眼皮-眼球灰岩地球化学特征及其古环境意义——以川中地区茅一段为例  

Geochemical characteristics and their paleoenvironmental significance of eyelid-eyeball limestones: a case study of the first Member of Maokou Formation in central Sichuan Basin

作　　者：赵威 邵红梅[1,2] 洪淑新 焦玉国[1,2] 白雪晶 刘云苗[1,2] 葛志丹 ZHAO Wei;SHAO Hongmei;HONG Shuxin;JIAO Yuguo;BAI Xuejing;LIU Yunmiao;GE Zhidan(Daqing Oilfield Laboratory of CNPC Key Laboratory of Carbonate Reservoirs,Daqing 163000,China;Exploration and Development Research Institute,Daqing Oilfield Co.,Ltd.,PetroChina,Daqing 163000,China)

机构地区：[1]中国石油天然气集团有限公司碳酸盐岩储层重点实验室大庆油田研究分室,黑龙江大庆163000 [2]中国石油大庆油田有限责任公司勘探开发研究院,黑龙江大庆163000

出　　处：《断块油气田》2024年第3期478-486,共9页Fault-Block Oil & Gas Field

摘　　要：在岩心观察和岩石薄片鉴定基础上,对川中地区茅一段眼皮-眼球灰岩岩心样品进行常量元素、微量元素、碳氧同位素及稀土元素测试分析,探讨了眼皮、眼球灰岩2种岩相地球化学特征及其古环境意义。研究结果表明:1)眼皮灰岩泥质质量分数为10%~45%,而眼球灰岩小于10%。2)眼皮、眼球灰岩δ^(13)CPDB平均值分别为4.38‰,3.84‰,δ^(18)OPDB平均值分别为-5.39‰,-6.00‰,总稀土元素质量分数平均值分别为10.54,3.43μg/g;眼皮、眼球灰岩均呈Ce负异常、Eu正异常特征,且眼球灰岩异常程度更高。3)眼皮、眼球灰岩不同常量氧化物之间的质量分数相关性明显,眼皮灰岩相关系数为0.52~0.95(平均值0.69),而眼球灰岩为0.91~0.99(平均值0.96)。4)眼皮灰岩微量元素、总稀土元素及陆源元素质量分数均显著高于眼球灰岩,反映2种岩相原始沉积物组成存在差异,眼皮灰岩陆源物质输入更高。5)眼皮、眼球灰岩均沉积于干热气候下的高盐度海水缺氧环境,平均古水深相近,平均古水温分别为19.9,22.5℃;眼球灰岩沉积时期气候更炎热,古气候周期性变化是造成原始沉积物组成差异的主要因素。研究成果对深化四川盆地茅一段眼皮-眼球灰岩成因认识具有重要意义。Based on core observation and rock thin section identification,core samples of eyelid-eyeball limestones in the first Member of Maokou Formation are selected for major elements,trace elements,carbon and oxygen isotopes and rare earth element(REE)tests,and the geochemical characteristics and their paleoenvironmental significance of two lithofacies,eyelid and eyeball limestones in central Sichuan Basin are discussed.It is found that:(1)The mud mass fraction of eyelid limestone ranges from 10%to 45%,and that of the eyeball limestone is less than 10%.(2)The average values ofδ^(13)CPDB of eyelid and eyeball limestones are 4.38‰and 3.84‰respectively,the average values ofδ^(18)OPDB are-5.39‰and-6.00‰respectively,and the average of total w(REE)are 10.54 and 3.43μg/g respectively;Ce negative anomaly and Eu positive anomaly are found in both eyelid and eyeball limestones,and the anomaly degree of eyeball limestone is higher.(3)The mass fractions of different major oxygenated compounds are significantly correlated with each other.The correlation coefficient of eyelid limestone ranges from 0.52 to 0.95(mean value is 0.69)and that of eyeball limestone ranges from 0.91 to 0.99(mean value is 0.96).(4)The mass fraction of trace elements,w(REE)and terrigenous elements of eyelid limestone are significantly higher than those of eyeball limestone,reflecting differences of original sedimentary materials between the two lithofacies and the higher input of terrigenous material in eyelid limestone.(5)Both eyelid limestone and eyeball limestone were deposited in an anoxic environment of high salinity seawater under dry and hot climate,with similar average paleowater depth,and average paleowater temperatures are 19.9 and 22.5°C respectively.The climate was hotter during the eyeball limestone sedimentary period,and the periodic change of paleoclimate was the main factor of the difference in original sedimentary material.These research results are of great significance to the understanding of the understanding of eyelid-eyeball

关 键 词：眼皮-眼球灰岩 地球化学 古环境 茅一段 川中地区 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]