四川盆地中二叠统茅口组白云岩中蕴藏丰富的天然气资源,但是这套白云岩的成因多年来一直存在争议.盆地东部茅口组白云岩储集层多发育在茅三段中下部,纵向上厚度介于3.0～46.8m之间,平面上沿北西—南东向基底断裂呈带状展布.野外和钻井岩心观察发现,白云岩内发育交织状张性裂缝,将岩石切割呈角砾状,裂缝多被粗晶方解石、白云石充填或半充填.根据围岩和裂缝中白云石晶体形貌和产出状态,在显微镜下识别出4类不同组构的白云石:第1类为灰泥基质中"星散状"自形粉晶—细晶白云石;第2类为半自形面状组构细晶白云石,呈他形—半自形镶嵌状;第3类为具"雾心亮边"的自形晶面状组构细晶—粗晶白云石,具糖粒状结构,晶间孔隙发育;第4类为脉体充填的粗晶鞍状双晶白云石.背散射照片显示前3类白云石的"雾心"部分晶面混浊、表面分布方解石残斑及微孔,而第3类白云石的"亮边"部分与第4类鞍状粗晶白云石脉则晶体明亮、洁净、致密,属新生矿物.上述4类白云石的成分均具有富Ca和贫Fe、Mn、Sr的特点,MgO含量变化较大,其中前两类白云石MgO含量总体低于白云石标准计量,而后两类白云石的MgO含量则接近或略高于标准计量.岩石学、矿物学和地球化学特征表明:茅口组白云岩主要经历了 2期白云化作用,初次白云化作用形成第1类、第2类白云石及"雾心"白云石,二次白云化作用形成"亮边"白云石和粗晶白云石脉体;2期白云化作用均发生得很早,可能始于同沉积期至浅埋藏期.白云石原位微量元素和原位锶同位素分析表明,白云化作用流体具有混源的特点,流体可能由富Ca地下水以及与火山活动有关的热液混合而成.推测中二叠世末期峨眉山地幔柱的喷发引起四川盆地内基底断裂再次活动,造成茅口组内张性构造裂缝发育,这为白云化流体混合及运移提供了通道.

陆内湖相烃源岩系是中国含油气盆地广泛发育的一类组分复杂且富含有机质的细粒沉积岩.随着非常规油气资源需求量日益增加,该岩系被作为致密油或页岩油层系受到广泛关注.然而,其极细的粒度增加了精细岩石学、矿物学研究难度,使它长期被简单视为陆源沉积岩.研究发现,该岩系中发育丰富的火山喷发及热液喷流产生的深源物质,并与油气的生成和富集表现出了极强的耦合关系.因此,探索深源物质如何参与烃源岩形成并影响油气生成亟待深入研究.作者详细总结并探讨了国内外近年来关于湖相烃源岩成因以及火山—热液活动带来的深源物质与油气形成关系的现阶段新发现与认识.并结合笔者研究团队基于新疆三塘湖盆地二叠系芦草沟组烃源岩的新发现,采用精细的岩石学、矿物学方法,结合无机和有机地球化学等方法,初步开展了该耦合关系的机理研究.认为火山—热液深源物质参与了烃源岩的沉积与成岩作用,并与正常湖相沉积物共同影响着油气的形成.建议重新认识湖相烃源岩的物质组成,从而拓展陆相生油理论,同时为同类型非常规油气资源勘探开发提供理论指导.

准噶尔盆地东部吉木萨尔凹陷中二叠统芦草沟组,沉积于陆内裂谷背景下岩浆—热液活动强烈的咸化湖盆中.在芦草沟组中发现一类与湖底热液活动有关的幔源热液沉积白云岩,包括方沸钠长白云岩、硅质白云岩与含水铵长石钠长白云岩.作者对该类白云岩开展微米级尺度的岩相学研究,结合同位素地球化学研究,探讨成矿流体性质与详细成因机理.岩矿特征和同沉积变形构造指示白云岩形成于沉积期.白云石为有序性较差的原白云石,呈微米级球状、葡萄状晶体,与方沸石、水铵长石、钠长石及玉髓等热液矿物彼此镶嵌结晶,高温下发生了白云石对钠长石碎屑的交代作用;白云岩锶同位素(平均为0.705687)显示成矿流体中幔源组分较多;白云岩具有重 δ13CPDB(平均为6.94‰)和轻δ18OPDB(平均为-8.12‰).基于成矿流体由幔源热液与湖水混合的假设,利用δ18OPDB计算估计,研究区白云岩的形成温度较普通云质岩高25～50℃.研究表明白云石为幔源热液喷出湖底后直接沉淀形成,并提出可能的成因模式.热液沉积白云岩是一种不可或缺的白云岩成因类型,研究成果对促进人们理解白云石的形成规律、推动完善成因岩石学理论具有重要意义.

在对准噶尔盆地吉木萨尔凹陷二叠系芦草沟组暗色湖相细粒岩进行研究时,发现多套以夹层形式产出、矿物组成多为不稳定—次稳定矿物、碎屑颗粒呈斑块状且结构成熟度普遍较低的碎屑岩.构成岩石的晶质碎屑均呈大小混杂、形态各异的棱角状,分选差,分布无规律,单矿物常见高温熔蚀成因港湾状边缘.地球化学特征显示:构成岩石的矿物颗粒为深部来源,甚至可能有幔源物质加入.认为岩石样品的碎屑颗粒不再源自传统认识中的周缘母岩风化搬运或热液沉淀,而是在陆内裂谷欠补偿湖盆背景下、源自地球内部不同深度、不同性质的岩浆—热液物质流体.这些深源岩浆—热液物质流体上涌进入湖(海)底喷流通道,由喷口喷出后,随喷口距离远近,在不同机械搬运方式和驱动力下参与沉积过程.

陆相细粒沉积岩是中国含油气盆地中重要的烃源岩和致密油储集层.随着对烃源岩、致密油、页岩油-气勘探开发研究的不断深入,陆相细粒沉积岩取得了一系列重要进展并持续进行着前沿探索.作者论述了传统细粒沉积岩基本概念及演变,岩石、矿物组成特征、成因机制与分类方法.结合近年来在陆内裂谷盆地陆相细粒沉积岩中广泛分布的火山—热液物质的新报道及研究成果,认为火山物质、热液喷流物质不仅参与了陆相黑色细粒岩系的沉积和成岩作用,也与油气生成有密切关系.加强对陆相细粒沉积研究,探讨深源碎屑及热液流体的来源及其对细粒沉积过程的影响,既有利于丰富、完善沉积学和陆相含油气盆地生油理论,也有利于更好地指导致密油、页岩油-气的勘探开发.

在对新疆北东部三塘湖盆地二叠系芦草沟组黑色细粒岩系进行研究时发现,这套长期被当作由黑色泥岩、凝灰岩和碳酸盐岩组成的岩系里还发育一套既不同于陆源碎屑、内碎屑沉积岩,也不同于热水沉积岩(喷流岩)的岩石,认为是一套以夹层形式发育在纹层状泥/页岩中,由气、液、固三相共存的深源岩浆—热液物质流体上涌进入湖(海)底喷流通道,由喷口喷出后与热液流体或与湖(海)水混合沉积形成的沉积岩—喷爆岩.喷爆岩呈薄层—纹层状展布,矿物组成种类单一,以不稳定、次稳定矿物为主.晶质颗粒碎屑或团块均呈大小混杂、形态各异的棱角状,分选差,分布无规律.基于大量岩芯、岩石薄片观察,结合电子探针及相关数据,以构成岩石碎屑颗粒的主要组成矿物为依据,将喷爆岩分为方解石喷爆岩、白云石喷爆岩、透辉石喷爆岩及长英质喷爆岩四类,并详细论述了各类岩石学、矿物学特征.研究结果显示构成喷爆岩的碎屑颗粒不再是传统认识的来自周缘母岩风化搬运或热液沉淀,而是在陆内裂谷欠补偿湖盆背景下、源自地球内部不同深度、不同性质的岩浆—热液物质流体.在此基础上,对喷爆岩与碎屑沉积岩、火山碎屑岩及喷流岩区别进行讨论,认为喷爆岩分别在矿物组成、物质来源、分布规模、形成方式等方面有别于上述三者.

新西兰北岛Waiotapu地热区位于Taupo火山带中部,以发育众多的第四纪酸性火山岩而闻名.通过X衍射、电子探针、扫描电镜、激光拉曼等方法对区内一处于活动间歇期的小型火山口堆积物岩矿特征及特殊结构进行研究.结果表明,火山口堆积物可分为3类:1)球粒流纹岩,矿物组成为:α方石英-PO鳞石英—正长石、奥长石、紫苏辉石—钛铁矿(钛磁铁矿);2)流纹质晶屑熔结凝灰岩,矿物组成为:奥长石晶屑、塑性玻屑;3)硫磺土,矿物组成为:单质硫、长英质细粒岩屑.结合前人实验矿物学结论后认为,球粒流纹岩中的球粒体为富火山玻璃的流纹岩喷出堆积后在热水作用下脱玻化形成的,是酸性火山岩早成岩期表生蚀变阶段的标志;而流纹质熔结凝灰岩则为岩浆喷溢出地表后,在塑性流动中冷凝结晶形成的,是酸性火山岩早成岩期冷凝固结阶段的标志.在此基础上,提出了Waiotapu地热区酸性火山岩的表生蚀变模式,为酸性火山岩冷凝固结—表生蚀变阶段的岩矿特征及蚀变作用研究提供现代对比实例.

新疆北部地区二叠系芦草沟组的黑色岩系是重要的生烃岩系.在准噶尔盆地吉木萨尔凹陷,该套岩系主要分布于3000～3500 m,并可分出3100～3170 m和3250～3370 m这2个致密油层段.两层段黑色岩系的岩性以凝灰岩、沉凝灰岩、凝灰质泥晶白云岩为主,夹丰富的纹层状、透镜状沥青质和藻类.黑色岩系中不仅发育火山喷发的深源碳酸质凝灰物质,而且夹有丰富的热液喷流的深源物质,它们多与泥晶微生物白云岩呈互层状,共同组成了具良好生烃能力的特殊烃源岩系.黑色岩系样品的热解分析表明,其中的游离烃S1含量较高(最高8.17 mg/g,平均1.56 mg/g),裂解烃S2含量也高(3.3～76.2 mg/g);总有机碳TOC为1.4％ ～ 7.9％,生烃潜量PI也为高值(0.02～0.51,平均为0.16),总体指示有机质丰度高、生烃潜能好.生物标志物C28和C29甾烷的含量大于C27,呈反“L”型,表明有机质类型以藻类和高等植物为主;高成熟度甾烷参数C2920S/(20S+20R)和C29ββ/(αα+ββ)在深源物质丰富的致密油层中较高(平均0.48和0.31),而在深源物质少的层位中较低(平均为0.37和0.26).上述2个层段的地化参数在纵向上的分布特征与镜质组反射率R0的分布规律(2个致密油层段中深源物质多时R0呈现异常高值)相吻合.综合分析认为,频繁的火山喷发物质和热液喷流的深源物质参与了该区湖相沉积烃源岩的生烃作用过程.

The Middle Permian Lucaogou Formation of Jimusar Depression,Junggar Basin is characterized by lacustrine fine-grained dolomitic sediments,which are composed of silt-sized to mud-sized terrigenous clasts,tuff clasts,carbonate and hydrothermal minerals.This paper is aimed to understand the sedimentary environment and formation mechanism of dolomitic rocks by studying their petrological,mineralogical and geochemical features.Petrological-mineralogical and major and trace element characteristics of the dolomitic rocks suggest the study area was a shallow salty lake formed under an arid climate during the Middle Permian,and was characterized by intense regional volcanism and active mantle-derived hydrothermal in the basin.The dolomites in the dolomitic rocks mainly present as euhedral-subhedral micritic crystals,forming fine lamination or mixing with other compositions,while fine-crystalline dolomites can only be found occasionally.The micritic dolomites,with low order degrees (0.46) and homogeneous compositions,are usually surrounded by laminations.The fine-crystalline dolomites are featured by welldeveloped metasomatic relict texture and thereby should be the product of diagenesis.Both two kinds of dolomites have high strontium and low magnesium contents,while fine-crystalline dolomites have higher contents of iron and manganese than that of micritic dolomites.The micritic dolomites have a low δ1sOPDs (av.-4.72‰).The forming temperature,54.61 ℃ to 186.46 ℃,is calculated from the δ18OpDB by assuming that the fluid was the mixture of lake water and mantle-derived hydrothermal fluid.The high δ13CPDB (av.8.79‰) of micritic dolomites might be resulted from the gigantic buried organic matter of Lucaogou Formation and metabolic activities of methanogens.In conclusion,the micritic dolomites are contemporaneous-penecontemporaneous protodolomite.Magnesium ion was supplied by the salty lake water,tuff materials as well as mantle-dervied hydrothermal fluid.The dynamic barrier of dolomite formation was broken by the high temperature brought from hydrothermal fluid and the metabolic activities of methanogens.

新疆准噶尔盆地火烧山油田的中二叠统平地泉组(对应芦草沟组)是一套典型的黑色含油层系,长期被认为是裂谷盆地(或岛弧盆地)中富含生烃母质的深湖相泥岩.通过矿物学、岩石学等方面的综合分析认为:平地泉组的岩石碎屑主要来源于地幔碱性—过碱性的超基性岩浆岩(以碳酸岩为主)和中酸性岩浆岩(以安山岩和流纹岩为主)的喷爆物和溢流物,以出现碱性—过碱性的碱性长石、富铝石英、岩浆方解石、霓石、锂云母、硅钡钛石、蛇纹石等超基性岩浆矿物和以碱性—过碱性的碱性长石、石英等中酸性岩浆矿物为特征.上述喷爆的矿物碎屑与基质在富含地幔流体的滨湖—沼泽—热泉环境中发生热液蚀变,最终形成富含幔源岩浆矿物及热液矿物的凝灰质沉积系列,并参与生烃过程.凝灰物质提供的热及丰富的营养物质促进了滨湖—沼泽—热泉中藻类、微生物等生烃母质勃发,并导致液态烃早生成;凝灰岩类中丰富的原生粒间孔和方沸石溶蚀孔是烃类的主要储集空间.凝灰岩层厚度差异较大,多与正常沉积岩互层或夹于厚层沉积岩中.

•Mantle-derived minerals are rich in lacustrine shale in Permian Lucaogou Formation.•Dolomite, diopside and analcime dominate and formed in magmatic-hydrothermal flows.•The shale was formed by density granular flows induced by subaqueous eruption.•The minerals are tracers of mantle materials and processes in a rift basin.

In recent years,more and more originally regarded as black oil and gas-bearing shales have been found,whose formation has close relationship with subaqueous volcanic activities,with much more fundamental research work on tight oil in China.However,our study of sedimentations of subaqueous eruption has not been well studied since their sediments are very tiny,not easy to be sampled,and extremely difficult to differentiate from mud-size clastic sediments.This paper reviewed the advances of the processes of fragmentation,transportation,and deposition of sediments originated by subaqueous eruption,on the basis of publications and research experience on some special intervals in interlaminated shales and dolostones in Permian Lucaogou Formation in Santanghu Basin.Three main features and their implications were documented.① Minerals in those intervals were angular with a low component maturity,and some of them were shard-like,suggesting volcanic-eruptive origin.② Intervals were laminated and thin bedded.The former had a sharp erosional base,and was internal normal graded,and showed crude orientation of elongate grains parallel to bedding plane,suggesting deposition of lateral tractive current;the latter showed messy accumulation without internal structure,suggesting deposition of dense granular flow.③ Intervals were localized and repetitive in stratigraphy,indicating origin from episodic-pulsating volcanic activities.We preliminarily interpreted those intervals as sedimentations of subaqueous volcanic-hydrothermal activities (phreatomagmatic/hydrovolcanic deposition).Then,the relationship of intraclasts,extraclasts,and deep-derived clasts,the difference of sedimentary rocks formed by subaqueous between subaerial eruptions,and the terminology of these eruptive rocks were discussed.Finally,macro to micro scale observation,micro-texture of minerals,attaching importance on hydrothermal exhalative sedimentations,and multidisciplinary studies were suggested for future research on those rocks.

The Upper Carboniferous Harjiawu Formation in Santanghu Basin occurs as a set of intermediate basic volcanics,pyroclastic rock and sedimentary rocks which develop many layers of source rock with different thicknesses.The results of Rock-Eval and saturated hydrocarbon GC-MS reveal that the organic matter abundance of source rocks is higher in Harjiawu Formation.The type of organic matter include typeⅢ,type I and the mixture of the both.The degree of thermal evolution of most samples has achieved mature stage.The higher values of Pr/Ph ratios(1.1-3.01),low values of G/C30hopane(0.047-0.158),and the tricyclic terpanes distribution indicate that the water environments are weak suboxic-weak and low saline during source rock deposition.Low C31R/C30 hopane ratios(0.186-0.310),very low C22/C21ratios(0.164-0.260),higher C24/C23 tricyclic terpane ratios(0.472-0.684)are consistent with the source rocks being deposited in a lacustrine environment.∑C21-/∑C22+,regular sterane distribution(C29C27C28and C29C28C27)and sterane/hopane ratios(0.06-0.20)point out that the biological sources of organic matternot only have higher plant,but also have a mass of bacteria and algae.

现代和地质历史中的海底、湖底的“黑烟囱型”热液活动及相关成岩、成矿和古生物活动已成为当今多学科的研究热点,而与“白烟型”热液喷流岩相关的研究相对薄弱.在阅读大量国内外文献基础上,结合实际的研究工作,回顾了热液喷流岩的研究历史及现状,重点介绍了作为标志性低温型热液矿物白云岩成因方面的进展,认为新疆三塘湖地区的二叠系芦草沟组“白烟型”热液喷流沉积的白云岩是“原生白云岩”的典型样本.现有资料表明已经报道的“白烟型”热液喷流岩发育层位(酒西盆地下沟组与三塘湖盆地芦草沟组)是所在地区的重要生烃层系,据此讨论了如下值得关注的问题:①热液活动及其伴生的嗜热细菌生物及食物链的特殊环境,使有机质得以富集,为油气生成提供了物质基础；②幔源物质的加入很可能带来了幔源烃类；③热液活动可使沉积盆地地温总体升高,加速烃源岩的快速成熟.最后对该领域的研究提出了问题和建议.

As the distribution of oceans and continents in paleozoic era is still a controversial issue,the paper makes an comprehensive comparative study on ophiolite and ophiolitic in periphery of Junggar Basin. The result indicates that Taerbahatai- Hongguleleng- Zhaheba- Aermantai ophiolite belt in the Northern Junggar,which may be the suture zone between the Siberian plate and Kazakhstan plate,is formed between early Paleozoic( 503 to 470 Ma) and late Paleozoic and the ocean basin it represented may be closed before early Carboniferous. However,Dalabute- Kelamaili ophiolite belt in the Southern Junggar,which is not featured with properties of plate suture zone but back- arc spread ocean basin,is formed in late Paleozoic( 391 to 329 Ma),and the ocean basin it represented may be closed in late early- Carboniferous.

Elashan volcanic rocks from late Triassic Elashan Group in southeastern margin of the Qaidam Basin are mainly consisted of a set of medium and acid volcanics combination,including rhyolite and dacite primarily,followed by andesites.The results of the analyses on principal elements,rare-earth elements and trace elements show that Rittman index(δ) of the samples are all below 4,and belongs to calc-alkaline volcanic rocks;the average of SiO2 is 71.95%,most of the samples have a characteristic of low aluminum,alkali content is higher,and that belongs to the sub-alkaline volcanic rocks.The ratios between LREE and HREE are large and negative Eu anomalies are obvious,so they have the typical late rare earth fractionation characteristics of magmatic differentiation.The samples display a characteristic of LREE enrichment.The discriminant diagram of tectonic environment shows its environment is volcanic arc-within plate volcanic region.This feature may reflect this volcanic activity happened in the tectonic environment of Qinling orogenic belt underthrusting to Qaidam block.

The main gas-bearing reservoir of Permian in the Jingbian gas field is He8 of the Shihezi Formation.In order to identify the sand body distribution characteristics of this area,sedimentology,petrography and paleogeography,logging geology are used in this article.On these bases,the sedimentary microfacies are studied in detail.It is suggested that delta-lake depositional system is one of the main types of sedimentation in the Jingbian gas field.The distribution of sand body is clearly controlled by the sedimentary microfacies.In the north of this area,controlled by the channel,distributary channel and underwater distributary channel,sand body lanes are near north-south spread.In the south of this area,the sandbody is belong to shore shallow sandbeaches and sheet sand,sand body lanes are near east-west spread.Frequent pulse of the lake level and shoreline advance and retreat movements controls the migration of facies and sand body distribution,when the lake level drops,the role of delta actives,the sand bodies are relatively developed.So the sandbody in subaqueous distributary channel and channel-mouth bank are the most favorable reservoir sections in this area.