The Nordkalott Project: studies of Quaternary geology in northern Fennoscandia

The Quaternary geology of the Nordkalott area in northern Fennoscandia is depicted in five maps. The themes of the maps are: Quaternary deposits, glacial geomorphology and paleohydrography, ice-flow indicators, Quaternary stratigraphy and ice-flow directions. The maps are briefly presented and an outline of the glacial history of the Nordkalott area is given.     

我国第四纪地质科学应用的新领域——海底光缆工程路由勘察

文章介绍了第四纪地质学的一个新的应用领域--海底光缆工程路由勘察.该项勘察是在全球经济发展,人类从工业化向信息化社会转变,信息化基础建设蓬勃兴起的时代出现并逐步完善的一个新的海洋工程领域.海底光缆建设在国内外得到迅速发展.我国修建的国内外海底光缆已达20余条.海底光缆工程路由勘察与第四纪地质学关系密切.海洋第四纪地质现象是它进行勘察和研究的主要内容.海底光缆路由勘察使用先进的仪器设备,采集的是数字化信息,能快速准确的成图.该图反映路由区海底所有的自然环境特征.勘察融汇了现代化的高新技术,拓宽了第四纪研究的领域,推动了第四纪地质学的发展.     

海拉尔盆地乌尔逊-贝尔凹陷的构造特征及其对油气成藏的影响

海拉尔盆地乌尔逊-贝尔凹陷是叠置于内蒙-大兴安岭古生代碰撞造山带的中新生代盆地,主要发育白垩系和第三系、第四系,其中以下白垩统为主。乌尔逊-贝尔凹陷在中新生代经历了多期变形作用,构造特征十分复杂,主要发育4个方向的构造带,其中北东向、北东东向和南北向断层带形成较早且长期活动;北西向断层带形成较晚,对上述三个方向构造主要起改造作用。研究区的构造不仅影响了烃源岩的分布、油气运移和聚集,而且影响了圈闭的形成和油气分布,是研究区有利的油气聚集带。     

对内蒙古阿拉善西部地下水流向问题的新认识

内蒙古阿拉善西部的水文地质研究程度很低,关于地下水的来源和流向仍然存在各种不同的认识,需要在沙漠腹地补充钻探资料加以验证。本研究在前人调查成果的基础上,选择巴丹吉林沙漠及其周边的4个控制点进行了水文地质钻探,获得关键性的含水层分布和地下水位数据,对地下水流向问题提出了新的认识。分析结果表明,阿拉善西部广泛发育厚度50 m以上的第四系孔隙含水层,与新近系和白垩系砂岩含水层一起构成主要的地下水渗透介质,使区域地下水流具有连续性。地下水总体自东向西、自南向北流动,水力梯度介于0.8‰与7.9‰之间。在区域尺度上,断裂带对浅层地下水的作用并不显著。     

Morphotectonic Methods To Infer Groundwater Flow Under Conditions Of Scarce Hydrogeological Data – The Case Of Northern Arava,Israel

In areas characterized by flat and weakly incised relief built of young and lithologically uniform sediments, structural and tectonic maps are often nonexistent or are of no great avail. Under such conditions, the regional morphotectonic analysis of the study area may be a useful method to produce the required basic hydrogeological information. The method consists of two basic steps: (1) definition of stream orders and, (2) the preparation of isobase maps. In the research of Quaternary geology, isobase surface analysis is regarded as a means for identifying young tectonic processes. The morphotectonic map is the final derivative of isobase maps. It portrays the basic lineaments or dislocation lines derived by analyzing deviations in the directions of isobase lines, of their spreading or compression, and of deviations between axes of valleys. The morphotectonic map presented in this paper portrays several major morphostructural units within the Arava graben, in the area between the Dead Sea and Nahal Paran. When combined with hydrological data from boreholes, it facilitates elucidation of groundwater flow paths and salinization focci controlled by structural elements.     

Land use/cover change and driving force analyses in parts of northern Iran using RS and GIS techniques

To accomplish integrated watershed management and land use planning, it is necessary to study the dynamic spatial pattern of land use and cover change related to socioeconomical and physical parameters. In this study, land use and cover change detection was applied to the Lajimrood Drainage Basin in northern parts of Iran, an area characterized by rich and diversified agricultural and forest mosaic. The main of changes in the study area were forest–arable land transformation, which was only considered in this study. In order to detect these changes, at first, based on 1:25,000 digital topographic maps dated 1967 and 1994 and ETM⁺ satellite image dated 2002, land use map in these three dates were prepared. The results showed that the area with forest land use decreased about 3.2% in transition 1967–2002. Also, arable land increased about 36.9%. We suggested a method to analyze the driving forces and the spatial distribution of land use change. The maps of elevation, slope, and aspect were derived and classified by using digital elevation model (DEM). Also, the maps of distance from road, drainage network, and building area were selected as socioeconomical factors. These maps were overlaid and crossed with land use change map and land use change area ratio was computed. The results showed that the elevation, slope, and aspect were physical effective factors in land use changing. Also, by increasing the distance from building area and roads, deforestation rate was reduced.     

Long-term trends of seasonal dusty day characteristics—West Iran

In order to examine the seasonal characteristics of the dust events over western parts of Iran, surface observations from 27 meteorological stations for the period 1951–2014 were analyzed to obtain spatial distributions and temporal variations and trend of dusty day frequency (DDF). Trends of DDF were analyzed by Mann–Kendall and Sen’s estimator of slope nonparametric statistics. Three meteorological stations were selected in north (Tabriz), middle (Kermanshah), and south of the study area (Ahwaz) as reference stations for detecting the regional differences of DDFs. The results showed that DDF is a variable season by season but in general, DDF increases from north to south and from east to west of Iran. The maximum of DDF is monitored in May, June, and July. There are tangible seasonal increasing–decreasing periods in which these changes are logically related with seasonal changes. Regardless of the existence of the maximum DDF in south and southwest of study area, the most intensive increasing DDF trend is calculated in west middle areas. The most widespread and intensive increasing DDF pattern in west of Iran is observed when it is spring. In this case, the dust storms replaced the rainfalls. Distance from dust sources, major movement ways of dust transporting synoptic systems, regional effective wind activity (such as Shamal wind), and arrangement of high mountains are the known factors affecting frequency variation, distribution, and rate of the trend of all the dust phenomena in west of Iran.     

Utilities of Landsat 7 data and selective image processing in characterization of radioactivity zones of Wadi Baba–Wadi Shalal Area, Westcentral Sinai, Egypt

Wadi Baba–Wadi Shalal area locates in the westcentral part of Sinai, Egypt. It is covered by a Precambrian basement rocks comprise the northern part of the Precambrian Arabo-Nubian crystalline massive. The lithologic and structural setting of the investigated area was interpreted from the digital Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data. The structural lineament analyses for the lithologic units and their relationships to the high-radioactivity zones (HRZ) and the characterizations of HRZ of the study area are the main tasks of this article. Extraction algorithm was applied using Geomatica PCI package under the user defined parameters. The extracted structural lineaments have been evaluated and chicked using the visual interpretation and published works. The short-wave infrared spectral ETM+ band-7 was selected as an optimum data for automatic lineaments extraction since it scored the highest lineament frequency (1856) compared to the other visible and near infrared bands. The aeroradiometric color raster total count equivalent thorium (eTh) and equivalent uranium (eU) maps were used to delineate the highest radioactivity zones of the study area. A selective image processing technique (SIPT) is a new approach in Geomatica (9.1), which gives rise to valuable results in this work. The SIPT was carried out for the subset of the ETM+ data of the highest radioactivity zones. The spatial distribution of the structural lineament pattern maps for some low-radioactivity zones (LRZ) and for the highest radioactivity zones of the study area are prepared with their frequency rose diagrams. The NE–SW trend is the predominant structural lineaments trend in the investigated area. The NE–SW to the ENE–WSW directions are the predominant structural lineament trends in both the LRZ and the HRZ. These high-radioactivity zones of the investigated area are characterized by high lineaments density and lineaments-intersection density, restricted to Um Bogma Formation and younger granitic rocks and are not controlled by structural lineament trends.     

洞庭盆地第四纪构造活动特征

利用沉积等厚线图，分析得出的洞庭盆地第四纪构造活动特征如下：北北东及近东西向两组断裂将盆地切割为一系列断块；盆地西部为箕状断块，东部为箕状凹陷、早、中更新世为盆地的断陷阶段，晚更新世以来进入坳陷阶段；第四纪以来构造沉降速率呈加速度增强；构造活动的时空变化控制着洞庭湖的演变。     

浅覆盖区第四系三维地质结构模型快速构建--以运漕幅为例

在浅覆盖区地质调查中,钻探和物探等方法常用于揭示地质体三维空间分布。本文借用三维可视化方法,以运漕幅作为研究区域,利用钻孔资料和人工解译的地质图快速构建第四系三维地质结构模型,以展现研究区第四系宏观地层格架。文中详细介绍了模型构建的数据源及流程。最后,结合虚拟勘探线剖面成果模型,探索以立体形象的方式显示区域地层分布。所构建的第四系模型可称之为三维地质图,其价值即体现在形象的展现地质体空间分布。     

Dike-filled extensional structures in Cenozoic deposits of the Kleszczów Graben (Central Poland)

The origin and development of the Cenozoic Kleszczów Graben were strongly influenced by a pre-existing fault pattern within the Permian–Mesozoic bedrock. Dike-filled fractures penetrating Neogene/Quaternary deposits, analysed in the opencast Bełchatów browncoal mine, follow extensional structural patterns parallel to the axes of the local anticlinal forms established (or rejuvenated) in the Quaternary. These structures are particularly well developed along the fold crests. The spacing and structural features of the fractures and normal faults are explained in terms of the tensile stress operating in beds subjected to folding. The main localities of the Quaternary folds precisely align with segments of two deep-seated reverse faults: the Kleszczów–Kodrąb Fault and the Gomunice–Piaski Fault. Both are NW–SE orientated dislocations along a hinge zone of the Laramide Łękińsko Anticline, subcropping the Cenozoic graben infill in the open mine. The origin of the Quaternary folds as fault-overlying folds is attributed to a young block uplift on the Łękińsko Anticline area, which is well recorded by a strong reduction in thickness of the Cenozoic sediments; the Quaternary succession is reduced in thickness twice as much as the Neogene. The successive stages of Quaternary reactivation of the Łękińsko Anticline (during the Cromerian through the Late Saalian), with diminishing intensity, are believed to be correlatable with the sequence of glacial rebound events coupled with mobility of the deep-rooted fault zone.     

Geomorphologic assessment of relative tectonic activity in the Maharlou Lake Basin,Zagros Mountains of Iran

Spatial differences of Quaternary deformation and intensity of tectonic activity are assessed through a detailed quantitative geomorphic study of the fault‐generated mountain fronts and alluvial/fluvial systems around the Maharlou Lake Basin in the Zagros Fold–Thrust Belt of Iran. The Maharlou Lake Basin is defined as an approximately northwest–southeast trending, linear, topographic depression located in the central Zagros Mountains of Iran. The lake is located in a tectonically active area delineated by the Ghareh and Maharlou faults. Combined geomorphic and morphometric data reveal differences between the Ghareh and Maharlou mountain front faults indicating different levels of tectonic activity along each mountain front. Geomorphic indices show a relatively high degree of tectonic activity along the Ghareh Mountain Front in the southwest, in contrast with less tectonic activity along the Ahmadi Mountain Front northeast of the lake which is consistent with field evidence and seismotectonic data for the study area. A ramp valley tectonic setting is proposed to explain the tectonosedimentary evolution of the lake. Copyright © 2011 John Wiley & Sons, Ltd.     

River drainage reorientation during placer gold accumulation, southern New Zealand

Many alluvial placer deposits around the world occur in river systems that have been affected by tectonic events, causing drainage reorientation and severance of links between placers and their sources. This study documents tectonic rejuvenation of topography in the Otago giant placer goldfield, New Zealand, which has resulted in numerous river capture and drainage reorientation events. These events have induced changes to gold transport directions and numerous stages of separation of detrital gold from primary sources. Goldfield-wide reconstructions of drainage patterns through time are as yet only possible for Miocene–Recent, and numerous earlier drainage changes back to Cretaceous primary orogenic mineralisation are probable. Variations in basement lithologies permit auriferous gravel provenance determinations, facilitating paleodrainage pattern reconstruction and documentation of river capture events. River capture events and timing of these events for gold-bearing paleodrainages have also been documented using genetic divergences of populations of freshwater galaxiid fish that were isolated by drainage reorientation. Gold-bearing quartz pebble conglomerates had a southeastward drainage in the Miocene. This was disrupted in the Pliocene by mountain range uplift and gold placer recycling, with deposition of lithic conglomerates containing only minor gold placers. The most dramatic changes in gold transport directions occurred through the Quaternary, as antiformal ranges grew across the pre-existing drainages. Miocene and Pliocene placers were recycled with numerous local (1–10 km scale) changes in river directions and numerous capture events. Large axial rivers were segmented into a more complex drainage pattern, and on-going river capture resulted in growth of the main Clutha River catchment at the expense of neighbouring catchments. The most productive placers developed in the Clutha River in late Quaternary when increased discharge from captured mountain catchments enhanced gold transport and concentration. Similar river drainage reorientation has occurred in other placer fields around the world, but the lack of preserved evidence inhibits documentation of most such changes.     

Neotectonics of the Somogy hills (Part II): Evidence from seismic sections

The Somogy hills are located in the Pannonian Basin, south of Lake Balaton, Hungary, above several important tectonic zones. Analysis of industrial seismic lines shows that the pre-Late Miocene substratum is deformed by several thrust faults and a transpressive flower structure. Basement is composed of slices of various Palaeo-Mesozoic rocks, overlain by sometimes preserved Paleogene, thick Early Miocene deposits. Middle Miocene, partly overlying a post-thrusting unconformity, partly affected by the thrusts, is also present. Late Miocene thick basin-fill forms onlapping strata above a gentle paleo-topography, and it is also folded into broad anticlines and synclines. These folds are thought to be born of blind fault reactivation of older thrusts. Topography follows the reactivated fold pattern, especially in the central-western part of the study area.

The map pattern of basement structures shows an eastern area, where NE–SW striking thrusts, folds and steep normal faults dominate, and a western one, where E–W striking thrusts and folds dominate. Folds in Late Neogene are also parallel to these directions. A NE–SW striking linear normal fault and associated N–S faults cut the highest reflectors. The NE–SW fault is probably a left-lateral master fault acting during–after Late Miocene. Gravity anomaly and Pleistocene surface uplift maps show a very good correlation to the mapped structures. All these observations suggest that the main Early Miocene shortening was renewed during the Middle and Late Miocene, and may still persist.

Two types of deformational pattern may explain the structural and topographic features. A NW–SE shortening creates right-lateral slip along E–W faults, and overthrusts on NE–SW striking ones. Another, NNE–SSW shortening creates thrusting and uplift along E–W striking faults and transtensive left-lateral slip along NE–SW striking ones. Traces of both deformation patterns can be found in Quaternary exposures and they seem to be consistent with the present day stress orientations of the Pannonian Basin, too. The alternation of stress fields and multiple reactivation of the older fault sets is thought to be caused by the northwards translation and counter-clockwise rotation of Adria and the continental extrusion generated by this convergence.     

Facies Analysis and Sequence Stratigraphy of Silurian Carbonate Ramps in the Turan (Kopeh-Dagh) and Central Iran Plates with Emphasis on Gondwana Tectonic Event

Two sections from the Silurian deposits in the Central Iran Micro and Turan Plates were measured and sampled. These deposits are mostly composed of submarine volcanic rocks, skeletal and non-skeletal limestone, shale and sandstone that were deposited in low to high energy conditions (from tidal flat to deep open marine). According to gradual deepening trend, wide lateral distribution of facies as well as absence of resedimentation deposits, a depositional model of a homoclinal ramp was proposed for these deposits. Field observations and facies distribution indicate that, two depositional sequences were recognized in both sections. These sections show similarities in facies and depositional sequence during the Early Silurian in the area. Although there are some opinions and evidences that demonstrated Paleo-Tethys rifting phase started at the Late Ordovician-Early Silurian, similarities suggest that the Turan and Iran Plates were not completely detached tectonic block during this time, and that their depositional conditions were affected by global sea level changes and tectonic events.     

AMS fabric and tectonic evolution of Quaternary intramontane extensional basins in the Picentini Mountains (southern Apennines, Italy)

In this work, we report the results of combined geological, structural, and anisotropy of magnetic susceptibility (AMS) studies carried out on Quaternary deposits in the Picentini Mountains, southern Apennines (Italy). The study concerns four small continental basins, Acerno, Tizzano, Iumaiano, and Piano del Gaudo, related to fluvial–lacustrine depositional environments, ranging in altitude from 600 to 1,200 m a.s.l. and strongly incised during recent time. Stratigraphic and structural analyses, integrated by low- and high-field anisotropy of magnetic susceptibility (AMS), show that the formation of these basins has been controlled by extensional and transtensional tectonics. Most of the AMS sites exhibit a well-defined magnetic foliation parallel to the bedding planes. A well-defined magnetic lineation has also been measured within the foliation planes. In the Iumaiano, Tizzano, and Piano del Gaudo basins, magnetic lineations cluster around NNE–SSW trend and are parallel to the stretching directions inferred by structural analysis of faults and fractures. On the basis of structural, sedimentological, and high-field AMS data, we suggest a tectonic origin for the magnetic lineation, analogously to what has been observed in other weakly deformed sediments from Neogene and Quaternary extensional basins of the Mediterranean region. Our results demonstrate that onset and the evolution of the investigated basins have been mainly controlled since lower Pleistocene by NW–SE normal and transtensional faults. This deformation pattern is consistent with a prevalent NE–SW extensional tectonic regime, still active in southern Apennines, as revealed by seismological and geodetic data.     

Paleoenvironment of geomorphic surfaces of an alluvial fan in the eastern Isfahan,Iran, in the light of micromorphology and clay mineralogy

Alluvial fans are one of the most important landforms in geomorphological and paloenvironmental studies. The objective of this study was the application of clay mineral assemblages and micromorphological properties of the studied paleosols in the geomorphic surfaces of an alluvial fan in the eastern Isfahan as proxies for paleoenvironmental and paleoclimatic changes. Micromorphology, X-ray diffraction, and scanning electron microscopy approaches were used to study the representative pedons. The results indicated that the illuviation process in the calcareous soils of the arid regions of the eastern Isfahan was probably in response to Quaternary moist conditions. There was no significant difference between clay coating properties of the studied relict and buried paleosols. Clay mineralogical study suggested that kaolinite and illite were inherited from the parent materials, while smectite and palygorskite were formed in the soil environment. Paleoargillic horizon was characterized by smectite and calcic (especially the calcrete) horizons were dominated by palygorskite. Palygorskite was accumulated by both neoformation and illuviation processes. High clay content, high intensity of smectite peak, and activity of the illuviation process in paleoargillic horizon demonstrated the seasonality of climate (rainfall) even in the moist periods of Quaternary in Central Iran. Clay mineralogical assemblages suggested a trend of increasing environmental aridity in the study area. This study, therefore, highlighted the role of clay mineralogical investigations in arid lands’ geomorphological and paleoenvironmental researches.     

The nature and provenance of Golestan loess deposits in northeast Iran

Mineralogical, textural, geochemical, and weathering characteristics of loess deposits in Golestan province of Iran suggest that they are mostly derived from felsic igneous rocks and are related to Quaternary palaeoclimate. Whole‐rock analyses indicate heavy minerals such as zircon, tourmaline and phyllosillicate minerals (e.g. muscovite, chlorite, illite) exert a significant control on the chemical composition. The loess samples display uniform chemical composition, indicative of similar alteration history. Chemical index of alteration suggests a weak to moderate degree of weathering in a felsic source area. Scanning electron micrographs of quartz grains reveal abundant silt‐sized quartz particles, a result of glacial grinding during the Late Pleistocene in Central Asia. Subsequently, these silt particles were transported from Central Asia to their depositional site by wind and paraglacial processes. Local topography of northeast Iran (Alborz Mountains) acted as a major barrier, entrapping the airborne particles on the plains of Golestan province. Copyright © 2012 John Wiley & Sons, Ltd.     

Quaternary neotectonics of the Somogy Hills, Hungary (part I): Evidence from field observations

Quaternary and directly underlying Late Miocene (Pannonian) outcrops were analysed by structural, tectono-morphologic and sedimentologic methods to describe the main fault directions, to separate mass movements from faulting and folding and to separate earthquake-induced sediment deformations from other (e.g. periglacial) effects in the Somogy Hills. This is a gentle hilly area elevated at 200–300 m above sea level, located immediately south of Lake Balaton, Hungary.

Quaternary outcrops showed several consistent directions of faulting, and co-depositional seismic activity. Three different Mohr-sets of faults/joints could be differentiated in Quaternary sediments. The three sets are considered Late Quaternary since all cut young loess sections and have morphological expressions.

On the basis of the microtectonic measurements and morphotectonic investigations, the following sequence of Quaternary events can be proposed:

1. A (W)NW–(E)SE compression and perpendicular extension would create E–W to WNW–ESE oriented right lateral, NNW–SSE to N–S oriented left lateral shear zones, and NW–SE striking normal faults. Some of these can be evidenced in morphology and among the individual fault measurements. Some reactivated faults might suggest that this field is a relatively older one, but fresh topographic elements suggest that this stress field might be operational sub-recently.

2. A second stress field with NNW–SSE extensional and ENE–WSW oriented compressional directions could be separated. This stress field could create NNE–SSW and NW–SE oriented shear fractures and ENE–WSW oriented conjugate normal faults. Flat thrusts giving ENE directed shear may also be active under this field.

3. A third stress field might be proposed with N–S compression and perpendicular extension directions. This would create NE–SW and NW–SE oriented shear fractures, which are observed in the measured fault data. It is remarkable that the NE–SW faults are all steep, subvertical, and give a very well defined fault set. Based on the fresh topographic expression, this stress field is also sub-recent.

The different sub-recent stress fields and related fault patterns might succeed each other or might alternate through time. The first and third deformations have fresh topographic expressions and cannot play synchronously. The observed features suggest a compressionally active neotectonics of the study area.     

我国古地理学的形成、发展、问题和共识

古地理是研究地质历史时期和人类历史时期的自然地理特征的科学,有重要的地学理论意义和生产实践意义,还与人类赖以生存的古今地理环境密切相关。我国古地理学来源于地层学、地史学、大地构造学、古生物学、沉积岩石学、自然地理学、第四纪地质学、考古学、人类历史地理学等,因此就相应地产生和形成了地层古地理学(或地史古地理学)、构造古地理学、生物古地理学、岩相古地理学(或沉积古地理学)、自然地理古地理学、第四纪古地理学、人类历史古地理学等分支学科。有许多类型的古地理图,如构造古地理图、生物古地理图、岩相古地理图、示意的或定性的古地理图、定量的古地理图、不同比例尺的古地理图、当今界限的古地理图、非当今界限的古地理图等。古地理图是古地理研究的集中表现,是古地理学的生长点。我国的古地理学有4个主要的发展趋势,即从单一到综合,从定性到定量,从手工作图到计算机作图,从理论到应用。《古地理学报》的创刊和开始进入我国科技期刊的先进行列是我国古地理学发展历史中的一件大事。2002年12月香山科学会议第197次学术讨论会围绕“多信息的古地理重建”这个主题,通过充分的讨论和争鸣,对我国古地理学的发展前景达到了共识,即根据多学科的、多层圈的、多时代的、第一手为主的和定量为主的信息资料,编制从长城纪到第四纪以及人类历史时期的、各种比例尺兼有的、既有地学理论意义又能为生产实践和人类生存环境的维护和改善服务的、综合各古地理学分支学科之长的古地理图,是时候了。这是一个巨大的工程。让我们共同努力,为促使这一有重大历史意义和现实意义的宏伟目标的早日实现而奋斗。