巴丹吉林沙漠南缘冲洪积物的光释光年代及其水文学意义

冲洪积物是古气候和古水文信息的重要记录,为了探讨巴丹吉林沙漠南缘地区全新世气候环境及其对区域地下水的影响,对沙漠南缘的水成沉积物进行了沉积学分析和光释光年代学测试,结果表明本文研究的两个沙漠南缘沉积剖面分别为全新世中期（6.6~5.2 ka）的间歇性河流沉积和暂时性流水形成的洪泛沉积.基于前人全新世中期沙漠中湖泊水位、气候环境重建,以及本文研究的冲洪积物的沉积特征与年代,表明在气候湿润的地质时期巴丹吉林沙漠南缘及山区的区域降水形成暂时性洪流和/或间歇性河流会对沙漠地区地下水进行补给.      

江苏晚白垩世赤山组沉积环境

本文对赤山组创名剖面的岩相及沉积环境进行了详细研究。赤山组为典型内陆盆地沙漠环境沉积物，具较复杂的层序结构，其下段主要为沙漠湖或干盐湖沉积，上段为风成沙丘沉积。对上段风成沙丘沉积系统的不同级别边界面的特征及成因进行了描述分析，探讨了赤山组沉积的构造背景，认为是在干热气候条件下，盆地已从断陷转为拗陷并逐渐封闭时的沉积物。     

四川盆地古近纪沙漠沉积特征及古风向意义

基于前人研究成果,通过野外地质调查、室内分析测试对四川盆地古近系柳嘉组红层沉积物的性质、结构、原生沉积构造及石英颗粒表面结构进行了系统分析,分析结果进一步证明了本区古沙漠的存在.将其沙漠沉积分为沙丘和丘间两种沉积类型,对丘间又细分为干丘间和湿丘间,针对不同的沉积类型也明确了相应的识别标志.通过对沙丘前积层倾向的测量,重...     

黔南桂西中三叠统浊积扇、物源及板块构造

引言广布于黔南桂西地区的中三叠世重力流沉积物(面积达7000km~2),由于在黔桂盆地的沉积演化历程中,占有重要地位,因而,历来为世人所注目。近年来,国内先后有许多单位和个人(西南石油学院地质系,1978、1979;张继淹,1985;苟汉成,1985;贺自爱,1956;)曾就这套沉积物形成的地质背景,沉积机理进行过有益的论述。但迄今为止,尚意见纷纭,争论颇     

岷江上游叠溪古堰塞湖沉积物粒度特征及环境意义

利用古堰塞湖沉积物中连续的地质记录来研究区域过去气候变化规律,这一方法是继通过深海沉积、极地与高山冰芯、黄土、湖泊、洞穴石笋、珊瑚等沉积物中的地质记录来研究全球气候变化途径之后的又一新途径。反映沉积物中环境信息的代用指标有多种,其中粒度特征就是其中一种,它可以反映沉积过程中的古环境、古气候特征。通过该项研究可以建立青藏高原东部边缘(岷江上游叠溪地区)2万年以来的古环境古气候演化规律以及地质环境的演化规律,找到气候环境变化与地质环境演化的相关性。本文采用精细粒度分析和系统粒度分析等方法提取了堰塞湖相沉积物的粒度特征资料,并与已有的冰川湖沉积物的研究成果进行了对比分析。通过精细分析得到了堰塞湖相沉积物多为粉土和黏土;深色沉积物与粗颗粒相对应,浅色沉积物与细颗粒相对应的关系;并结合有机质测试发现:深色沉积物有机质含量多于浅色沉积物,表明粗颗粒土代表的是雨水充沛水动力条件好且植被相对茂盛的气候环境特征,细颗粒土则与其相反;沉积物中深浅交替的纹层厚度约为2～5 cm;这些特征与冰川湖沉积物特征差别很大,因此其代表的气候环境意义也完全不同。通过整个剖面的系统粒度分析得到了整个沉积过程的粒度变化特征,并据此结合年代测试结果将整个沉积剖面划分了7个粒度变化周期,揭示了该沉积过程中该地区经历了7次气候环境的变迁。     

江苏及邻区上白垩统赤山组中古沙漠沉积

当今地球上,沙漠地区分布甚广,集中分布在南北回归线附近的副热带,以及虽处在温带,但远离海洋的大陆内部。约占陆地面积的十分之一。形成沙漠的主要条件是干旱气候,造就沙漠沉积的主要动力因素是风力。按照“将今论古”的原则,地质历史时期中干旱气候的环境也经常发生,不乏存在沙漠和沙漠沉积。但是,由于地质时期的古代沙漠沉积的识别比较困难,尤其是沙漠沉     

腾格里沙漠丘间地风沙沉积210Pb初探

210Pb方法被广泛运用于不同环境沉积物年龄和沉积速率的测定[1~7],以及陆地沉积环境侵蚀速率研究[8]。本文拟运用210Pb方法对前人未涉及过的沙漠沉积环境作初步研究,了解在沙漠风沙沉积中210Pb比活度的分布,探讨210Pb方法对风沙沉积物年龄和沉积速率的适用性。同时,试图通过对样品粒径与总210Pb(210Pbtot)比活度的关系建立拟合方程,为运用210Pb方法进行沉积物研究提供粒度校正方面的参考。运用210Pb计年的前提之一是具有稳定的沉积环境[9]。腾格里沙漠位于阿拉善台地东南部一断陷盆地,东界贺兰山,西北以雅布赖山与巴丹吉林沙漠相隔,南侧…     

长江口海区表层沉积物及其有机质分布特征

根据我队1978—1979年调查资料编制了长江口海区沉积物类型及沉积分区图、沉积物有机质分布图,统计了各类沉积物、各沉积区沉积物的粒度成分和有机质含量。讨论了长江三角洲分布范围、沉积物有机质富集的海洋环境、沉积物有机质与常量组分关系等。以启东咀塌鼻子沙北水槽为界分为现阶段长江三角洲和主要为1200年前形成的前阶段长江三角洲。     

渤海古沙漠沉积特征分析

根据世界沙漠的分布特点和沙漠的发育条件,作者认为晚更新世末期渤海气候干冷,雨量稀少,西北风强盛,松散沉积物丰富,具备发育沙漠的条件.文章从以下方面证明渤海古沙漠的存在:(1)渤海约有四分之一区域为残留砂沉积;(2)在全新世盖层下的更新世砂质沉积具有高倾角的前积纹层;(3)渤海东南缘陆地和岛屿有古渤海沙漠衍生黄土分布.综合分析认为末次冰期时,渤海中部和辽东湾古沙漠发育程度好,渤海湾次之,莱州湾未发育沙漠.     

中国沙漠物源研究:回顾与展望

沙漠物源研究不仅在风沙地貌学上有重大的理论和实践意义,而且对联结大气粉尘排放、黄土堆积、气候系统和海洋生物地球化学循环也有重要价值。在简要回顾中国沙漠研究的基础上,梳理了中国沙漠物源研究的理论、方法和主要成果,结合国际上沉积物物源分析的趋向,指出目前世界沙漠物源的研究都是基于沉积物组份属性统计的反演模型,这种研究范式在数据获取、处理与解释方面存在缺陷,如沉积物的取样设计与测试分析、未消除"粒级依赖"对沉积物组份影响、数据未进行对数变换、忽视Dickinson图解应用的前提条件等。提出今后中国沙漠物源研究的方向:①采用正确统一的取样设计和分析方法对各沙漠的沉积物组份属性进行系统研究,建立中国沙漠沉积物组份的属性数据库;②选择若干典型沙漠,利用其周边山地详尽的地质构造、母岩和气候数据,定量构建沉积物生成的正演模型,模拟源区生成沉积物的数量、成分和结构,并用建成的沉积物组份属性数据验证和校正;③定量评估河流冲积物、冲积-湖积物、洪积-冲积物和基岩风化的残积、坡积物对中国各沙漠物源的贡献率与迁移路径,研究中国各沙漠中细颗粒物质的形成机制,对比中国沙漠与低纬度沙漠物源的形成机制;④定量研究历史和地质时间尺度沙漠-黄土-深海沉积物物源的内在联系及其驱动因素,建立陆地-大气-海洋物质循环的机理模型。     

鄂尔多斯盆地志丹群沉积时期的古沙漠盆地体系

笔者基于一个完整的沙漠盆地内，各种地理景观、沉积环境与沉积作用、沉积类型间有机的密切联系，提出并使用沙漠盆地体系和沙漠盆地沉积体系的概念，结合将今论古的原理，在大量实际资料的分析、研究基础上，首次确定了在志丹群洛河组和罗汉洞组上段的沉积期间，有两期不同的古沙漠盆地体系和古沙漠盆地沉积体系的存在。根据各种沉积类型和剖面结构的古环境和古地理意义，对它们的次级环境和沉积体系进行了划分和讨论，重塑了这两期古沙漠盆地体系的古地理环境．依据保存的条件和地表的出露，笔者识别与恢复出洛河期古沙漠盆地体系从现盆地南部向北依次是砾模环境、丘外过渡环境和沙丘环境，而岩漠环境一般是不易被保存的，罗汉洞晚期的古沙漠盆地体系仅保存有沙丘环境和位于其南、北两侧的丘外过渡环境，而岩漠环境和现盆地市部的砾漠环境未被保存，现盆地北部的砾漠环境可能是未出露。对各种环境中的沉积类型和特征、剖面结构等均作了详尽地叙述和讨论。最后，并指出古沙漠相或古风成相的研究在沉积学的理论上和国民经济实践中的重要意义。     

Significance of interdune deposits and bounding surfaces in aeolian dune sands

Bounding surfaces and interdune deposits provide keys for detailed interpretations of the development, shape, type, wavelength and angle of climb of aeolian bedforms, as well as overall sand sea conditions. Current alternate interpretations of bounding surfaces require very different, but testable models for sand sea deposition. Two perpendicular traverses of Jurassic Entrada Sandstone, Utah, reveal relations among cross-strata, first-order bounding surfaces, and horizontal strata. These field relations seem explicable only as the deposits of downwind-migrating, climbing, enclosed interdune basins (horizontal strata) and dune bodies consisting of superimposed smaller crescentic dunes (cross-stratified deposits). A 1.7 km traverse parallel to the palaeowind direction provides a time-transgressive view showing continuous cosets of cross-strata, first-order bounding surfaces and interdune deposits climbing downwind at an angle of a few tenths of a degree. Changes occur in the angle of climb, cross-strata structure, and interdune deposits; these reflect changes in depositional conditions through time. A 1.5 km traverse perpendicular to the palaeowind direction provides a view at an instant in geological time showing first-order bounding surfaces and interdune deposits forming flat, laterally discontinuous lenticular bodies. The distribution of interdune sedimentary structures in this traverse is very similar to that of some modern interdune basins, such as those on Padre Island, Texas. Hierarchies of bounding surfaces in an aeolian deposit reflect the bedform development on an erg. The presence of three orders of bounding surfaces indicates dune bodies consisting of smaller, super-imposed dunes. The geometry of first-order bounding surfaces is a reflection of the shape of the inter-dune basins. Second-order bounding surfaces originate by the migration of the superimposed dunes over the larger dune body and reflect individual dune shape and type. Third-order bounding surfaces are reactivation surfaces showing stages in the advance of individual dunes. The presence of only two orders of bounding surfaces indicates simple dunes. Modern and Entrada interdune deposits show a wide variety of sediment types and structures reflecting deposition under wet, damp, and dry conditions. Interdune deposits are probably the best indicators of overall erg conditions and commonly show complex vertical sequences reflecting changes in specific depositional conditions.     

川东南地区早志留世晚期沉积特征及沉积模式分析

通过对川东南地区野外露头、大量岩心、测井等资料的综合研究结果表明,研究区早志留世晚期发育2个沉积体系组,包括3种沉积相及众多亚相、微相类型。其中三角洲沉积主要发育于靠近江南—雪峰山隆起的川东南—湘西地区;碳酸盐岩台地沉积主要发育于川南—黔北地区;陆棚沉积主要发育于宜宾—重庆一带。沉积模式显示了早志留世晚期川东南地区为受古隆起控制的局限海盆,研究区东部发育一套以碎屑岩为主的小河坝组,由于江南—雪峰山不断隆起,向研究区提供了大量物源,沉积了一套向上变粗的三角洲沉积。研究区南部受黔中隆起控制,由于黔中隆起相对稳定,在其北侧主要发育了与小河坝组同时异相的石牛栏组碳酸盐岩台地沉积。该新认识有助于了解川东南地区小河坝组砂体的时空展布,以及预测该区有利油气聚集区带。对下一步油气勘探部署具有重要的理论意义和实际指导价值。     

Feature: The sedimentary signature of deserts and their response to environmental change

Desert sedimentary systems comprise a variety of related sub-environments including aeolian dunes, intervening interdunes, sandsheets, salt flats, playa lakes, ephemeral fluvial systems and alluvial fans. These are highly sensitive, and undergo subtle but systematic morphological and sedimentary adjustments in response to externally-imposed environmental change. This article presents a dynamic model explaining how desert successions – particularly aeolian dune and interdune environments – are determined both by intrinsic sedimentary behaviour, such as dune migration, and by the imposition of externally-forced changes such as climate change.     

Textural characteristics and genesis of the aeolian sediments in the Kuwaiti desert

Several types of aeolian deposits have been recognized in Kuwait: (a) smooth sand sheets that resemble desert floor sand, (b) immobile sands that include rugged vegetated sand sheets and wadi fill deposits, and (c) mobile sands that form active sand sheets and sand dunes. Simple size frequency curves illustrate the genetic relationship between the various aeolian sediment types. The four size parameters, namely, mean size, sorting, skewness and kurtosis, were calculated. Scatter plot diagrams of sorting versus mean size and sorting versus kurtosis are effective in differentiating smooth sand sheet deposits from dune sands. Active sand sheet deposits can also be recognized because they are usually located between the two end members–smooth sand sheets and dune sands. Size parameters change with location regardless of their types. Coarsening and positive skewness usually increase downwind. Mineralogical and textural characteristics of the aeolian deposits in Kuwait revealed that they are mostly derived from the lower Mesopotamian muddy flood plain deposits, the sand fraction of the Al-Dibdibba gravelly deposits and the disintegrated material from calcretic and gypcretic duricrusts. Distribution of depositional and deflational areas indicates that the northern desert of Kuwait is characterized by a positive sand budget, whereas the southern desert has a negative sand budget.     

四川盆地白垩纪沙漠石英沙颗粒表面特征

石英具有较大的硬度和较高的化学稳定性，因而其颗粒表面特征能很好地反映沉积环境。而通过扫描电镜研究石英颗粒表面微细特征是分析沉积环境行之有效的方法。虽然多数人认为四川盆地白垩纪地层存在沙漠沉积(打儿凼组和夹关组)，但仍有人对沙漠沉积的存在持怀疑态度，并认为是河流成三角洲沉积。过去关于其沉积环境的判别主要是根据沉积结构和构造，并未对其石英沙颗粒表面特征进行过系统分析。笔者对采自四川盆地白垩系不同层位地层的样品进行了石英沙颗粒表面特征系统分析。结果表明，石英沙颗粒表面特征分析可以成功地将石英沙区分为风成和水成沉积。因此，本文从石英沙颗粒表面特征方面进一步肯定了四川盆地白垩纪古沙漠的存在。     

风成沙丘间沉积成因类型与风成垂向层序--以鄂尔多斯早白垩世内陆古沙漠为例

依据鄂尔多斯早白垩世内陆古沙漠沉积实例,探讨了沙丘间的成因分类,按照沙丘间底床的表面环境,将沙丘间划分为干旱型、潮湿型和覆水型三种沉积类型,并阐明了其沉积和组合特征;在此基础上,提出了风成垂向层序模式;鉴于沙漠同一相带的沙丘间类型及其沉积组合具有一定的共性特征,进一步建立和阐明了古沙漠分带的风成层序样式.     

Erosional and depositional characteristics of regional overwash deposits caused by multiple hurricanes

Regional-scale washover deposits along the Florida Gulf and Atlantic coasts induced by multiple hurricanes in 2004 and 2005 were studied through coring, trenching, ground-penetrating radar imaging, aerial photography, and prestorm and poststorm beach-profile surveys. Erosional and depositional characteristics in different barrier-island sub-environments, including dune field, interior wetland and back-barrier bay were examined. Over the eroded dune fields, the washover deposits are characterized by an extensive horizontal basal erosional surface truncating the old dune deposits and horizontal to slightly landward-dipping stratification. Over the marshes in the barrier-island interior, the washover deposits are characterized by steep tabular bedding, with no erosion at the bottom. Overwash into the back-barrier bay produced the thickest deposits characterized by steep, prograding sigmoidal bedding. No significant erosional feature was observed at the bottom. Washover deposits within the dense interior mangrove swamp demonstrate both normal and reversed graded bedding. The washover deposits caused by hurricanes Frances (2004) and Jeanne (2004) along the southern Florida Atlantic coast barrier islands are substantially different from those along the northern Florida barrier islands caused by Ivan (2004) and Dennis (2005) in terms of regional extension, erosional features and sedimentary structures. These differences are controlled by different overall barrier-island morphology, vegetation type and density, and sediment properties. The homogeneity of sediment along the northern Florida coast makes distinguishing between washover deposits from Ivan and Dennis difficult. In contrast, along the Atlantic coast barrier islands, the two overwash events, as demonstrated by two phases of graded bedding of the bimodal sediments, are easily distinguishable.     

柴达木盆地旺尕秀地区上侏罗统-下白垩统风成砂的发现及其意义*

本次研究在柴达木盆地旺尕秀地区上侏罗统红水沟组上覆地层中,首次发现了风成沉积。地层主体为一套棕黄色细-中砂岩,由分选、磨圆好的石英砂组成;扫描电镜下可见风成砂特有的碟形撞击坑和新月形撞击坑等特征;层内普遍发育风成大型高角度板状交错层理,层系厚度巨大,风成沙丘前积层特征明显;发育液化作用产生的牵引褶曲、倒转褶曲等常见的风成沙丘同沉积变形构造。根据岩性和沉积构造特征共在地层中识别出4种沉积亚相: 沙丘亚相、丘间亚相、旱谷亚相和沙漠湖亚相,其中沙丘亚相以风成大型交错层理为显著特征,丘间、旱谷和沙漠湖亚相则以水成沉积为主。风成砂沉积的存在丰富了柴达木盆地中生代的沉积类型,为区域地层对比及西北地区晚中生代古气候和古环境研究提供了新的证据和材料。     

Aeolian stratification and facies association in desert sediments, Arran basin (Permian), Scotland

ABSTRACT Permian aeolian sediments on the island of Arran are divisible into dune (including draa) and interdune deposits. Both types display a distinctive and unusually wide variation in grain size. The dominant features of the dune deposits are grainfall lamination, sandflow lamination, and inverse graded lamination associated with ripple-form lamination and normal graded lamination. The flat-lying aeolian interdune deposits are characterised by granule and sand ripples, horizontal lamination in coarse sand and granules, plane bed lamination and inverse graded lamination. Associated structures include ripple-form lamination and deflation lags. Three types of trace fossil associated with completely bioturbated horizons occur in some low-angle dune and interdune deposits.
The aeolian facies interfinger with alluvial fan deposits giving rise to three recognizable facies belts. Marginal aeolian deposits are associated with fluvial conglomerates and are dominated by interdune deposits and occasionally very thin barchan deposits (set height 3-37 cm). Intermediate aeolian deposits are characterized by interbedded crescentic dune, small draa (dune set height 5 cm-4.5 m) and interdune deposits, and rare fluvial and lake sediments. Basinal aeolian deposits are dominated by draa deposits (dune set height 0.2-28 m) associated with rare interdune sediments. Transverse dunes and draas were moved by north-eastern palaeowinds towards the foot of the alluvial fans. The aeolian sediments were deposited in a fault-bounded desert basin.