具有地形坡折带的坳陷湖盆层序地层模拟   总被引：8，自引：1，他引：8  

胡宗全  朱筱敏 《沉积学报》2002,20(2):217-221

层序地层学研究已在陆相湖盆中取得良好的应用效果，在陆相湖盆的地层对比、沉积体系空间分布预测中发挥重要作用。坳陷湖盆在基底受压变形过程中，常在盆缘形成地形坡折带，以坡折为界，基底的沉降速率和原始地形坡度等控制层序发育的重要因素在其两侧均存在显著的差异，这在很大程度上控制了层序的发育模式和沉积体系的空间配置关系。通过对基底沉降速率、湖平面变化速率、沉积物充填速率、沉积物充填准则、岩相确定原则等数学模 型的建立，模拟了具有地形坡折带的坳陷湖盆的层序发育和相演化过程。实际资料与模拟结果的对比分析表明，模拟具有很好的效果。  相似文献   

库车坳陷侏罗纪沉积环境和层序地层分析   总被引：19，自引：0，他引：19  

吴朝东  林畅松  申延平  谢小建  肖建新  刘景彦  史艳丽 《沉积学报》2002,20(3):400-407

通过对库车坳陷野外露头和钻井资料以及地震剖面的综合分析,对库车盆地侏罗纪沉积环境、层序划分进行了研究.库车盆地在侏罗纪时期为一非对称型坳陷型盆地,主要物源在盆地的北部.划分了13个三级层序,三个层序组,反映了三个大级别的旋回.最大湖侵期为阳霞组中上部,与当时有一个明显的气候变热期相一致.沉积环境在侏罗纪早期为辫状河-辫状河三角洲环境、中期为曲流河-三角洲环境,后期为三角洲和浅湖环境,中期有短暂的海泛发生.影响侏罗纪湖平面变化的主控因素为构造运动、气候变化、物源条件、河水的流入以及海侵的影响.在中侏罗世早期、晚期的最大湖侵和海泛的短暂时期,形成了厚层的烃源岩分布.库车坳陷侏罗系虽然砂体分布广泛,厚度较大,然而由于陆相沉积环境的控制,非均质性较强、  相似文献   

Temporal patterns of suspended sediment yield following moderate to extreme hydrological events recorded in varved lacustrine sediments     

Scott Lamoureux 《地球表面变化过程与地形》2002,27(10):1107-1124

A 487‐year annually laminated (varved) sediment record from Nicolay Lake, Cornwall Island, in the Canadian High Arctic was evaluated to determine the impact that years with high sediment yields had on sediment yields in subsequent years. All of the 40 largest years showed evidence for increased sediment yield in the subsequent 10–30 years. The positive anomalies in lagging years were approximately scaled according to the size of the initiating year, although many intermediate years (25‐ to 100‐year recurrence) showed weak or variable responses. The smallest events considered (10‐ to 25‐year recurrence) showed a consistent, but low‐amplitude response. Additionally the 10‐year events revealed frequent negative sediment yield anomalies in the preceding decade. This behaviour was interpreted as a frequent sediment activation cycle initiated by the modest year, and leading to sediment yield hysteresis lasting 15–25 years. The largest years (greater than 50‐year recurrence) showed consistently above‐average sediment yields in the preceding decade, in part due to the frequent occurrence of moderate (Q₁₀) years. It is hypothesized that temporary storage of sediment and previous initiation of erosion sites resulted in extraordinary sediment yields during intense summer rainfall events. This study demonstrates the potential use of varved lake sediment records to improve our understanding of long‐term sediment dynamics. These records present an opportunity to further develop and test sediment dynamic and routing models to gain insight into the interaction of time and space in fluvial and sediment delivery processes. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Late-Glacial and Early Holocene Environmental and Climatic Change at Lake Tambichozero, Southeastern Russian Karelia     

Barbara Wohlfarth  Ludmila Filimonova  Ole Bennike  Leif Bjrkman  Lars Brunnberg  Nadja Lavrova  Igor Demidov  Gran Possnert 《Quaternary Research》2002,58(3):261

High-resolution lithostratigraphy, mineral magnetic, carbon, pollen, and macrofossil analyses, and accelerator mass spectrometry ¹⁴C measurements were performed in the study of a sediment sequence from Lake Tambichozero, southeastern Russian Karelia, to reconstruct late-glacial and early Holocene aquatic and terrestrial environmental changes. The lake formed ca. 14,000 cal yr B.P. and the area around the lake was subsequently colonized by arctic plants, forming patches of pioneer communities surrounded by areas of exposed soil. A minor rise in lake productivity and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P. The rise in summer temperatures probably led to increased melting of remnant ice and enhanced erosion. The distinct increase in lake productivity and the development of open Betula-Populus forests, which are reconstructed based on plant macrofossil remains, indicate stable soils from 10,600 cal yr B.P. onward. Pinus and Picea probably became established ca. 9900 cal yr B.P.  相似文献   

Late Quaternary Spring-Fed Deposits of the Grand Canyon and Their Implication for Deep Lava-Dammed Lakes     

Darrell S. Kaufman  Gary O'Brien  Jim I. Mead  Jordon Bright  Paul Umhoefer 《Quaternary Research》2002,58(3):329

One of the most intriguing episodes in the Quaternary evolution of the Grand Canyon of the Colorado River, Arizona, was the development of vast lakes that are thought to have backed up behind lava erupted into the gorge. Stratigraphic evidence for these deep lava-dammed lakes is expectedly sparse. Possible lacustrine deposits at six areas in the eastern canyon yielded no compelling evidence for sediment deposited in a deep lake. At two of the sites the sediment was associated with late Quaternary spring-fed pools and marshes. Water-lain silt and sand at lower Havasu Creek was deposited 3000 cal yr ago. The deposit contains an ostracode assemblage similar to that living in the modern travertine-dammed pools adjacent to the outcrop. The second deposit, at Lees Ferry, formed in a spring-fed marsh 43,000 cal yr ago, as determined by ¹⁴C and amino acid geochronology. It contains abundant ostracode and mollusk fossils, the richest assemblages reported from the Grand Canyon to date. Our interpretation of these sediments as spring-fed deposits, and their relative youth, provides an alternative to the conventional view that deposits like these were formed in deep lava-dammed lakes that filled the Grand Canyon.  相似文献   

Historic Dead Sea Level Fluctuations Calibrated with Geological and Archaeological Evidence     

Amos Frumkin  Yoel Elitzur 《Quaternary Research》2002,57(3):334

The Dead Sea, the Holocene terminal lake of the Jordan River catchment, has fluctuated during its history in response to climatic change. Biblical records, calibrated by radiocarbon-dated geological and archaeological evidence, reinforce and add detail to the chronology of the lake-level fluctuations. There are three historically documented phases of the Dead Sea in the Biblical record: low lake levels ca. 2000–1500 B.C.E. (before common era); high lake levels ca. 1500–1200 B.C.E.; and low lake levels between ca. 1000 and 700 B.C.E. The Biblical evidence indicates that during the dry periods the southern basin of the Dead Sea was completely dry, a fact that was not clear from the geological and archaeological data alone.  相似文献   

泥石流多发干旱河谷区植被恢复研究   总被引：10，自引：2，他引：10  

沈有信  张彦东  刘文耀 《山地学报》2002,20(2):188-193

云南东北部东川小江流域的干旱河谷土地退化十分严重，土地表层的砾石含量已超过60％，有机质含量、全氮、有效氮、有效磷、有效钾的含量相对于残存燥红土明显下降。草坡是当地的主要植被类型，并未起到防治土地退化的应有作用。以合欢（Leucaena glauca)、马桑（Coriaria sinica)种植为主的恢复方式对土地的恢复有明显的改善作用。高密度的乔木树种合欢的种植使林下的草本物种的数量和组成发生了极大变化，较耐荫的植物占据了林分下层，且物种数量较草坡减少，群落多样性指数降低。三种马桑种植方式下，不但原有的草坡群落的物种仍有大量的生存空间，而且为一些新物种创造了生存环境，从而使物种的种类较原有草坡地增加，提高了群落的多样性指数。合欢种植的生物量最高，对解决当地薪柴严重短缺意义重大，马桑种植在增加灌木层生物量的同时，并未改变草坡的物种组成，还可兼顾解决当地的饲草和放牧，应大力推广。  相似文献   

两个相连湖泊的微生态系统——云南高原湖泊中浅水的星云湖和深水的抚仙湖研究   总被引：4，自引：0，他引：4  

大久保贤治  熊谷道夫  坂本充  宋学良  张子雄 《云南地理环境研究》2002,14(2):10-19

抚仙湖是中国云南省的一个深水湖，连接着富营养化的浅水湖－－星云湖，星云湖排放含绿藻的水进入抚仙湖。两湖位于省会昆明附近，由于地方文化、集约化农业、以及旅游业的发展，两湖已经富营养化。因为湖泊体积容量的级别差异，深水湖的富营养化几乎没被注意，抚仙湖秋季下层滞水带缺氧已经关注了20年，似乎下层滞水带是深水湖富营养化的指标或趋势。抚仙湖看起来目前情况尚好，可以说寡营养，然而，外界负荷是潜在的，且是以稳定的加速度进行的。在此对浅水湖富营养化的原因进行了讨论，包括在其它云南湖泊观察到富营养化的过程，再者，对两个连相湖的藻和蓝藻碎片的大小构成进行比照。为了与深水的抚仙湖状况进行比较，简略介绍了一个日本的深湖及其径流系统。其中，涡流和它的微生态系统，在两者中相关性很好。对于以涡流生态系统的见解判断微生态系统的深水湖富营养化问题将给予概括。  相似文献   

岷江干旱河谷三种主要灌丛地上生物量的分布规律   总被引：24，自引：1，他引：24  

刘国华  张洁瑜  张育新  周建云  关文彬  马克明  傅伯杰 《山地学报》2003,21(1):24-32

灌丛是岷江干旱河谷主要的植被类型之一,也是该地区相对稳定的生态系统类型。在岷江干旱河谷的水土保持中发挥着重要的作用。本文通过野外样地调查和实验,研究了岷江干旱河谷分布最为广泛的莸灌丛、小花滇紫草灌丛和川甘亚菊灌丛3种灌丛类型的地上生物量,并探讨了其分布规律和影响因素。结果表明:(1)在3种灌丛类型中,川甘亚菊灌丛的平均地上生物量最大,达4819 8kg·hm-2,其次是莸灌丛,为1652 9kg·hm-2,而滇紫草灌丛的平均地上生物量最小,仅为1407 2kg·hm-2;(2)在同一灌丛类型中,不同样地的灌丛地上生物量存在着差异,其中莸灌丛的地上生物量的变化幅度最大,为304 2～5804 7kg·hm-2;滇紫草灌丛地上生物量的变化幅度为241 1～3889 2kg·hm-2;川甘亚菊灌丛地上生物量的变化幅度相对较小,为2089 8～6457 5kg·hm-2;说明川甘亚菊灌丛的群落结构相对稳定。(3)莸灌丛的地上生物量随海拔的上升而减少,而小花滇紫草灌丛和川甘亚菊灌丛的地上生物量则随海拔梯度的升高而增加,但三者都呈现出较好的相关性。(4)在3种灌丛类型中,莸灌丛的土壤水分条件相对较好,其次为小花滇紫草灌丛,川甘亚菊灌丛的土壤水分条件最差。3种灌丛中,小花滇紫草灌丛和川甘亚菊灌丛的地上生物量受土壤水分条件的影响较大,表现为随着土壤水  相似文献   

西藏自治区洛扎县冰湖溃决危险度评价   总被引：7，自引：1，他引：7  

刘淑珍  李辉霞  鄢燕  柴宗新  杜少平 《山地学报》2003,21(Z1):128-132

西藏自治区湖泊星罗棋布,在高山极高山地区分布大量冰湖,受各种因素的影响,有时会产生冰湖溃决并形成灾害。本文根据最新TM遥感影像对西藏自治区洛扎县283个冰湖进行了初步评价。依据冰湖类型、规模、后方现代冰川与冰湖的距离及冰湖离居民地、公路等设施的距离等,将冰湖溃决分为高危险度、中危险度及低危险度。并针对高危险度的冰湖提出防护对策。  相似文献