EARLY CARBONIFEROUS RUGOSA IN YANFANG OF QUJING DISTRICT,YUNNAN

：Yumushan block on the north margin of Qilian mountain, with Jiudong basin and Minle basin to the west and east respectively, belongs to the fore-land depression in NNW direction at the north margin of the Qilian mountain fold belt. The Yumushan block has been thought of as a fault-uplift, which separates the two basins formed during late Yanshanian orogeny. However, the recognition of fault zones at the western margin of the Yumushan block, and the tectonic and sedimentary analyses of the Yumushan block and the basins, cast doubts to the tectonic property of the block. It is suggested that the two basins be derived from an united large basin at least during Mesozoic and the Yumushan block be nappe sheet formed due to NE imbricate thrusting on the north margin fault zone of the Qilian mountain. This proposal would provide valuable clues to further exploration of oil-gas and water resources in Hexi corridor basin belt.     

Study of Residual Basin and Tectonolayering Based on Airborne Gravity and Magnetic Data

This paper takes the South Yellow Sea as an example to show a new method for comprehensive geological-geophysical research such as residual basin and tectonolayering using airborne gravity and magnetic data in China. Based on airborne gravity and magnetic data, by measuring and analyzing stratigraphic density and susceptibility, the depths to the pre-Sinian magnetic basement top, the pre-Jurassic top and the Cenozoic bottom, are obtained by forward and inverse methods constrained by seismic and drilling data; and furthermore, the residual thicknesses of the Sinian–Triassic, the Jurassic–Cretaceous and the Cenozoic are calculated. Based on airborne gravity and magnetic anomalies, the faults in the pre-Sinian magnetic basement, the Jurassic-Cretaceous and the Cenozoic are respectively interpreted by the qualitative and quantitative methods. On the basis of the above study, and combining regional important tectonic events, four tectonolayers are divided in the vertical succession in South Yellow Sea, namely the pre-Sinian magnetic basement, the Sinian-Triassic, the Jurassic-Cretaceous and the Cenozoic. The result shows that there are thick Cenozoic and Jurassic-Cretaceous strata and thin residual Sinian-Triassic strata in the Suzhong-Huangnan depression area, but there are thin or only sporadic Mesozoic-Cenozoic terrestrial strata and thick Sinian-Triassic marine strata reserved in Subei-Huangzhong uplift area and Sunan-Wunansha uplift area. The four tectonolayers are very different in structures as well as distributions in plane.     

Paleozoic and Mesozoic Basement Magmatisms of Eastern Qaidam Basin,Northern Qinghai‐Tibet Plateau: LA‐ICP‐MS Zircon U‐Pb Geochronology and its Geological Significance

The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian (493.1±4.9 Ma), the Silurian (422.9±8.0 Ma-420.4±4.6 Ma) and the Late Permian-Middle Triassic (257.8±4.0 Ma-228.8±1.5 Ma), respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma (main), 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic (P-T) granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism (293.6-270 Ma) occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation (triggered at the middle and lower crust), whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover (the upper crust).     

http://www.sciencedirect.com/science/article/pii/S1674987111001009

The North Yellow Sea Basin is a Mesozoic and Cenozoic basin.Based on basin-margin facies,sedimentary thinning,size and shape of the basin and vitrinite reflectance.North Yellow Sea Basin is not a residual basin.Analysis of the development of the basin’s three structural layers,self-contained petroleum systems,boundary fault activity,migration of the Mesozoie—Cenozoic sedimentation centers, different basin structures formed during different periods,and superposition of a two-stage extended basin and one-stage depression basin,the North Yellow Sea Basin is recognized as a superimposed basin.     

Tectonic Evolution of the Junggar Foreland Basin in the Late Carboniferous-Permian

A comprehensive study has been carried out to subdivide and correlate the Upper Carboniferous and Permian sedimentary successions in the Junggar basin based on outcrops and drilling and geophysical data. The study results, combined with geological analyses of the basin's periphery and the basement, as well as studies of the sedimentary rocks within the basin, the unconformities, tectonic geometry, kinematics and geodynamics, lead to the conclusion that the Junggar basin was characterized by the development of foreland basin systems during the Late Carboniferous and Permian. During that period, three foreland basin systems were developed: (1) the northwest foreland basin system, which trended nearly north-south from Mahu to the Chepaizi Palaeo-mountain during its early stage of development and thus it was also referred to as the west foreland basin system; (2) the Karamaili foreland basin system in the east and (3) the Northern Tianshan foreland basin system in the south. These systems are different in s     

Structural Characteristics and Formation Mechanism in the Micangshan Foreland,South China

Lying at the junction of the Dabashan,Longmenshan and Qinling mountains,the Micangshan Orogenic Belt coupled with a basin is a duplex structure and back-thrust triangular belt with little horizontal displacement,small thrust faults and continuous sedimentary cover.On the basis of 3D seismic data,and through sedimentary and structural research,the Micangshan foreland can be divided into five subbelts,which from north to south are:basement thrust,frontal thrust,foreland depression-back-thrust triangle,fore...     

Inversion of two-phase extensional basin systems during subduction of the Paleo-Pacific Plate in the SW Korean Peninsula:Implication for the Mesozoic “Laramide-style” orogeny along East Asian continental margin

During subduction, continental margins experience shortening along with inversion of extensional sedimentary basins. Here we explore a tectonic scenario for the inversion of two-phase extensional basin systems, where the Early-Middle Jurassic intra-arc volcano-sedimentary Oseosan Volcanic Complex was developed on top of the Late Triassic-Early Jurassic post-collisional sequences, namely the Chungnam Basin. The basin shortening was accommodated mostly by contractional faults and related folds. In the basement, regional high-angle reverse faults as well as low-angle thrusts accommodate the overall shortening, and are compatible with those preserved in the cover. This suggests that their spatial and temporal development is strongly dependent on the initial basin geometry and inherited structures.Changes in transport direction observed along the basement-sedimentary cover interface is a characteristic structural feature, reflecting sequential kinematic evolution during basin inversion. Propagation of basement faults also enhanced shortening of the overlying sedimentary cover sequences. We constrain timing of the Late Jurassic-Early Cretaceous(ca. 158-110 Ma) inversion from altered K-feldspar 40 Ar/39 Ar ages in stacked thrust sheets and K-Ar illite ages of fault gouges, along with previously reported geochronological data from the area. This "non-magmatic phase" of the Daebo Orogeny is contemporaneous with the timing of magmatic quiescence across the Korean Peninsula. We propose the role of flat/low-angle subduction of the Paleo-Pacific Plate for the development of the "Laramide-style" basement-involved orogenic event along East Asian continental margin.     

Iranshahr Blueschists as Results of Subduction of the Neotethys Inner Makran Oceanic Crust, SE Iran

<正>The Makran accretionary prism is one of the most extensive subduction accretions on Earth.It is characterized by intense folding,thrust faulting and dislocation of the Cenozoic units consisted of sedimentary,igneous and metamorphic rocks.It is located in the southeast of Iran and southwest of Pakistan.Rock     

Heterogenetic CBM Sweet Spots Evaluation Methods of Faulted Basin

<正>1 Introduction The Jixi basin is a Mesozoic and Cenozoic rift coal basin in Jiamusi uplift.The recent coal bed gas in Jixi basin shows that the coal bed methane resources prospect is good,and the resources potential is large(TANG Shuheng,2000;Zhang Xinmin,2002).However,it is in the face of the problems such as narrow zone of sedimentary facies,rapid phase transformation,thin coal seam,coal     

Redefining the Age of the Cenozoic Shanwang Formation in Shanwang Basin

<正>Objective The Shanwang Basin is a small Cenozoic sedimentary basin located in Linqu county,Shandong province.The Shanwang Formation,especially the diatomaceous shale member,contains diverse and finely preserved flora and fauna fossils(Fig.1).Previous paleontological study and radiometric dating show that it was formed in the Miocene.However,on the precise age of the formation,there are such different opinions as Late Miocene,Middle     

综合物探方法在巴彦毛都盆地寻找砂岩型铀矿的应用

通过在巴彦毛都盆地开展磁法、电阻率测深、自然电场法、^210Po等综合物探方法，基本查明了该盆地基底形态与埋深、盖层结构与找矿目的层发育特征、深部层间氧化带发育情况及铀矿化信息，为该盆地砂岩型铀矿远景评价提供了依据。     

克鲁伦河盆地及其邻区古河道型砂岩铀矿成矿条件分析

本文在综合分析古河道型砂岩铀矿成矿条件的基础上,着重探讨了克鲁伦河盆地、呼查乌拉－呼伦湖盆地的区域地质背景、基底与沉积盖层特征,指出了盆地的铀成矿远景。     

准噶尔盆地北部层间氧化带砂岩型铀矿形成条件分析

本文从盆地结构、沉积盖层的构造特征、岩相岩性条件、区域水文地质条件、还原介质条件等方面分析了准噶尔盆地北部层间氧化带形成的地质背景 ,认为该区具有丰富的铀源条件及适合层间氧化带发育的地层组合。区内普遍发育次生氧化砂体 ,其前缘存在还原障。基底的抬升使盖层具备了次生活化改造条件 ,盖层中发育明显的后生铀成矿作用。     

古河道砂岩型铀矿成矿若干问题探讨

本文在综合分析国内、外古河道砂岩型铀矿床资料的基础上，着重探讨了矿化类型的划分、形成的区域地质背景、气候与地貌条件、基底与沉积盖层、古河谷与古河道、矿化产出特征、后生成矿作用等有关铀矿形成条件和成矿作用的问题，并指出了今后的找矿方面。     

隆起对砂岩型铀矿成矿的控制及找矿启示

沉积盆地古隆起对油气成藏起到明显控制作用, 对砂岩型铀矿成矿的制约也不可忽视。砂岩型铀矿通常就位于盆地边缘构造斜坡带和盆地内部隆起附近。隆起对砂岩型铀矿成矿的控制具体体现在: 控制地下水补-径-排体系、控制层间氧化作用、控制沉积相带发育、伴生断裂促进物质输运以及为成矿供给铀等。中国北方沉积盆地中新生代以来经历复杂的构造活动, 盆地域内非均衡发展而多形成隆起, 因此我国铀矿找矿尤其需要重视隆起对铀成矿的控制。其中, 盆地内部找矿应重点关注被大幅抬升的隆起, 而盆地边缘构造斜坡带上找矿需重视微隆起以及基底上覆地层的褶皱。将隆起作为关键控矿要素, 优选适用的攻深找盲方法, 精细刻画盆地基底隆升形成的背斜、褶皱及伴生断裂, 可有效提高铀矿找矿效率并拓展铀矿找矿空间。     

柴东盆地重磁场特征及构造单元划分

本文通过对柴东盆地各地质体（层）物性参数和重磁场特征分析，推断解释盆地的基底结构、岩相特征，磁源体埋深，断裂构造性质及其控盆作用和对沉积覆盖层凹凸格局的影响，对柴东盆地的基底及盖层构造单元进行了划分。笔者建议在相对稳定的地区，寻找基底埋藏浅、沉积盖层厚度较薄，有利于轴成矿的斜坡带。     

A passive seismic approach to estimating the thickness of sedimentary cover on the Nullarbor Plain,Western Australia

Passive seismic approaches, using a single-station, enable rapid, cost-effective and non-invasive estimates of the thickness of sedimentary rocks overlying crystalline basement. This approach was applied to estimate the Cenozoic and Cretaceous succession beneath the Nullarbor Plain in southeastern Western Australia. Passive seismic data acquired at the majority of the 94 sites show a single, strong resonance frequency peak between 0.4 and 0.6 Hz suggesting an impedance contrast of a single subsurface layer. Modelling these resonance frequencies against known stratigraphy at 12 drill holes shows that this impedance contrast corresponds to the contact of the base of the Cenozoic–Cretaceous sedimentary succession of the Eucla and Bight basins with the crystalline basement. Data from the remaining sites produced sediment thickness estimates ranging from only tens of metres near the western edge of the Nullarbor Plain to over 860 m near its southern margin. Near this margin, rapid thickening of the sedimentary cover is coincident with an interpreted paleosea-cliff or indicative of localised faulting. Beneath the Western Australian portion of the Nullarbor Plain the sedimentary cover is on average 320 m thick with the succession thinning gradually towards the margins of the basin. A passive seismic approach is thus seen as a useful screening tool for the mineral exploration industry in areas that are under cover allowing for better targeting and cost-reduction in greenfields exploration.     

俄罗斯古河谷型铀矿成矿地质条件

本文概述了俄罗斯古河谷型铀矿成矿地质条件，包括大地构造、盆地基底和沉积盖层、古河谷特征、古气候、后生地球化学分带和铀矿化特征等方面，并说明其成矿机理。     

合肥盆地基底构造属性

根据合肥盆地及周边地表地质、地震剖面、同位素测年及MT等新资料的综合研究,提出中-新生代合肥盆地的基底是一个不同构造类型基底的叠合与复合.上古生界以前的基底以六安断裂为界,其北为华北板块陆壳型-过渡壳型结晶基底及其上的华北克拉通-被动大陆边缘盆地沉积的上元古-下古生界基底;其南为大别型结晶基底及其上的北淮阳弧后盆地沉积的上元古-下古生界变质基底,而上古生界基底属于弧后前陆盆地型沉积.六安断裂是合肥盆地部位北大别弧、北淮阳晚元古-早古生代弧后盆地在早古生代晚期-晚古生代早期与华北板块的弧-陆碰撞缝合线.     

Alpine tectonics of granites in basement of Ysyk-Köl Basin,northern Tien Shan

The Ysyk-Köl Basin filled with Lower Jurassic–Quaternary sedimentary rocks is the largest intermontane negative structural unit of the northern Tien Shan. The basement of this basin is composed of Precambrian–Paleozoic rocks, largely of Ordovician and Silurian granitoids exposed in mountain ranges of the basin framework and as separate anticlinal domes situated in areas occupied by the Mesozoic–Cenozoic sedimentary cover. The postmagmatic tectonic internalstructure of the Chonkurchak (Chunkurchak), Kyzyl-Choku, Kyzyl-Bulak, and Prishib massifs emplaced in the basement, as well as their relationships to the sedimentary cover, are described in the paper. The study was carried out using the morphostructural method, detailed geological mapping, structural kinematic analysis, and petrographic examination of rocks. The internalstructure of Paleozoic granites in the basement and indications of their 3D tectonic flow are characterized. It is shown that granites underwent 3D deformation after their emplacement in the consolidated crust, and this process had a substantial influence on tectonic processes at the plate and orogenic stages of regional evolution.