湘西北早寒武世热水活动对周缘沉积的影响  

Effect of Early Cambrian Hydrothermal Activities on the Peripheral Deposition in Northwestern Hunan

作　　者：段宸章 黄俨然[1,2] 罗满 高钧健 DUAN ChenZhang;HUANG YanRan;LUO Man;GAO JunJian(School of Earth Sciences and Spatial Information Engineering,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China;Hunan Provincial Key Laboratory of Shale Gas Resource Utilization,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China)

机构地区：[1]湖南科技大学地球科学与空间信息工程学院,湖南湘潭411201 [2]湖南科技大学页岩气资源利用湖南省重点实验室,湖南湘潭411201

出　　处：《沉积学报》2025年第2期467-480,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41603046);湖南省自然科学基金项目(2023JJ30231)。

摘　　要：【目的】湘西北早寒武世的热水活动对当时的沉积地层造成了巨大影响,但对周缘区域的具体影响和程度范围尚不清楚。【方法】运用总有机碳、X射线衍射、主微量元素等分析,对该地区的花页1井(HY1)、湘安1井(XA1)、湘吉1井(XJ1)下寒武统牛蹄塘组底部开展沉积地球化学特征对比研究。【结果】各井皆相对远离热水活动,热水沉积的贡献少,但地化指标仍显示黑色岩系兼具正常和热水沉积的特征。比较而言,XJ1所受影响最大,XA1基本不受影响,而HY1则介于两者之间,Co/Zn、La_(N)/Ce_(N)与ΣREE以及ΣLREE/ΣHREE是较好的热水活动示踪指标。Ba、Mo、Ni、U、V等元素在牛蹄塘组底部高度富集,强还原—硫化的沉积环境可能是富集的主要原因,有机质丰度在一定范围内与各元素的富集程度有较好的正相关关系。受热水活动影响依次减弱的XJ1、HY1与XA1在沉积地球化学特征上存在一定差异,XA1表现为更依赖深海内源远端碎屑的供给。【结论】热水活动提供了富含上述元素的物质基础,同时加强了周缘沉积环境的还原性,有利于元素及有机质的进一步富集,这种影响伴随距离的增大而逐渐衰减,然而元素含量本身的变化多样也导致了在热水沉积响应上相对模糊。[Objective]The hydrothermal activities during the Early Cambrian in northwest Hunan significantly influenced the sedimentary strata at that time.However,the specific influence of the hydrothermal activities on the surrounding area remains unclear.[Methods]Based on the analysis of total organic carbon(TOC),X-ray diffraction(XRD),major and trace elements,etc.,the differences in the sedimentary geochemistry at the bottom of lower Cambrian Niutitang Formation in wells Huanye 1(HY1),Xiangan 1(XA1),and Xiangji 1(XJ1)in northwestern Hunan were compared and analyzed[.Results]Research shows that combined with the sedimentary setting and structural characteristics of the early Cambrian,the specific influence and extent of hydrothermal activities on the peripheral sediments were systematically revealed.These wells were far from the hydrothermal activities,and the contribution from the hydrothermal activities is small.However,certain geochemical indicators suggest that there are both normal and hydrothermal deposition characteristics at the bottom of the Niutitang Formation black shales.XJ1 was the most affected by the hydrothermal activity,XA1 was practically unaffected,and HY1 was moderately affected.Co/Zn,La_(N)/Ce_(N),ΣREE,and ΣLREE/ΣHREE are indicators for showing hydrothermal activities.Ba,Mo,Ni,U and V are highly enriched in that stratum.The sedimentary environment of strong reducing or vulcanization may be the main factor for the enrichment of these elements.The abundance of organic matter within a certain range has a positive correlation with the enrichment degree of the different elements.XJ1,HY1 and XA1,which are affected by the hydrothermal activities in turn,differ in their response of sedimentary geochemistry characteristics.XJ1 in the deepsea basin is more dependent on the supply from the deep internal source of the remote debris.[Conclusions]The hydrothermal activities provide a material basis that is rich in these elements by the contrast in different wells.Furthermore,the hydrothermal activities strength

关 键 词：湘西北地区 牛蹄塘组 热水活动 黑色岩系 元素富集 氧化还原条件 

分 类 号：P618.13[天文地球—矿床学]