塔里木盆地轮南古隆起形成时间的判定

轮南古隆起位于塔里木盆地北部,是一个大型基底卷入型鼻状背斜。卷入背斜构造变形的地层包括下古生界及其以下地层。它的形式演化控制着轮南复式油气聚集区的形成与分布。过轮南古隆起的地震剖面上显示,这里发育上泥盆统东河砂岩底、志留系底和上奥陶统底3个与古隆起形成密切相关的不整合面。上奥陶统底是一个低角度不整合面至平行不整合面,地层间断很小。志留系与下伏地层之间是一个低角度不整合接触,存在一定规模的地层间断。东河砂岩与下伏地层之间是一个明显的角度不整合接触,是一个较大的地层间断。东河砂岩直接不整合覆盖在下志留统甚至更老地层之上。上奥陶统至下志留统（中-上志留统缺失）为生长地层;上奥陶统之下的地层是前生长地层;东河砂岩及其上覆的石炭系是生长后地层。根据已有构造分析成果,塔里木盆地中志留世—中泥盆世处于造山后区域性伸展构造背景。据此分析,轮南古隆起（背斜）的构造变形起始于中奥陶世末—晚奥陶世初,持续至早志留世。此后进入风化夷平阶段,古隆起依然存在,但是背斜构造变形已经结束。至东河砂岩沉积时,轮南古隆起基本被夷平,并逐渐被埋于地下。     

Lower Palaeozoic unconformities in an intracratonic platform setting: glacial erosion versus tectonics in the eastern Murzuq Basin (southern Libya)

The stratigraphic record of the eastern Murzuq Basin has been importantly influenced by deformation resulting in angular and/or deeply erosional unconformities, though the overall context is intracratonic. Major transgressive events and the Ordovician glaciation are nevertheless documented, allowing the delineation of tectonic-, eustasy- or climate-driven unconformities. Lower Palaeozoic key events and related unconformities that characterize the North Gondwana platform have therefore a signature in the eastern Murzuq Basin. The basement/cover unconformity, also known as the infra-Tassilian surface, truncates all the deformed and metamorphosed Lower Cambrian and older rocks. Above is a ?Middle Cambrian to Lower Ordovician megasequence (Murizidié and Hasawnah Fms.), which is in turn truncated by an intra-Ordovician, angular unconformity. This megasequence is unconformably overlain by a Middle Ordovician (Hawaz Fm.) to Silurian (Tanzzuft and Akakus Fms) megasequence, which includes the Upper Ordovician glaciogenic unit (Mamuniyat Fm.), bounded at the base by a polygenic glacial erosion surface showing corrugated glacial lineations, tillites, and glaciotectonic structures. The Middle Ordovician to Silurian megasequence is finally truncated by a base-Devonian, angular unconformity overlain by fluvial sandstones. Regarding the possibility that those fluvial deposits may be as younger as Late Devonian in the eastern Murzuq Basin based on palaeoflora, the so-called Caledonian unconformity might be here a much younger (mid-Eifelian?) surface, and the occurrence of the Lower Devonian “Tadrart Fm.” is questioned. The Upper Ordovician glacial erosion surface, which is sometimes referred to as the Taconic unconformity, usually truncates Middle Ordovician strata in the Murzuq Basin but reaches significantly deeper stratigraphic levels in places that have been previously involved in the intra-Ordovician deformation event. In the Murizidié (southeastern Murzuq Basin), the infra-Tassilian surface, the intra-Ordovician unconformity, and the Upper Ordovician glacial erosion surface amalgamate together. Here, an estimate of the glacial erosion depth cannot be derived from the stratigraphic hiatus beneath the glacial incision, the main part of which relate to the intra-Ordovician tectonic event. The Upper Ordovician climate-related glacial erosion surface is not a valid unconformity for a sequence hierarchy framework of the Lower Palaeozoic, although it presents most of the physical attributes of tectonic-driven unconformities.     

新疆昆仑山中泥盆世四射珊瑚

新疆昆仑山中泥盆世四射珊瑚较为丰富.本文只描述Atelophyllum sp.,Cyatho-phyllum sp.,Disphylloides philomena,Disphyllum carinatum(sp.nov.),Xystriphyllumkunlunense(sp.nov.)等5属3种,其中有二个新种.其共生的有床板珊瑚、层孔虫、及腕足类等.它们均产于中泥盆统布拉克巴什群.可与新疆北部、内蒙、甘肃、陕西、贵州等地的同期地层对比.     

川滇黔桂地区志留纪构造－岩相古地理

晚奥陶世与早志留世之间的都匀运动，使滇中古隆起与黔中古隆起成为一整体隆起带（习惯上称黔中古陆），把滇东南和黔南与滇东北-黔北-川南分隔为南、北两个不同的构造沉积域。南侧的曲靖一带出露下、中寒武统，其上分别与中、上志留统和下泥盆统呈假整合，其间缺失奥陶纪和早志留世的沉积物。北侧的禄劝－武定一带，下古生界的沉积序列与之相反，有完整的奥陶纪沉积组合，上与泥盆系假整合，其间无志留纪的沉积。这表明黔中古陆两侧的沉积域各为独立的系统。中晚志留世，黔中古隆起南侧应归属于上扬子与滇黔桂地块前陆挠曲盆地的一部分，由曲靖向北东经赫章哑都-贵阳南转向湘西，向南则与云南的绿春海相连，黔中古隆起北侧的沉积域则为上扬子前陆（川南-黔北）盆地的边缘相。     

Lines of Tobulata evolution

Branching (fruticose)Tabulata (Coelenterata, Anthozoa) appeared in the Middle Cambrian; massive forms may have appeared in the Cambrian but certainly by the Early Ordovician. Auloporoids are most primitive; sarcinulids and syringoporids evolved from advanced (erect) auloporids. Another evolutionary sequence led from primitive auloporids to lichenariids which gave rise to both favositids and halysitids. Tetradiids are considered a group separate from the Tabulata but probably had a common ancestor in the primitive auloporids. -- W. A. Oliver, Jr.     

昆仑山阿其克库勒湖地区泥盆系研究的新进展

<正> 东昆仑阿其克库勒湖地区泥盆系为新疆地质局区调一队赵子允等(1982)在阿其克库勒湖地区1/100万区调报告中首次报导。1980年出版的青藏高原地质图(1∶150万)将其划为下石炭统。赵子允等根据在阿其克库勒湖以南的一套厚约4000m的碳酸盐岩中含Favosites和Squameofavosites等     

New Devonian plant fossil occurrences on the New South Wales South Coast: geological implications

Devonian fossil localities are summarised for coastal southeastern Australia, including both marine invertebrates representing a major late Frasnian (Late Devonian) transgression, and plant remains of Middle–Late Devonian age in associated non-marine strata. Lycopsid plant specimens (Leptophloeum) from near Majors Creek, NSW, first documented by Edgeworth David and E. F. Pittman in association with marine fossils to demonstrate a Late Devonian age, are illustrated for the first time. Lycopsid plants of presumed Middle Devonian age are illustrated from three new localities: Yowrie River inland from Cape Dromedary, Tuross River northwest of Narooma and Charlies Forest Road northeast of Braidwood. The Yowrie River occurrence (in float) indicates probable Middle Devonian strata upstream that are not shown on published maps. The Tuross River occurrence is in sheared and folded strata previously mapped as Ordovician, and the Braidwood occurrence demonstrates Devonian black shales adjacent to previously mapped Ordovician. Evidence supporting alternative thrust or simple fold interpretations for the Budawang Synclinorium is discussed, and relevant Ordovician fossil localities are listed.     

Basement geology of the southern Thomson Orogen

Abstract

The diverse geological and geophysical data sets compiled, interrogated and interpreted for the largely undercover southern Thomson Orogen region reveal a Paleozoic terrane dominated by deformed metasedimentary rocks intruded by S- and I-type granites. An interpretive basement geology map and synthesis of geochronological constraints allow definition of several stratigraphic packages. The oldest and most widespread comprises upper Cambrian to Lower Ordovician metasedimentary rocks deposited during the vast extensional Larapinta Event with maximum depositional ages of ca 520 to ca 496 Ma. These units correlate with elements of the northern Thomson Orogen, Warburton Basin and Amadeus Basin. The degree of deformation and metamorphism of these rocks varies across the region. A second major package includes Lower to Middle Devonian volcanic and sedimentary units, some of which correlate with components of the Lachlan Orogen. The region also includes a Middle to Upper Ordovician package of metasedimentary rocks and a Devonian or younger package of intermediate volcaniclastic rocks of restricted extent. Intrusive units range from diatremes and relatively small layered mafic bodies to batholithic-scale suites of granite and granodiorite. S-type and I-type intrusions are both present, and ages range from Ordovician to Triassic, but late Silurian intrusions are the most abundant. Two broad belts of intrusions are recognised. In the east, the Scalby Belt comprises relatively young (Upper Devonian) intrusions, while in the west, the Ella Belt is dominated by intrusions of late Silurian age within a curvilinear, broadly east–west trend. The stratigraphic distributions, characteristics and constraints defined by this interpretive basement mapping provide a basic framework for ongoing research and mineral exploration.     

Tectonics and geodynamics of Gorny Altai and adjacent structures of the Altai–Sayan folded area

Packages of Late Paleozoic tectonic nappes and associated major NE-trending strike-slip faults are widely developed in the Altai–Sayan folded area. Fragments of early deformational phases are preserved within the Late Paleozoic allochthons and autochthons. Caledonian fold-nappe and strike-slip structures, as well as accompanying metamorphism and granitization in the region, are typical of the EW-trending suture-shear zone separating the composite Kazakhstan–Baikal continent and Siberia. In the Gorny Altai region, the Late Paleozoic nappes envelop the autochthon, which contains a fragment of the Vendian–Cambrian Kuznetsk–Altai island arc with accretionary wedges of the Biya–Katun’ and Kurai zones. The fold-nappe deformations within the latter zones occurred during the Late Cambrian (Salairian) and can thus be considered Salairian orogenic phases. The Salairian fold-nappe structure is stratigraphically overlain by a thick (up to 15 km) well-stratified rock unit of the Anyui–Chuya zone, which is composed of Middle Cambrian–Early Ordovician fore-arc basin rocks unconformably overlain by Ordovician–Early Devonian carbonate-terrigenous passive-margin sequences. These rocks are crosscut by intrusions and overlain by a volcanosedimentary unit of the Devonian active margin. The top of the section is marked by Famennian–Visean molasse deposits onlapping onto Devonian rocks. The molasse deposits accumulated above a major unconformity reflects a major Late Paleozoic phase of folding, which is most pronounced in deformations at the edges of the autochthon, nearby the Kaim, Charysh–Terekta, and Teletskoe–Kurai fault nappe zones. Upper Carboniferous coal-bearing molasse deposits are preserved as tectonic wedges within the Charysh–Terekta and Teletskoe–Kurai fault nappe zones.Detrital zircon ages from Middle Cambrian–Early Ordovician rocks of the Anyui–Chuya fore-arc zone indicate that they were primarily derived from Upper Neoproterozoic–Cambrian igneous rocks of the Kuznetsk–Altai island arc or, to a lesser extent, from an Ordovician–Early Devonian passive margin. A minor age population is represented by Paleoproterozoic grains, which was probably sourced from the Siberian craton. Zircons from the Late Carboniferous molasse deposits have much wider age spectra, ranging from Middle Devonian–Early Carboniferous to Late Ordovician–Early Silurian, Cambrian–Early Ordovician, Mesoproterozoic, Early–Middle Proterozoic, and early Paleoproterozoic. These ages are consistent with the ages of igneous and metamorphic rocks of the composite Kazakhstan–Baikal continent, which includes the Tuva-Mongolian island arc with accreted Gondwanan blocks, and a Caledonian suture-shear zone in the north. Our results suggest that the Altai–Sayan region is represented by a complex aggregate of units of different geodynamic affinity. On the one hand, these are continental margin rocks of western Siberia, containing only remnants of oceanic crust embedded in accretionary structures. On the other hand, they are represented by the Kazakhstan–Baikal continent composed of fragments of Gondwanan continental blocks. In the Early–Middle Paleozoic, they were separated by the Ob’–Zaisan oceanic basin, whose fragments are preserved in the Caledonian suture-shear zone. The movements during the Late Paleozoic occurred along older, reactivated structures and produced the large intracontinental Central Asian orogen, which is interpreted to be a far-field effect of the colliding East European, Siberian, and Kazakhstan–Baikal continents.     

First results of U–Pb dating of detrital zircons from the Upper Ordovician sandstones of the Bashkir uplift (Southern Urals)

The first results of U–Pb dating of detrital zircons from Upper Ordovician sandstones of the Bashkir uplift in the Southern Urals and U–Pb isotopic ages available for detrital zircons from six stratigraphic levels of the Riphean–Paleozoic section of this region are discussed. It is established that the long (approximately 1.5 Ga) depositional history of sedimentary sequences of the Bashkir uplift includes a peculiar period lasting from the Late Vendian to the Emsian Age of the Early Devonian (0.55–0.41 Ga). This period is characterized by the following features: (1) prevalence of material from eroded Mesoproterozoic and Early Neoproterozoic crystalline complexes among clastics with ages atypical of the Volga–Urals segment of the East European Platform basement; (2) similarity of age spectra obtained for detrital zircons from different rocks of the period: Upper Vendian–Lower Cambrian lithic sandstones and Middle Ordovician substantially quartzose sandstones.     

Stratiform base-metal deposits in the Eastern province of the Southern Urals, Russia

The stratiform base-metal Biksizak and Amur deposits, Kolpakovsky and Andree-Yul??evsky group of ore occurrences localized in the Eastern province of the Southern Urals and the adjacent Central Urals are considered in this paper. Their geology, composition of ore, and orebody morphology are characterized. These objects and occurrences occupy different geological positions, being hosted in (1) Ordovician, Silurian, and Devonian limestones formed in an island-arc setting (Biksizak deposit, Kolpakovsky occurrence); (2) Middle and Upper Devonian flyschoid sequences at a distance from the active volcanic zone (Amur deposit); and (3) Riphean (?) platform cover (Andree-Yul??evsky group of occurrences). The objects considered differ in origin. The hydrothermal Pb-Zn ores of the Biksizak deposit and the Kolpakovsky occurrence are epigenetic with respect to the host rocks. They were formed in the Early Carboniferous and related to early collisional minor andesite and quartz diorite porphyry intrusions. The hydrothermal-sedimentary Amur massive sulfide Zn deposit of the Filizchai type was formed at the end of Middle Devonian. Zinc occurrences of the Andree-Yul??evsky group are probably products of regeneration of older stratiform lodes.     

渤海湾盆地北部奥陶纪岩相古地理

渤海湾盆地北部主要包括黄骅坳陷、沧县隆起、冀中坳陷和下辽河坳陷,区内奥陶系厚 6 0 0～ 80 0m,主要由石灰岩和白云岩组成。下奥陶统分为冶里组和亮甲山组,中奥陶统分为下马家沟组、上马家沟组和峰峰组,上统缺失。其中下马家沟组、上马家沟组和峰峰组又进一步划分为下段和上段。早奥陶世冶里期和亮甲山期,本区以局限海环境为主,其内散布着一些潮坪和滩。中奥陶世,本区岩相古地理面貌变化旋回极为明显,下马家沟期早期潮坪广布,晚期以局限海为主;上马家沟期早期又是潮坪广布,晚期以开阔海为主;峰峰期早期潮坪广布,晚期又以开阔海为主。在奥陶纪,本区经历了 4个大的海侵-海退旋回,其中上马家沟期晚期是本区乃至整个华北地台的最大海侵期。     

綦江观音桥中上奥陶统微量元素地球化学特征

中上扬子地区广泛发育着完整的奥陶系地层,其中的上奥陶统宝塔组中出现地球化学异常。綦江观音桥剖面中上奥陶统地层的地球化学研究表明,宝塔组中V、Ni出现亏损,V/(V+Ni)值表现为低值,而Th/U、Ni/Co与Sr/Ba值却表现为高值,判断晚奥陶世中宝塔期为强氧化气候,海水突然加深,是一次明显的海侵过程。中上奥陶统地球化学异常是华夏板块与扬子板块相互作用的结果。     

新疆北部下中泥盆统层序及其界线讨论

新疆北部是中国北方下中泥盆统出露最全地区之一,1977年曾作为中国北方槽区典型剖面.笔者根据最新资料研究,重新选定了下中泥盆统标准层序(自下而上):下泥盆统:乌吐布拉克组、曼格尔组.芒克鲁组;中泥盆统:乌鲁苏巴斯套组、纸房组.并根据岩性变化及床板珊瑚化石资料,对乌吐布拉克组进行了重新审定,将原沙尔布尔提山剖面乌吐布拉克组下2层归入上志留统.重点讨论了下泥盆统的底界及下与中泥盆统间的界线.     

北祁连造山带东段上奥陶统一下、中泥盆统砂岩碎屑组分与物源分析

北祁连造山带东部武威斜豪-古浪石城子-靖远水泉-带上奥陶统一下、中泥盆统砂岩碎屑组分源区大地构造背景的判别结果表明,上奥陶统砂岩中的沉积物主要来自弧造山带内的过渡岛弧源区,并且早期可能含有较多的来自未分割岛弧源区的物质,下志留统砂岩中的沉积物主要来自碰撞造山带,而下、中泥盆统砂岩中的沉积物主要来自卷入碰撞造山带内的分割...     

Pre-Tertiary Orogenies in the Himalaya: A review of various evidences

Various sedimentary sequences of the Himalaya reflecting different tectonic cycles when compared with the ages of (i) unconformity, (ii) pre-Tertiary metamorphism, (iii) granites and (iv) pre-Tertiary deformations point to following pre-Tertiary Orogenies: (i) Sundernagar (Middle Precambrian), (ii) Shali (Vendian), (iii) Jasim-Kurgiakh (Ordovician), (iv) Blaini-Thidsi (Upper Paleozoic) and (v) Tal-Chikkim (Middle-Upper Cretaceous). Besides these, minor impulses identifiable are: (i) Bandel-2 (Middle Riphean), (ii) Tangze (Devonian), (iii) Infra Krol (Upper Permian), (iv) Tandi (? Callovian) and (v) Krol (Upper Jurassic - Lower Cretaceous). Due to paucity of deformation structures related to these earth movements, it is suggested that these were either (i) mainly epeirogenic, (ii) feebly orogenic or (iii) they produced folds which were coaxial with subsequent Himalayan folds hence indistinguishable from the latter.     

塔里木盆地早古生代晚期构造-沉积响应

摘要：伴随相对海平面由上升转为下降的周期变化,塔里木盆地在早古生代经历了一次大规模的扩张→挤压→隆升的开合旋回,早期(震旦纪—中奥陶世)处于拉张的构造背景下,呈现西台(碳酸盐台地)东盆(满加尔．库鲁克塔格深水盆地)的古地理格局。中西部广大地区沉积了巨厚的浅水台地相碳酸盐岩,以中晚寒武世的下丘里塔格群和早中奥陶世的上丘里塔格群为标志;东部的满加尔-库鲁克塔格则以厚度不大的远洋硅-灰泥沉积为主。盆地构造性质的转换及沉积古地理的巨大改变发生于中奥陶世中晚期,以塔中、塔北的隆起和塘古孜巴斯坳陷及阿瓦提-满加尔坳陷的形成为标志,呈近南北向隆-坳相问的盆地格局。沉积记录的响应表现为碳酸盐台地的消失、陆源物质的逐渐注入和向上变粗、火山活动和火山碎屑的出现以及巨厚砂泥质浊积岩在塔东盆地内的充填等。因此,中晚奥陶世—中泥盆世是塔里木盆地海域逐渐萎缩、盆地不断隆升和相对海平面逐渐下降的一个过程。     

新疆昆其布拉克地区床板珊瑚、日射珊瑚新资料

描述了由施恩全等于1987年采自新疆且末县昆其布拉克地区上奥陶统孔其布拉克组中上部的晚奥陶世床板珊瑚，日射珊瑚化石，计有8属，13种（其中新种6个）：AgetolitesaltunensisWang，A．KingqiensisWang（Sp．nov．），Cateniporaaqiangensiswang（sp．nov．），Taeniolitescf．zhejiangensisLinetChow，Proheliolitessp．,Priporacf．multispinosaLinetChow，PlasmoporellaqiemoensisWang（sp．nov．），Pl．altunensiWang（sp．nov．），Pl．of．columellaBondarenko，Pl．com-plexawang（sp．nov），Pl．sp，Sibiriolitescf．sibiricusmongolicusBond.etMin.,Diploeporaaltune-sisWnagsp．nov。笔者将其归入Agetolites—Plasmoporella组合。这些化石首次被发现，对于研究阿尔金山地区上奥陶统生物群和地层对比具有十分重要的理论意义和实践意义。     

塔里木盆地古生代重要演化阶段的古构造格局与古地理演化

塔里木盆地在古生代经历了中-晚奥陶世、晚奥陶世末、中泥盆世末等多个重要的盆地变革期,形成了多个重要的不整合,盆地构造古地理发生了重要的变化。中、晚奥陶世盆地的变革形成了由巴楚古斜坡-塔中隆起-和田河隆起构成的大型古隆起带、相对沉降的北部坳陷带以及由于挤压挠曲沉降形成的塘古孜巴斯坳陷带。中部古隆起带制约着晚奥陶世东窄西宽的弧立碳酸盐岩台地体系的发育,而开始形成于震旦纪的满加尔拗拉槽及东南侧的塘古孜巴斯坳陷接受了巨厚的中、晚奥陶世重力流沉积。奥陶纪末的盆地变革形成了北东东向展布的西南-东南缘和西北缘的强烈隆起带,总体的古构造地貌控制着早志留世北东东向展布的滨浅海陆源碎屑盆地的沉积格局。中泥盆纪世末期的盆地强烈隆升并遭受了夷平化的剥蚀作用,形成了大范围分布的角度不整合面,并以塔北隆起和塔东隆起的强烈抬升为显著特征。盆地古构造地貌从东低西高转为东高、西低,制约着晚泥盆和早石炭世由东向西南方向从滨岸到浅海的古地理分布。中、晚奥陶世主要不整合及其剥蚀量的分布反映出北昆仑向北碰撞和挤入是造成盆地南缘、东南缘及盆内隆起的主要原因。南天山洋的俯冲、碰撞在奥陶世末至早志留世已对盆地西北缘产生影响,导致塔北英买力隆起的抬升和遭受剥蚀。     

塔里木盆地塔河奥陶系碳酸盐岩储层埋藏成岩和构造-热流体作用及其有效性

对层状风化壳模式的认识一度支撑着塔里木盆地下古生界深层碳酸盐岩油气勘探,但这类深层碳酸盐岩储层显示出的强烈非均质性使得勘探风险愈来愈大。研究以塔里木盆地塔河地区中—下奥陶统碳酸盐岩储层为典型实例,重点论述了成岩作用和构造—热流体复合作用对储层的制约,并结合表生岩溶等其它要素开展了储层分布综合解释。研究认识到:①奥陶系碳酸盐岩正常深埋藏成岩作用的主要效应是碳酸盐的沉淀而不是碳酸盐的溶解,建设性改造主要与表生岩溶作用（古喀斯特）或构造—热流体作用有关,并导致了碳酸盐岩储层强烈的非均质性。②从中下奥陶统到上奥陶统,下部碳酸盐岩地层热流体活动迹象明显优于上部地层。③奥陶系碳酸盐岩构造—热流体的建设性改造作用主要发生在中—晚泥盆世与二叠纪叠加改造的断裂构造交汇区,以及中—晚奥陶世、前石炭纪形成的表生岩溶发育区;有效储层与高能沉积相带关系有限。为此,提出了奥陶系碳酸盐岩构造—流体作用与储层形成概念模式,这为进一步认识储层的形成分布规律提供了新的线索。