云南兰坪—思茅盆地江城勐野井钾盐矿床SHK4孔含盐系粘土矿物特征及其成钾环境指示意义

SHK4孔揭示了晚白垩世含盐系勐野井组(K2me)地层, 根据岩性特征将该孔划分为三个粘土矿物单元, 依次反映了从淡化期到成盐期再到淡化期的转换过程。单元Ⅰ粘土矿物主要为伊利石(70.6%)和高岭石(26.7%), 以及极少量的绿泥石(2.7%)。处于高盐度环境下的单元Ⅱ沉积物粘土矿物主要为伊利石(53.6%)和绿泥石(46.4%)。而这一时期物源区面积的急剧减小在一定程度上改变了粘土矿物的输入类型。单元Ⅲ的粘土矿物主要为伊利石(44.5%)、绿泥石(41.8%)和高岭石(10.7%)。另外粘土矿物组合与沉积过程中的卤水演化程度有着良好的对应关系, 表明富K、Mg的高盐度环境对粘土矿物的形成转化应具有一定的制约作用。考虑到含盐系地层发育时研究区的地质构造背景, 以及SHK4孔伊利石结晶度(平均0.35°Δ2θ)与化学指数(>0.5)的特征, 认为埋藏成岩作用对SHK4孔粘土矿物的形成也具有一定程度的影响。     

可可西里盐湖表层沉积物中粘土矿物的环境信息

通过对可可西里盐湖表层沉积物中粘土矿物的研究,以期获得近年来湖区的某些环境信息.研究结果表明:沉积物中的粘土矿物主要为伊利石和绿泥石,非粘土矿物主要为石英、方解石和长石以及少量白云石、文石、闪石和石膏等.样品中＜2μm的粘土矿物以伊利石和绿泥石为主,局部样品含少量有序伊/蒙混层.根据样品分布特点和粘土矿物的组合类型,将样品划分为3个区域:1区和3区的矿物组合为伊利石、绿泥石和有序伊/蒙混层;2区为伊利石和绿泥石,无伊像混层矿物.其中1区和3区样品的结晶度(IC)范围为0.41～0.59,均值为0.51;2区样品的结晶度范围为0.25～0.40,均值为0.34,明显低于1区和3区,说明2区样品中的伊利石具有更高的结晶度.样品的伊利石化学指数(CI)均小于0.5,表明该伊利石为富Fe-Mg伊利石,主要是物理风化作用的结果.伊利石和绿泥石作为主要粘土矿物反映了近年来整个湖区的环境以干冷为主,局部区域(1区和3区)出现的少量有序I/S混层矿物则指示在短期内曾经历过短暂的干湿交替环境.此外,在酸性介质条件下,少量伊利石发生弱水解作用导致晶格中的K+淋失,并转化为伊/蒙混层矿物,同时也降低了伊利石的结晶度.     

西昆仑山前陆盆地粘土矿物特征及其地质意义

为重建西昆仑山地区晚新生代的地质构造及环境演变过程,本文利用X射线衍射（XRD）及扫描电子显微分析（SEM）方法,对西昆仑山前陆盆地（叶城盆地）该时期沉积的一套磨拉石建造中的粘土矿物进行了研究。结果表明,在整个晚中新世到早更新世的沉积物地层中,粘土矿物的种类始终以伊利石和蒙脱石为主,含少量的绿泥石和高岭石。但伊利石、蒙脱石、高岭石的相对含量,以及伊利石结晶度值等均显示出明显的变化。在8~3.5 Ma B.P.期间,伊利石相对含量值和结晶度值均比较高,而蒙脱石相对含量低,并有少量的高岭石产出;在3.5~3.3 Ma B.P.期间,伊利石相对含量值和伊利石结晶度值均急剧降低,而相反,蒙脱石相对含量值急剧升高,高岭石基本消失;3.3~2.8 Ma B.P.期间沉积物的粘土矿物参数与8~3.5 Ma B.P.时期的粘土矿物参数非常接近;而2.8~1.8 Ma B.P.期间沉积物的粘土矿物参数则与3.5~3.3 Ma B.P.期间的粘土矿物参数相类似。根据沉积物中的粘土矿物特征变化规律可以推断,物源区母岩成分的变化是粘土矿物特征变化的主要原因,古气候古环境变化则是次要影响因素。粘土矿物特征的变化规律显示西昆仑山体在晚新生代具有不均匀的阶段性隆升的特点,在3.5 Ma B.P.、3.3 Ma B.P.、2.8 Ma B.P.左右分别发生了三次明显的构造隆升事件,而且总伴随着风化母岩成分的变化。物源区在早更新世中期（12.5 Ma B.P.)很可能处于干旱的古气候古环境中。     

粘土矿物研究在塔里木盆地石油勘探中的应用

以塔里木盆地粘土矿物的分布特征及其组合形式、演化与形成机理为依据,探讨了粘土矿物在地层划分对比中的应用及其与有机质热演化、成岩阶段的关系和对储层物性的影响。研究表明,在侏罗系和白垩系两个不同古环境中形成的粘土矿物及其组合特征,为地层对比提供了一定的证据。泥岩中伊利石／蒙皂石间层中蒙皂石含量的纵向变化与有机质热演化及成岩阶段的关系不大。对储层物性影响不大但有利于储集性能的是以高岭石为主的粘土矿物组合类型及粘土矿物的早期自生（伊利石／蒙皂石间层矿物）衬垫式以及非自生（伊利石）衬垫式产状。     

风成三趾马红土与第四纪黄土的粘土矿物组成异同及其环境意义

文章基于X射线衍射、热分析和理化分析,对西峰三趾马红土的粘土矿物组成进行较系统研究,并与上覆第四纪黄土和古土壤样品进行对比.结果表明,二者的粘土矿物类型相似,以伊利石为主,其次是绿泥石、蒙脱石和高岭石; 但伊利石结晶度明显低于第四纪黄土,而与发育较好的第四纪古土壤(如S4和S5)相当; 三趾马红土中的粘土矿物组成主要为碎屑成因,成壤作用只对伊利石结晶度有明显影响.根据现代土壤粘土矿物地带性分布规律,三趾马红土的粘土矿物组合指示了大约6Ma以来,我国北方黄土高原地区一直处于温带半湿润-半干润的环境条件下,以后的气候主要在此范围内波动.但伊利石结晶度的变化指示了晚中新世-上新世总体比第四纪较高的风化成壤强度,体现了较强的夏季风效应.     

广西东攀剖面二叠系顶部粘土矿物特征及古气候意义

对广西东攀剖面二叠系顶部20个样品中的粘土矿物进行X射线衍射分析。伊利石结晶度值显示这些样品形成于中晚成岩带的地质环境;伊利石、蒙脱石纵向分布规律和伊利石结晶度与伊利石含量的关系表明伊利石除陆源碎屑来源外,可能有部分为蒙脱石伊利石化而成;伊利石结晶度变化曲线和伊蒙混层类型的变化规律表明,本区粘土矿物组合与含量的变化除受到后期成岩作用的影响外,还明显地受沉积因素的控制;伊利石结晶度、伊利石化学指数、高岭石和伊利石的含量、伊蒙混层类型显示东攀剖面以9、10层界线上方5cm为界,古气候由干冷变为湿暖;水介质由偏碱性向酸性转变。     

柴西地区第三系发育平行层面缝岩石的粘土矿物特征

柴西地区第三系地层中多发育平行层面缝,通过岩心及荧光显微镜观察并借助扫描电子显微镜(SEM)和X射线衍射仪(XRD),确定了柴西地区第三系发育平行层面缝岩石自上而下存在2种粘土矿物组合:伊/蒙间层+伊利石+绿泥石+(高岭石)→伊利石+绿泥石+伊/蒙间层+绿/蒙间层+(高岭石),粘土矿物占全岩矿物比例介于7%～27%之间,粘土矿物吸附并保存了有机质,这是异常高压、强还原环境、有机质及平行层面缝优势输导体系和强水动力作用多种因素叠加影响的结果。     

准噶尔盆地南缘新生界粘土矿物分布及影响因素

根据粘土矿物的相对含量研究了准噶尔盆地南缘新生界砂岩粘土矿物类型、组合特征及纵、横向分布规律及其主要影响因素。划分出无序伊/蒙混层型、部分有序伊/蒙混层型、伊利石+伊/蒙混层型、蒙皂石型以及含坡缕石型等5类粘土矿物组合。按照伊/蒙混层相对含量的变化,粘土矿物纵向上演化呈正常转化型(伊/蒙混层相对含量降低)、反向转化型(伊/蒙混层相对含量增加)和“S”型(伊/蒙混层相对含量呈曲线变化)3种形式。平面上,伊/蒙混层和伊利石这两类主要粘土矿物从湖盆的边缘向中心分别呈现减少和增多的趋势,湖盆边缘相带以无序伊/蒙混层型、蒙皂石型和含坡缕石型为主,湖盆中心则为部分有序伊/蒙混层型和伊利石+伊/蒙混层型组合等类型。上述分布规律的控制因素主要有沉积环境、构造运动及层序发育等。     

粘土矿物地温计在沉积盆地热演化研究中的应用

在成岩过程中形成的粘土矿物真实地记录了地层形成的成岩温度及其盆地热演化的信息,可以作为沉积盆地的热史指标。本文主要介绍了伊利石/蒙皂石间层矿物（以下简称伊/蒙间层或I/S间层）、伊利石结晶度、绿泥石化学成分三种常用的粘土矿物地温计的发展历史、基本原理和影响因素;回顾了我国沉积盆地热演化研究中粘土矿物地温计的应用现状,并对未来的应用推广工作提出了若干参考建议。     

南黄海南部坳陷下第三系阜宁组、戴南组泥岩的粘土矿物与热成熟度的关系

粘土矿物在埋藏成岩过程中的重要变化是膨胀型粘土逐渐减少(如蒙脱石),伊利石、绿泥石结晶度逐渐增加(半高宽减小)。通过对具有代表性的常6—1—1井粘土矿物X衍射分析,系统研究了伊利石10A峰、绿泥石7A峰的半高宽、A/H值(背影峰面积/峰高)与镜质体反射率R_0以及有机质热变指数LOM的对应关系。研究结果表明伊利石(特别经乙二醇处理过)的10A峰半高度及A/H值可以估算有机质成熟与否;可以作为预测源岩生油门限以及油气保存阶段的指标。     

藏北羌多——查布地区下二叠统划分与早二叠世动物群特征

下二叠统分角木茶卡组和肖茶卡组。角木茶卡组为碳酸盐岩夹玄武岩,局部夹含砾板岩,厚1000-2500m。含(蜒)类组合Monodiexodina-Parafusulina,珊瑚组合 Lytvolasma Szechuanophyllum,腕足类组合Costiferina-Neospirifer-Spiriferella等。属冷、暖动物群混生类型。肖茶卡组为碳酸盐夹玄武岩,800-2900m。含(蜒)Neoschwagerina,珊瑚组合Iranophyllum-Waagenophyllum,腕足类组合Neospirifer-Spiriferella-Marginifera等,属暖水型动物群。这些反映了早二叠世时冈瓦纳大陆北缘浅海台地深拗陷带碳酸盐和火山岩的沉积特征。     

广西田东剖面二叠纪-三叠纪之交的生物绝灭及生态演化

本文以广西田东地区浅海相二叠系-三叠系剖面为研究对象,对二叠纪-三叠纪之交的生物绝灭与浅海生态环境演化进行了深入的探讨。镜下化石鉴定与统计结果表明在P/T界线附近生物物种两次急剧减少,一次为生物大绝灭所致,另一次为生物迁徙所致。另外,本剖面上所研究的物种的数量变化是突变的,而不是渐变的。在残存期内,腹足类生物较有孔虫生物表现出较强的自我恢复和适应环境的能力。整个剖面沉积为一个海浸的过程,其二叠系-三叠系界线之交生态环境发生了很大的变迁。     

新疆西天山博罗科努成矿带岩浆岩时空分布、 构造演化与成矿响应

博罗科努成矿带位于新疆西天山北缘,近年来找矿成果突出.在充分收集前人研究成果的基础上,初步总结了博罗科努带岩浆岩时空分布特点及其年龄资料,重点分析了与成矿关系密切的晚古生代岩浆作用的性质.博罗科努带地质历史与北天山洋的演化密切相关,前寒武纪统一基底形成,北天山洋打开.寒武纪为被动陆缘环境,北天山持续扩张.奥陶纪北天山洋向伊犁地块之下俯冲,该带进入大陆弧演化阶段.泥盆纪—晚石炭世早期为俯冲高峰期,引发了一系列钙碱性的岩浆活动;早二叠世该带已进入陆相环境,但北天山洋残余洋盆的俯冲持续到中二叠世;晚二叠世全面进入陆内演化阶段,区域构造应力性质由挤压变为伸展.伴随洋-陆构造演化,形成了莱历斯高尔和阿希两大矿集区,分别对应2套成矿系统:与侵入岩浆活动有关的矽卡岩-斑岩-热液脉型铁、铜、钼、金、锑、铅、锌成矿系统和与次火山热液活动有关的浅成低温热液-斑岩型金、铅、锌、铜成矿系统.     

Sedimentology of the continental end‐Permian extinction event in the Sydney Basin,eastern Australia

Upper Permian to Lower Triassic coastal plain successions of the Sydney Basin in eastern Australia have been investigated in outcrop and continuous drillcores. The purpose of the investigation is to provide an assessment of palaeoenvironmental change at high southern palaeolatitudes in a continental margin context for the late Permian (Lopingian), across the end‐Permian Extinction interval, and into the Early Triassic. These basins were affected by explosive volcanic eruptions during the late Permian and, to a much lesser extent, during the Early Triassic, allowing high‐resolution age determination on the numerous tuff horizons. Palaeobotanical and radiogenic isotope data indicate that the end‐Permian Extinction occurs at the top of the uppermost coal bed, and the Permo‐Triassic boundary either within an immediately overlying mudrock succession or within a succeeding channel sandstone body, depending on locality due to lateral variation. Late Permian depositional environments were initially (during the Wuchiapingian) shallow marine and deltaic, but coastal plain fluvial environments with extensive coal‐forming mires became progressively established during the early late Permian, reflected in numerous preserved coal seams. The fluvial style of coastal plain channel deposits varies geographically. However, apart from the loss of peat‐forming mires, no significant long‐term change in depositional style (grain size, sediment‐body architecture, or sediment dispersal direction) was noted across the end‐Permian Extinction (pinpointed by turnover of the palaeoflora). There is no evidence for immediate aridification across the boundary despite a loss of coal from these successions. Rather, the end‐Permian Extinction marks the base of a long‐term, progressive trend towards better‐drained alluvial conditions into the Early Triassic. Indeed, the floral turnover was immediately followed by a flooding event in basinal depocentres, following which fluvial systems similar to those active prior to the end‐Permian Extinction were re‐established. The age of the floral extinction is constrained to 252.54 ± 0.08 to 252.10 ± 0.06 Ma by a suite of new Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry U‐Pb ages on zircon grains. Another new age indicates that the return to fluvial sedimentation similar to that before the end‐Permian Extinction occurred in the basal Triassic (prior to 251.51 ± 0.14 Ma). The character of the surface separating coal‐bearing pre‐end‐Permian Extinction from coal‐barren post‐end‐Permian Extinction strata varies across the basins. In basin‐central locations, the contact varies from disconformable, where a fluvial channel body has cut down to the level of the top coal, to conformable where the top coal is overlain by mudrocks and interbedded sandstone–siltstone facies. In basin‐marginal locations, however, the contact is a pronounced erosional disconformity with coarse‐grained alluvial facies overlying older Permian rocks. There is no evidence that the contact is everywhere a disconformity or unconformity.     

新疆准噶尔盆地和塔里木盆地二叠纪孢粉组合的比较及其植物区系和地层意义

根据二十年来积累的准噶尔和塔里木盆地二叠纪孢粉组合序列资料 ,结合其他动植物化石证据 ,初步做了两地二叠纪孢粉生物地层对比 ,并讨论了植物区系性质 ,指出准噶尔盆地在晚石炭世早期已属亚安加拉区 ,塔里木盆地在早二叠世虽总体上属欧美区 ,但已混生若干安加拉—亚安加拉成分 ,中、晚二叠世基本上已属亚安加拉区。孢粉证据支持准噶尔板块在早石炭世已与哈萨克斯坦板块—西伯利亚板块对接、塔里木板块在早二叠世与准噶尔板块对接的假说。二叠纪时 ,两地处于亚热带—暖温带 (4 0°N以南 ) ,气候总体上为半干旱气候 ,但干旱程度并不严酷 ,局部地区或层位偶尔还形成薄煤层或煤线 ,准噶尔盆地还有干湿的周期性变化和年度的季节变化     

Ocean Chemistry Revealed by Mineralogical and Geochemical Evidence at the Permian–Triassic Mass Extinction, Offshore the Persian Gulf, Iran

The Upper Permian Dalan Formation and the Lower Triassic Kangan Formation in the Persian Gulf area are mainly composed of shallow marine facies limestone and dolomite. Two subsurface-cored intervals were investigated in order to understand the original mineralogy and paleoceanic conditions. The decreasing trend of Sr concentration in these deposits shows that aragonite was precipitated during the Late Permian and then gradually changed to calcite toward the Permian–Triassic boundary (PTB). The dissolution rate of aragonite decreased from 60 m below the PTB toward the boundary, with the only exception at 10 m below the Permian-Triassic Boundary (PTB) due to the Permian–Triassic unconformity in this region. The increasing trend of Mg/Ca ratio in a global scale at the end-Permian time shows that the interpreted variation of mineralogy does not result from the change of this ratio. The increasing pCO2 and decreasing pH are considered to be the main controlling factors. The increase of Ca2+ at the end-Permian time due to the input of meteoric waters is too little to fully compensate this effect. A local maximum of the Si content just at the PTB confirms the input of runoff waters.     

Early and Middle Permian paleoclimates of the Baoshan Block, western Yunnan, China: insight from carbonates

In Permian times the Baoshan Block of western Yunnan, southwest China formed the eastern part of the Cimmerian Continent. Most biogeographical and sedimentological data indicate that the Early Permian Dingjiazhai Formation formed on the block under conditions strongly influenced by the Permo-Carboniferous glaciation. After Early Permian rifting, with post-glaciation climatic amelioration, and as the Baoshan Block drifted northwards to approach South China and Indochina, faunal elements characteristic of Gondwana affinity decreased, while those of Cathaysian affinity increased. Finally, Late Permian faunas are characterized by exclusively Cathaysian elements. This shift of marine provinciality becomes an important indicator in understanding the Permian paleoclimatic evolution of the region. This research investigated the composition of carbonate grain associations and the early diagenetic features of limestones from the upper part of the Dingjiazhai Formation, and from the overlying Yongde and Shazipo formations. A sharp distinction in petrological and diagenetic features is recognized between the Dingjiazhai Formation and the two overlying formations. The Dingjiazhai carbonates are characterized by the bryonoderm (bryozoan-echinoderm)-extended facies of the heterozoan association, with no non-skeletal grains. Because early diagenetic cement was rarely formed, the Dingjiazhai carbonates experienced strong diagenetic compaction. In contrast, the Yongde and Shazipo carbonates show a chloroforam facies of photozoan association, with the common occurrence of non-skeletal grains. These carbonates were well cemented during early diagenetic processes. From comparison with Permian cool-water carbonates from northern Pangea and Tasmania, Australia, the Dingjiazhai carbonates are interpreted as deposits of warm-temperate conditions, while the overlying carbonates are considered to be deposits of subtropical or tropical conditions. This climatic interpretation, based on the petrographic features of the Permian carbonates, agrees well with existing biogeographical data from the region.     

内蒙古阿拉善左旗乌兰尚德地区志留系圆包山组笔石化石的发现及其地质意义

阿拉善盟阿拉善左旗杭乌拉山以北哈日奥布日格断凹陷盆地两侧,北东向出露770km2的哑地层,前人将其划为二叠系双堡塘组,但该套地层的岩性和岩石组合及层序特征,与内蒙古岩石地层所述的双堡塘组的现在定义和地质特征及区域变化完全相悖。采用现代沉积学理论和层序地层学方法,开展岩石组合、基本层序、沉积构造与沉积环境研究,划分出3个段级填图单元。根据发现的笔石化石和被晚泥盆世中粗粒黑云母花岗闪长岩侵入的关系,将地层时代确定为早志留世,改划为志留系圆包山组。泥盆纪区域变质变形作用使其发生浅变质和片理化变形,并形成轴向北东的复式向斜构造。后期叠加构造变形,形成紧闭倒转褶皱。志留系圆包山组的确定对本区地层划分和区域构造演化研究有重要意义。     

甘肃北山小草湖火山岩系形成时代的重新厘定

甘肃北山小草湖一带敦煌岩群的北侧分布着一套发生韧性变形的火山岩系(前人称之为小草湖岩片)。该火山岩系的宏观岩貌、岩石学、岩石地球化学等特征与相邻的二叠纪火山岩系相似,为大陆裂谷火山岩系列。本次研究在糜棱岩化英安岩中获得285Ma±4Ma的LA-ICP-MS单颗粒锆石微区U-Pb同位素年龄,证明该火山岩系的时代并非志留纪,而是二叠纪,属于天山石炭纪—二叠纪大火成岩省的组成部分。这一新资料对甘肃北山构造格局及其演化历史的研究具有重要意义。     

新疆博格达地区中二叠世—早三叠世构造-气候-沉积演化及耦合机制*

博格达地区的盆山关系演化、博格达山初始隆升时间、构造-气候-沉积耦合机制等前沿科学问题一直是国内外研究的热点,也一直困扰和制约准噶尔盆地东南缘的油气勘探开发进程。基于博格达山北缘野外露头和阜康凹陷、吉木萨尔凹陷的岩心、地震及钻测井资料,综合运用沉积学、地球化学等多种方法,阐明了博格达地区中二叠统—下三叠统展布及沉积相特征,恢复了相应的古气候变化,结合区域研究成果重建了中二叠世至早三叠世构造-气候-沉积演化过程。认为博格达地区中二叠世为裂谷—坳陷盆地构造背景,在干旱—半干旱气候条件下,发育以博格达地区为湖泊中心的辫状河三角洲—湖泊沉积体系;晚二叠世博格达山发生初始隆升,早期湖盆消亡并在博格达北坡山前发育冲积扇,古气候由半干旱变化为半湿润;早三叠世博格达地区构造环境相对稳定,但是逐渐趋于温暖湿润的古气候对区域风化程度和沉积条件起主要控制作用,博格达山体遭受强烈风化剥蚀,北侧形成扇三角洲—湖泊沉积体系。