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烟台附近海岸风沙地貌的初步研究 总被引：5，自引：0，他引：5
在野外调查基础上,对烟台附近海岸风沙分布、风沙地貌类型及地貌发育过程进行了探讨。指出全新世海岸变迁是海岸风沙地貌发育的基础,6000aB.P.以来有5个风沙堆积期,前4个风沙堆积期与4个海平面下降期一致,第5风沙堆积期与小冰期一致。 相似文献
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国内外红层分布及其地貌发育的对比研究 总被引：2，自引：0，他引：2
为了解全球红层的时空分布规律及其地貌发育的差异,对国内外红层的分布、形成年代、地质构造背景、古地理环境、岩性和地貌特征等进行了对比研究。结果表明：国内红层主要分布于东南、西南、西北等地区,形成年代主要为中生代,尤以白垩纪为主,构造环境主要为古陆块活化时形成的断陷/拗陷盆地;沉积环境几乎全部为陆相,形成于干旱或半干旱古气候条件;岩性复杂,兼具砾岩、砂岩、粉砂岩和泥岩,发育了丹霞地貌、红层高原、红层山地和红层丘陵等多种地貌类型。国外红层的形成年代跨度很大,从前寒武纪到新近纪均有发育,呈现出从老陆块向新陆块扩展的趋势;构造环境分为山前/山间拗陷堆积、地台拗陷堆积、裂谷盆地堆积和弧后盆地堆积;沉积环境以陆相为主,兼具滨-浅海相和海陆过渡相,也形成于干旱、半干旱气候;岩性以砂岩、粉砂岩和泥岩为主,砾岩较少;发育的地貌类型相对单一。 相似文献
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腾格里沙漠东南缘晚第三纪古风成砂及其环境 总被引：5，自引：3，他引：2
通过对地层、沉积构造、粒度、石英砂表面微结构及动物群、孢粉组合的分析表明,晚第三纪期间腾格里沙漠东南缘及附近地区曾呈现类似现代风沙迁移、堆积的风沙地貌过程。当时气候炎热干旱,干湿季变化明显,生物气候带为亚热带疏林草原甚至荒漠草原。 相似文献
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海岸是陆、海、气相互作用的地带。海岸风沙沉积是这一特殊动力环境的产物,是研究海岸环境演变及海平面变化的良好信息载体。中国海岸主要存在3种风沙沉积,分别为“老红砂”、沙丘岩及海岸沙丘。本文通过比较已报道的风沙堆积的物质组成、地层变化等,进一步总结了海岸风沙沉积的特征;选择已开展绝对测年的沉积剖面,利用概率密度函数分析了风沙沉积年代的分布特征,考察了中国海岸风沙活动历史,结合其他气候记录,探讨了不同地质历史时期海岸风沙堆积的关键影响因素。结果表明：“老红砂”沉积主要记录了冰期-间冰期尺度的风沙活动,在120 ka BP前后、73—55 ka BP等时期,风沙活动主要与海平面下降时陆架提供的丰富沙源和强盛的冬季风有关;而在105 ka BP、80 ka BP前后,风沙活动与高海平面时期丰富的沙源或季风气候的季节性增强有关;55 ka BP以来风沙活动强度降低更多地反映了沉积记录保存环境的变化,末次冰期海岸风沙沉积大多分布在现代海面之下,并不代表实际的海岸风沙活动减弱。相比之下,海岸沙丘沉积所记录的风沙活动主要发生在近3 000 a,可能与中国海岸冬季风的增强有关。 相似文献
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70年来中国风沙地貌学的发展 总被引：10，自引：0，他引：10
风是除流水之外塑造地球景观的第二大流体,以其为外营力形成的风沙地貌在全球干旱区广泛分布,超过40%的全球陆地面积受风沙地貌过程的影响,与人类生存环境存在着密切的关系,19世纪末以来受到国际学术界的持续关注。中国干旱半干旱地区广泛发育风沙地貌,但风沙地貌研究比国际研究晚半个多世纪,始于20世纪50年代后期。本文总结了新中国成立70年来中国风沙地貌学发展的3个阶段：初创阶段（1949—1977年）、充实发展阶段（1978—1999年）和国际化研究阶段（2000年至今）。现在中国风沙地貌研究的水平整体与国际并行,部分领先。中国具有重要国际影响力的风沙地貌研究工作包括沙丘移动规律、风沙地貌区域综合研究、中国独特风沙地貌发育演变过程、戈壁地貌学研究、沙丘二次流以及地外星球的探索研究。中国风沙地貌学研究有在未来领跑国际研究的潜势,但风沙地貌学家必需有4个方面的战略思考,即综合集成、地球系统科学引领、全球视野和深空时代的发展。 相似文献
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我国山地植被的垂直分布规律 总被引：19，自引：3，他引：16
地球上植被的大型分布,明显地呈现地带性变化。平地上表现为水平地带性,包括纬度地带性和干燥度地带性;山地上表现为垂直(地)带性,就是所谓“三维空间”分布现象。我国地广山多,自然条件复杂,研究山地植被的分布规律不但具有理论意义,而且也富有实践意义。 相似文献
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昆仑山北麓地跨昆仑-阿尔金山与塔里木盆地两大地貌单元,毗邻塔克拉玛干沙漠,区内沙源物质丰富,东北风与西北风盛行,风沙活动强烈,沙漠化程度达0.62,是目前我国风沙危害最严重的区域.地貌过程与风沙危害发生的关系,主要表现为风沙地貌过程加强引起风沙危害发生,流水地貌过程减弱使风沙危害加重,人工地貌过程对风沙危害有加强与减弱两方面的作用.区内风沙危害严重与地貌结构,沙漠、砾漠(戈壁)和雅丹面积占73.5%,风沙地貌面积大,沙源物质丰富;气候干旱少雨,荒漠区植被稀疏,风力强劲,风蚀风积强烈;河流稀少,流水地貌过程弱;水资源不足且分布不均,绿洲面积仅占13.49%,绿洲区人工地貌过程对荒漠环境扰动破坏大等有关.针对地貌及其过程对风沙危害的影响及发展趋势,提出了6条防治地貌过程加剧引起风沙危害的措施. 相似文献
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青海湖滨土地沙漠化驱动机制 总被引：1，自引：1，他引：0
在自然因素和不合理人为活动的影响下,青海湖流域及其周边地区正面临土地沙漠化、湿地萎缩、草场退化、水土流失等严重的生态环境问题。本文分析了青海湖滨土地沙漠化现状及其驱动因素。结果表明:青海湖滨广泛分布的古风沙沉积物是现代沙漠化的沙物质来源,现代流动沙丘的粒度特征与古风成沙丘粒度极为相似,两者的继承与改造关系极为明显。草皮层及其下的粉沙土层是古沙丘的保护层。保护层的机械破坏,使下伏松散的古风沙沉积物暴露,是形成沙漠化的关键一步。随后在风蚀、雨水冲刷及其他因素的共同作用下,松散的古风沙沉积物被侵蚀,引起草皮层坍塌,导致古沙丘活化,风沙活动加剧,形成风沙沉积。流水侵蚀和地层沉陷是导致草皮层机械破坏的主要因素。青海湖水位下降,河流沉积,风沙入湖,都可使沙地面积增加,但仅限于湖边局部地方。 相似文献
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湖泊滨岸带风成沉积一直是湖泊沉积研究的薄弱点。占据青海湖湖盆面积近五分之一的东岸沙丘为研究现代湖泊滨岸带提供了一个现代沉积实例。随着沉积学的不断发展,研究内容已经从"一元"的传统相模式逐渐过渡为"二元"的"源-汇"体系。以野外地质考察和遥感影像资料为基础,结合文献调研和相关测试分析资料,进行分析。结果表明：团保山前发育有相对广阔的滨岸沉积,指示了青海湖湖水曾经达到山前地带。大面积的滨岸沉积和古沙丘出露水面以及风对山体的吹蚀,为湖东风砂堆积提供了物源基础。干旱-半干旱气候为沙丘的形成提供了有利的气候条件。断陷湖盆的长条形地貌使得风沿着长轴方向吹扬,造成风成堆积物在长轴的一端堆积。高大的团保山/达坂山的山前复杂地貌特征为金字塔沙丘的形成提供了有利的地形条件。西北风产生的波浪和沿岸流作用于沙岛和海晏湾的滨岸带,导致滨浅湖的砂堆积形成沿岸沙坝。随着湖平面的下降,沿岸沙坝出露水面,并逐渐闭合形成障壁岛-泻湖沉积。 相似文献
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Reconstructing the geomorphic evolution of large coastal dunes along the southeastern shore of Lake Michigan 总被引：1，自引：0，他引：1
Coastal dunes are common along the eastern shore of Lake Michigan, with the most common being large (>30 m high), parabolic dunes that mantle lake terraces south of Manistee, MI. Although these dunes are an important resource in Michigan, and thus intensely managed by various state agencies, their geomorphic history is poorly understood. This study examines four sites near Holland, MI, through stratigraphic and radiocarbon analyses and is the most detailed geomorphic reconstruction conducted of coastal parabolic dunes in the region. Results from this study could benefit the environmental agencies in their management of the coastal dune ecosystem.Deposition of Eolian sand apparently began 5500 cal. years BP (i.e., during the Nipissing high stand). Most (75%) dune building occurred between 4000 and 2500 cal. years BP but was punctuated by brief periods of stability that resulted in the development of Entisols (A/C horizonation). Entisol burial occurred because the sand supply apparently increased during both the receding and rising lake levels. Subsequently, each dune stabilized for 2000 years, allowing the formation of Inceptisols (i.e., A/E/Bs/C horizonation). This interval of dune stability correlates with sites south of Holland and occurred while Lake Michigan fluctuated slowly and the beach potentially prograded. These combined variables of slow fluctuation and potential beach progradation hypothetically protected the dunes from wave erosion. Dunes near Holland became active again 1000–500 cal. years BP and grew both vertically and laterally. This activity intensified in the past 500 cal. years BP and hypothetically occurred due to recession of the lake shore such that wave erosion at the modern bluff base resumed. Results from this study indicate that coastal dunes along Lake Michigan are similar to many coastal dunes around the world, including those along the intermediate beaches in SE Australia. 相似文献
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Alan F. Arbogast 《Journal of Arid Environments》1996,34(4):403-414
Stratigraphic evidence and radiocarbon dating of sediments from the Great Bend Sand Prairie in Kansas indicates that significant deposits of aeolian sand have accumulated in the region during the late Holocene. Radiocarbon ages obtained from total humates in buried soils suggest that five periods of late-Holocene stability and soil formation are preserved in dune fields at approximately 2300, 1400, 1000, 700, 500 and 300 years B.P. Reactivation of aeolian sand in the past 1000 years has resulted in a variety of well defined, parabolic dunes. In general, events in the region correspond with established chronologies elsewhere on the Great Plains and in particular correlate well with dune fields in north-eastern Colorado. Overall, results indicate that the threshold of landscape stability on the Great Bend Sand Prairie can easily be crossed in the current climatic regime. 相似文献
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中国海岸风沙沉积的成因与特征 总被引：11，自引：4，他引：7
东部和南部沿海是我国风景优美、气候宜人, 工农业与交通事业发达和人口密集的重要经济区。在16, 000多公里的海岸上, 风沙作用的海岸线就有近3, 000公里, 目前它们都在不同程度上处于风沙作用而后退或大大改观的状态。 相似文献
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Several sand flats located on the northern shores of the Late Pleistocene palaeolake of the Konya plain (inner Anatolia, Turkey), are related to changes in lake levels. In this paper, the two main dune systems are mapped according to their geomorphological, sedimentological and dynamic characteristics, and their significance is discussed with regard to the environmental changes since the Late Pleistocene, both at time of the former lake and during the drier periods of the Holocene. Cross-sections show the relationship of the dunes to the topography of the basement. Analyses of the sand fraction show distinct characteristics in size distribution, quartz and shell contents, wind erosion effects on the quartz grains and petrographic composition. Interpretation of the results, coupled with information provided by the geomorphology of the dune systems studied in the field and from aerial photographs and satellite images, highlights the importance and variations in time of local factors such as prevailing winds, sand sources, changes in lake levels and vegetation. A chronology of the main sand fields is proposed, based on the evidence of three main droughts during the Upper Pleistocene. The older one, much eroded (maximum height=3 m), covers a limestone surface at +50 m above the bottom of the dried lake. An Optical Scanning Luminescence (OSL) date shows a last period of accumulation at 14,328±3220 years. The younger one (maximum height=12 m) has moved over the emerged Late Pleistocene lacustrine marls. An OSL date gives an age of 5674±988 years for the last accumulation period. Evidence of very recent activation of this younger dune system is apparent as a result of overgrazing and excessive land reclamation. A third period of dominant wind action and dune construction is responsible for the installation of a younger and thin dune field over the Mid-Holocene lacustrine deposits of the Karapinar lake. The success of the stabilization programme of the dunes over the last 30 years shows that the last period of dune movement is not related to climate change but to overpressure on the land due to the needs and activities of an increasing population. 相似文献
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The characteristics of foredunes created in a municipal management program on a developed barrier island are evaluated to identify how landforms used as protection structures can be natural in appearance and function yet compatible with human values. Shoreline management zones include a naturally evolving, undeveloped segment; a noneroding, developed segment; eroding and noneroding segments of an “improved beach” where dunes have been built by artificial nourishment; and a privately built, artificially nourished dune on the shoreline of an inlet.A disastrous storm in 1962 resulted in an aggressive program for building dunes using sand fences, vegetation plantings, purchase of undeveloped lots, and sediment backpassing to maintain beach widths and dune elevations. The present nourished and shaped foredune in the improved beach is higher, wider, and closer to the berm crest than the natural dune. Restricted inputs of aeolian sand keep the surface flat and poorly vegetated. A stable section of this engineered shore has a wider beach, and sand fences have created a higher foredune with greater topographic diversity. The cross shore zonation of vegetation here is more typical of natural dunes, but the environmental gradient is much narrower. The privately built dune is low, narrow, and located where it could not be created naturally. Foreshore and aeolian sediments in the undeveloped segment and the improved beach are similar in mean grain size (0.16–0.21 mm) and sorting (0.31–0.39φ), but sediment on the surface of the nourished dune is coarser (28.1% gravel) with a more poorly sorted sand fraction (1.30φ) representing lag elements on the deflation surface.Willingness to enhance beaches and dunes for protection has reduced insurance premiums and allowed the municipality to qualify for funds from the Federal Emergency Management Agency (FEMA) to replace lost sediment, thus placing an economic value on dunes. Success of the management program is attributed to: (i) timing property-purchase and dune-building programs to periods immediately after storms (causing residents to accept high dunes that restrict access or views); (ii) instituting a vigorous education program (reminding residents of hazards during nonstorm periods); (iii) maintaining control over local sediment supplies (to keep pace with erosion and create new shoreline environments); (iv) investing private and municipal economic resources in landforms (qualifying them for external funds for replacement); and (v) maintaining, augmenting, or simply tolerating biodiversity and natural processes (retaining a natural heritage). 相似文献
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全新世共和盆地沙地时空演化及其驱动机制 总被引：6，自引：3，他引：3
通过分析青藏高原东北部共和盆地现代固定沙丘、半固定-半流动沙丘和流动沙丘的粒度与地球化学元素特征,建立了不同类型沙丘沉积物的理化指标体系,并尝试性地将其用于地质时期沙漠演化研究。同时,结合区域典型风成砂-古土壤剖面的相变特征,探讨了全新世共和盆地沙地的时空演化过程及其驱动机制。结果表明：全新世共和盆地沙地存在多次活化、扩张和固定、缩小,除11.8～10.1 ka为流动沙地以外,其余阶段多在半流动-半固定沙地和固定沙地之间频繁转换,这一变化特征与其相邻的柴达木盆地沙地和青海湖地区环境变化具有良好的可比性。此外,发现沙地环境变化对湿度状况十分敏感,而湿度又受控于区域冬,夏季风的强度,也就是说全新世共和盆地沙地演化是气候变化的产物。 相似文献