即是在扬子北缘裂谷演化相对平静时期沉积的一套浅水碳酸盐岩,混合了海底喷流热液。
The Sinian Dengying Formation is distributed extensively in northern margin of the Yangtze Platform. It is mainly composed of dolomite and siliceous dolomite with minor chert. In order to discuss the redox conditions of the paleo-sea water during its sedimentation period and their implications for hydrothermal sedimentation trace elements and rare earth elements( REE) of dolomite,siliceous dolomite,and chert of the Dengying Formation have been analyzed in this study.Results show that V/Cr and Ni/Co ratios of the dolomite,siliceous dolomite,and chert of the Dengying Formation are higher than 2 and 5,respectively,with V/( V+Ni) ratios varying from 0. 6 to 0. 84 and negative Ce anomalies,indicating that these rocks were deposited in a weakly oxidized shallow paleo-sea water carbonate platform environment at the time. In addition,dolomite and siliceous dolomite have obvious positive Eu anomalies and U/Th ratios of over 1. They have similar REE patterns to that of the sea water though their negative Ce anomalies and the depletion of LREE are relatively weak.The above characteristics together with the calculated temperatures of sea-water based on Si-O isotopic compositions of chert in the Dengying Formation by previous researchers imply that seafloor hydrothermal fluid was mixed in sea water in the sedimentation process of various rocks of the Dengying Formation. It is suggested that the northern margin of the Yangtze Platform was in a rift environment in the Sinian period of late Proterozoic era. The evolution from active stage to inactive stage of rifting was represented by the transformation from active volcanism to submarine hydrothermal sedimentation.The Dengying Formation,mainly composed of a series of shallow sea-water carbonates,was deposited in a mixture of seawater and submarine exhalative hydrothermal fluid in the inactive stage of rifting.
The Sinian Dengying Formation is distributed extensively in northern margin of the Yangtze Platform. It is mainly composed of dolomite and siliceous dolomite with minor chert. In order to discuss the redox conditions of the paleo-sea water during its sedimentation period and their implications for hydrothermal sedimentation trace elements and rare earth elements( REE) of dolomite,siliceous dolomite,and chert of the Dengying Formation have been analyzed in this study.Results show that V/Cr and Ni/Co ratios of the dolomite,siliceous dolomite,and chert of the Dengying Formation are higher than 2 and 5,respectively,with V/( V+Ni) ratios varying from 0. 6 to 0. 84 and negative Ce anomalies,indicating that these rocks were deposited in a weakly oxidized shallow paleo-sea water carbonate platform environment at the time. In addition,dolomite and siliceous dolomite have obvious positive Eu anomalies and U/Th ratios of over 1. They have similar REE patterns to that of the sea water though their negative Ce anomalies and the depletion of LREE are relatively weak.The above characteristics together with the calculated temperatures of sea-water based on Si-O isotopic compositions of chert in the Dengying Formation by previous researchers imply that seafloor hydrothermal fluid was mixed in sea water in the sedimentation process of various rocks of the Dengying Formation. It is suggested that the northern margin of the Yangtze Platform was in a rift environment in the Sinian period of late Proterozoic era. The evolution from active stage to inactive stage of rifting was represented by the transformation from active volcanism to submarine hydrothermal sedimentation.The Dengying Formation,mainly composed of a series of shallow sea-water carbonates,was deposited in a mixture of seawater and submarine exhalative hydrothermal fluid in the inactive stage of rifting.
引文
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Bostr9m K.1983.Genesis of ferromanganese deposits-diagnostic criteria for recent and old deposits.In:Rona P A,ed.Hydrothermal Process at Seafloors Spring Centers.Boston,MA:Springer,473-483
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Jiang S Y,Chen Y Q,Ling H F,Yang J H,Feng H Z,Ni P.2006.Trace-and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in lower Cambrian strata,Yangtze Platform,South China.Mineralium Deposita,41(5):453-467
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Kawabe I,Toriumi T,Ohta A,Miura N.1998.Monoisotopic REE abundances in seawater and the origin of seawater tetrad effect.Geochemical Journal,32(4):213-229
Klinkhammer G P,Elderfield H,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
Knoll A H.2003.Biomineralization and evolutionary history.Reviews in Mineralogy Geochemistry,54(1):329-356
Ling H F,Chen X,Li D,Wang D,Shields-Zhou G A,Zhu M Y.2013.Cerium anomaly variations in Ediacaran-earliest Cambrian carbonates from the Yangtze gorges area,South China:implications for oxygenation of coeval shallow seawater.Precambrian Research,225:110-127
Lipinski M,Warning B,Brumsack H J.2003.Trace metal signatures of Jurassic/Cretaceous black shales from the Norwegian shelf and the barents sea.Palaeogeography,Palaeoclimatology,Palaeoecology,190:459-475
Marchig V,Erzinger J,R9sch H.1987.Sediments from a hydrothermal field in the central valley of the Galapagos rift spreading center.Marine Geology,76:243-251
Mclennan S M.1989.Rare earth elements in sedimentary rocks:influence of provenance and sedimentary processes.Reviews in Mineralogy,21(8):169-200
Rimmer S M,Thompson J S,Goodnight S A,Robl T L.2004.Multiple controls on the preservation of organic matter in devonian-mississippian marine black shales:geochemical and petrographic evidence.Palaeogeography,Palaeoclimatology,Palaeoecology,215(1-2):125-154
Schr9der S,Grotzinger J.2007.Evidence for anoxia at the EdiacaranCambrian boundary:The record of redox-sensitive trace elements and rare earth elements in Oman.Journal of the Geological Society,164(1):175-187
Sverjensky D A.1984.Europium equilibria in aqueous solution.Earth Planetary Science Letters,67(1):70-78
Webb G E,Kamber B S.2000.Rare earth elements in Holocene reefal microbialites:a new shallow seawater proxy.Geochimica et Cosmochimica Acta,64(9):1557-1565
Zhang P,Hua H,Liu W G.2014.Isotopic and REE evidence for the paleoenvironmental evolution of the late Ediacaran Dengying section,Ningqiang of Shaanxi province,China.Precambrian Research,242:96-111
Zhou C M,Jiang S Y,Xiao S H,Chen Z,Yuan X L.2012.Rare earth elements and carbon isotope geochemistry of the Doushantuo Formation in South China:Implication for middle Ediacaran shallow marine redox conditions.China Science Bulletin,57(16):1998-2006
陈宝赟.2013.南郑马元铅锌矿矿床地球化学特征与矿床成因研究.硕士学位论文.西安:长安大学
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
陈旭,徐均涛,成汉钧,汪明洲,陈祥荣,许安东,邓占球,伍鸿基,邱金玉,戎嘉余.1990.论汉南古陆及大巴山隆起.地层学杂志,14(2):81-116
陈雅丽,储雪蕾,张兴亮,翟明国.2015.陕南镇巴地区灯影组白云岩的碳、硫同位素和微量元素指示:埃迪卡拉纪末期浅海的氧化还原环境.中国科学(D辑),45(7):963-981
丁振举,刘丛强,姚书振,周宗桂.2000.海底热液沉积物稀土元素组成及其意义.地质科技情报,19(1):27-30,34
侯满堂,王党国,邓胜波,杨宗让.2007.陕西马元地区铅锌矿地质特征及矿床类型.西北地质,40(1):42-60
胡修棉,王成善.2001.古海洋溶解氧研究方法综述.地球科学进展,16(1):65-71
江纳言,贾蓉芬,王子玉.1994.下扬子区二叠纪古地理和地球化学环境.北京:石油工业出版社
李耀西,宋礼生,周志强,杨景尧.1975.大巴山西段早古生代地层志.北京:地质出版社
刘淑文,石顺,李荣西,高云宝,刘玲芳,段立志,陈宝赟,张少妮.2013.扬子板块北缘马元铅锌矿床稀土元素地球化学研究,32(5):979-988
卢武长.1986.稳定同位素地球化学.成都:成都地质学院出版社
罗冰,杨跃明,罗文军,文龙,王文之,陈康.2015.川中古隆起灯影组储层发育控制因素及展布.石油学报,36(4):416-426
齐文,侯满堂,汪克明,杨宗让,王党国.2004.陕西南郑县马元一带发现大型层控型铅锌矿带.地质通报,23(11):1139-1142
陶洪祥,王全庆,李旭,何恢亚.1985.杨子地台北缘裂谷系构造初析.中国区域地质,(13):95-104
王中刚,于学元,赵振华.1989.稀土元素地球化学.北京:科学出版社
杨兴莲,朱茂炎,赵元龙,张俊明,郭庆军,李丙霞.2007.黔东前寒武纪-寒武纪转换时期微量元素地球化学特征研究.地质学报,81(10):1391-1397
叶俭.1992.四川盆地北缘下古生界的沉积相.西安:西北大学出版社
伊海生,彭军,夏文杰.1995.扬子东南大陆边缘晚前寒武纪古海洋演化的稀土元素记录.沉积学报,13(4):131-137
伊海生,林金辉,赵西西,周恳恳,李军鹏,黄华谷.2008.西藏高原沱沱河盆地渐新世-中新世湖相碳酸盐岩稀土元素地球化学特征与正铕异常成因初探.沉积学报,26(1):1-10
曾志刚.2011.海底热液地质学.北京:科学出版社,183-237
张国伟,于在平,董云鹏,姚安平.2000.秦岭区前寒武纪构造格局与演化问题探讨.岩石学报,16(1):11-21
张录易.1986.陕西宁强晚震旦世晚期高家山生物群的发现和初步研究.中国地质科学院西安地质矿产研究所所刊,(13):67-88
张同钢,储雪蕾,张启锐,冯连君,霍卫国.2004.扬子地台灯影组碳酸盐岩中的硫和碳同位素记录.岩石学报,20(3):717-724
张艳妮,李荣西,段立志,张少妮,朱瑞静,陈宝赟.2014.上扬子地块北缘灯影组硅质岩系硅、氧同位素特征及其成因.矿物岩石地球化学通报,33(4):452-456
Barrett T J,Jarvis I,Jarvis K E.1990.Rare earth element geochemistry of massive sulfides-sulfates and gossans on the Southern Explorer Ridge.Geology,18(7):583-586
Bau M.1991.Rare-earth element mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium.Chemical Geology,93(3-4):219-230
Bostr9m K.1983.Genesis of ferromanganese deposits-diagnostic criteria for recent and old deposits.In:Rona P A,ed.Hydrothermal Process at Seafloors Spring Centers.Boston,MA:Springer,473-483
Goldberg E D,Koide M,Schmitt R A,Smith R H.1963.Rare-earth distributions in the marine environment.Journal of Geophysical Research,68(14):4209-4217
Hatch J R,Leventhal J S.1992.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian(Missourian)Stark Shale Member of the Dennis Limestone,Wabaunsee County,Kansas,USA.Chemical Geology,99(1-3):65-82
Jiang S Y,Chen Y Q,Ling H F,Yang J H,Feng H Z,Ni P.2006.Trace-and rare-earth element geochemistry and Pb-Pb dating of black shales and intercalated Ni-Mo-PGE-Au sulfide ores in lower Cambrian strata,Yangtze Platform,South China.Mineralium Deposita,41(5):453-467
Jones B,Manning D A C.1994.Comparison of geochemical indices used for the interpretation of Palaeoredox conditions in ancient mudstones.Chemical Geology,111(1-4):111-129
Kawabe I,Toriumi T,Ohta A,Miura N.1998.Monoisotopic REE abundances in seawater and the origin of seawater tetrad effect.Geochemical Journal,32(4):213-229
Klinkhammer G P,Elderfield H,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
Knoll A H.2003.Biomineralization and evolutionary history.Reviews in Mineralogy Geochemistry,54(1):329-356
Ling H F,Chen X,Li D,Wang D,Shields-Zhou G A,Zhu M Y.2013.Cerium anomaly variations in Ediacaran-earliest Cambrian carbonates from the Yangtze gorges area,South China:implications for oxygenation of coeval shallow seawater.Precambrian Research,225:110-127
Lipinski M,Warning B,Brumsack H J.2003.Trace metal signatures of Jurassic/Cretaceous black shales from the Norwegian shelf and the barents sea.Palaeogeography,Palaeoclimatology,Palaeoecology,190:459-475
Marchig V,Erzinger J,R9sch H.1987.Sediments from a hydrothermal field in the central valley of the Galapagos rift spreading center.Marine Geology,76:243-251
Mclennan S M.1989.Rare earth elements in sedimentary rocks:influence of provenance and sedimentary processes.Reviews in Mineralogy,21(8):169-200
Rimmer S M,Thompson J S,Goodnight S A,Robl T L.2004.Multiple controls on the preservation of organic matter in devonian-mississippian marine black shales:geochemical and petrographic evidence.Palaeogeography,Palaeoclimatology,Palaeoecology,215(1-2):125-154
Schr9der S,Grotzinger J.2007.Evidence for anoxia at the EdiacaranCambrian boundary:The record of redox-sensitive trace elements and rare earth elements in Oman.Journal of the Geological Society,164(1):175-187
Sverjensky D A.1984.Europium equilibria in aqueous solution.Earth Planetary Science Letters,67(1):70-78
Webb G E,Kamber B S.2000.Rare earth elements in Holocene reefal microbialites:a new shallow seawater proxy.Geochimica et Cosmochimica Acta,64(9):1557-1565
Zhang P,Hua H,Liu W G.2014.Isotopic and REE evidence for the paleoenvironmental evolution of the late Ediacaran Dengying section,Ningqiang of Shaanxi province,China.Precambrian Research,242:96-111
Zhou C M,Jiang S Y,Xiao S H,Chen Z,Yuan X L.2012.Rare earth elements and carbon isotope geochemistry of the Doushantuo Formation in South China:Implication for middle Ediacaran shallow marine redox conditions.China Science Bulletin,57(16):1998-2006
陈宝赟.2013.南郑马元铅锌矿矿床地球化学特征与矿床成因研究.硕士学位论文.西安:长安大学
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
陈旭,徐均涛,成汉钧,汪明洲,陈祥荣,许安东,邓占球,伍鸿基,邱金玉,戎嘉余.1990.论汉南古陆及大巴山隆起.地层学杂志,14(2):81-116
陈雅丽,储雪蕾,张兴亮,翟明国.2015.陕南镇巴地区灯影组白云岩的碳、硫同位素和微量元素指示:埃迪卡拉纪末期浅海的氧化还原环境.中国科学(D辑),45(7):963-981
丁振举,刘丛强,姚书振,周宗桂.2000.海底热液沉积物稀土元素组成及其意义.地质科技情报,19(1):27-30,34
侯满堂,王党国,邓胜波,杨宗让.2007.陕西马元地区铅锌矿地质特征及矿床类型.西北地质,40(1):42-60
胡修棉,王成善.2001.古海洋溶解氧研究方法综述.地球科学进展,16(1):65-71
江纳言,贾蓉芬,王子玉.1994.下扬子区二叠纪古地理和地球化学环境.北京:石油工业出版社
李耀西,宋礼生,周志强,杨景尧.1975.大巴山西段早古生代地层志.北京:地质出版社
刘淑文,石顺,李荣西,高云宝,刘玲芳,段立志,陈宝赟,张少妮.2013.扬子板块北缘马元铅锌矿床稀土元素地球化学研究,32(5):979-988
卢武长.1986.稳定同位素地球化学.成都:成都地质学院出版社
罗冰,杨跃明,罗文军,文龙,王文之,陈康.2015.川中古隆起灯影组储层发育控制因素及展布.石油学报,36(4):416-426
齐文,侯满堂,汪克明,杨宗让,王党国.2004.陕西南郑县马元一带发现大型层控型铅锌矿带.地质通报,23(11):1139-1142
陶洪祥,王全庆,李旭,何恢亚.1985.杨子地台北缘裂谷系构造初析.中国区域地质,(13):95-104
王中刚,于学元,赵振华.1989.稀土元素地球化学.北京:科学出版社
杨兴莲,朱茂炎,赵元龙,张俊明,郭庆军,李丙霞.2007.黔东前寒武纪-寒武纪转换时期微量元素地球化学特征研究.地质学报,81(10):1391-1397
叶俭.1992.四川盆地北缘下古生界的沉积相.西安:西北大学出版社
伊海生,彭军,夏文杰.1995.扬子东南大陆边缘晚前寒武纪古海洋演化的稀土元素记录.沉积学报,13(4):131-137
伊海生,林金辉,赵西西,周恳恳,李军鹏,黄华谷.2008.西藏高原沱沱河盆地渐新世-中新世湖相碳酸盐岩稀土元素地球化学特征与正铕异常成因初探.沉积学报,26(1):1-10
曾志刚.2011.海底热液地质学.北京:科学出版社,183-237
张国伟,于在平,董云鹏,姚安平.2000.秦岭区前寒武纪构造格局与演化问题探讨.岩石学报,16(1):11-21
张录易.1986.陕西宁强晚震旦世晚期高家山生物群的发现和初步研究.中国地质科学院西安地质矿产研究所所刊,(13):67-88
张同钢,储雪蕾,张启锐,冯连君,霍卫国.2004.扬子地台灯影组碳酸盐岩中的硫和碳同位素记录.岩石学报,20(3):717-724
张艳妮,李荣西,段立志,张少妮,朱瑞静,陈宝赟.2014.上扬子地块北缘灯影组硅质岩系硅、氧同位素特征及其成因.矿物岩石地球化学通报,33(4):452-456