鄂尔多斯北部侏罗纪延安组、直罗组孢粉化石及其古气候意义

神山沟剖面位于鄂尔多斯盆地东北缘内蒙古东胜地区,侏罗纪延安组、直罗组富含孢粉化石。延安组为煤系沉积地层,岩性以灰白色砂岩、灰色粉砂岩夹泥岩为主,局部发育砾岩,可见5、6套煤层;直罗组为重要的含铀岩系,岩性以灰色-黄绿色砂岩、灰色粉砂岩夹紫红色泥岩、泥质粉沙岩为主。文中通过对神山沟剖面延安组和直罗组孢粉化石的分析,在延安组中识别出Cyathidites-Dictyophyllidites-Cycadopites(CDC)和Cyathidites-Osmundacidites-Lycopodiumsporites-Concentrisporites-Disacciatrileti(COLCD)2个孢粉组合带,通过对孢粉化石属种的分析,得出本剖面延安组孢粉组合的时代为早中侏罗世早期;直罗组孢粉组合为Cyathidites-Osmundacidites-Cycadopites-Disacciatrileti(COCD)组合带,时代中侏罗世中期。结合地质、元素地球化学、古植物及其孢粉化石的定量分析表明,从延安组向直罗组其总体上反映了从温暖潮湿的亚热带向半干旱-干旱炎热的气候转变,反映燕山运动早期中侏罗世一次重要的古气候变化事件,古气候对煤、砂岩型铀的成矿具有特殊的地质意义。     

鄂尔多斯盆地东北缘高头窑地区中侏罗世植物群的发现

系统研究了鄂尔多斯盆地东北缘高头窑一带的中侏罗统延安组植物化石，18属31种。其组成特征表明，当前植物群属于典型的Coniopteris-Phoenicopsis植物群，其时代为中侏罗世。与植物群伴生的昆虫化石的研究提供了一致的时代意见。     

龙江盆地西缘中侏罗世孢粉植物群及其对古气候的指示

对产于龙江盆地中侏罗统万宝组含煤地层中的孢粉化石进行了系统研究,共识别出中侏罗世孢粉化石45属73种,蕨类植物孢子15属16种,裸子植物花粉30属57种,自下而上建立了Alisporites-Chasmatosporites-Cyclogranisporites,Chasmatosporites-Piceites-Cyclogranisporites及Cyclogranisporites-Baculatisporites-Protopinus3个孢粉组合。该孢粉植物群以裸子植物花粉占优势,蕨类孢子次之,其中,裸子植物花粉以松柏类植物的双囊花粉和苏铁类、本内苏铁类、银杏类植物的单沟花粉为主。通过对龙江盆地万宝组孢粉植物群的组成分析,其时代应为中侏罗世。结合对该地质时期的植物群生态环境的研究,万宝组孢粉植物群反映了由半湿润到湿润的暖温带-亚热带的气候特点,并存在一定低矮山地的古环境。     

尔多斯盆地盐池地区延安组孢粉组合的发现及其古气候意义

为恢复鄂尔多斯盆地盐池地区早—中侏罗世古气候,重建古环境,对宁东2井进行孢粉分析和黏土矿物测试,建立孢粉组合、孢粉谱。延安组下部为Inaperturopollenites- Psophosphaera- Protopinus组合,地质年代为早侏罗世托阿尔期晚期;延安组上部为Cyathidites- Deltoidospora- Cycadopites组合,地质年代为中侏罗世早期,下/中侏罗统界线位于钻孔2144. 5~2153. 0 m之间。据孢粉谱建立的古气候和古植被得出,早侏罗世托阿尔期晚期为暖温带半湿润型气候,植被类型为针叶林,中侏罗世早期总体为亚热带湿润型,植被面貌有早期的针阔叶混交林- 草丛型向晚期的针叶林- 稀草型转变。两组合总体上反映的早侏罗世托阿尔期晚期至中侏罗世早期湿度由半湿润向湿润转变,温度由低向高转变,孢粉谱所指示的气候变化趋势与黏土矿物指标所反映的气候变化趋势一致。气候的转变对该地区聚煤作用有着明显的促进作用。     

新疆且末地区中侏罗世杨叶组孢粉化石的发现及其地质意义

新疆且末县江尕勒萨依村杨叶组首次发现了大量孢粉化石。经鉴定共计37属81种,根据孢粉化石组合特征及地层分布将其命名为Cyathidites-Neoraistrickia-Disacciatrileti组合,时代为中侏罗世早期,与西北区、华北区同时代地层中孢粉组合可以很好的对比。通过研究孢粉组分与母本植物的亲缘关系,得出中侏罗世早期江尕勒萨依地区植被主要由真蕨类植物、石松类植物和乔木的松柏类及苏铁类组成,反映古气候为热带-亚热带湿润气候。     

内蒙古锡林浩特侏罗纪红旗组孢粉化石的发现及其古气候意义

内蒙古锡林浩特煤矿侏罗纪红旗组下部首次发现了大量孢粉化石,经鉴定计有孢粉化石26属39种。根据孢粉化石组合特征及地层分布将其命名为Dictyophyllidites-Cyathidites-Classopollis组合,时代属早侏罗世晚期,与华北区、东北区及西北区同时期地层中的孢粉组合能很好地对应。此外,通过孢粉化石组分研究,确定该区早侏罗世古植物主要为掌鳞杉科、松柏类、苏铁科、桫椤科、双扇蕨科等,古植被类主要为针、阔混交林,进而推断该期为亚热带半干旱—半湿润、偏湿润的古气候。     

鄂尔多斯盆地早中侏罗世延安组软沉积物变形及成因分析

古地震相关的软沉积物变形构造在盆地演化中具有指示盆地及其周缘构造活动的作用.在鄂尔多斯盆地延安组岩心描述和野外调查过程中,于定边西南部DT3522井、安塞延河剖面中,发现并识别出软沉积物液化变形层,包括液化作用相关的枕状层、液化砂岩脉、液化角砾岩、泥火山,以及负载构造、球枕构造等9种变形构造.通过软沉积物变形层位对比,变形特征研究,结合区域构造背景认为,鄂尔多斯盆地延安组延7油层组沉积末期,发生了3期古地震活动,且呈现地震强度先弱后强的特征.     

吐鲁番拗陷中侏罗世孢粉植物群及古环境

根据吐鲁番拗陷葡１井和草南１井中侏罗世的孢子花粉化石及其组合特征，研究孢粉植物群、古植被面貌及古生态环境，探讨中侏罗世的古气候性质、演变及其对聚煤作用和油气生成的影响。     

辽西金羊盆地北票组孢粉组合及其时代和古气候意义

金羊盆地内的北票组是辽西地区重要的含煤及生烃潜力层,确定其时代和古气候环境对进一步研究北票组有非常重要的意义.在坤头营子地区北票组剖面中采集到20件孢粉样品进行孢粉学研究,并对侵入北票组的花岗斑岩及该组地层下部的兴隆沟组安山岩进行了锆石U-Pb同位素测年.系统的分析、鉴定和研究表明:北票组自下而上可划分为3个孢粉组合,下部以Monosulcites-Chasmatosporites-Polycingulatisporites为代表,中部以Protopinus-Paleoconiferus-Alisporites为代表,上部以Monosulcites-Protopinus-Paleoconiferus为代表.锆石U-Pb同位素测年结果分别为172.6 Ma和189 Ma.最终确定北票组的形成时代为早侏罗世中、晚期,自下而上反映了从半湿润的北亚热带气候向湿润的温带气候转变的特征.      

鄂尔多斯盆地早中侏罗世延安组软沉积物变形及成因分析

在统计分析我国2000~2018年油气生产量、消费量及进口量数据的基础上，通过研究与总结我国当前油气需求及勘探开发特点，提出了我国未来油气勘探的趋势，并认为中国油气资源在未来较长期将处于短缺状态.剖析了自然生态产品的价值及油气勘探开发对生态产品价值的影响，阐述政府应对油气产业实施并加强生态管理与规划.政府可通过健全法律法规和激励型环境经济政策培养生态产品市场，分层次对油气产业进行精细管理，并建立国家能源生态技术实验室，通过在生态敏感区规划建立油气区生态产品示范项目，不断提升油气区自然生态产品的价值，对石油天然气产业实行生态产品管理机制，为稳步推进自然生态产品价值的实现奠定基础.     

新疆吐鲁番—哈密盆地托克逊凹陷早侏罗世孢粉植物群及其意义

吐鲁番—哈密盆地托克逊凹陷早侏罗世地层中产孢粉化石共53属74种。通过对纵向上典型属种及优势组分含量变化规律的分析可划分为两个孢粉组合：Osmundacidites-Protopinus-Cycadopites组合和Cyathidites-Piceaepollenites-Cycadopites组合，它们分别产自八道湾组和三工河组。根据孢粉组合特征及与国内外有关化石群进行比较，八道湾组的时代应属早侏罗世早期；三工河组的时代应为早侏罗世晚期。托克逊地区当时的植被是由银杏、苏铁类和松柏类等乔木．并伴有真蕨类等草本植物组成。古气候应属亚热带气候。     

The Relationship between Jurassic Coal Measures and Sandstone-type Uranium Deposits in the Northeastern Ordos Basin, China

Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan'an Formation and the lowstand system tract of the Zhiluo Formation,and there is a regional unconformity between them. The Dongsheng uranium deposit is associated with the Jurassic coal measures. Research data indicate that the Jurassic coal measures in the study area have a certain hydrocarbon-generating capacity,although the metamorphic grade is low(Ro=0.40%–0.58%). In the Dongsheng region alone,the accumulative amount of generated coalbed methane(CBM) is about 2028.29 × 108 –2218.72 × 108 m~3; the residual amount is about 50.92 × 108 m~3,and the lost amount is about 1977 × 108 m~3. Analysis of the burial history of the host rocks and the evolutionary history of the Dongsheng uranium deposit suggests that the Jurassic coal measures generated hydrocarbon mainly from Middle Jurassic to Early Crataceous,which is the main mineralization phase of the Dongsheng uranium deposit. By the Late Cretaceous,a mass of CBM dissipated due to the strong tectonic uplift,and the Dongsheng uranium deposit stepped into the preservation phase. Therefore,the low-mature hydrocarbon-containing fluid in the Jurassic coal measures not only served as a reducing agent for the formation of sandstone-type uranium deposits,but also rendered the second reduction of paleo-interlayer oxidation zone and become the primary reducing agent for ore conservation. Regional strata correlation reveals that the sandstone-type uranium reservoir at the bottom of the Zhiluo Formation is in contact with the underlying industrial coal seams in the Yan'an Formation through incision or in the form of an unconformity surface. In the Dongsheng region with poorly developed fault systems,the unconformity surface and scour surface served as the main migration pathways for low-mature hydrocarbon-containing fluid migrating to the uranium reservoir.     

鄂尔多斯盆地马岭油田侏罗系延安组储层特征研究

侏罗系延安组是鄂尔多斯盆地马岭油田的主力油层之一。通过岩心观察、薄片鉴定、扫描电镜观察等,研究马岭油田侏罗系延安组储层特征及其控制因素。结果表明,马岭油田延安组储层纵向上自延10期至延4+5期,其沉积相由辨状河相演化为网状河三角洲相。受沉积相影响,延10至延4+5油层组碎屑岩石英含量逐渐减少、长石含量增加,碎屑岩粒度变细,储层厚度变薄。马岭油田各探区储层物性受物源影响,近物源区如北区、南区、镇原区的储层物性较好。上里塬区位于河流下游区,碎屑岩粒度细,储层物性较差。研究区储层的成岩作用程度较低,压实作用和胶结作用使储层物性变差,溶蚀作用则改善了储层物性。     

鄂尔多斯盆地侏罗系直罗组砂岩发育特征

根据岩性旋回结构,在全盆地范围将直罗组划分为上、下两段。分段制图表明,直罗组上、下段地层厚度展布规律与全组厚度展布规律基本一致,均表现为西厚东薄;上段地层较下段厚。下段砂岩层数少、单层厚度大;而上段砂岩以层多、层薄为特点。直罗组砂岩总体成熟度较低,区域制图和碎屑组分等反映周缘存在多个源区。砂岩粒度分布表现为河道和分流河道等沉积特征。直罗组砂岩发育多种反映陆上河流沉积环境的层面和层理构造。综合分析认为,在今残留盆地范围内,直罗组下段以辫状河、曲流河沉积为主,东北部可见三角洲平原沉积。上段以辫状河、曲流河、三角洲和湖泊沉积为主。直罗组下段辫状河道砂岩具有良好的渗透性、连通性和成层性,是砂岩型铀矿和石油的良好储层。
     

Factors Controlling Hydrocarbon Accumulation in Jurassic Reservoirs in the Southwest Ordos Basin,NW China

The sedimentary, paleogeomorphological and reservoir characteristics of the Jurassic Yan’an Formation in the southwestern Ordos Basin, northwestern China, were studied by means of casting thin sections, scanning electron microscopy, inclusion analysis and identification of low-amplitude structures. A model for reservoir formation is established, and the controlling effects of sedimentary facies, paleotopography, low-amplitude structures and formation water on oil reservoirs are revealed. There are significant differences in the sedimentary characteristics, structural morphology and paleowater characteristics between the reservoirs above the Yan 10 Member and those in the Yan 9 to Yan 7 Members. The Yan 10 Member contains fluvial sediments, whereas the Yan 9 to Yan 7 members contain delta-plain anastomosing-river deposits. The distribution of high-permeability reservoir is controlled by pre-Jurassic paleogeomorphology and sedimentary facies. Some of these facies exhibit high porosity and high permeability in a lowpermeability background. The main hydrocarbon accumulation period was the late Early Cretaceous, filling was continuous, and the charging strength altered from weak to strong and then from strong to weak. The Yan 10 reservoir is mainly controlled by the paleogeomorphology: hydrocarbons migrated upward at a high speed through the unconformity surface, and accumulated in the favorable traps formed by paleogeomorphic structural units, such as gentle slopes or channel island. Furthermore, groundwater alternation in these areas was relatively stagnant, providing good reservoir preservation conditions. The reservoirs in the Yan 9 and higher members are controlled by the sedimentary facies, lowamplitude structure and paleowater characteristics. Hydrocarbons migrated through the three-dimensional delivery system, influenced by favorable sedimentary facies and high-salinity groundwater, then accumulated in the favorable low-amplitude structural traps that formed during the hydrocarbon production period.     

鄂尔多斯盆地东北部塔然高勒地区还原介质对砂岩型铀矿的控制

为明确鄂尔多斯盆地塔然高勒地区直罗组、延安组地层中煤、黄铁矿等还原介质与砂岩型铀矿的共存关系,选取直罗组含矿砂体及其中的黄铁矿、炭屑以及延安组煤层等为研究对象,综合利用钻孔编录、显微镜和电子探针分析等手段开展研究。结果表明,研究区铀矿体与延安组煤层、直罗组炭屑具有空间和成因上的关联,延安组煤层为铀的沉淀提供了大量的还原剂,而直罗组炭屑里的腐植酸对铀酰离子起到吸附和络合的作用;铀石是该区最主要的铀矿物类型,其与莓球状黄铁矿、蚀变黄铁矿、胶状黄铁矿、钛铁矿、白钛石伴生关系明显;有机质、黄铁矿等还原介质的含量及空间分布可以作为铀成矿的指示标志。     

甘肃宝积山盆地中侏罗世植物群特征及古生态、古气候研究

本文对甘肃宝积山盆地窑街组植物大化石进行了系统研究,经鉴定共有19属50种,结合已有的宝积山盆地中侏罗世植物化石资料,发现甘肃宝积山盆地中侏罗世植物群由27属73种组成。其中,银杏类植物10属30种,真蕨类植物5属26种,松柏类植物5属6种,楔叶类植物3属5种,苏铁类植物2属4种,裸子植物球果和种子化石2属2种。基于当前植物群组成特征,对植物化石埋藏学特性进行分析,确定植物化石主要为原地埋藏或亚原地埋藏,少数属种为异地埋藏,并通过对化石类群古生态特征进行分析,结合现生植物的生存环境,初步重建了宝积山盆地中侏罗世植物群落,划分为四个植物群落:岸边—湿地楔叶类植物群落、低地蕨类—苏铁类植物群落、坡地银杏类植物群落和高地松柏类植物群落。通过对植物群组成特征和植物化石叶相特征的统计分析,并与其他气候带植物群特征进行对比,推断中侏罗世时期甘肃宝积山盆地为温暖潮湿的暖温带气候。     

利用露头、井震及地球化学综合厘定层序界面

侏罗系为鄂尔多斯盆地主要的含煤和含铀岩系,目前对侏罗系层序界面的识别主要依靠野外露头、录井岩性等进行宏观厘定,但在宏观特征无明显差别的地层中,层序界面厘定往往存在人为经验识别的随意性。为此,通过东北缘露头剖面和近千口钻孔电测曲线等常规识别工作,综合二维地震剖面和化学蚀变指数（CIA）垂向上的变化,在鄂尔多斯盆地东北缘侏罗系中识别出3个长期旋回层序界面（TSB1—TSB3）和7个中期旋回层序界面（SB1—SB7）。由于CIA垂向上的变化反映了延安组和直罗组沉积期古气候环境的变化,可将其用于层序界面厘定。综合识别层序界面不仅可以提高识别的准确性,而且可以赋予关键层序界面古沉积环境属性,减弱人为经验识别的影响,从而为整个盆地侏罗系层序地层的划分对比提供可靠依据。     

Two New Species of Protocedroxylon Gothan (Pinaceae) from the Middle Jurassic of Eastern Inner Mongolia, NE China

Two new coniferous wood taxa, Protocedroxylon zhangii sp. nov. and P. zhalantunense sp. nov., are described from the Middle Jurassic Wanbao Formation in Zhalantun City, Inner Mongolia, NE China. The new discovery represents the first record of petrified wood in the Wanbao Formation, and contributes to further understanding the floral composition, especially that of the forest, of the Wanbao Formation. Anatomically, the two new species are characterized by having a mixed type of radial pitting and Abietineentüpfelung. In extant conifers, Abietineentüpfelung is considered to be characteristic of the wood of Pinaceae. The new discovery further indicates that the first occurrence of Abietineentüpfelung in conifer-like wood should be earlier than the Kimmeridgian. The palaeolatitudinal distribution pattern of Protocedroxylon indicates that the genus is a palaeobiogeographically consistent group, which was probably restricted to wetter and cooler temperate climates. In combination with distinct growth rings, the occurrence of Protocedroxylon suggests that a cool temperate and seasonal climate might have prevailed during the sedimentation period of the Wanbao Formation in eastern Inner Mongolia, NE China. Such a view is also in agreement with the palaeoclimatic conditions indicated by the plant megafossils of the Wanbao Formation.     

Detrital-zircon geochronology of the Jurassic coal-bearing strata in the western Ordos Basin,North China: Evidences for multi-cycle sedimentation

The western Ordos Basin(WOB), situated in a tectonic transition zone in the North China Craton, acts as an excellent example for studying the Mesozoic intraplate sedimentation and deformation in Asia. In this study, U-Pb ages for 1203 detrital zircons of 14 sandstone samples collected from 11 sections are presented to unravel the sediment source locations and paleogeographic environments of the Early-Middle Jurassic coal-bearing Yan'an Formation in the WOB. Data show that there are five prominent age groups in the detrital zircons of the Yan'an Formation, peaking at ca. 282 Ma, 426 Ma, 924 Ma, 1847 Ma, and2468 Ma. Samples from the northern, middle, and southern parts of the WOB contain these five age categories in various proportions. In the northern region, the Yan'an Formation exclusively contains Early Permian detrital zircons with a single age group peaking at 282 Ma, matching well with the crystallizing ages of the widespread Early Permian granites in the Yinshan Belt to the north and the Alxa Block to the northwest. While in the southern region, the Yan'an Formation mainly contains three groups of detrital zircons, with age peaks at 213 Ma, 426 Ma, and 924 Ma. These zircon ages resemble those of the igneous rocks in the Qilian-Qinling Orogenic Belt to the south-southwest. Samples in the middle region, characterized by a mixture age spectrum with peaks at 282 Ma, 426 Ma, 924 Ma, 1847 Ma and 2468 Ma, are previously thought to have mixed derivations from surrounding ranges. However, by referring to the detrital-zircon age compositions of the pre-Jurassic sedimentary successions and combining with paleontological and petrographic analysis, we firstly propose that the sediments of the Yan'an Formation in the middle region were partly recycled from the Triassic and Paleozoic sedimentary strata in the WOB.The occurrence of recycled sedimentation suggests that the Late Triassic-Early Jurassic intraplate compressional deformation was very intense in the WOB, especially for regions in front of the Qilian Orogenic Belt.