Evidence for Middle Pleistocene temperate-climate high sea-level and lowland-scale glaciation, Chapel Hill, Norwich, UK     

Adrian Read  Claire A. Mills  Jonathan R. Lee  Ian Candy  James Rose 《Proceedings of the Geologists' Association. Geologists' Association》2007,118(2):143-156

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长江荆江河段古决口扇遥感专题分析及成因研究     

詹云军  薛重生 《地质科技情报》2002,21(4):55-59

运用遥感影像信息及其图像处理的波段优化组合技术识别出了荆江河段大量的古决口扇，并对决口扇在荆江河段的空间分布及识别特征进行了研究。运用GIS的空间叠加分析，发现古决口扇群与该区域的地貌格局、新构造活动带、河床边界条件及水文条件相关，并对荆江防洪提出了合理的建议。  相似文献   

拱王山风化壳的发育特征及其环境和构造意义   总被引：6，自引：0，他引：6  

冯金良  崔之久 《地理与地理信息科学》2002,18(2):56-60

风化壳的化学、粘粒矿物及磁化率等实验分析表明 ,云南东川拱王山地区碳酸盐岩风化壳的红土化程度较低 ,处于Ca、Mg淋失阶段的后期或SiO2 淋失、Fe、Mn富积的早期。该地区风化壳在不同程度上存在与现代环境的不相容性。它们是在古风化壳基础上发育的继承性风化壳。在不同海拔高度的山前剥蚀面上 ,风化壳红土化程度的差异 ,是不同时期风化作用的产物。除山顶残留古夷平面上的风化壳之外 ,随海拔高度的增加 ,风化壳的风化程度存在逐渐增强的趋势 ,这一现象反映了该区新构造运动的间歇性抬升特征。  相似文献   

Late Cenozoic transpression in southwestern Mongolia and the Gobi Altai-Tien Shan connection     

W. Dickson Cunningham  Brian F. Windley  D. Dorjnamjaa  J. Badamgarov  M. Saandar 《Earth and Planetary Science Letters》1996,140(1-4):67-81

The Gobi Altai region of southwestern Mongolia is a natural laboratory for studying processes of active, transpressional, intracontinental mountain building at different stages of development. The region is structurally dominated by several major E—W left-lateral strike-slip fault systems. The North Gobi Altai fault system is a seismically active, right-stepping, left-lateral, strike-slip fault system that can be traced along the surface for over 350 km. The eastern two-thirds of the fault system ruptured during a major earthquake (M = 8.3) in 1957, whereas degraded fault scarps cutting alluvial deposits along the western third of the system indicate that this segment did not rupture during the 1957 event but has been active during the Quaternary. The highest mountains in the Gobi Altai are restraining bend uplifts along the length of the fault system. Detailed transects across two of the restraining bends indicate that they have asymmetric flower structure cross-sectional geometries, with thrust faults rooting into oblique-slip and strike-slip master faults. Continued NE-directed convergence across the fault system, coupled with left-lateral strike-slip displacements, will lead to growth and coalescence of the restraining bends into a continuous sublinear range, possibly obscuring the original strike-slip fault system; this may be a common mountain building process.

The largely unknown Gobi-Tien Shan fault system is a major left-lateral strike-slip fault system (1200 km + long) that links the southern ranges of the Gobi Altai with the Barkol Tagh and Bogda Shan of the easternmost Tien Shan in China. Active scarps cutting alluvial deposits are visible on satellite imagery along much of its central section, indicating Quaternary activity. The total displacement is unknown, but small parallel splays have apparent offsets of 20 + km, suggesting that the main fault zone has experienced significantly more displacement. Field investigations conducted at two locations in southwestern Mongolia indicate that late Cenozoic transpressional uplift is still active along the fault system. The spatial relationship between topography and active faults in the Barkol Tagh and Bogda Shan strongly suggests that these ranges are large, coalescing, restraining bends that have accommodated the fault's left-lateral motion by thrusting, oblique-slip displacement and uplift. Thus, from a Mongolian perspective, the easternmost Tien Shan formed where it is because it lies at the western termination zone of the Gobi-Tien Shan fault system. The Gobi-Tien Shan fault system is one of the longest fault systems in central Asia and, together with the North Gobi Altai and other, smaller, subparallel fault systems, is accommodating the eastward translation of south Mongolia relative to the Hangay Dome and Siberia. These displacements are interpreted to be due to eastward viscous flow of uppermost mantle material in the topographically low, E–W trending corridor between the northern edge of the Tibetan Plateau and the Hangay Dome, presumably in response to the Indo-Eurasian collision 2500 km to the south.  相似文献   

商州盆地第四纪新构造活动特征及对盆地形成的控制   总被引：1，自引：0，他引：1  

李靠社  白胜利  李宗科 《陕西地质》1995,(1)

在白垩纪和第三纪构造盘地基础上形成的商州第四纪盆地内，新构造断裂活动可分为早更新世末期平缓褶皱及与之相伴的压性断裂和中更新世末期张性断裂。该盆地属一北浅南深的掀斜断块，除北界外，南、西和东界均具断裂特点，其形成经历了挤压和引张两个阶段。  相似文献   

汶川大地震同震新构造活动特征和地震破坏程度的初步调查与认识     

付小方  侯立玮  文辉  李海兵  邹付戈 《四川地质学报》2008,28(4):358-364

汶川8．0级特大地震波及半个亚洲,震撼整个中国。本文通过在灾区的实地初步调查,对龙门山同震新构造活动、发震断裂构造和地表破裂的分布、产状、强度、继承性复活与新生特征、新构造活动与地震地质灾害的关系等进行了初步总结,并探讨了同震新构造活动对地震破坏程度的控制与影响。  相似文献   

Palaeo-path investigation of the lower Ajay River (India) using archaeological evidence and applied remote sensing     

Suvendu Roy  Abhay Sankar Sahu 《国际地球制图》2016,31(9):966-984

Numerous palaeochannels, oxbow lakes and elongated sediment fills in Eastern India, particularly along the lower Ajay River, provide a record of channel shifting during the Late Quaternary. Proper characterization of these features is useful for discussing the dynamic evolution of the river system in the Ajay-Damodar Interfluve region. Remote sensing data, archaeological evidence and sedimentology aid in reconstructing the geomorphic history of the lower Ajay River. Archaeological studies help in calculating the rate and direction of channel migration. The channel migration rate varies from 0.32 to 3.41 m/year in the study area. Bouguer gravity anomalies suggest that the rate of channel migration may be controlled by the density variations of the basement rocks. Furthermore, neotectonics activity played a significant role in the migration of Ajay River towards north-east direction.  相似文献   

Investigation of drainage basin geometry near an anomalously straight reach of the Big Black River,Mississippi, USA     

Zachary A. Musselman  Alex Aguilar 《自然地理学》2016,37(2):169-187

Drainage basin geometry was analyzed in the lower portion of the Big Black River, Mississippi. The study was centered on a reach of the Big Black River that encompasses an anomalous straight reach (ASR) and has morphometric characteristics that differ from those of upstream and downstream reaches. The study area was divided into three reaches, defined by alluvial valley and active floodplain width, sinuosity, and slope. Tributary streams with confluences in the three study reaches were investigated for evidence of surface tilting, and channel and valley slopes and sinuosity were measured. The average stream channel and valley slopes within the middle reach are nearly double those of the upper and lower reaches. Lateral stream migration within the tributary basins was quantitatively analyzed by measuring the asymmetry factor (AF) and transverse topographic symmetry factor (T) indices. While AF results suggest minimal to no lateral migration within the tributaries, the T results show some shifting. The results are inconclusive regarding the possible effect of neotectonic activity in the study area near the ASR. The mean southward migration may indicate a preferred migration direction relative to the general dip of the coastal plain and plunge of the Mississippi Embayment.  相似文献   

Hydrogeochemical outline of thermal waters and geothermometry applications in Anatolia (Turkey)     

Halim Mutlu  Nilgün Güle 《Journal of Volcanology and Geothermal Research》1998,85(1-4)

The chemical compositions of a total of 120 thermal water samples from four different tectonically distinct regions (Central, North, East and West Anatolia) of Turkey are presented and assessed in terms of geothermal energy potential of each region through the use of chemical geothermometers. Na–Ca–HCO₃ type waters are the dominant water types in all the regions except that Na–Cl type waters are typical for the coastal areas of West Anatolia and for a few inland areas of West and Central Anatolia where deep water circulation exists. The discharge temperature of the springs ranges up to 100°C, and the bottom-hole temperatures in drilled wells up to 232°C. Geothermometry applications yield reservoir temperatures of about 125°C for Central Anatolia, 110°C for North Anatolia, 136°C for East Anatolia and 251°C for West Anatolia, the latter agreeing with some of the bottom hole temperatures measured in drilled wells. The results reveal that the highest geothermal energy potential in Turkey is associated with the West Anatolian extensional tectonics which provides a regional, deep-seated heat source and a widespread graben system allowing deep circulation of waters. The North Anatolian region, bounded to the south by the dextral North Anatolian Fault along which most of the geothermal sites are located, has the lowest energy potential, probably due to the restriction of the heat source to local magmatic activities confined to pull-apart basins. The East Anatolian region (undergoing contemporary compression) and the Central Anatolian region (where the compressional regime in the east is converted to the extensional regime in the west) have moderate energy potential. Although the recently active volcanoes suggest the presence, at depth, of still cooling magma chambers that are potential heat sources, the lack of well-developed fault systems is probably responsible for the comparatively low energy potential of these regions. Almost all the thermal waters of Turkey are saturated with respect to calcite and, hence, have a significant calcite scaling potential which is particularly high for West Anatolian waters.  相似文献   

Mass movements in hilly areas (with examples from Nigeria)     

A. E. Scheidegger  D. E. Ajakaiye 《Natural Hazards》1994,9(1-2):191-196

In mountainous areas of great relief, mass movements occur regularly as the result of the normal cyclic landscape development process. However, mass movements also occur in areas of lower relief, i.e. in areas of less geomorphic activity. An extreme case of this type has been found in the development of cracks in a flat savannah area of Nigeria which has generally been ascribed to purely hydrological causes. Nevertheless, it can be shown that the development of the cracks occurs along the shear lines of the neotectonic stress field, so thatgeotectonic processes represent the ultimate cause of the mass movements here as well. Conditions intermediate between those obtaining in mountainous and flat areas are found inhilly regions. In this instance, we have investigated a further particular area of Nigeria: the hills and river valleys near Ankpa in Benue State. Nevertheless, the instabilities in the ground may again have a much deeper primary cause. The primary unstable features appear as gullies; these are seen to form a definite orientation pattern; - which fact would point to a tectonic predesign. This contention can be substantiated by studying numerically the orientation pattern of the gullies/cracks and making a statistical analysis thereof. The pattern of the gullies is then compared with joint orientation measurements. It turns out that the pertinent orientation patterns agree within a few degrees with each other indicating that the gullies/cracks and the joints have been created by the same cause: viz. by the action of the stress field: the latter must beneotectonic, since the joints are found in recent laterite.  相似文献