松辽盆地及外围石炭系-二叠系划分与对比

以东北地区晚古生代大地构造演化最新研究进展为主要依据,结合地层发育及生物古地理特征,将研究区分为2个地层大区,5个地层区,9个地层分区.在各省区岩石地层清理结果的基础上,结合近年来区域地质调查及地层学方面的研究进展及本次工作的新认识,建立起各地层区岩石地层序列.利用已有生物化石资料,结合最新的牙形刺、孢粉等微体化石及同位素测年资料,应用生物地层和同位素年代地层的综合研究方法,基本明确了各组级岩石地层单位时代,并将其纳入最新的国际年代地层系统.在不同地层区之间进行横向对比,建立了松辽盆地外围石炭-二叠系在国际年代系统框架下的地层划分对比格架.     

云南墨江共埂中二叠统坝溜组地层剖面及地层划分

简要介绍云南墨江共埂中二叠统坝溜组地层剖面,对采集的蜓化石进行了生物地层研究,根据蜓化石在剖面上的垂直分布,建立了4个蜓化石带:Pseudodoliolina ozawai富集带,Schwagerina ex gr.cushmani-Pseudofusulina radioflucta合带,Pseudofusulina...     

浙江桐庐县刘家奥陶纪剖面生物地层学初步研究

新发现的浙江桐庐刘家剖面位于马金一乌镇断裂与球川一萧山断裂之间,是浙西北地区以碎屑岩沉积为主的代表性奥陶纪地层剖面。根据所获得的宁国组和胡乐组的笔石化石,初步建立了该层段的笔石生物地层序列,自下而上包括Tetragraptusapproximatus带、Corymbograptusdeflexus带、Azygograp...     

鄂西地区奥陶纪至早志留世生态地层探究

在鄂西地区奥陶纪至早志留世地层中选出化石丰富、研究程度相对较高的7个主要门类进行属级兴衰的定量统计,依据各生物类群在各不同阶段的化石丰度绘制成各生物相在纵向上的演化图,从中识别出10个新生事件和10个消失事件,并依此建立10个生态地层单元。     

豫西登封地区下三叠统中的遗迹化石及其沉积环境

豫西登封地区下三叠统刘家沟组及和尚沟组系一套河湖相沉积,通过沉积特征和沉积序列分析,建立了8种类型的沉积序列,并在该套地层中发现丰富的陆相遗迹化石,已鉴别出8个遗迹属10个遗迹种。根据遗迹化石的组成、产状和分布特征,建立了3种遗迹组合:1)Scoyenia遗迹组合,出现于周期性暴露的极浅水河漫滩及小型河漫湖泊环境;2)Arenicolites遗迹化石组合,产生于水体较动荡的滨湖沉积环境;3)Taenidium-Planolites遗迹化组合,形成于水体较平静的浅湖沉积环境。基于沉积特征、沉积序列及伴生遗迹化石组成与分布特征的综合分析,提出了该区早三叠世地层中遗迹化石组合的沉积环境模式。     

康滇地轴西缘锦屏山地区的生物地层

笔者在1：5万腊窝乡,里庄幅区域地质调查中,对区内出露的沉积盖层中的生物地层层序,古生物化石的产出状态,组合面貌和发育特征等进行了详细的研究,将区内生物地层单位分为码多－马尔康分区雅小区和盐源－丽江分区两个片区,自下而上,雅江小区建立有6个生物化石带,盐源－丽江分区建立有14个生物化石带。     

华南峡东地区埃迪卡拉（震旦）纪年代地层划分初探

华南峡东地区埃迪卡拉纪地层连续,出露完整,化石丰富,顶、底界线清楚,是世界上同时代地层最具代表性的序列之一,也是解决埃迪卡拉纪年代地层划分、竞争相关界线层型剖面的最理想地区之一。根据近年来峡东地区埃迪卡拉系的同位素年代学、生物地层学和化学地层学等方面的研究积累,本文以生物地层序列(生物演化阶段)为基础标志,以碳稳定同位素组成的重要变化界面为辅助标志,对峡东地区埃迪卡拉纪地层进行年代地层的划分,提出2统5阶方案。下统名称建议用峡东统,下分九龙湾阶和陈家园子阶;上统名称建议用扬子统,下分吊崖坡阶、第四阶和第五阶。在此基础上,根据生物地层和碳稳定同位素地层学的特征,初步探讨了与其他地区埃迪卡拉系的对比关系。这一划分和对比方案只是目前研究的阶段性认识,更完整的划分对比意见还有待今后的进一步完善。     

Discussion on the Chronostratigraphic Subdivision of the Ediacaran ( Sinian)in the Yangtze Gorges Area, South China

华南峡东地区埃迪卡拉纪地层连续,出露完整,化石丰富,顶、底界线清楚,是世界上同时代地层最具代表性的序列之一,也是解决埃迪卡拉纪年代地层划分、竞争相关界线层型剖面的最理想地区之一.根据近年来峡东地区埃迪卡拉系的同位素年代学、生物地层学和化学地层学等方面的研究积累.本文以生物地层序列(生物演化阶段)为基础标志,以碳稳定同位素组成的重要变化界面为辅助标志,对峡东地区埃迪卡拉纪地层进行年代地层的划分,提出2统5阶方案.下统名称建议用峡东统,下分九龙湾阶和陈家园子阶;上统名称建议用扬子统,下分吊崖坡阶、第四阶和第五阶.在此基础上,根据生物地层和碳稳定同位素地层学的特征,初步探讨了与其他地区埃迪卡拉系的对比关系.这一划分和对比方案只是目前研究的阶段性认识,更完整的划分对比意见还有待今后的进一步完善.     

新疆喀喇昆仑山地区泥盆纪地层划分与特征

在新疆西昆仑地区1∶5万区域地质调查中,对分布于喀喇昆仑山地层区中的泥盆纪地层,开展剖面测量和区域填图,系统收集其岩性岩相、岩石组合、分布特征、接触关系、生物化石、基本层序等资料,并展开了多重地层划分与对比研究。研究表明区内泥盆纪地层由中下统大王顶组,中统黄羊滩组、落石沟组和上统天神达坂组组成,各组之间均为整合接触关系,除天神达坂组未获生物化石外,其他层位均获有丰富的古生物化石。其中新建大王顶组和黄羊滩组2个岩石地层单位,以及腕足类3个、珊瑚类1个、菊石类1个、三叶虫类1个,共计6个生物地层单位。全面系统厘定和完善了区内泥盆纪的岩石地层序列、生物地层序列和年代地层序列,黄羊滩组是重要的铜矿和石膏矿赋矿层位。从而极大地提高了喀喇昆仑山地区泥盆纪地层研究程度,也为本区地质构造演化和成矿规律分析提供了必要地史资料。     

吉南地区青沟子剖面寒武纪生物地层单位清理的初步意见

吉南地区的寒武纪生物化石（以三叶虫为主）极其发育，前人曾对其进行了详尽的研究，先后建立了７个阶１７个化石带。但化石带的含义不甚明确，多以标准分子为代表，即标准化石带（时间带？）。笔者等于１９９１￣１９９３年在白山市幅（１／５万）区调填图时，以区内的青沟子剖面为例，利用前人在该剖面上连续采集的三叶虫生物化石资料，按照多重地层划分的原则，对生物地层单位进行了初步清理，建立了５个正式生物地层单位－延限带     

Gondwana biostratigraphy of the Purnea Basin (eastern Bihar,India), and its correlation with Rajmahal and Bengal Gondwana basins

Integrated biostratigraphic studies are undertaken on the newly discovered Gondwana successions of Purnea Basin which have been recognized in the subsurface below the Neogene Siwalik sediments. The four exploratory wells, so far drilled in Purnea Basin, indicated the presence of thick Gondwana sussession (± 2450m) with varied lithological features. However, precise age of different Gondwanic lithounits of this basin and their correlation with standard Gondwana lithounits is poorly understood due to inadequate biostratigraphic data.Present biostratigraphic studies on the Gondwana successions in the exploratory wells of PRN-A, RSG-A, LHL-A and KRD-A enable recognition of fifteen Gondwanic palynological zones ranging in age from Early Permian (Asselian-Sakmarian) to Late Triassic (Carnian-Norian). Precise age for the Gondwanic palynological zones, recognized in the Purnea Basin and already established in other Indian Gondwana basins, are provided in the milieu of additional palynological data obtained from the Gondwana successions of this basin.The Lower Gondwana (Permian) palynofloras of Purnea Basin recorded from the Karandighi, Salmari, Katihar and Dinajpur formations resemble the palynological assemblages earlier recorded from the Talchir, Karharbari, Barakar and Raniganj formations respectively, and suggests the full development of lower Gondwana succession in this basin. The Upper Gondwana (Triassic) succession of this basin is marked by the Early and Middle to Late Triassic palynofloras that resemble Panchet and Supra-Panchet (Dubrajpur/Maleri Formation) palynological assemblages, and indicates the occurrence of complete Upper Gondwana succession also in the Purnea Basin.The lithological and biostratigraphic attributes of Gondwana sediments from Purnea, Rajmahal and western parts of Bengal Basin (Galsi Basin) are almost similar and provides strong evidences about the existence of a distinct N-S trending Gondwana Graben, referred as the Purnea-Rajmahal-Galsi Gondwana Graben. Newly acquired biostratigraphic data from the Gondwana sediments of CHK-A, MNG-A and PLS-A wells from central part of Bengal Basin and Bouguer anomaly data suggest that these wells fall in a separate NE-SW trending graben of “Chandkuri-Palasi-Bogra Gondwana Graben”. Although, the post-Gondwana latest Jurassic-Early Cretaceous Rajmahal Traps and and intertrappean beds succeed the Upper Gondwana successions in Rajmahal, Galsi and Chandkuri-Palasi Gondwana basins, but not recorded in the drilled wells of Purnea Basin, instead succeeded by the Neogene Siwalik sediments.     

珠江口盆地新生代沉降特征及其影响因素分析

为了研究珠江口盆地的沉降特征、沉降特征时空差异性以及影响因素,文章共选取了32口人工井进行沉降史计算,并进行综合分析,从中又特选出12口典型人工井进行对比分析,编绘和对比分析了3条典型沉降演化图。结果表明:盆地整体沉降可分为3幕,第一幕为始新世,平均总沉降速率为85 m/Ma;第二幕为渐新世至中中新世,平均总沉降速率为146 m/Ma;第三幕为晚中新世至第四纪,平均总沉降速率为104 m/Ma。同一时期不同构造单元之间及同一构造单元在不同时期,沉降与演化特征都存在差异性,各时期沉降速率平面分布表现出"分区"、"分带"的特征,沉降演化的差异性变化与盆地的演化阶段及其构造特征有关。盆地整体沉降特征受成盆动力学影响,而沉降特征差异性受盆地动力学和构造格局共同影响。珠江口盆地整体沉降表现为"幕式"特征,沉降及其演化特征表现出明显的时空差异性,盆地动力学特征和构造格局共同影响盆地的沉降特征。     

Cenozoic Calcareous Nannofossil Biostratigraphy of Sediments from Lingfeng Well in East China Sea

In the past15 years,the Cenozoic calcareous nannofossilsin the East China Sea were biostratigraphically studied duringthe extensive offshore petroleum exploration in a number ofbasins on the shelf of the East China Sea.A number of Pale-ocene to Quaternary nannofossil zones were recognized basedon the nannofossils from m any offshore wells (SBMGS,1989,1985 ) .These previous studies indicated a lot of biostratigraphicproblems,resulting in difficulties in the understanding of afurther detail…     

Ostracod Biostratigraphy of the Late Cretaceous Qingshankou Formation in the Songliao Basin

An ostracod biostratigraphic study was performed on 425 samples from the composite geological section constructed by using cores taken from five selected wells drilled in the Late Cretaceous Qingshankou Formation in the Songliao basin.A total of 19 ostracod zones are established in the formation,of which 3 are newly established and 3 are revised.The 19 ostracod zones are described in detail.This study provides a basis for the detailed stratigraphic division and correlation of the Qingshankou Formation and the Gaotaizi oil reservoir in the oilfield in the Songliao basin.     

Badenian (Middle Miocene) basin development in SW Hungary: subsidence history based on quantitative paleobathymetry of foraminifera

A quantitative paleobathymetric study of Badenian foraminifera was carried out from Tekeres-1 and Tengelic-2 boreholes, north of the Mecsek Mts., SW Hungary. Paleobathymetric data, based on plankton/benthos ratio provided input for the analysis of the subsidence history. The biostratigraphic framework is mainly provided by calcareous nannoplankton (zones NN5-NN7). Changes in sedimentation rates are also considered, partly calculated from number of benthos per unit sediment, and partly estimated from the changes of lithofacies. Relative sea-level changes are calculated from changes of paleowater depth and coeval sedimentary thickness. The result is examined as the sum of accommodation space created by subsidence and eustasy. In that period of time eustatic changes were about an order of magnitude smaller than changes created by movements of the basin floor. According to our model in early Badenian (up to the half of NN5 nannozone) a very rapid transtension-related subsidence of about 500 m occurred. This was interrupted by a short period of uplift of minor magnitude at about the first third of NN5 zone; thereafter, subsidence continued and the basin floor reached its deepest position. Still within the NN5 nannozone (Early Badenian) a significant uplift occurred, terminating the life of the deep basin. The Late Badenian (NN6) is characterized by a relatively small rate of subsidence and presumably quiet tectonism. During this period bathymetric changes are thought to be controlled primarily by eustatic changes. The first uplift - only interrupting subsidence - is regarded as the result of the change of the local stress field because of convergence along the curvature of strike slip faults. The second uplift, which stopped the subsidence of the basin floor is thought to be of a regional character and is attributed to the compression generated between Tisza and Alcapa tectonic units.     

Breakup between Australia and Antarctica: A brief review in the light of new data

The arguments justifying the revised timing of breakup between Australia and Antarctica (Cande and Mutter, 1982) and the reconstruction of Broken Ridge and Kerguelen Plateau (Mutter and Cande, 1983) are reviewed and considered with respect to new subsidence data. The age of breakup was revised from anomaly 22 time (55 My B.P.) to anomaly 34 time (85 My B.P.). The rough topography of the Diamantina Zone can be attributed to very slow spreading (−5 mm/yr.) beginning between the times of anomaly 34 and anomaly 19. The reconstruction of Broken Ridge and Kerguelen Plateau at anomaly 34 time shows overlap of these two features, but the overlap problem is nearly resolved by anomaly 18 time ( ~ 42 My B.P.). Normal seafloor spreading rates (22 mm/yr.) commenced at anomaly 19 time ( ~ 43 My B.P.). Subsidence patterns calculated from biostratigraphic data from wells drilled along Australia's southern margin are interpreted as more consistent with the revised age of Australia-Antarctic breakup. Subsidence curves systematically show rapid subsidence associated with the rift phase of margin development followed by much slower thermally-controlled subsidence during the drift phase. The timing of the rift-to-drift transition is believed to coincide with the age of breakup ( ~ 60 to 110 My B.P.). In addition, the subsidence curves indicate a west-to-east propagation of breakup along the southern margin. Magnetic anomaly patterns and stratigraphie observations are consistent with this hypothesis.     

Basin- and Mountain-Building Dynamic Model of “Ramping-Detachment-Compression” in the West Kunlun-Southern Tarim Basin Margin

Analysis of the deformation structures in the West Kunlun-Tarim basin-range junction belt indicates that sediments in the southwestern Tarim depression were mainly derived from the West Kunlun Mountains and that with time the region of sedimentation extended progressivdy toward the north. Three north-underthrusting （subducting）, steep-dipping, high-velocity zones （bodies） are recognized at depths, which correspond to the central West Kunlun junction belt （bounded by the Kiida-Kaxtax fault on the north and Bulungkol-Kangxiwar fault on the south）, Quanshuigou fault belt （whose eastward extension is the Jinshajiang fault belt） and Bangong Co-Nujiang fault belt. The geodynamic process of the basin-range junction belt generally proceeded as follows： centering around the magma source region （which largely corresponds with the Karatag terrane at the surface）, the deep-seated material flowed and extended from below upward and to all sides, resulting in strong deformation （mainly extension） in the overlying lithosphere and even the upper mantle, appearance of extensional stress perpendicular to the strike of the orogenic belt in the thermal uplift region or at the top of the mantle diapir and localized thickening of the sedimentary cover （thermal subsidence in the upper crust）. Three stages of the basin- and mountain-forming processes in the West Kunlun-southern Tarim basin margin may be summarized： （1） the stage of Late Jurassic-Early Cretaceous rampingrapid uplift and rapid subsidence, when north-directed thrust propagation and south-directed intracontinental subduction, was the dominant mechanism for basin- and mountain-building processes; （2） the stage of Late Cretaceous-Paleogene deep-level detachment-slow uplift and homogeneous subsidence, when the dominant mechanism for the basin- and mountain-forming processes was detachment （subhorizontal north-directed deep-level ductile shear） and its resulting lateral propagation of deep material; and （3） the stage of Neogene-pre     

Analysis of refracturing in horizontal wells: Insights from the poroelastic displacement discontinuity method

In this paper, a fully coupled 2‐dimensional poroelastic displacement discontinuity method is used to investigate the refracturing process in horizontal wells. One of the objectives of refracturing is to access new reserves by adding new hydraulic fractures in zones that were bypassed in the initial fracturing attempt. Pore pressure depletion in the vicinity of old fractures directly affects the state of stress and eventually the propagation of newly created hydraulic fractures. Thus, a poroelastic analysis is required to identify guidelines for the refracturing process, in particular to understand the extension of the pore pressure depletion, and eventually, the orientation of new as well as old fractures. We propose a fully coupled approach to model the whole process of child fracture propagation in a depleted area between 2 parent fractures in the same wellbore. This approach omits the need of using multistep workflow that is regularly used to model the process. The maximum tensile stress criterion (σ criterion) is used for hydraulic fracture propagation. The proposed method is verified using available analytical solutions for total stress and pore pressure loading modes on a line fracture in drained and undrained conditions. Then, test cases of multifractured horizontal wells are studied to calculate the time evolution of the stress and pore pressure fields around old fractures and to understand the effect of these fields on the propagation path of newly created fractures. Finally, the effect of the pore pressure depletion on the propagation path of the newly created fractures in the bypassed area of the same wellbore is studied. The results show that the depleted areas around old fractures are highly affected by the extent and severity of the stress redistribution and pore pressure depletion. It is observed that a successful creation of new fractures may only happen in certain time frames. The results of this study provide new insights on the behavior of newly created fractures in depleted zones. They also clarify the relationship between stress change and pore pressure depletion in horizontal wells.     

Early Carnian anoxic event as recorded in the southern Tethyan margin,Tunisia: an overview

Considerable attention has been given to the Carnian (Late Triassic) Pluvial and Reingraben events associated with organic-rich shale accumulation in the Germanic basin, Alps, southern Appenines as well as in northwestern Tethyan margins. Less interest has been shown to the southern Tethyan portion represented by the northern margin of Africa, including Tunisia. Tunisian basins represented by the Tellian domain, Tunisian trough, the ‘Dorsale’, and the North–South Axis (NOSA) belong to the southern Tethyan margin, where northern and central areas record the early Carnian anoxic event within an extensive carbonate platform. This short-lived (~2 million year) period of anoxia ranges within the Aonoides to Austriacum ammonite zones, and corresponds in Tunisia generally to intermediate to shallow water environments marked by organic-rich black limestone, dolomite, and shale. Interestingly, toward the south, the dysaerobic conditions in the Jeffara–southern Dahar basin appear to have prevailed locally also in the early Carnian. Here we review evidence of early Carnian anoxia in Tunisia based on the analysis of more than 17 Triassic sections and wireline logs from several petroleum exploration wells penetrating the black dolomites, limestones, and shales. In addition, biostratigraphic and complete geochemical reviews have been undertaken from published papers and unpublished internal reports to better assess this important and promising hydrocarbon source interval.