Preliminary study on Late Triassic to Early Jurassic strata and floral variation in Hechuan region of Chongqing,southern Sichuan Basin

The end-Triassic mass extinction event is extensively known, however, the terrestrial response of this event is still poorly understood. Here we briefly report our preliminary results on the variation of floral diversity through the Triassic/Jurassic boundary deposits in the Tanba section of Hechuan region, Chongqing, southern China. It is recognized that the floral biodiversity of the Hechuan region shows a distinct change through the Triassic and Jurassic transition; and the floral diversity loss reaches up to 92 5% at species level. Meanwhile, in northeastern region of the Sichuan Basin, the floral diversity declines by about 50% across the T/J boundary at species level with a remarkable turnover of genera and species. The potential reasons and mechanisms that cause the floral diversity differentiation of the T/J boundary in the Sichuan Basin are briefly discussed in this note.     

Preliminary investigations on fossil diversity variation of Mesozoic Marattialean ferns in China

The Marattiales is one of the oldest lineages of vascular plants with extensive fossil records dated back to the Carboniferous. Understanding the fossil diversity variation and distribution pattern is helpful for exploring the evolutionary history of this fern group. In this work, the preliminary analysis of diversity change and distribution of the Mesozoic Marattialean fossil records in China are reported covering the Triassic and Jurassic periods based on available published data. In addition, a brief discussion is made regarding to the potential causes for these variation and distribution of this fern group.     

Sedimentological features and biostratigraphy of Jurassic/Cretaceous deposits in continental basins in Priamurie, Far East Russia

The paper describes the sedimentary features and biostratigraphy of the transitional Jurassic to Cretaceous deposits in the continental basins of Priamurie formed after the collision between the Siberian and North China blocks. In Upper Priamurie, the collision occurred in the late Early Jurassic as dated by the emplacement of the post-collisional granites (191Ma) . While in Lower Priamurie and West Priokhotie it could take place in the late Middle Jurassic on the basis of fossil evidence from an accretionary turbidite complex. This event reflected the environmental change from coastal-marine to alluvial plains, often boggy, where coals accumulated. The environmental change is in harmony with that of biota. Systematic study of floral and spores/pollen assemblages, particularly in the sections of interbedded marine and non-marine deposits, makes clear the chronostratigraphic succession of floral associations and shows the possibility of their application for subdivision and correlation of the continental deposits of Priamurie. The coastal-marine environment of the residual post-collisional sublatitudinal basins in the western part of Priamurie (Upper Amur and Dep basins) was replaced by the continental in the late Middle Jurassic and in the eastern part in the Berriasian-Valanginian ( Torom Basin) . Similar environmental change commenced in the submeridional rift basins: the Bureya Basin in the Callovian and the Partizansk Basin in the Hauterivian. Changes in ecosystems occurred frequently during theMiddle Jurassic-Neocomian, but the most substantial changes took place in the late Middle Jurassic and in the end of Late Jurassic.     

Preliminary investigations on fossil diversity variation of Mesozoic Marattialean ferns in China

The Marattiales is one of the oldest lineages of vascular plants with extensive fossil records dated back to the Carboniferous. Understanding the fossil diversity variation and distribution pattern is helpful for exploring the evolutionary history of this fern group. In this work, the preliminary analysis of diversity change and distribution of the Mesozoic Marattialean fossil records in China are reported covering the Triassic and Jurassic periods based on available published data. In addition, a brief discussion is made regarding to the potential causes for these variation and distribution of this fern group.     

塔里木盆地库车坳陷东部上三叠统—中侏罗统物源特征及其地质意义

根据砂岩岩石薄片、石英阴极发光和重矿物组合分析,结合沉积构造及地震解释成果,对塔里木盆地库车坳陷东部上三叠统—中侏罗统物源体系及其演化进行详细分析,确定了物源方向及母岩性质。结果表明:塔里木盆地库车坳陷东部上三叠统—中侏罗统物源主要来自北部南天山造山带物源区,以岩浆岩和变质岩母岩为主,兼有少量沉积岩物源的影响。其中,塔里奇克组砂岩中陆源碎屑岩岩屑含量较高,阴极发光条件下不发光石英含量较高,重矿物组合具有高锆石、白钛矿和磁铁矿含量以及低石榴子石含量的特征,母岩可能为上奥陶统—上三叠统早期沉积;阿合组及阳霞组砂岩中岩浆岩岩屑含量升高,重矿物组合以较高的石榴子石含量为特征,阴极发光条件下石英主要为蓝紫色及棕褐色发光,其母岩主要来自二叠系及其下伏地层;克孜勒努尔组及恰克马克组砂岩中变质岩岩屑含量明显升高,石榴子石含量极高,阴极发光条件下棕褐色发光石英含量增多,表明变质岩母岩的影响增强。晚三叠世—中侏罗世,研究区物源区母岩演化具有明显规律性,即晚三叠世受较多沉积岩母岩影响,早侏罗世岩浆岩母岩供给增多,中侏罗世以变质岩母岩为主。晚三叠世,库车坳陷东部南天山造山带大幅抬升,导致大量变质岩母岩卷入造山带遭受剥蚀;早—中侏罗世,南天山造山带中段构造活动具有东西分段的特点,吐格尔明30团剖面以东早侏罗世砂岩率先具有高石榴子石含量的特点,而西部地区中侏罗世砂岩才大量出现石榴子石,表明南天山造山带中段的虎拉山及额尔宾山在早侏罗世隆升-剥蚀强烈,而哈尔克山在中侏罗世才进入强烈抬升期。     

准噶尔盆地南缘东段油气成藏条件及成藏模式

准噶尔盆地南缘东段是准噶尔盆地油气勘探的重点地区。以成盆、成烃和成藏理论为指导,应用盆地分析、有效烃源岩评价、储层(裂缝)预测、盆地模拟及流体包裹体分析等技术和方法,综合研究分析了准噶尔盆地南缘东段油气成藏条件,预测了油气资源潜力,建立了油气成藏模式。研究结果表明,该区发育上二叠统、中上三叠统和中下侏罗统三套烃源岩。最主要的烃源岩层为上二叠统,是油气资源分布的主要层位;主要储集层为柴窝堡区块的上二叠统和米泉区块的中下三叠统及中下侏罗统,其物性较差,总体为较好含气储层,是主要的勘探目的层。存在自源(侧向排烃)、它源(垂向排烃)两类油气成藏模式。柴窝堡区块北部和米泉区块仍然是有利的油气勘探地区。     

利用Q型聚类分析研究鄂尔多斯盆地多种能源矿产间的关系

为揭示鄂尔多斯盆地多种能源矿产间的关系,根据盆地石油、油气伴生水以及煤、煤层夹矸、铀矿及围岩样品的氯仿沥青中57种元素的分析结果,进行了Q型聚类分析。结果表明:侏罗系下统延安组石油、侏罗系中统直罗组石油与三叠系延长组石油有相近的成因特征;三叠系延长组石油沥青、三叠系延长组含油砂岩沥青与侏罗系中统直罗组石油沥青具有类似的成因特征;神木侏罗系下统延安组煤沥青、东胜侏罗系中统直罗组煤沥青、铜川陈家山侏罗系下统延安组煤层石油以及铜川陈家山侏罗系下统延安组煤沥青成因特征相近;铜川陈家山侏罗系下统延安组煤层石油沥青可能与准格尔黑岱沟石炭二叠系煤沥青具有成因上的联系;侏罗系下统延安组石油沥青与放射性铀矿的形成具有密切关系;天然气的物质来源复杂,且与石油和煤的进一步演化有一定关系。鄂尔多斯盆地多种能源矿产成因较复杂、相互间关系密切,且具有多源性成藏(矿)特征。     

聚龙山向斜三叠系含水层岩溶发育史及地下水流场控制意义

聚龙山向斜三叠系含水层经历了多期次岩溶综合作用, 其岩溶发育演化规律对于深入认识该地区水文地质条件及分析地下水流场具有重要意义。运用历史比较法, 结合研究区三叠系含水层水化学、同位素、钻孔等资料, 对聚龙山向斜构造演化与岩溶发育史进行了探讨, 进而恢复了地下水流场的演化过程。结果表明, 震旦纪-中三叠世, 研究区构造运动总体表现为垂向上的升降, 沉积的海相地层为岩溶发育提供了物质基础, 但不具备岩溶发育条件, 主要在二叠系茅口组和三叠系嘉陵江组顶面形成古岩溶作用。晚三叠世-早侏罗世, 聚龙山向斜以缓慢隆升为主, 在荆当凹陷的湖盆中相继沉积陆源碎屑, 由于广泛覆盖在碳酸盐岩之上的三叠系巴东组碎屑岩刚接受剥蚀, 导致该时期主要表现为位于水下的埋藏型岩溶。中侏罗世-早白垩世, 燕山运动产生的挤压应力促使研究区形成EW-NW向褶皱、断裂及裂隙, 控制了碳酸盐岩的平面分布格局。部分碳酸盐岩裸露, 岩溶开始发育, 这时期地表水和地下水向荆当凹陷汇集。晚白垩世-古近纪, 随着江汉断陷盆地形成, 盖层巴东组碎屑岩剥蚀线逐渐向南退却, 岩溶发育进一步加强, 产生的老岩溶水系和部分地下水向最低基准面江陵断陷排泄。新近纪以来, 构造运动的间歇性快速抬升使岩溶不断向深部发育, 形成五级岩溶台面和多级地下水流系统, 地表水和地下水最终排泄至长江。地下水流场具有山区到凹陷-断陷盆地-长江的多级次演化机制。      

西准噶尔达拉布特断裂系构造演化特征

呈北东走向横贯于西准噶尔的达拉布特断裂系,是一组倾向北西的犁状断层。断裂系的形成、发育是由于碰撞后的西伯利亚、哈萨克斯坦和塔里木三大陆块在早石炭世以后,仍在不断地相向运动。由此所形成的断裂系,其早期是以左行陡倾的走滑断层形式出现;中期受陆内俯冲作用的影响,被强烈的推覆构造改造成上陡下缓的犁状断层;娩近时期,断裂处于引张状态,表现为正断层性质,形成了明显的断层地貌。     

大巴山弧形构造带中段渔渡地区侏罗纪叠加变形研究

大巴山构造带是秦岭造山带南部发育的一个以逆冲推覆构造为特征的构造带。通过在大巴山弧形构造带中段渔渡地区进行的详细构造解析发现,大巴山构造带在侏罗纪以来经历了至少两期变形叠加,变形地层三叠系嘉陵江组—侏罗系沙溪庙组。早期变形以与滑脱构造相关的轴向北西—北北西向箱状或隔挡状褶皱为主,并在深部发育顺层滑脱构造,变形时代为晚侏罗世到早白垩世。晚期变形与北侧逆冲相关,导致右行走滑变形,主要形成右行走滑断层和北西—北北西向紧闭褶皱,变形时代比第一期稍晚,为晚侏罗世之后到早白垩世。两期变形形成的褶皱延伸方向一致,与区域构造线的方向协调,而且在远离北侧镇巴断裂的地区变形强度有减弱的趋势,两期变形叠加形成共轴或斜交叠加构造。研究表明,变形与大巴山冲断—推覆构造带向南逆冲有关。     

Anomozamites (Bennettitales) from Middle Jurassic Haifanggou Formation,western Liaoning,China

The Middle Jurassic Hangfanggou Formation is well exposed in Shangsanjiao and Xiasanjiao villages area,Baimashi town of Huludao,western Liaoning,China.Recently,abundant fossil plants were collected from the Hangfanggou Formation.One new species,Anomozamites sanjiaocunensis sp.nov.(Bennettitales),is described in this study.This is the first report of the genus Anomozamites from the Haifanggou Formation based upon the leaf morphology and epidermal structures.The discovery of the new species extends significantly the stratigraphic and geographic distribution of Anomozamites in the Middle Jurassic.It also shows that Anomozamites was a common member of Bennettitales once lived in the Middle Jurassic warm temperate region.The new species also improves the knowledge on understanding the leaf morphology,epidermal features and the diversity of Anomozamites during the Middle Jurassic.The epidermal characters of the new species and its associated plants reveal that the plants grew in a warm and moderately humid environment in the warm temperate zone.The presence of some deciduous plants,such as ginkgoaleans,czekanowskialeans and conifers,indicate the climate with seasonal fluctuations in temperature.     

东昆仑地质特征及晚古生代——中生代构造演化

东昆仑造山带是一个经历多期构造活动的复杂造山带,大致划分为昆北花岗岩浆弧带、昆中双型俯冲带、昆南混杂岩带。其地质特征反映了昆中断裂带在历次构造演化中的主导性。。晚元古代华北、华南两大古板块沿昆中断裂一线俯冲碰撞,为后期构造演化奠定了基础。晚古生代—中生代构造演化别具一格。经整体分析、现位恢复,具有泥盆—早二叠伸展滑覆、早二叠纪末—中三叠纪B型俯冲、中三叠纪末—早侏罗纪A型斜向俯冲三个演化阶段。     

通南巴地区地层水演化特征及其油气意义

考虑川东北地层水的水化学特征(包括地层水矿化度、地层水的变质程度、脱硫系数等),根据封盖层的发育分布及其内部结构,分析盖层对地层水的分隔性能;结合区域构造演化史,分析地质历史上地表水对地层水的改造程度,研究地层水演化特征.结果表明:通南巴地区地层水主要经历早期深埋形成封存变质水期—局部地层水渗滤改造期—深层水封闭,浅层水进入开启期—晚期重建封闭期等变化;中下三叠统存在一套良好的膏岩层且埋藏较深,没有经历地表水改造,使得保存条件明显优于上三叠统须家河组及中下侏罗统地层,具有较好的保存条件;砂泥互层具有较高渗透能力的须家河组受到地表水的淋滤作用,油气保存条件较差,油气勘探潜力有限.     

鲁东文登地区文登型(超单元)花岗岩体的SHRIMP锆石年代学

文登岩体主要岩性为不同粒度的二长花岗岩,原划为三叠纪。根据新测的锆石SHRIMP U-Pb年龄为(167±3)Ma,(167±2)Ma,(157.1±1.4)Ma,结合野外接触关系改划为侏罗纪。文登花岗岩体属侏罗纪钙碱系列的侵入体,主要显示长英质陆壳深熔花岗岩的特征。推断其形成于中下地壳深度,可能来源于加厚陆壳的部分熔融,是加厚下地壳的拆沉作用的产物,而且可能标志着中国东部岩石圈减薄的开始。     

龙门山北段天井山构造演化及其对油气聚集的控制

龙门山褶皱冲断带位于四川克拉通以东,被围限在扬子、华北和羌塘三大陆块拼贴构造间.以全工区地震精细解释为基础,结合野外调查,选取近东西向的剖面06fsc0003—02tjs1111线,利用平衡剖面法恢复天井山构造带的造山过程.结果表明:天井山构造带的演化可划分为伸展拉张成盆阶段(震旦纪—中三叠世末)、陆隆伸展演化阶段(晚三叠世—中侏罗世末)、挤压抬升剥蚀阶段(晚侏罗世—现今)3期.根据生储盖组合和油气运移条件,认为自元古代以来最大主应力性质发生多次改变,控制构造变形、生储盖组合分布及厚度、断裂特征和油气运聚.印支期冲断带下盘(现今天井山背斜前翼下部)发育形成于印支期晚期的冲起构造,其内断层发育,将二叠系、志留系及寒武系烃源岩与二叠系储层和圈闭串通,有利于烃类的运聚,且有飞仙关组泥岩作为直接盖层,保存条件较好,是油气集聚的有利部位.该研究能够加深对龙门山褶皱冲断带油气分布预测的认识,对油气勘探具有指导意义.     

The Formation, Movement and Evolution Pattern of Jurassic Terrestrial Deposit Basin in Daqingshan Region

The authors have reconstructed the original shape of Jurassic basin in Daqingshan region and discussed the movement and evolution pattern of the basin. The basin developed between Paleozoic strata sliver and metamorphic rock sliver in late stage of Early Jurassic and extended in latitude direction. The palco - terrene of the basin is higher in north and west than south and east. The boundary of basin is largest in Changhangou stage of Middle Jurassic. After middle Jurassic, the region took place Yenshan movement, and then the basin changed obviously from weakly extending environment of Early and Middle Jurassic to extruding environment of late Jurassic, and the paleoclimate of the basin changed from warmth and wetness to dry. The basin finished the evolution history in the late stage of Late Jurassic with the development of thrust.     

下侏罗统辛涅缪尔阶—普林斯巴阶界线地质事件研究进展

早侏罗世经历了赫塘期、辛涅缪尔期、普林斯巴期和土阿辛期, 其中土阿辛期大洋缺氧事件(T-OAE)被广泛研究。但在辛涅缪尔阶-普林斯巴阶界线处, δ13C_org及δ13C_carb曲线均发生负偏, 局部伴随黑色页岩沉积。其在英国、法国、意大利、葡萄牙以及中国等地区都有记录, 碳同位素的变化伴随着环境、气候的变化, 研究显示该事件可能是全球性的, 被称为“S-P界线事件”(SPBE)。此次地质事件与T-OAE事件类似, 也显示了一次大洋缺氧事件, 其发生时有轻碳同位素被排入了大气系统中, 但是轻碳同位素的来源尚不明确, 部分学者认为是大火成岩省喷发时排放的轻碳物质注入了海洋-大气系统所致。目前对该事件的研究主要集中于欧洲海相地层, 其对陆地生态系统的影响还知之甚少。我国四川盆地下侏罗统湖相沉积发育良好, 下侏罗统自流井组东岳庙段沉积有与大安寨段(T-OAE发生层段)类似的黑色页岩及介壳灰岩, 其有机碳同位素负偏, 显示了S-P界线事件的影响, 其与T-OAE类似也对四川盆地早侏罗世古湖泊产生了影响。      

广西西湾煤系首次发现牙形刺及其地层意义

西湾煤系是广西重要含煤层位之一,以碳酸盐岩夹煤层为特征,自下而上分天堂组和大岭组,主要煤层赋存于大岭组中。煤系时代有晚三叠世与早侏罗世之争。1988年笔者之一冯少南,曾报道了天堂组产植物化石Danaeopsis fecunda Halle,为煤系时代归属提供了重要古生物依据。今年笔者在大岭组的灰岩中分析出牙形刺,认为大岭组的时代应属晚三叠世,并进一步说明大岭组为潮坪泻湖→滨海沼泽相沉积。     

豫西济源——义马盆地早中生代湖泊沉积体系的演化

豫西济源—义马盆地早中生代地层谭庄组中上段（Ｔ３）和鞍腰组（Ｊ１）是典型的湖泊体系沉积。谭庄组沉积期湖泊相对较浅,受气候控制。由于受季风环流的影响,推测晚三叠世晚期的季节性更强。在三叠纪末—早侏罗世,发生了走滑构造作用。鞍腰组沉积期为走滑引张体制下的湖泊,水体较深,反映了构造沉降的开始。在随后的走滑挤压阶段,该湖泊为三角洲和河流相碎屑沉积物充填。     

鄂尔多斯盆地地层埋藏演化与油气成藏分析

地层埋藏状况对有机质生烃及油藏保存具有重要的控制作用.通过对鄂尔多斯盆地晚三叠世以来地层埋藏史和有机质热演化生烃史的恢复,对比盆地不同地区之间地层剥蚀和埋藏特点,探讨地层埋藏演化特征对油气成藏的影响,分析地层埋藏对有机质生烃及油藏保存条件的影响.结果表明:在鄂尔多斯盆地晚三叠世以来经历的4期(T3、J1、J2、K1)沉降—抬升循环演化过程中,不同地区的沉积埋藏深度和埋藏速率存在明显差异.一方面导致各地区间长7烃源岩进入生烃的时间提前或滞后.北部古峰庄地区和中部白豹地区在J2期已进入早期生烃,姬塬和镇北地区在J3期进入早期生烃,而南部西峰、洛川地区和东部陕北地区早期生烃的时间是K1早中期.进入大量生烃阶段的时间基本都在K1期.另一方面导致地区间成藏封存条件的变化.在北部和中南部地区,地层埋藏深度大,沉积速率高,形成很好的封闭条件.各生烃阶段,特别是早期生成油气也可很好地保存而成藏.