Low-frequency current variability observed at the shelfbreak in the northeastern Gulf of Mexico: November 2004–May 2005     

M.R. Carnes  W.J. TeagueE. Jarosz 《Continental Shelf Research》2008

Fourteen acoustic Doppler current profilers (ADCPs) were deployed on the shelf and slope for 1 year just west of the DeSoto Canyon in the Northeastern Gulf of Mexico by the Naval Research Laboratory (NRL) as part of its Slope to Shelf Energetics and Exchange Dynamics (SEED) project. The winter and spring observations are discussed here in regards to the low-frequency current variability and its relation to wind and eddy forcing. Empirical orthogonal function (EOF) analyses showed that two modes described most of the current variability. Wind-forced variability of the along-shelf flow was the main contributor in Mode 1 while eddies contributed much of the variability in Mode 2. Wind-stress controlled currents on the shelf and slope at time scales of about a week. On longer time scales, variations in the currents on both the outer shelf and slope appear to be related to seasonal variations in the time-cumulated wind stress curl. Winds were dominant in driving the along-shelf transports, particularly along the slope. However, the effective wind stress component was found to be aligned with the west Florida shelf direction rather than the local shelf direction. Eddy intrusions, which were more numerous in winter and spring than in summer and fall, and winds were found to contribute significantly to cross-shelf exchange processes.  相似文献   

南岭地区钨矿床共（伴）生金属特征及其地质意义初探   总被引：8，自引：0，他引：8  

华仁民  张文兰  李光来  胡东泉  王旭东 《高校地质学报》2008,14(4):527-538

南岭是世界上最重要的钨矿产地,南岭钨矿床中与钨共（伴）生的有色、稀有及贵金属种类很多,数量可观,也是我国重要的矿产资源。论述了南岭及其邻近地区众多钨矿床中与钨共生或伴生的锡、钼、铋、铌钽、铜、铅锌、金银、稀土等元素的不同状况和特征,其中锡、钼、铋是南岭钨矿床中最普遍最重要的共（伴）生元素,铌钽只在演化程度较高的花岗岩相关的钨矿床中伴生产出,铜、金作为钨矿床伴生金属的意义较小,而钨矿床中伴生的银、铅锌具有相当重要的意义。从元素地球化学性质、南岭的区域地背景、花岗岩演化、多期多阶段成矿作用等方面出发,分析和解释了它们之间相互共（伴）生的原因及差异性,探讨了其地质意义。  相似文献   

YANSHANIAN AND HIMALAYAN EVOLUTION OF THE WESTERN TARIM AREA(XINJIANG CHINA):FROM THE JURASSIC TROUGH UP TO THE NEOGENE AND QUATERNARY FLEXURAL BASIN     

Joseph Canerot    Qu Guosheng  WT  ”BX 《地学前缘》2000,(Z1)

YANSHANIAN AND HIMALAYAN EVOLUTION OF THE WESTERN TARIM AREA(XINJIANG CHINA):FROM THE JURASSIC TROUGH UP TO THE NEOGENE AND QUATERNARY FLEXURAL BASINtheNationalNaturalScienceFoundationofChina (No ..4982 5 10 2 )  相似文献   

Magnetism of igneous rocks from the Tourmakeady and Glensaul inliers, W. Ireland: mode of emplacement and aspects of the Ordovician field pattern     

E. R. Deutsch  K. M. Storetvedt 《Geophysical Journal International》1988,92(2):223-234

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Sources of M_w 5+ earthquakes in northeastern Italy and western Slovenia: An updated view based on geological and seismological evidence     

Pierfrancesco Burrato  Maria Eliana Poli  Paola Vannoli  Adriano Zanferrari  Roberto Basili  Fabrizio Galadini 《Tectonophysics》2008,453(1-4):157

We present an overview of the seismogenic sources of northeastern Italy and western Slovenia, included in the last version of the Database of Individual Seismogenic Sources (DISS 3.0.2) and a new definition of the geometry of the Montello Source that will be included in the next release of the database. The seismogenic sources included in DISS are active faults capable of generating M_w > 5.5 earthquakes. We describe the method and the data used for their identification and characterization, discuss some implications for the seismic hazard and underline controversial points and open issues.In the Veneto–Friuli area (NE Italy), destructive earthquakes up to M_w 6.6 are generated by thrust faulting along N-dipping structures of the Eastern Southalpine Chain. Thrusting along the mountain front responds to about 2 mm/a of regional convergence, and it is associated with growing anticlines, tilted and uplifted Quaternary palaeolandsurfaces and forced drainage anomalies. In western Slovenia, dextral strike–slip faulting along the NW–SE trending structures of the Idrija Fault System dominates the seismic release. Activity and style of faulting are defined by recent earthquakes (e.g. the M_s 5.7, 1998 Bovec–Krn Mt. and the M_w 5.2, 2004 Kobarid earthquakes), while the related recent morphotectonic imprint is still a debated matter.We reinterpreted a large set of tectonic data and developed a segmentation model for the outermost Eastern Southalpine Chain thrust front. We also proposed the association of the four major shocks of the 1976 Friuli earthquake sequence with individual segments of three major thrust fronts. Although several sub-parallel active strike–slip strands exist in western Slovenia, we were able to positively identify only two segments of the Idrija Fault System. A comparison of the regional GPS velocity with long-term geological slip-rates of the seismogenic sources included in DISS shows that from a quarter to half of the deformation is absorbed along the external alignment of thrust faults in Veneto and western Friuli. The partitioning of the deformation in western Slovenia among the different strike–slip strands could not be quantified.  相似文献   

Worldview-Ⅱ遥感影像的阴影检测方法研究     

罗艳  辛俊伟  何海清 《测绘科学》2017,42(9)

针对HIS空间变换阴影检测方法仅利用三原色波段数据进行阴影检测而未考虑影像数据之间的相关性及冗余度这一问题,该文结合最佳指数法提出一种适用于多光谱的Worldview-Ⅱ遥感卫星影像阴影检测方法,并引进归一化水体差异指数剔除掉水体的干扰,构建出适用于阴影检测的波段指数模型。实验结果表明,该方法针对Worldview-Ⅱ影像具有普适性,且相对于利用三原色数据进行阴影检测方法能更有效地避免植被信息的干扰,能够精确、快速地检测阴影区域,对后期的阴影去除等研究具有重要的参考价值。  相似文献   

Bathymetric mapping and sub-bottom profiling through lake ice with ground-penetrating radar   总被引：2，自引：1，他引：2  

Brian J. Moorman  Frederick A. Michel 《Journal of Paleolimnology》1997,18(1):61-73

Bathymetric mapping of lakes with sonar is essentially limited to the ice-free summer months. Recent developments in ground-penetrating radar technology have greatly increased its portability and capabilities for imaging through fresh water. The suitability of a backpack portable ground-penetrating radar (GPR) system for bathymetric mapping of ice-covered Arctic lakes was investigated by performing grid surveys on three lakes with water depths up to 19 m. It was demonstrated that GPR can now be used to quickly produce high quality bathymetric maps and sub-bottom profiles showing sediment type and lacustrine sediment thickness. While water depths were measured with a precision of ±3%, lacustrine sediment thickness measurements (up to 5 m) had an estimated precision of ±15%.  相似文献   

内蒙古锡林郭勒盟布金黑铅锌矿床Ⅱ号矿脉地质特征及成矿预测     

蔡文艳  付丽娟  权鸿雁  李文  韩屹  王可勇  张雪冰 《世界地质》2016,35(2):418-428

布金黑铅锌矿床为典型的中温热液脉型矿床,矿体呈脉状、透镜状产出于寿山沟组下段的变质砂板岩之中,其中Ⅱ号矿脉是该矿床主要的工业矿体,总体呈近EW向展布。通过矿区地质、矿化特征、磁法测量及OPIS计算机模拟,指出在断裂构造EW与NE方向转变的地带易成矿,且矿化体具有高极化率、高磁化率、高厚度和高品位特征。磁异常图表现为呈近东西向线性分布的磁异常水平一阶90°、135°导数等值线与近EW向断裂相对应,异常梯度大的区域对应断裂构造方向改变地带。OPIS预测图表明矿体的位置对应数据的高值的中心部位、中心部位附近,或位于断裂面距离变化较陡部位。据此,圈定了Ⅰ、Ⅱ、Ⅲ、Ⅳ四处外围找矿靶区及Ⅱ-1、Ⅱ-2、Ⅱ-3三处深部找矿靶区,其中Ⅱ-2靶区已被验证。  相似文献   

Excursion to kettering and thrapston: Saturday,July 7th, 1900     

J.F. Blake 《Proceedings of the Geologists' Association. Geologists' Association》1900,16(10):516-517

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Excursion to Bristol: Monday,August 16th,and Five Following Days     

《Proceedings of the Geologists' Association. Geologists' Association》1880,6(8):396-402

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