珠江三角洲晚更新世地层三维结构重建及其指示意义

更新世以来沉积环境演变对探讨珠江三角洲发育形成、古地理环境的变迁具有重要意义。在收集、整理9425个钻孔数据基础上, 文章重新厘定了钻孔中更新统地层, 利用ArcGIS和GoCAD重建了珠江三角洲更新统地层和基底断裂的三维结构。结果表明: 地层沉积中心分布说明了更新统石排段和西南镇段地层分布、内部结构受到了NW、NE以及近EW向三组断裂的控制; 更新世西江、北江和东江等主要古河谷的发育位置与珠江三角洲盆地基底较深的位置基本吻合, 且沿着构造线发育形成平行岭谷地貌, 但与现今河道位置不同。西南镇段沉积时沉积中心、分布范围以及厚度与石排段有所不同, 反映了珠三角基底断块发生了不均匀沉降。

     

Spatial variability of palaeosols across Cretaceous interfluves in the Dunvegan Formation, NE British Columbia, Canada: palaeohydrological, palaeogeomorphological and stratigraphic implications

A basic sedimentological and palaeopedological framework is now in place for non-marine sequence models. The variability of interfluve palaeosols has not, however, been systematically documented, nor have the stratigraphic implications of that variability been incorporated into sequence models. Interfluve palaeosol variability in the deltaic Dunvegan Formation, NE British Columbia, Canada, is investigated, for which a detailed allostratigraphic and palaeogeographic framework has been developed, based on abundant well (> 2300 logs) and outcrop (> 60 sections) control. Regionally extensive valley fills and interfluves have been mapped in coastal plain deposits over an area of about 50 000 km². This palaeogeographic framework permits interfluve surfaces exposed in outcrop to be located in terms of distance from the margins of coeval valleys. The micromorphological, geochemical and mineralogical characteristics of five representative sequence-bounding palaeosols located from 250 m to more than 15 km from coeval valley margins are described. These interfluve palaeosols are similar to modern Alfisols and all record (i) aggradation on an alluvial/coastal plain; (ii) a subsequent static and/or degradational phase related to valley incision, non-deposition and soil thickening; and (iii) a final aggradational phase related to valley filling and renewed sedimentation across the coastal plain. Within this overall template, however, variations in palaeosol thickness, redoximorphic features, illuvial clay content and geochemistry suggest developmental control by hydrological characteristics that were influenced by both the nature of the underlying alluvial sediments and distance from the valley margin. The presence of mature interfluve palaeosols with complex developmental histories suggests that landscape dissection may have been related to terrace development associated with valley incision. Palaeosols closer to valley margins are thicker, contain more illuvial clay and display characteristics suggesting better drained conditions relative to those palaeosols that developed further from valley margins. Subsequent deposition on interfluves also reflects distance from valleys, with those sites close to valleys accumulating cumulic soils with evidence of brackish groundwater, whereas far from valleys (> 10–15 km), groundwater was fresh and clastic supply minimal, encouraging peat formation. Variations in drainage and palaeotopography during landscape dissection resulted in different palaeosol development styles on interfluve surfaces that can be shown, on the basis of physical correlation, to have the same geomorphic age. These observations support the concept of the soil-forming interval as a basis for pedostratigraphic correlation in ancient terrestrial deposits. Palaeosol variability on interfluves is to be expected, and recognition and documentation of this variability is an important prerequisite to palaeogeomorphological, palaeoclimatic and sequence stratigraphic interpretations.     

青海化隆县独特的峡谷丹山地貌景观及其科学价值

“峡谷丹山”是内外地质营力共同作用而形成的多成因地貌组合,不仅具有非常高的景观价值,而且具有重要的科学价值。青海省化隆县拉木峡为黄河一级支流,发育典型的角度不整合和丹霞地貌,因而成为青藏高原隆升和黄河形成演化研究的良好区域。以该地貌组合类型的形态特征、成因机制及形成年代研究为目标,采用野外地质调查等方法,对组成峡谷的岩石及地层、构造背景开展研究,系统总结与分析拉木峡地貌景观的形成动力和演化过程,进而探讨其对青藏高原隆升及黄河演化的指示意义。拉木峡由约900 Ma前的新元古代化隆岩群片麻岩及角度不整合于其上的约54 Ma前的新生代古近纪西宁群红色砂砾岩层组成。约8 Ma前青藏高原快速隆升,丹霞地貌雏形开始形成。自1.1 Ma黄河贯通化隆盆地后,受拉木峡流水强烈侵蚀下切和重力崩塌的持续作用,发育“峡谷丹山”地貌组合景观。峡谷险峻幽深、丹霞栩栩如生,成为极具典型性、独特性和稀有性的国家级地质遗迹,对青藏高原隆升、黄河形成演化和新生代气候环境的研究具有重要价值。     

冰后期以来长江水下三角洲层序地层特征及沉积环境演化*

长江水下三角洲层序地层学研究有助于全面了解长江三角洲地层特征和沉积环境演化模式。通过对长江水下三角洲下切河谷区YD0901和YD0903孔岩心的详细沉积物粒度、特征元素比值(Cl/Ti和Zr/Rb)、沉积相对比分析,恢复了冰后期以来长江水下三角洲层序地层格架。研究区冰后期以来自下而上依次出现河流相、潮汐河流相、河口湾相、浅海相和三角洲相的沉积相序。末次冰期海平面下降,古长江形成下切河谷,古河间地发育硬黏土层,构成五级Ⅰ型层序界面。之后海平面回升,分别于15 cal ka BP和8.0 cal ka BP形成最大海退和最大海侵界面,水下三角洲区域最大海侵发生时间略滞后于平原区,约为7.5 cal ka BP。据此3个层序界面将冰后期地层划分为低位体系域、海侵体系域和高位体系域。钻孔岩心记录揭示了14.8 cal ka BP海侵到达研究区;14.8~13 cal ka BP期间,受MWP-1A冰融水事件影响海平面快速上升,海岸线向陆推进速率可达71.9,km/ka;海退期间各钻孔沉积速率较低,直至2 cal ka BP开始,沉积速率明显增加。     

鲁西南地区煤成气盖层类型及分布

运用石油地质学与煤成气地质学等研究方法,分析了鲁西南地区煤成气盖层类型及其分布特征。研究表明,鲁西南地区除发育较好的煤成气烃源岩、储集层外,盖层保存也较完整,具备了该地区良好的煤成气成藏条件。在各凹陷区内,石炭—二叠系保存完整,其煤层上覆的泥质岩分布广泛,且多含有机质,厚度100～400m,其中包括一套对煤成气封闭能力最佳的杂色铝土质泥岩层(俗称"B层铝土"),厚10～30m;古近系也发育了多套以泥质岩为主的沉积,泥质岩总厚度达1000m以上,这些泥质岩大多为暗色,富集有机质。这些形成于不同时期的煤系地层上覆泥岩层共同构成了本区较好的区域性盖层。尤其在成武凹陷、鱼台凹陷和大汶口凹陷发育的古近系化学蒸发岩类——石膏、岩盐,是该地区煤成气最重要的区域盖层。     

Palaeovalleys and protozoan assemblages in a Late Carboniferous cyclothem, Sydney Basin, Nova Scotia

The early Stephanian Bonar Cyclothem of the Sydney Basin, Nova Scotia, contains an erosional surface cut through coastal plain strata with economic coals and distributary channel bodies. The erosion surface is interpreted as a palaeovalley 20 m deep and at least 7 km wide that marks a sequence boundary formed during relative fall in sea level. The palaeovalley is filled with stacked alluvial channel bodies which become more isolated as the valley fill passes upward into red, alluvial plain deposits, probably laid down in an anastomosed river system. In an adjacent, interfluve area, calcretes and red, vertic palaeosols cap coastal strata. Assemblage analysis of agglutinated foraminifera and thecamoebians indicates that the palaeovalley was filled with freshwater sediments before an initial marine transgression flooded the alluvial surface and adjacent interfluve. Valley incision probably reflects glacioeustatic sea level fall. However, the alluvial nature of the valley deposits suggests that valley filling reflects an abundant sediment supply during lowstand and/or transgressive stages and was not a direct consequence of sea level rise. During the subsequent transgression phase, aggradation was rapid as sediment supply apparently kept pace with rising sea level. Features of both channel and extra-channel facies suggest that seasonality intensified during the transition from coastal plain to palaeovalley and alluvial plain deposition.     

基于数字高程模型的岩溶地貌类型划分——以1:5000西南岩溶区地质填图试点为例

数字高程模型可以定量描述地貌,而基于峰丛洼地实体的岩溶地貌量化统计方法目前尚未确立。文章在1：50 000地质测量的基础上,将西南岩溶区地质填图试点地区的地层重新划分组合为火山岩层组、碎屑岩层组、灰岩层组、白云岩层组、泥灰岩层组、灰岩碎屑互层层组、白云岩碎屑岩互层层组7种层组类型;基于1：50 000数字地形图构建了研究区数字高程模型（DEM）,通过空间分析技术建立了区域洼地锥峰DEM,以岩溶层组为统计单元,分析出各个单元的锥峰洼地数字特征,并定义锥峰洼地发育系数（k）,量化峰丛洼地发育程度,将研究区地貌划分为5种地貌类型：峰丛洼地（k＞8.5）,锥峰洼地极为发育;峰丛谷地（1.9＜k≤8.5）,锥峰较为发育,洼地中等发育;丘岭谷地（0.9＜k≤1.9）,锥峰弱发育,洼地极少发育;溶蚀中山（0＜k≤0.9）,锥峰、洼地极少发育;侵蚀中山（k=0）,发育冲沟,无岩溶形态发育。     

Improved groundwater vulnerability mapping for the karstic chalk aquifer of south east England

The Cretaceous age Chalk of south east England forms an important aquifer. Within chalk the storage and transmission of groundwater is enhanced by subsurface karstic weathering. The case study presented in this paper demonstrates that current approaches to assessing groundwater vulnerability to pollution and delineating source protection zones are flawed, as they do not take proper account of the karstic nature of chalk.Improved techniques, based on understanding the geological and geomorphological controls of karst development in chalk, are proposed to overcome the shortcomings of published groundwater vulnerability maps. The results also demonstrate the inadequacies of current groundwater modelling approaches for defining source protection zones. The techniques follow European Commission research recommendations by taking account of recharge, presence of overlying cover deposits, the nature of chalk karst and the way in which it influences the flow of groundwater. The approach described allows for better informed decisions to be made about chalk aquifer management to ensure adequate protection and conservation of groundwater. For example, the published groundwater vulnerability map shows Lambeth Group deposits classified as being a minor aquifer of low groundwater vulnerability in the chosen study area. However, by applying the new techniques, they are classified as having an Aquifer Vulnerability Rating of moderate to very high, when taking the karstic development of the underlying chalk into account.     

Glacio-periglacial landforms within the Susquehanna Great Bend area of New York and Pennsylvania

Previous attention has been called to the morphology of the glaciated Appalachian Plateau, including periglacial phenomena (Coates, 1970; Conners, 1969). This paper deals with an unusually well-developed hierarchy of small landforms in the Great Bend area of the Susquehanna River. Essential properties of these features include: (1) concentration in N-S valleys, (2) till composition, (3) concavo-convex form, sometimes ending in a hill on the valley floor, (4) alternation with steep, truncated bedrock spurs, (5) a col in the interfluve at their head. These characteristics could be explained by the following sequence of events. A prior fluvial landscape was eroded with tributary streams forming lateral valleys that head in cols along the divides. The main stream flowed south between interlocking spurs. Ice then widened the valley, leaving truncated spurs and a straightened stream. Deposition of locally derived till filled tributary valleys, similar to till shadows (Coates, 1966). In periglacial conditions, while nivation was widening the tributary valley heads, solifluction in the unstable till was forming the concavo-convexities that alternate with the truncated bedrock spurs. The hierarchy of forms range from minor convexities to small hills on the main valley floor. Thus, the features are primarily of periglacial origin, but owe their development and position to prior subaerial and glacial events. The cycle may have occurred during more than a single glacial episode. The recession of bedrock spurs and the valley floor convexity of the till features have caused a reversal in stream sinuosity of the main valley.     

陕北黄土地层地貌特征及工程特性综述

陕北地区作为我国能源基地、农牧业生产基地和旅游基地,工程活动正在不断加强,但对于陕北黄土地区的区域工程特性研究较少。因此,结合野外调研以及相关勘察资料,对陕北黄土地层地貌及工程特性进行了综合分析。研究结果表明: 陕北黄土地层可划分为全新统风积沙、上更新统黄土、中更新统黄土、新近系岩石和古近系岩石; 陕北黄土地貌可划分为黄土侵蚀-构造堆积地貌、黄土现代构造(变形)地貌、黄土湿陷地貌和黄土侵蚀地貌; 因沉积年代和赋存环境的不同,陕北南部和北部黄土的工程特性(主要包括湿陷性、渗透性以及力学性质)迥异。陕北黄土地层地貌特征及工程特性的研究不仅与陕北地区的工程地质、水文地质和环境地质等研究有着密切的联系,而且对于陕北黄土分布区的生态、经济以及国防等国计民生建设具有重要的指导意义。     

古近系地层取心钻进速度影响因素初步分析

河北平原古近系地层主要发育有东营组、沙河街组和孔店组,其岩性以泥灰岩、泥岩、钙质泥岩、石膏泥岩和砂岩为主。影响取心钻探钻进速度的物理力学因素较多,本文主要以岩石密度、抗压强度和弹塑性为主进行了研究分析。研究得出岩石密度和抗压强度均随着地层深度的增加而增加,古近系东营组和沙河街组一段至三段岩石密度明显低于沙河街组四段和孔店组,钻进取心速度差异明显;古近系地层中的泥岩段由于粘土矿物成分占比增加造成岩石弹塑性增强,对钻进速度的影响比较明显;文中提出了古近系地层取心钻探过程中地层的可钻性级别及合理的钻头类型匹配。     

Climate and other factors in the development of river and interfluve profiles in Bhutan, Eastern Himalayas

The longitudinal profiles of the main N–S aligned rivers and the crests of the interfluve mountain ranges of Bhutan have been plotted against latitude. The river profiles are highly variable, even between branches of the same system. The main rivers in Eastern Bhutan are antecedent and rise in Tibet. They have irregular concave bed profiles in deep steeply sided valleys. The rivers further west rise on the southern slopes of the High Himalaya. They have stepped profiles with steep concave sections in gorges through the southern mountains and one or more concave sections upstream, separated by knickpoints. All of the N–S interfluve ranges rise steeply from the piedmont. Some then dip to major passes before again rising irregularly northwards to the High Himalaya, whilst others continue to climb northwards as irregular monoclines. The combination of various types of river and interfluve profiles creates a range of valley forms. The heterogeneity means that it is not possible to generalise about a typical Bhutanese river, interfluve or valley relief profile. There is no indication that the rivers of Bhutan have more knickpoints than those of the Central and Western Himalayas. Rainfall and runoff data, soils and natural vegetation have been examined for indications of significantly drier conditions in eastern Bhutan. The rainfall data show an eastwards decrease in the southern foothills, probably due to the rainshadow cast by the Meghalaya Plateau to the south, but mean annual totals are about or above three metres throughout, and the whole of this zone has a wet climate. There is no marked E–W climatic trend in the drier interior of Bhutan. We attribute the general topographic structure of Bhutan, and the variability of river and interfluve profiles and valley forms more to tectonic factors than to climatic variation.     

Hazardous geology zoning and influence factors in the near-shore shallow strata and seabed surface of the modern Yellow River Delta,China

In this study, on the basis of 3,200 km shallow stratigraphic section and side-scan sonar data of the coastal area of the Yellow River Delta, we delineated and interpreted a total of seven types of typical hazardous geologies, including the hazardous geology in the shallow strata (buried ancient channel and strata disturbance) and hazardous geology in the seabed surface strata (pit, erosive residual body, sand patch, sand wave and scour channel). We selected eight parameters representing the development scale of the hazardous geology as the zoning indexes, including the number of hazardous geology types, pit depth, height of erosive residual body, length of scour channel, area of sand patch, length of sand wave, width of the buried ancient channel and depth of strata disturbance, and implemented the grid processing of the research area to calculate the arithmetic sum of the zoning indexes of each unit grid one by one. We then adopted the clustering analysis method to divide the near-shore waters of the Yellow River Delta into five hazardous geology areas, namely the serious erosion disaster area controlled by Diaokou lobe waves, hazardous geology area of multi-disasters under the combined action of the Shenxiangou lobe river wave flow, accumulation type hazardous geology area controlled by the current estuary river, hazardous geology area of single disaster in the deep water area and potential hazardous geology area of the Chengdao Oilfield. All four of the main factors affecting the development of hazardous geology, namely the diffusion and movement of sediment flux of the Yellow River water entering the sea, seabed stability, bottom sediment type and distribution, as well as the marine hydrodynamic characteristics, show significant regional differentiation characteristics and laws. These characteristics and laws are consistent with the above-mentioned zoning results, in which the distribution, scale and genetic mechanism of hazardous geology are considered comprehensively. This indicates that the hazardous geology zoning based on the cluster analysis is a new attempt in research regarding the hazardous geology zoning of the near-shore waters of the modern Yellow River Delta and that this type of zoning has a high level of reasonability.     

南疆库车河新生界剖面磁性地层研究

据磁性地层研究，并借助于同位素年龄测定和河谷地貌研究资料，库车河第三系可划分为（自老而新）库姆格列木群、苏雅依组、吉迪克组、康村组、库车组和西域组，第四系可划分为坎村组、乌苏群、新疆群和全新统，结合塔里木盆地及周缘的实际情况将第四系下限暂置于１．６ＭａＢ．Ｐ．，上、下第三系的分界时限为２４．０ＭａＢ．Ｐ     

黑龙江省前寒武纪变质地层划分对比研究进展

黑龙江省前寒武纪地层分布广泛,出露零星。通过对黑龙江省前寒武纪地层年代学、沉积建造、发育矿床特征及地层对比的综合分析显示,黑龙江省前寒武纪变质岩系和古生界锆石测年数据中出现有较多的太古宙、古元古代的谐和年龄,在古生代火成岩中也存在太古宙和古元古代捕获锆石的年龄数据信息,且黑龙江省前寒武纪变质基底主要为中-新元古界,产出沉积变质型铁矿和中、大型石墨矿床,发育典型的硅铁建造、孔兹岩系或含石墨岩系,并可在区域上对比。结合黑龙江省近年1：25万区域地质调查和相关科学研究成果,在额尔古纳地块上划分出古元古代表壳岩,将《黑龙江省区域地质志》置于新太古代的麻山群,置于古元古代的兴东群、东风山群、兴华渡口群修订为岩群,并依据近年来的区域地质调查成果、高精度测年资料、典型建造类型与变质程度等,将时代厘定为中-新元古代,同时依据建造和产出铁矿特征在宁安西南部地区划分对比出塔东岩群,为黑龙江省前寒武纪地质研究提供了地层学方面的资料。     

兰州市城市供水现状评价及可持续发展对策研究

兰州市辖3县5区,总面积1.3万km2。位于陇西黄土高原西部,海拔1 500~3 500m,地势总体上表现为西南部高、东北部低。广覆黄土的低山丘陵及其夹峙的河谷平原,构成了本区的基本地貌景观。平原区生态地质环境较好,特别是河谷平原内的一、二级阶地,具有地形平坦、地势开阔的优越条件,是人类生产与生活最佳地段、也是人口相对密集的区域,如兰州黄河河谷平原、永登庄浪河谷平原、榆中盆地、秦王川盆地等。本文剖析,评价其供水现状,提供可持续发展的对策,具有重要意义。     

旅游地质资源环境特点及保护——以三江并流带为例

旅游地质资源环境是地理环境的一部分,但是它又有其自身的特点.归纳它的特点、规律,分析它与其他因素的关系,有利于环境的保护.本文在三江并流带旅游地质资源环境的基础上,尝试总结了旅游地质资源环境的几个特点,并以此为指导,提出了三江并流带旅游地质资源开发与环境保护的几点建议.     

新疆西部苏盖特构造带构造特征及勘探前景

苏盖特构造带位于新疆昆仑山弧形推覆体前缘.本文通过研究苏盖特构造带的构造特征,确定了地震反射层的地质属性,认为苏盖特构造带由表层推覆体及下部下第三系-二叠系之间的地层经过3次重复形成的叠瓦状推覆体构成.苏盖特构造带活动始于上新世阿图什组沉积期,定型于更新世.通过研究西昆仑逆冲推覆体及已钻探井的地表油源、储层特征及储盖组合,认为苏盖特构造带具有两套好的油源即石炭-二叠系及侏罗系油源,两套好的储集层即白垩系和下第三系储层,相应地,发育两套储盖组合,具有良好的圈闭及运聚条件,是有利的勘探目标区.     

贵州茅台组的沉积环境

本文根据岩性组合、剖面结构及与下伏地层接触关系等特征,认为贵州地区上白垩统茅台组是炎热干燥气候条件下,于燕山构造运动后未曾夷平基面上沉积的河湖相红色磨拉石建造,沉积盆地性质为山间盆地。茅台组现今的大范围零星散布,主要是喜马拉雅运动后遭受长期侵蚀剥蚀造成的。     

青海格尔木早更新世昆仑河砾岩的发现及其地质意义

昆仑河发源于昆仑山,是格尔木河的重要支流之一。前人所报道的新近纪与第四纪地层,主要集中于昆仑山垭口地区,而在昆仑河—格尔木河谷地中,只有中更新世以来的最新地层,从而提出了发生于1.1~0.6 Ma BP间的“昆仑—黄河运动”的概念。然而在昆仑河谷中发现了厚达20 m的钙质胶结的河流相砾石层(昆仑河砾岩),其分布、特征及其与纳赤台沟组、三岔河组和低阶地沉积等上覆地层的不整合接触关系,以及ESR法测定的该砾石层2个钙质胶结物样品的年龄(分别为1 042 ± 104 ka BP与1 269 ± 126 ka BP)均表明,早在距今1.27~1.42 Ma之前昆仑河—格尔木河河谷已经形成,而且已深切到现今的谷底。此后河谷内的多次切割与堆积,不应是构造运动的结果,而可能是冰期与间冰期气候变化所引起的侵蚀与搬运能力变化造成的。同样,昆仑山相对于柴达木盆地的强烈隆升至少应发生于距今1.27~1.42 Ma之前。