西秦岭岷县地区二叠纪裂陷带斜坡沉积及其构造意义   总被引：1，自引：0，他引：1  

王治平  陈素华 《现代地质》1995,9(3):300-310

秦岭造山带西段，二叠纪裂陷作用非常活跃。位于西秦岭中部的岷县红崖、梅州一带，二叠系以粉碎屑沉积为主，泥质较少。根据对其岩石类型、沉积构造、岩石组合和生物特征的分析，认为这套地层主要形成于海底扇体系的内扇和中扇环境，外扇不发育，系由碎屑流和浊流沉积组成，包括内扇的水道和水下天然堤沉积及中扇的网状水道和朵叶体沉积。这套地层沿中秦岭南缘呈ＮＷＷ－ＳＥＥ方向延伸，代表了二叠纪西秦岭裂谷的存在及其继续裂陷的活动特征。  相似文献   

Reply to Sandgren and Smol: further discussion on chrysophyte cyst taxonomy     

Heikki Simola 《Journal of Paleolimnology》1993,9(1):63-68

  相似文献   

Late Quaternary kinematics of the Pallatanga strike-slip fault (Central Ecuador) from topographic measurements of displaced morphological features   总被引：2，自引：0，他引：2  

Thierry Winter  Jean-Philippe Avouac  Alain Lavenu 《Geophysical Journal International》1993,115(3):905-920

The northeast-trending Pallatanga right-lateral strike-slip fault runs across the Western Cordillera connecting N50E-N70E trending normal faults in the Gulf of Guayaquil with N-S reverse faults in the Interandean Depression. Over most of its length, the fault trace has been partly obscured by erosional processes and can be inferred in the topography only at the large scale. Only the northern fault segment, which follows the upper Rio Pangor valley at elevations above 3600 m, is prominent in the morphology. Valleys and ridges cut and offset by the fault provide an outstanding record of right-lateral cumulative fault displacement. The fault geometry and kinematics of this particular fault segment can be determined from detailed topographic levellings. The fault strikes N30E and dips 75 to the NW. Depending on their size and nature, transverse morphological features such as tributaries of the Rio Pangor and intervening ridges, reveal right-lateral offsets which cluster around 27 ± 11m, 41.5 ± 4 m, 590 ± 65 m and 960 ± 70 m. The slip vector deduced from the short-term offsets shows a slight reverse component with a pitch of about 11.5 SW. The 41.5 ± 4 m displacements are assumed to be coeval with the last glacial termination, yielding a mean Holocene slip-rate of 2.9- 4.6 mm yr⁻¹. Assuming a uniform slip rate on the fault in the long term, the 27 m offset appears to correlate with an identified middle Holocene morphoclimatic event, and the long term offsets of 590 m and 960 m coincide with the glacial terminations at the beginning of the last two interglacial periods.  相似文献   

Nonseismic phenomena in the generation and augmentation of tsunamis     

Patricia A. Lockridge 《Natural Hazards》1990,3(4):403-412

While earthquakes generate about 90% of all tsunamis, volcanic activity, landslides, explosions, and other nonseismic phenomena can also result in tsunamis. There have been 53 000 reported deaths as a result of tsunamis generated by landslides and volcanoes. No death tolls are available for many events, but reports indicate that villages, islands, and even entire civilizations have disappeared. Some of the highest tsunami wave heights ever observed were produced by landslides. In the National Geophysical Data Center world-wide tsunami database, there are nearly 200 tsunami events in which nonseismic phenomena played a major role. In this paper, we briefly discuss a variety of nonseismic phenomena that can result in tsunamis. We discuss the magnitude of the disasters that have resulted from such events, and we discuss the potential for reducing such disasters by education and warning systems.  相似文献   

频率测深的地形影响及其校正方法   总被引：3，自引：1，他引：3  

阎述  陈明生 《煤田地质与勘探》1994,22(4):45-49

从含源麦克斯韦方程出发，按照二维地形条件下的线源非齐次赫姆霍兹方程确定其边界条件，用边界元法计算了起伏地形条件下线源的频测影响曲线，并将其转换为二维地形点源赤道偶极装置频测曲线。总结了地形对频测曲线影响的规律，提出了地形校正的方法。  相似文献   

EFFECTS OF THE ENVELOPE DEGREE OF OROGRAPHY ON THE SIMULATED CLIMATE PROPERTIES   总被引：4，自引：0，他引：4       下载免费PDF全文

钱永甫  董梁 《Acta Meteorologica Sinica》1995,(3)

A primitive equation model with a zonal domain and a p-σ incorporated vertical coordinate systemis used to study the effects of the envelope degree of orography on the simulated properties of bothwinter and summer climates.Results show that the orography with a larger envelope degree can im-prove the simulations to certain extent,especially in winter.It is found that the simulated propertiesof climate are mainly determined by the co-effects of the land-sea and the orographic distributions,and the envelope degree of orography has a secondary effect.However it should be taken properly inorder to improve simulations:otherwise,it would be harmful.Different envelope degrees of orogra-phy can be adopted in different areas.  相似文献   

EFFECTS OF TOPOGRAPHY ON PROPAGATION AND DEVELOPMENT OF INERTIA GRAVITY WAVE          下载免费PDF全文

Wang Xingbao 《Acta Meteorologica Sinica》1995,9(4):488-500

Effects of topography on the propagation and development of inertia gravity waves areinvestigated by means of WKBJ method.The equation of wave action conservation is obtained.It isfound that the inertia gravity wave tends to propagate to the higher elevation area,meanwhile theamplitudes of the waves increase.While the inertia gravity waves propagate to a lower elevation area,their amplitudes decrease.  相似文献   

Unified Approach to Photon-Counting Microlaser Rangers, Transponders, and Altimeters   总被引：1，自引：0，他引：1  

John J. Degnan 《Surveys in Geophysics》2001,22(5-6):431-447

Unlike current manned systems, NASA's next generation SLR2000 Satellite Laser Ranging (SLR) station is fully autonomous, eye-safe, relatively compact and inexpensive, and, during daytime tracking, operates at signal-to-noise ratios several orders of magnitude below unity. Tiny, passivelyQ-switched microlasers generate ultra-short pulses with output energies on the order of 100 J at few kHz rates to achieve mm-levelranging precision to satellite altitudesof 20,000 km. Special ranging receivers, combined with Poisson statistical analysis of the received photon distribution, enable the system to rapidly and reliably identify and extract the single photon laser echoes from the solar background. The enhanced rate of return, combined with a uniform signal strength, can actually drive down both systematic and random range errors. The new SLR2000 technology has already spawned exciting new applications. Compact microlaser altimeters, capable of mapping the surface of a planet or other celestial body at multikilohertz rates, is one such application, and a high altitude, airborne version is currently being developed under NASA's Instrument Incubator Program. Interplanetary microlaser transponders would be capable of performing decimeter ranging or subnanosecond time transfer to spacecraft throughout the inner Solar System, resulting in improved knowledge of planetary motions and librations and enhanced General Relativity experiments.  相似文献   

亚洲中东部岩石圈下层网络状塑性流动与应变场   总被引：6，自引：0，他引：6  

王绳祖 《地质论评》2001,47(5):459-466

在板块边缘驱动力的挤压作用下,岩石圈下层（含下地壳和岩石圈地幔）塑性流动网络的共轭角随着变形的增大而由初始的直角变为钝角,因此,可根据共轭角的增量推测应变的大小,并给出该层的应变场,亚洲中东部所含3个塑性流动网络系统的研究表明,岩石圈下层的应变场控制或影响着上部地壳的构造变形和地形起伏,表现在应变“凸锋~”与地形凸峰之间的相互对应以及“稳定”块体的低应变效应和应变的波动传播,网络共轭角推测应变的方法为认识板内应变场和构造变形提供了新的途径。  相似文献   

闽西南地区块状硫化物矿床的喷流-沉积成矿作用     

郑志强  林东燕 《福建地质》2007,26(4):222-228

通过对闽西南地区石炭纪—早二叠世主要块状硫化物矿床的区域成矿背景、贮矿层位特征以及矿石矿物成分、结构构造,硫同位素地球化学特征、成矿温度等分析研究,指出该地区石炭纪—早二叠世块状硫化物矿床的形成多与海底火山活动有关,贮矿层中伴有典型的喷流沉积岩—硅质岩,并提出闽西南地区块状硫化物矿床存在海底喷流-沉积成矿作用的新认识。  相似文献