下扬子地区中上二叠系泥页岩元素分布特征及指示意义  

Distribution Characteristics and Indicative Significance of Elements in Middle-Upper Permian Shale in Lower Yangtze Region

作　　者：张启燕 葛天助 刘晓 高卿楠 史维鑫 ZHANG Qi-yan;GE Tian-zhu;LIU Xiao;GAO Qing-nan;SHI Wei-xin(Cores and Samples Center of Natural Resources,China Geological Survey,Beijing 100083,China)

机构地区：[1]自然资源实物地质资料中心,北京100083

出　　处：《科学技术与工程》2025年第4期1349-1358,共10页Science Technology and Engineering

基　　金：中国地质调查局地质调查项目(DD20230601);科技基础资源调查专项(2022FY101802)。

摘　　要：下扬子地区中上二叠统泥页岩是区域重要的烃源岩,但以往对于其不同沉积相的元素特征研究还有所欠缺。本次对下扬子地区港地1井中上二叠系泥页岩岩心进行连续X射线荧光分析(X-ray fluorescence,XRF)元素扫描,分析中上二叠系地层Si、Al、Ca、Fe等主量元素和Sr、Rb、Ti等微量元素含量及其比值的变化规律,并结合样品矿物成分分析,讨论沉积环境演化特征。结果显示:垂向上对陆源沉积具有较强指示意义的Al、Ti、Si、Rb等元素具有较高-高-低的变化规律,而指示海相沉积的Ca、Sr等元素主要集中在上部的大隆组,其他层位含量较低。元素比值具有一定规律,其中Rb/Sr、Ba/Sr呈现低-高-低的变化趋势,Al/(Al+Fe+Mn)比值最大值为0.8,最小值为0.4,平均值为0.71,普遍大于0.6,指示生物成因为重要的来源。中上二叠统整体属于过渡相-海相的还原环境,从下而上沉积环境从深水盆地相-深水陆棚相-海陆过渡相-浅水陆棚相变化,期间水体从较深-较浅-较深的整体变化趋势。其中孤峰组初期为深水盆地相,随后逐步进入到深水陆棚相,龙潭组以海陆过渡相为主。沉积时期相对海平面变化比较频繁,深水期岩性以自沉积的灰岩为主,对应元素Ca含量较高,浅水期则主要为浅灰色泥页岩沉积,对应的主要元素则变化为Si、Al。而大隆组海平面发生短期沉降之后水体逐步加深,以陆棚沉积为主。The shale of Middle-Upper Permian in the Lower Yangtze area is an important source rock in the region,but the research on the elemental characteristics of different sedimentary facies is still lacking in the past.Continuous X-ray fluorescence(XRF)element scanning was performed on the shale core of the Middle-Upper Permian in Well Gangdi 1 in the Lower Yangtze Region.The contents of main elements such as Si,Al,Ca,Fe and trace elements such as Sr,Rb,Ti and their ratios in the middle and upper Permian strata were analyzed,and the evolution characteristics of sedimentary environment were discussed in combination with the quantitative analysis of mineral composition of samples.The results show that the elements such as Al,Ti,Si and Rb,which have strong indicative significance for terrestrial deposition,have a high-high-low variation in the vertical direction.The Ca,Sr and other elements indicating marine deposits are mainly concentrated in the upper Dalong Formation,and the content of other layers is low,and there are abnormal values in some areas.The ratio of element content has a certain rule,among which Rb/Sr and Ba/Sr show a low-high-low trend.The maximum value of Al/(Al+Fe+Mn)ratio is 0.8,the minimum value is 0.4,and the average value is 0.71,which is generally greater than 0.6,indicating an important source of biogenesis.The Middle-Upper Permian belongs to the transitional-marine reduction environment.From bottom to top,the sedimentary environment changes from deep-water basin facies to deep-water shelf facies to sea-land transition facies to shallow-water shelf facies.During this period,the water body changes from deep-shallow-deep.Among them,the early stage of the Gufeng Formation is the deep-water basin phase,and then gradually enters the deep-water shelf phase.The Longtan Formation is dominated by the sea-land transition phase,and the relative sea level changes frequently during the sedimentary period.In the deep-water period,the lithology is dominated by self-deposited limestone,and the corresponding elemen

关 键 词：沉积环境 X射线荧光分析(XRF) 元素分布 中上二叠系 下扬子地区 

分 类 号：P534.46[天文地球—古生物学与地层学]