萍乐坳陷西段早三叠世飞剑潭组的创建及地层层序研究     

袁建芽 《华东地质学院学报》2000,23(2):116-120

描述了创建剖面,划分了6地性段,并从沉积特征研究入手,确定了各种沉积相,微相及沉积体系,通过对小层序组划分,结合层序界面,首泛面和最大海泛面确定体系域和层序,在萍乐坳陷西段早三叠世飞剑组划分出4个正层序。  相似文献   

戈壁砾石防护效应的风洞实验与野外观测结果--以敦煌莫高窟顶戈壁的风蚀防护为例   总被引：24，自引：0，他引：24  

薛娴  张伟民  王涛 《地理学报》2000,55(3):375-383

为了解决威胁敦煌莫高窟安全的风蚀问题,将风洞实验与野外观测结合起来研究砾石覆盖对风蚀的抑制效应,发现①砾石的形状和高度在增加地表粗糙度、抑制风蚀危害中起着非常重要的作用。②风蚀作用停止后的稳定床而有其特定的粒径配置和砾石覆盖度。根据实验和野外观测的结果,对莫高窟顶戈壁地区的砾石床面进行分析并制定了具体的防护措施。本研究适合我国广大西北干旱区的风蚀防护。  相似文献   

丹棱-思濛砾石层成因与时代   总被引：6，自引：0，他引：6  

张倬元陈叙伦  刘世青夏克勤 《山地学报》2000,18(Z1):8-16

根据组成丹棱-思氵蒙砾石层的不同岩性的砾石的统计分析,论证了该砾石层的物源区。应用粒组分析资料经数据处理取得的趋势分布所显示的砾石分选性和递变规律,并应用沃克划分砾岩成因类型的组构标志,判别砾石层成因。最后根据砾石的风化程度和川西前陆盆地第四纪演化特征,以及青衣江阶地位相所显示的第四纪沉积物序次,论述了丹棱-思氵蒙砾石层的形成时代。结论认为,丹棱-思氵蒙砾石层为冲积成因,物源区为青衣江流域,为古青衣江出山后在前陆盆地中充填的冲积扇,当时青衣江古河道由洪雅黄坪流经丹棱最后在思氵蒙汇入岷江。现代的丹棱-思氵蒙河是青衣江改道出平羌峡汇入大渡河后残留下来的断头河。砾石层的形成时代为早中更新世(Q12)。  相似文献   

用钻进参数仪实时判层   总被引：5，自引：1，他引：4  

滕子军 《煤田地质与勘探》2000,28(2):58-60

利用钻进参数仪采集的各岩石的钻速、钻压、转速3个参数数据进行回归分析,计算各种岩石的视可钻性指数,并在钻进中实时判层。   相似文献   

有关煤层气勘探评价的若干问题     

王涛  黄文涛 《江西地质》2000,14(4):306-308

煤层气的勘探评价,是开展煤层气勘探与开发工作的基础。当前要搞好勘探评价工作,需注意解决以下３个方面的问题：广泛搜集、认真总结国外煤层勘探开发的资料,精心筛选出适合我国国情的勘探评价参数体系;改进与完善煤层气勘探评价参数的测试技术,制定出与国际惯例相容的测试指南,为勘探评价提供准确的、可比性强的定量依据;做好勘探评价的经济财务分析工作,认真开展可行性研究评价,坚持综合勘探、综合评价原则。  相似文献   

ESR DATING OF THE CENOZOIC STRATA AT LAOJUNMIAO SECTION, YUMEN AND ITS SIGNIFICANCE FOR UPLIFT OF TIBETAN PLATEAU     

Shi Zhengtao  Ye Yuguan  Zhao Zhijun  Fang Xiaomin  Li Jijun 《地学前缘》2000,(Z1)

ESR DATING OF THE CENOZOIC STRATA AT LAOJUNMIAO SECTION, YUMEN AND ITS SIGNIFICANCE FOR UPLIFT OF TIBETAN PLATEAU  相似文献   

Architectural Model of a Dryland Gravel Braided River, based on 3D UAV Oblique Photogrammetric Data: A Case Study of West Dalongkou River in Eastern Xinjiang, China     

YIN Senlin  ZHU Baiyu  GUO Haiping  XU Zhenhu  LI Xiaoshan  WU Xiaojun  CHEN Yukun  JIANG Zhibin 《《地质学报》英文版》2023,97(1):269-285

Three-dimensional unmanned aerial vehicle(UAV) oblique photogrammetric data were used to infer mountainous gravel braided river lithofacies, lithofacies associations and architectural elements. Hierarchical architecture and lithofacies associations with detailed lithofacies characterizations were comprehensively described to document the architectural model, architectural element scale and gravel particle scale.(1) Nine lithofacies(i.e., Gmm, Gcm, Gcc, Gci, Gcl, Ss, Sm, Fsm and Fl) were identifi...  相似文献   

砾石掺量及侧限压力对黏土类土石混合体动力特性的影响分析          下载免费PDF全文

周爱兆  黄献文  刘顺青  蔡国军  王炳辉 《地震工程学报》2020,42(1):205-214

黏土类土石混合体常作为路基填料在工程中广泛应用,然而其在交通荷载作用下的动力特性方面研究较少。为此,本文以0.05 Lc(Lc为圆柱试样直径)为土体、块石分类阈值,根据土石混合体中砾石掺量、侧限压力的不同,采用自振柱仪对其在小应变(10^-6~10^-4)下的动剪切模量和阻尼比进行研究。结果表明:土石混合体最大动剪切模量随砾石掺量的增加而不断增大,且在20%~40%掺量区间内增幅最大,随侧限压力的增加而增大,且增幅逐渐变小;在应变幅值相同的条件下,动剪切模量衰变程度随砾石掺量的增加而不断减少,且在20%~40%掺量区间内减幅最大,随侧限压力的增加而减小,且减幅逐渐变小;最小、最大阻尼比随砾石掺量和侧限压力的增加而减少。结合试验结果分别从颗粒“骨架”结构性、动态结构稳定性、材料密实度、能量耗散等方面阐述块石掺量和侧限压力对土石混合体动剪切模量和阻尼比的影响机理。最后采用优化Hardin-Drnevich模型建立砾石掺量、侧限压力与土石混合体动力特性参数(最大动剪切模量、参考剪应变、最大阻尼比、最小阻尼比)之间的估算公式,以期为土石混合路基的动力设计和施工提供指导。  相似文献   

Co-evolution of coarse grain structuring and bed roughness in response to episodic sediment supply in an experimental aggrading channel     

Marwan A. Hassan  Matteo Saletti  Chendi Zhang  Carles Ferrer-Boix  Joel P.L. Johnson  Tobias Müller  Claudia von Flotow 《地球表面变化过程与地形》2020,45(4):948-961

We use flume experiments to better understand how gravel-bed channels maintain bed surface stability in response to pulses of sediment supply. Bed elevations and surface imagery at high spatial resolutions were used to quantify the co-evolution of surface grain-size distribution (GSD), bed roughness statistics, and bed surface structures (clusters, cells and transverse features). Using a new semi-automated method, we identified individual stone structures over a 2 m × 1 m area throughout the experiments. After an initial coarsening, surface GSD and armouring ratio remained nearly stable as sediment pulses caused net bed aggradation. In contrast, individual grain structures continued to form, increase or decrease in size, and disappear throughout the experiments. The response of the bed to sediment pulses depended on the history of surface roughness evolution and bed surface structure development, as these factors changed much more in response to supply perturbations earlier in the experiments compared to later, even as the bed continued to aggrade. We interpret that the dynamic production and destruction of bed surface structures can act as a ‘buffer’ to sediment supply pulses, maintaining a stable bed surface during aggradation with minimal change in grain size or armouring. © 2019 John Wiley & Sons, Ltd.  相似文献   

Distinguishing between debris flows and hyperconcentrated flows: an example from the eastern Swiss Alps          下载免费PDF全文

Nancy C. Calhoun  John J. Clague 《地球表面变化过程与地形》2018,43(6):1280-1294

Much research has been done on water‐rich mass flows, but the distinction between hyperconcentrated flows and debris flows, and whether the two are indeed different processes, continue to be debated. Here, we contribute to the ongoing discussion of these phenomena by describing and interpreting the deposit of a large landslide‐induced mass flow in the eastern Swiss Alps. About 9400 years ago, 10‐12 km³ of limestone detached from the wall of the Vorderrhein River valley and rapidly fragmented while sliding towards the valley bottom. The rock mass struck the valley floor with enormous force and liquefied at least 1 km³ of valley‐fill sediments. A slurry of liquefied sediment – the ‘Bonaduz gravel’ – traveled tens of kilometres down the Vorderrhein valley from the impact site, carrying huge fragments of rockslide debris that became stranded on the valley floor, forming hills termed ‘tomas’. Part of the flow was deflected by a cross‐valley barrier and traveled 14 km up a tributary of the Vorderrhein valley. The Bonaduz gravel is >65 m thick and fines upward from massive sandy cobble gravel at its base to silty sand at its top. Sedimentologic and geomorphic evidence indicates that Bonaduz gravel was transported as a hyperconcentated flow, likely above a basal carpet of coarse diamictic sediment that behaved as a debris flow. The large amount of water involved in the flow indicates that at least part of the Flims rockslide entered a lake. The Bonaduz deposit shares many properties with sediments left by hyperconcentrated flows generated in flumes, including normal grading and elutriation pipes produced by the rapid escape of fluids when the flow comes to rest. These properties are characteristic of non‐Newtonian laminar flows with high sediment concentrations. Our study reinforces laboratory and theoretical studies showing that debris flows and hyperconcentrated flows are different processes. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献