豫西栾川潭头盆地白垩纪－古近纪古气候研究

豫西栾川潭头盆地是一个晚白垩世—古近纪陆相沉积盆地,沉积了一套以红色碎屑岩为主的晚白垩世-古新世地层。本文以孢粉分析为主,综合区内古生物学、岩石学、沉积学等古气候标志,认为研究区高峪沟组下段沉积时期属半干旱的热带气候;上段下部沉积时期为半干旱半湿润的亚热带-热带气候;上段上部沉积时期为半湿润的亚热带气候。大章组底部沉积时期属半湿润的暖温带气候。根据区内古气候特征及化石资料分析认为,研究区K/E界线位于高峪沟组上段的上部与下部之间。     

札达盆地构造旋回层及其地质意义

札达盆地位于青藏高原南西部,其北东和南西侧分别为阿依拉日居和波林断裂系所限.在盆地内沉积了一套上新世-更新世地层,从下至上可分四段,上部为湖相泥岩段,下部三段代表了三个构造沉积旋回,它们有类似的沉积特征,即:每段下部为辫状河沉积的砾岩层,中部主要为曲流河沉积的砂岩层,并逐渐过渡到上部湖相泥岩.旋回沉积特征和地层变形反映了本区从上新世以来处于挤压状态,并有强烈垂向运动,为青藏高原在近几个百万年来持续隆升提供了依据.     

梅河盆地古近系梅河组沉积层序演化特征

梅河盆地为典型的断陷型含煤、油页岩盆地。通过岩芯、测井和地震的层序标志识别,在梅河盆地梅河组识别出1个巨层序、2个超层序和4个三级层序。其中,砂砾岩段、下部含煤段、中部泥岩段、上部含煤段分别对应着三级层序I、II、III和IV。通过对层序地层格架的认识,结合构造、沉积分析,揭示了研究区梅河组沉积层序演化规律,三级层序地层格架内沉积演化分别为:层序I发育了盆地初始裂陷阶段的冲积型和扇三角洲沉积;层序II发育了盆地裂陷扩张阶段扇三角洲、沼泽和浅水湖泊沉积;层序III发育了盆地最大扩张阶段深水湖泊沉积;层序IV发育了盆地萎缩阶段扇三角洲和湖泊沉积。因此,梅河盆地梅河组的层序I到层序IV的演化揭示了中国东部伸展环境下断陷盆地从初始裂陷阶段到盆地萎缩阶段完整的不同沉积层序演化特征。     

安徽巢湖二叠系栖霞组碳酸盐岩斜坡沉积

长期以来,人们均认为下扬子地区广泛发育的栖霞组碳酸盐岩属于浅海碳酸盐岩台地沉积。但以巢湖地区为例研究表明,栖霞组主要为碳酸盐岩斜坡沉积。碳酸盐岩碎屑流沉积物形成了臭灰岩段和顶部灰岩段的层状石灰砾岩,分布于斜坡上部;等深流沉积物形成了上、下硅质层段的砂屑硅质粒泥灰岩,主要分布于斜坡下部。而上、下硅质层段中的钙、硅质页 (泥 )岩属于斜坡远端和盆地沉积;唯有本部灰岩段可能属于浅海碳酸盐岩台地沉积。这一认识不仅突破了传统观念,而且有助于重新认识下扬子板块二叠纪的古地理特征和盆地构造演化。     

金宝屯盆地晚侏罗世含煤地层沉积环境

金宝屯盆地是一中生代内陆盆地。含煤地层为上侏罗统协尔苏组,主要由灰绿色、灰色砾岩和砂岩,灰黑色、黑色细砂岩和粉砂岩、泥岩及灰白色中—粗砂岩组成,平均厚110m。区内不同沉积环境,出现在盆地演化的不同阶段和盆地的不同部位。下部砾岩段沉积期以冲积扇环境为主;含煤段沉积期为冲积扇-河流-湖泊环境组合;成煤后演化为曲流河环境;上部砂岩砾岩段沉积期以辫状河沉积为主。聚煤作用发育于盆地中的湖泊分布区,发生于盆地快速沉降之后的整体稳定、缓慢沉降阶段的早期,煤层直接覆于湖相厚层泥岩之上。盆地仅经历了一个快—慢沉降旋回,煤层的形成受控于这种“无振荡聚煤作用”。     

松辽盆地三肇凹陷青一段多边形断层的发育及其油气地质意义

松辽盆地青一段发育大量密集分布的小型张性断层系,其成因一直以来颇受争议。本文选取松辽盆地三肇凹陷为研究区,通过新连片三维地震剖面精细解释及沿层相干切片分析等手段,详细描述了三肇凹陷青一段密集张性断裂系统的剖面和平面特征,提出:1青一段张性断裂系主体为非构造成因的多边形断层,其成因可能是由青山口组青一段泥岩超压幕式排烃破裂所导致,同时盆地构造反转活动对断层发育特征具有重要影响;2凹陷内多边形断层主要发育于嫩江组沉积末期,明水组沉积末期盆地强烈构造反转致使早期形成的多边形断层再活动,且对部分多边形断层的发育进行改造;3多边形断层起到沟通青一段烃源岩和分别位于其上部与下部的葡萄花、扶杨2个油气储层的作用,是凹陷内油气成藏的重要运移通道;4嫩江组沉积末期,超压使油气通过多边形断层从青一段短距离向下部扶杨储层"倒灌"运聚成藏;明水组沉积末期,超压导致油气沿重新开启的多边形断层向上部葡萄花储层或向下部扶杨储层运移聚集形成油气藏,同时垂向延伸较长的多边形断层对下部扶杨油藏可能具有一定的破坏作用。     

松辽盆地东缘岳王城剖面嫩江组二段生物地层及其对湖侵事件的响应

松辽盆地嫩江组二段下部沉积期发生了大规模的湖侵事件,在整个盆地范围形成一套黑色泥页岩夹油页岩。然而,前人对嫩江组二段的地层及相关地质事件的研究主要基于井下岩心,地表露头不多见。通过调查,在松辽盆地东缘农安县青山口第二松花江沿岸发现一新的剖面——岳王城剖面,出露连续的嫩江组一段顶部—二段下部地层。通过对该套地层进行厘米级的描述和详细的分层,将该剖面地层划分为24层,累计厚度31.54m。第1层为嫩江组一段顶部,为青灰色砂质泥岩,含少量介形类化石;第2~24层为嫩江组二段下部,主体为暗色泥页岩夹油页岩、泥灰岩等,含丰富的介形类、叶肢介、鱼类,少量有孔虫及其他生物。此外,在嫩江组底部还发现一层火山灰和一层磷块岩。对其中的介形类化石进行初步研究,识别出11属18种。通过介形虫古生态和沉积学研究,并结合其他手段,初步探讨了该沉积期的湖泊环境,认为嫩二段下部沉积期经历了一次大规模湖侵,从一段顶部的滨浅湖过渡为二段下部的深湖环境,之后湖平面在波动中逐渐下降。     

东营凹陷沙河街组湖相碳酸盐岩碳氧同位素组分及其古湖泊学意义

湖相碳酸盐岩的碳、氧稳定同位素分析能提供重要的环境信息。山东东营凹陷沙河街组湖相碳酸盐岩主要分布在沙一段和沙四段。对47个碳酸盐岩样品碳、氧同位素组分的分析表明:沙一段、沙四中和沙四上亚段下部沉积时期东营湖均是程度不同的封闭型湖泊。古盐度和蒸发／降雨:沙四中亚段和沙四上亚段下部沉积时期＞沙一段沉积时期＞沙四上亚段上部沉积时期;古湖水面:沙四上亚段上部沉积时期＞沙一段沉积时期＞沙四中亚段和沙四上亚段下部沉积时期;古生产力:沙一段沉积时期＞沙四上亚段上部沉积时期＞沙四中亚段和沙四上亚段下部沉积时期。     

准噶尔盆地中部下侏罗统三工河组二段沉积相及储层特征

准噶尔盆地中部下侏罗统三工河组二段广泛发育三角洲相。二段下部在研究区东北部以大型辫状河三角洲前缘沉积夹滑动浊流沉积为特征,西部以扇三角洲沉积为特征,在中部两者交汇叠加。二段上部在东北部和西部都为曲流河三角洲前缘亚相沉积,在区中部交汇叠加。三工河组二段砂岩发育大量原生孔隙和次生孔隙,为有利储层。沉积微相类型控制砂体储集性能,成岩作用对砂岩储集性的改造并不强烈。二段下部的辫状河三角洲前缘河道微相及扇三角洲前缘河道微相具有大孔中渗的特点,为Ⅰ、Ⅱ类储层;上部的曲流河三角洲前缘分支河道及前缘席状砂微相,具中孔中、低渗的特点,为Ⅱ和Ⅲ类储层。     

北羌塘盆地沃若山地区中—下侏罗统雀莫错组一段沉积环境分析

北羌塘盆地沃若山地区中—下侏罗统雀莫错组一段主要为一套碎屑岩沉积,主要岩性包括紫红色含砾砂岩?中—细砂岩和泥质粉砂岩,形成于氧化环境?通过对雀莫错组一段碎屑岩岩性特征?沉积构造?概率累积曲线?萨胡判别式?粒度参数散点图和C-M图等分析表明,雀莫错组一段砂岩分选性较差,在概率直方图上多表现为双峰或多峰,概率累积曲线主要为“两段式”,少见“三段式”,跳跃总体含量较高,滚动总体和悬浮总体较少?在Sk-σi散点图中,雀莫错组一段的砂岩均落入河砂范围内;在C-M图上表现为PQ段发育,QR段次之,为一套典型的河流相沉积?雀莫错组的沉积从河流-冲积扇相开始,之上为三角洲相和局限台地相沉积,总体上表现为逐渐变深的海侵序列?     

Early Cretaceous sedimentary evolution of the northern Lhasa terrane and the timing of initial Lhasa-Qiangtang collision

Lower Cretaceous strata in the Baingoin basin of the northern Lhasa terrane record initial collision between the Lhasa and Qiangtang blocks, followed by the early uplift of central Tibet. North-south traverses across the Baingoin basin highlight major differences between the Duba Formation in the north and the quasi-coeval Duoni Formation in the south. The Duba Formation documents upward transition from shallow shelf and deltaic environments to coarse-grained siliciclastic fluvial sedimentation. Abundance of detrital zircons yielding Jurassic-Cretaceous ages with εHf(t) values mainly between −2 and +10, occurrence of chert, Cr-spinel, and pyroxene grains, together with southward paleocurrent directions indicate that the Duba Formation was sourced from the southern Qiangtang terrane and Bangong-Nujiang suture zone to the north. The Duoni Formation in the south was deposited in shelfal to fan-delta and fluvial environments. Abundant volcanic clasts, detrital zircons yielding Cretaceous ages with mainly negative εHf(t) values, and northward paleocurrents indicate an active volcanic source located in the central Lhasa terrane to the south, with minor input from the northern Lhasa terrane. Only the northern part of the Baingoin basin was directly controlled by the Lhasa-Qiangtang collision and may thus be considered a peripheral foreland basin, whereas the southern part was mainly influenced by tectonic processes related to the northward subduction of Neotethyan lithosphere, and may thus be comparable to a retroarc foreland basin. But these sedimentary features and the 139–79 Ma Baingoin plutonic intrusion do not fit well with classical foreland-basin models. Zircon chronostratigraphy constrains the final consumption of Bangong-Nujiang oceanic lithosphere and initial collision between the Lhasa and Qiangtang microcontinents to have taken place by 122 Ma, which has major implications for paleotectonic reconstructions of the Tibetan Plateau.     

西藏那曲地区流纹岩LA-ICP-MS锆石U-Pb年龄和地球化学特征

对西藏那曲地区的中—晚侏罗世拉贡塘组流纹岩进行LA-ICP-MS锆石U-Pb测年,得出该流纹岩的时代为116.6Ma±0.81Ma,属早白垩世,与区域上多尼组和则弄群的时代一致,属同一地质事件的产物,说明该火山岩不属拉贡塘组,应不整合于拉贡塘组之上。流纹岩SiO2含量均值为71.01%,富集Rb、Th元素,亏损P、Eu、Ti元素,εHf（t）值集中在-0.030～2.277之间,平均值为0.75,对应的两阶段模式年龄为682～782Ma和1015～1175Ma,大于流纹岩的形成时代。流纹岩具同碰撞型火山岩的特征,不具传统岛弧环境的特征,构造环境可能存在两种可能：班公湖-怒江特提斯洋俯冲已经结束,进入陆-陆碰撞阶段,羌塘地块和拉萨地块开始碰撞;班公湖-怒江洋还未完全关闭,残留洋与拉萨地块发生碰撞。在碰撞的过程中,下地壳不断加厚并发生部分熔融形成酸性流纹岩。     

Early–Middle Jurassic evolution of the northern Yangtze foreland basin: a record of uplift following Triassic continent–continent collision to form the Qinling–Dabieshan orogenic belt

The northern Yangtze foreland basin system was formed during the Mesozoic continental collision between the North and South China plates along the Mianlue suture. In response to the later phase of intra-continental thrust deformation, an extensive E–W-trending molasse basin with river, deltaic, and lake deposits was produced in front of the southern Qinling–Dabieshan foreland fold-and-thrust belt during the Early–Middle Jurassic (201–163 Ma). The basin originated during the Early Jurassic (201–174 Ma) and substantially subsided during the Middle Jurassic (174–163 Ma). A gravelly alluvial fan depositional system developed in the lower part of the Baitianba Formation (Lower Jurassic) and progressively evolved into a meandering river fluvial plain and lake systems to the south. The alluvial fan conglomerates responded to the initial uplift of the southern Qinling–Dabieshan foreland fold-and-thrust belt after the oblique collision between the Yangtze and North China plates during the Late Triassic. The Qianfoya Formation (lower Middle Jurassic) mainly developed from shore-shallow lacustrine depositional systems. The Shaximiao Formation (upper Middle Jurassic) predominantly consists of thick-bedded braided river delta successions that serve as the main body of the basin-filling sequences. The upward-coarsening succession of the Shaximiao Formation was controlled by intense thrusting in the southern Qinling–Dabieshan fold-and-thrust belt. Palaeogeographic reconstructions indicated an extensive E–W foredeep depozone along the fold-and-thrust belt during the Middle Jurassic (174–163 Ma) that was nearly 150 km wide. The depozone extended westward to the Longmenshan and further east to the northern middle Yangtze plate. The northern Yangtze foreland basin was almost completely buried or modified by the subsequent differential thrusting of Dabashan and its eastern regions (Late Jurassic to Cenozoic).     

西藏安多地区粗面岩的特征及其锆石SHRIMP U-Pb定年

安多粗面岩位于班公湖-怒江缝合带中段,紧邻安多蛇绿岩带的北侧,出露面积约30km2,堆积厚度约1500m,属陆相火山岩。火山机构面貌保存较完整。岩石类型包括安粗岩、石英安粗岩、粗面岩及少量火山碎屑岩,以粗面岩为主,属钾玄岩系列。岩石地球化学和同位素示踪特征表明岩石属相对高压型的粗面岩,是与大陆碰撞后造山有关的钾质火山岩。岩浆主要来源于加厚的陆壳下部,但也有幔源组分的贡献。粗面岩中锆石SHRIMP U-Pb年龄为79.9Ma±1.9Ma,是粗面质岩浆上侵结晶的年龄,表明安多粗面岩的喷溢时代为晚白垩世, 也暗示班公湖-怒江洋盆安多段早白垩世晚期已经闭合,晚白垩世时期羌塘地块与拉萨地块已成为统一的陆块,并具有加厚的陆壳。     

西藏南部聂拉木地区侏罗纪—白垩纪盆—山转换过程中的沉积学响应

西藏南部聂拉木—定日地区沉积地层记录着侏罗纪被动大陆边缘到白垩纪前陆盆地的盆—山转换演化历史。侏罗纪发育巨大的海侵—海退沉积序列，晚侏罗世喜马拉雅特提斯海底扩张速度明显加快，从0.32 cm/a上升为1.24 cm/a。前陆盆地演化分为早期深水复理石和晚期海相磨拉石两个阶段。前陆早期发育向上急剧加深的深水砂泥质复理石建造、黑色页岩建造和岛弧型火山岩建造沉积；前陆晚期海相磨拉石沉积总体表现为向上变粗、变浅的沉积序列。     

Sedimentary history of the Tethyan basin in the Tibetan Himalayas

After an epicontinental phase, the sedimentary rocks in the Tibetan Himalayas document a complete Wilson cycle of the Neo-Tethyan (Tethys Ill) evolution between the Gondwana supercontinent and its northward drifting margin (Lhasa block) from the Late Permian to the Eocene.During the Triassic rift stage, the basin was filled with a huge, clastic-dominated sediment wedge with up to > 5 000 m of flysch in the northern zone. Widespread deltaic clastics and shallow-water carbonates of late Norian to earliest Jurassic age in the southern zone mark, in conjunction with decreasing tectonic subsidence, the transition to the drift stage.Some 4 500 m of Jurassic and Early Cretaceous shallow-water carbonates and siliciclastics accumulated on the Tethyan Indian passive margin. Deepening-upward sequences with condensed beds at their tops alternate with repeated progradational packages of shelf sediments. Extensive abyssal sediments with basaltic volcanics in the northern deep-water zone reflect continued ocean spreading and thermal subsidence. Paleomagnetic data, gained separately for the northern Indian plate and the Lhasa block, indicate that the Neo-Tethys reached its maximum width about 110 Ma ago with a spreading rate of 4.8 cm/year, before it commenced to close again.During the remnant basin stage in the Late Cretaceous and Paleogene, a shallowing-upward megasequence, capped by a carbonate platform, developed in the southern inner shelf realm. In the northern slope/basin plain zone, turbidites and chaotic sediments, derived from both the acretionary wedge and the steepening slope of the passive margin, accumulated. The depositional center of the remnant basin shifted southward as a result of flexural subsidence and southward overthrusting.The sediments from the Triassic to the Paleogene are tentatively subdivided into five mega-sequences, which are controlled mainly by regional tectonics. Climatic influence (e.g., carbonate deposition), due to northward plate motion, is partially subdued by terrigenous input and/or increased water depth. During the Oligocene and Miocene, crustal shortening led to rapid uplift and the deposition of fluvial molasse in limited basins.     

库车新生代构造性质和变形时间

库车构造位于南天山古生代碰撞造山带之南,为塔里木盆地最北的一个构造带。它自北而南可分为边缘逆冲（ 隐伏构造楔） 、斯的克背斜带、北部线性背斜带、拜城盆地、南部背斜带。每个背斜带又包含有若干逆冲断层相关褶皱,它们是断层转折褶皱、断层传播褶皱、滑脱褶皱、断层传播 滑脱混生褶皱、双重逆冲构造、突发构造、三角带构造。底部逆冲断层向南变浅,堆叠逆冲岩席向南变薄,总体上形成一个向南的逆冲构造楔。逆冲断层在斯的克背斜带侵位最早（２５ Ｍａ） ,在北部线性背斜带为１６９ Ｍａ,拜城盆地中的大宛其背斜为３６ Ｍａ,南部背斜带为５３ Ｍａ（ 北部） 和１８ Ｍａ（ 南部） ,变形作用向南变新。库车构造是印 藏板块碰撞的内陆构造响应,是二叠纪前陆盆地复活而成的再生前陆盆地变形带     

Geochemistry,detrital zircon geochronology and Hf isotope of the clastic rocks in southern Tibet: Implications for the Jurassic-Cretaceous tectonic evolution of the Lhasa terrane

In order to reconstruct tectonic evolution history of the southern margin of Asia (i.e., Lhasa terrane) before the India-Asia collision, here we present a comprehensive study on the clastic rocks in the southern Lhasa terrane with new perspectives from sedimentary geochemistry, detrital zircon geochronology and Hf isotope. Clasts from the Jurassic-Early Cretaceous sedimentary sequences (i.e., Yeba and Chumulong Formations) display high compositional maturity and experienced moderate to high degree of chemical weathering, whereas those from the late Early-Late Cretaceous sequences (Ngamring and Shexing Formations) are characterized by low compositional maturity with insignificant chemical weathering. Our results lead to a coherent scenario for the evolution history of the Lhasa terrane. During the Early-Middle Jurassic (∼192-168Ma), the Lhasa terrane was speculated to be an isolated geological block. The Yeba Formation is best understood as being deposited in a back-arc basin induced by northward subduction of the Neo-Tethys ocean with sediments coming from the interiors of the Lhasa terrane. The Middle Jurassic-Early Cretaceous Lhasa-Qiangtang collision resulted in the formation of a composite foreland basin with southward-flowing rivers carrying clastic materials from the uplifted northern Lhasa and/or Qiangtang terranes. During the late Early-Late Cretaceous (∼104-72Ma), the Gangdese magmatic arc was uplifted rapidly above the sea level, forming turbidites (Ngamring Formation) in the Xigaze forearc basin and fluvial red beds (Shexing Formation) on the retro-arc side. At the end of Late Cretaceous, the Lhasa terrane was likely to have been uplifted to high elevation forming an Andean-type margin resembling the modern South America before the India-Asia collision.     

西藏安多地区早古生代及中生代造山记录:来自安多微陆块-南羌塘锆石U-Pb年代学及Hf同位素研究

安多地区位于青藏高原腹地,为拉萨地体、羌塘地体及安多微陆块的结合部位,是研究拉萨地体、羌塘地体起源以及特提斯造山过程的关键位置。我们对采自安多地区的前中生代基底岩石及侏罗系沉积岩样品进行了岩石学、锆石U-Pb年代学及Hf同位素研究。研究结果表明:安多花岗片麻岩中锆石同时记录了510～505Ma岩浆年龄以及187Ma变质年龄;187Ma的变质锆石与510～505Ma的岩浆锆石具有相似的Hf同位素模式年龄(1.7～1.5Ga),表明寒武纪花岗岩主要来源于古老地壳重熔。碎屑锆石年代学分析结果揭示了安多微陆块石英岩具有498～484Ma、800～1000Ma和1800～1950Ma的年龄峰值,与南羌塘地体及特提斯喜马拉雅碎屑锆石年龄分布特征相似,表明其在早古生代时位于冈瓦纳大陆北部印度陆块边缘。南羌塘坳陷东南部中侏罗世砂岩及钙质砂岩碎屑锆石年代学分析结果显示其具有182～171Ma、450～600Ma、800～1000Ma、1800～1950Ma及2400～2600Ma的年龄峰值,这种年龄分布特征与安多微陆块及南羌塘地体相似,而与拉萨地体不同,说明南羌塘坳陷东南部下-中侏罗统物源主要来自安多微陆块及南羌塘地体,在早-中侏罗世时安多微陆块与南羌塘地体已经发生了碰撞造山。     

东昆仑野马泉地区磷灰石裂变径迹热年代学及构造意义

通过对东昆仑西段野马泉地区所获得的5个磷灰石样品的裂变径迹分析, 探讨该地区构造演化特征.磷灰石裂变径迹年龄分为153.8 Ma、106.8~81.0 Ma、48.7~44.4 Ma 3个年龄组, 其中153.8 Ma记录了班公湖-怒江洋闭合事件; 106.8~81.0 Ma是拉萨地块与羌塘地块碰撞拼合事件对东昆仑地区的远程效应; 48.7~44.4 Ma是印度-欧亚大陆碰撞之后伸展事件的体现.野马泉地区热历史分为3个阶段:第1阶段(130~110 Ma)持续隆升, 对应班公湖-怒江洋闭合后拉萨地块与羌塘地块拼合事件; 第2阶段(110~14 Ma)持续隆升, 90 Ma之前隆升速度较快, 与阿尔金断裂走滑及西大滩断裂韧性变形有关, 90 Ma之后进入一个时间较长的平稳抬升期; 第3阶段(14 Ma至今)受青藏高原新近纪以来强烈构造活动的影响, 快速隆升.3个阶段的隆升速率和隆升量分别0.021 mm/a和0.42 km、0.01 mm/a和1.0 km、0.1 mm/a和1.43 km, 平均隆升速率为0.028 mm/a, 总隆升量为2.86 km.