Outflow channel sources, reactivation, and chaos formation, Xanthe Terra, Mars     

Jose A.P. Rodriguez  Sho Sasaki  James M. Dohm  Hideaki Miyamoto  Goro Komatsu  Justin C. Ferris 《Icarus》2005,175(1):36-57

The undulating, warped, and densely fractured surfaces of highland regions east of Valles Marineris (located north of the eastern Aureum Chaos, east of the Hydraotes Chaos, and south of the Hydaspis Chaos) resulted from extensional surface warping related to ground subsidence, caused when pressurized water confined in subterranean caverns was released to the surface. Water emanations formed crater lakes and resulted in channeling episodes involved in the excavation of Ares, Tiu, and Simud Valles of the eastern part of the circum-Chryse outflow channel system. Progressive surface subsidence and associated reduction of the subsurface cavernous volume, and/or episodes of magmatic-driven activity, led to increases of the hydrostatic pressure, resulting in reactivation of both catastrophic and non-catastrophic outflow activity. Ancient cratered highland and basin materials that underwent large-scale subsidence grade into densely fractured terrains. Collapse of rock materials in these regions resulted in the formation of chaotic terrains, which occur in and near the headwaters of the eastern circum-Chryse outflow channels. The deepest chaotic terrain in the Hydaspis Chaos region resulted from the collapse of pre-existing outflow channel floors. The release of volatiles and related collapse may have included water emanations not necessarily linked to catastrophic outflow. Basal warming related to dike intrusions, thermokarst activity involving wet sediments and/or dissected ice-enriched country rock, permafrost exposed to the atmosphere by extensional tectonism and channel incision, and/or the injection of water into porous floor material, may have enhanced outflow channel floor instability and subsequent collapse. In addition to the possible genetic linkage to outflow channel development dating back to at least the Late Noachian, clear disruption of impact craters with pristine ejecta blankets and rims, as well as preservation of fine tectonic fabrics, suggest that plateau subsidence and chaos formation may have continued well into the Amazonian Period. The geologic and paleohydrologic histories presented here have important implications, as new mechanisms for outflow channel formation and other fluvial activity are described, and new reactivation mechanisms are proposed for the origin of chaotic terrain as contributors to flooding. Detailed geomorphic analysis indicates that subterranean caverns may have been exposed during chaos formation, and thus chaotic terrains mark prime locations for future geologic, hydrologic, and possible astrobiologic exploration.  相似文献   

辽宁省深部构造特征及其地质意义     

郑秀岩 《国土资源》1997,(3)

本文应用了最新取得的“五统一”区域重力成果，并经过对浅表松散槽（如下辽河断陷，大岩体等）的密度亏损进行补偿改正后，求取了全省的区域重力场及其垂向二次导数，计算了莫氏面等深度图。在分析区域重力场及其垂向二次导数异常特征和莫氏面起伏特征的基础上，划分出辽宁深部构造的基本格局。从平面上探讨了深部构造与地形地势、地质构造及矿产分布的关系，从剖面上剖析了辽宁省地壳分层的宏观特征  相似文献   

山东省侵入岩岩石单位及其代号的厘定   总被引：1，自引：0，他引：1       下载免费PDF全文

王世进  张成基  宋明春  王沛成 《山东国土资源》2002,18(1):9-20

根据《1∶2 5万区域地质调查技术要求 (暂行 )》和我省正在进行的 1∶2 5万区调修测取得的阶段性成果 ,对山东省侵入岩岩石单位及其代号进行了厘定 :不同类型的花岗岩类均作为正式填图单位按“年代 岩性和典型产地方法”确定填图单位代号 ,而独立侵入体、脉岩和包体 ,以及基性—超基性岩则作为非正式填图单位按“年代 岩性方法”确定填图单位代号。  相似文献   

菏泽市地质灾害现状与防治          下载免费PDF全文

张本进  徐淑和  黄文峰  张洪波 《山东国土资源》2003,19(5):26-27,31

菏泽市地质灾害类型主要为地震、地面塌陷、地面沉降、地裂缝、砂土液化、土地盐渍化及地氟病等，其发育与分布受地质构造、水文地质条件的控制以及气象、人类活动等因素的影响。就其分布、危害、致灾原因等做了分析，并提出了防治建议和对策。  相似文献   

Correlation of the Jurassic-Cretaceous siliceous-volcanogenic sediments in northwestern surroundings of the Pacific (Koryak Upland)     

V. S. Vishnevskaya  N. I. Filatova 《Stratigraphy and Geological Correlation》2008,16(6):618-638

In distribution areas of the Pekul’neiveem and Chirynai formations customary distinguishable in the Koryak Upland, complicated tectonostratigraphic units are composed of alternating thrust sheets of different lithologic composition and age, which are juxtaposed because of widespread thrust faulting, as is proved by the radiolarian analysis. Nineteen radiolarian assemblages of different age are first established here in the Lower Jurassic-Hauterivian succession of siliceous-volcanogenic sediments. In the Lower Jurassic interval, the lower and upper Hettangian, lower and upper Sinemurian, and Pliensbachian beds are recognized. Paleontological characterization is also presented for the Aalenian (or Toarcian?-Aalenian), upper Bajocian, lower and upper Bathonian, and Callovian beds of the Middle Jurassic. Within the Upper Jurassic, the Oxfordian-early Kimmeridgian, late Kimmeridgian-early Tithonian, Tithonian, and late Tithonian-early Berriasian radiolarian assemblages are distinguished. The late Berriasian-early Valanginian, middle-late Valanginian, and Hauterivian radiolarian assemblages are first recognized or compositionally revised. Radiolarians and lithofacies data are used to correlate the tectonostratigraphic units and individualize the jasper-alkali basaltic (lower Hettangian), chert-terrigenous (Hettangian-Sinemurian), jasper-cherty (Pliensbachian-Aalenian), jasper (Bajocian-Hauterivian), jasper-basaltic (upper Bajocian-Valanginian), Fe-Ti basaltic (upper Bajocian-Bathonian), tuffitejasper-basaltic (Bathonian-Hauterivian), and terrigenous-volcanogenic (Bajocian-Valanginian) sequences. The correlation results are extrapolated into other continental areas flanking the Pacific, i.e., to the western Kamchatka, northern and northwestern coastal areas of the Sea of Okhotsk, where the analogous radiolarian assemblages are characteristic of comparable allochthonous units of terrigenous-siliceous-volcanogenic sediments.  相似文献   

Rain-induced debris and mudflow triggering factors assessment in the Santiago cordilleran foothills,Central Chile   总被引：1，自引：1，他引：0  

Sergio A. Sepúlveda  Cristóbal Padilla 《Natural Hazards》2008,47(2):201-215

Debris and mudflows are some of the main geological hazards in the mountain foothills of the Chilean capital city of Santiago. There, the risk of flows triggered in the basins of ravines that drain the range into the city increases with time due to the city growth. A multivariate statistical study based on the logistic regression method is presented. The model provides equations that allow the computation of combined meteorological triggering factors associated with a probability of rain-induced flow occurrence. Daily rainfall, accumulated rainfall and the snowfall level, traditionally considered as the relevant factors, are analysed for a 25-year period. The results show a strong relevance of the rainfall on the day of the flow event over the other factors. However, the relatively low probabilities returned for some real flow events suggest that the model does not capture all the significant variables and the problem is more complex than as it has been traditionally assumed, and further investigations are needed to develop predictive models of flow triggering.  相似文献   

CO2地质埋存渗漏风险及补救对策   总被引：7，自引：1，他引：6  

许志刚  陈代钊  曾荣树 《地质论评》2008,54(3):373-386

目前,将CO2埋存于地下深部地质构造（如油气藏、煤层、地下含水层及岩溶盐腔）的减排方案能有效地减缓温室效应而备受关注。无论什么储集体,我们都希望CO2在地下埋存的时间越长越好。然而,对于一项具体工程的实施,必然存在一些客观和主观因素造成CO2渗漏,比如废弃井的不完善或不合理处理、地层断裂系统和水动力系统以及地震所造成的渗漏等等。存在渗漏就可能会对周围人和生态环境造成危害。因此,进行CO2地质埋存的风险评估是相当有必要的,是我们能长期有效安全地进行该项减排方案必不可少的基础和保证。本文即想从建立一套完整的风险评估、管理和监测体系的角度并以加拿大Weyburn油田为例,深入分析CO2地质埋存中可能存在的渗漏风险和途径,建立CO2渗漏风险评估机制,并针对具体的渗漏可能性提出相应的补救对策,为全球范围内,尤其对我国刚刚开展CO2地质埋存研究工作提供一些有益的思路。  相似文献   

Inertial and hydrodynamic inertial loads on floating units     

Marcelo Ramos Martins   《Ocean Engineering》2007,34(16):2146-2160

The analysis of the dynamic behavior of floating units usually employs a coordinate system with origin in the unit's center of gravity, which significantly simplifies the global mass matrix. Hydrodynamic coefficients are then computed considering the same coordinate system. However, to analyze other conditions of mass distribution and maintain the simplicity of a global mass matrix, it is necessary to determine again the hydrodynamic coefficients, thereby reducing the efficiency of the entire process. Another important point is that the geometries frequently used in floating units are such that the cross-terms of an added mass are relatively unimportant when compared with the main terms, and it is, therefore, common to use only some of them to analyze the unit's dynamic behavior. Recently, however, in the search for production systems suitable for water depths greater than 3000 m, other geometries have been considered in technical and economic feasibility studies. It is possible that for these new geometries all terms of the added mass matrix must be included in the analysis. This paper presents the full development used to determine the complete global mass matrix, the inertial and hydrodynamic inertial loads that make use of the added mass matrices considering any coordinate system and the six degrees of freedom, including all cross-terms.  相似文献   

镇江地质灾害治理工程项目管理中的问题与对策探讨          下载免费PDF全文

张剑 《江苏地质》2008,32(1):64-69

地质灾害治理工程项目管理是地质灾害管理的具体体现和实施过程,其基本任务是根据地质灾害管理目标和管理方法,组织实施防治工程,保障取得预期的减灾成果。就镇江市地质灾害治理工程项目管理目前现状,从规范文件、招标机构、管理工具、管理经验、干扰因素、风险评价、人员素质等方面进行粗浅分析,并针对存在的问题提出相应的对策,借以提高镇江市地质灾害治理工程项目管理的能力和水平,以便今后地质灾害治理项目管理更好地完善和发展。  相似文献   

江苏新沂市露采矿山地质环境现状及恢复治理措施          下载免费PDF全文

杨小川  张春 《江苏地质》2008,32(2):144-147

新沂市的矿产资源开发利用程度低,潜力大,矿山开采规模小、资源浪费严重,采矿毁坏土地和植被,破坏生态环境,对自然地貌景观破坏严重;采矿掘进面高差大,边坡陡立,埋下诱发山体崩塌、滑坡等地质灾害隐患,易造成人员伤亡事故;露采矿山地质环境整治滞后,绝大多数露采矿山地质环境没有得到有效整治。根据露采矿山开采中存在的问题,提出了包括管理措施、工程技术措施和经济政策措施等地质环境恢复治理措施。  相似文献