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   

灌淤土壤可溶性盐分空间变异性与棉花生长关系研究   总被引：8，自引：3，他引：8  

杨玉玲  田长彦  盛建东  文启凯 《干旱区地理》2002,25(4):329-335

运用地统计学方法，在灌淤土壤上进行了棉田土壤可溶性盐分的空间变异规律与棉花生长关系系统研究。传统统计学分析表明土壤盐分测试数据基本符合正态分布；在一定取样间距下，土壤可溶性盐分的田间合理取样数目为27。半方差分析显示：土壤可溶性盐分具中等的水平变异性，但随着聚样深度的增加未表现出明显的垂直变异特性；随着棉花的生长发育，土壤可溶性盐分呈现出逐渐减弱的时间变异规律，采用直线或曲线拟合方程估计了可溶性盐分的半方差图及其参数，并绘制了其相应的等值线图。土壤可溶性盐分与棉花产量之间的相关分析表明：可溶性盐分含量与棉花产量之间呈显著负相关关系，且花铃期的相关性较播前显著。研究结果为提高田间试验有效性以及盐渍化土壤改良提供了科学依据与基础资料。  相似文献   

青海省盐湖钾、镁、锂盐资源开发利用探讨   总被引：4，自引：4，他引：4       下载免费PDF全文

严军  黄小良 《盐湖研究》2002,10(4):63-69

论述了青海省盐湖资源中钾、镁、锂盐工业的资源状况、生产现状以及开发利用的迫切性 ,并对钾、镁、锂盐资源的综合利用进行了探讨  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   

腾格里沙漠地区盐湖钾盐资源特征   总被引：2，自引：2，他引：2       下载免费PDF全文

李博昀  刘振敏  徐少康  刘国庆 《盐湖研究》2002,10(1):18-23

腾格里沙漠地区盐湖众多 ,以沉积石盐和芒硝为主 ,并赋存有丰富的晶间卤水 ,卤水中K+含量较高 ,在调查的 1 7个盐湖中有 1 2个盐湖KCl含量达到综合利用品位或工业边界品位。通过地质调查、遥感及航空γ能谱测量资料解译 ,本区多数盐湖具有相似的成钾条件 ,形成 4个成钾远景区 ,具有一定的找钾前景  相似文献   

Human Modification of the Geomorphically Unstable Salt River in Metropolitan Phoenix     

Martin Roberge 《The Professional geographer》2002,54(2):175-189

In‐stream gravel mining, massive bridge piers, and channelization have all contributed to the geomorphic instability of the Lower Salt River channel in Arizona. Dam closure, changing dam operating rules, and the frequent modification of the channel bed have decreased our ability to predict the Salt River hydrology. Engineering practice has adapted to this situation and to a public that is increasingly intolerant of service disruptions by constructing larger bridges and extending levees. Building these larger structures may be counterproductive; future construction should not constrict the channel and should re‐establish a braided river to decrease the energy available to the system.  相似文献