Saraçköy Volcanic Suite: implications for the subductional phase of arc evolution in the Galatean Arc Complex,Ankara, Turkey     

Ali&#x; Koyi&#x;i&#x;t  John Alan Winchester  Erdi&#x;n Bozkurt  Grenville Holland 《Geological Journal》2003,38(1):1-14

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Palaeomagnetism of the Tan y Grisiau granite,North Wales: Evidence for a subvolcanic origin in Late Ordovician times     

J. D. A. Piper  D. A. G. Nowell  T. P. Crimes 《Geological Journal》1995,30(1):39-47

Progressive thermal demagnetization of samples from the Tan y Grisiau granite defines a coherent easterly positive characteristic remanence (D/I = 124.9/60.3°;, 42 samples, R = 40–51, a₉₅ = 4.8°;) residing in magnetite. An ancient reversal of magnetization is recovered in the highest blocking temperature spectrum of a few samples and suggests that a cooling-related dipolar axis is recorded by this pluton. Only facies of the granite which have been reddened, probably by submagmatic streaming, have recorded a stable remanence. Adjustment for tilt yields a very steep remanence (D/I = 193/88°;) incompatible with any known Early Palaeozoic and younger field direction from Britain. The in situ remanence has a similar declination to the primary magnetization in Late Ordovician dolerites from the Welsh Borderlands and yields a comparable palaeolatitude (41.5°;S). It is concluded that the Tan y Grisiau pluton was magnetized in Late Ordovician times after deformation. Folding in this region is therefore interpreted to be substantially of Taconic (Late Ordovician) origin and not Acadian in age. As both in situ and tilt-adjusted remanence directions are incompatible with Silurian and younger palaeofield directions from Britain, the pluton is interpreted as a subvolcanic component of the North Wales igneous province. Large anticlockwise rotation of Avalonia is identified between Late Ordovician and Late Silurian times.  相似文献   

The Kuroshio east of Taiwan and the currents east of the Ryūkūy-guntōduring October of 1995     

Yuan Yaochu  Liu Yonggang  Cho-teng Liu  Su Jilan 《海洋学报(英文版)》1998,17(1):1-13

On the basis of hydrographic data obtained during two October cruises of 1995, a modified inverse method is used to compute the Kuroshio east of Taiwan and the currents east of the Ryukyu-gunto.The net northward volume transport(VT) of the Kuroshio through Section TK₂-K₂ southeast of Taiwan is about 57.8×10⁶ m³/s.There are four current cores of the Kuroshio at Section TK₂-K₂.Its main core is near the south of Taiwan, and its maximum speed is about 257 cm/s at the surface.After the Kuroshio flows through Section TK₂-K₂, there are three branches of the Kuroshio.The main branch of the Kuroshio flows northward into Section TKa east of Su''ao.The second branch of the Kuroshio flows northward through Section TKa and then enters the East China Sea through the region between Yonakunijima and Iriomote-shima.The net northward VT of the Kuroshio through Section TK4 is about 21.6×10⁶ m³/s.The eastern branch of the Kuroshio flows northeastward through the region between a stronger cyclonic eddy and a recirculating anticyclonic gyre, and then flows continuously northeastward to the region east of the Ryūkyū-guntō and becomes a part of the origin of the western boundary current east of the Ryūkyū-guntō.Another part of the origin of the western boundary current east of the Ryūkyū-guntō comes from a recirculating anticyclonic gyre.From the above, in the regions east of Taiwan end east of the Ryūkyū-guntō the pattern of circulation during October of 1995 differs from the pattern of circulation during early summer of 1985.There are several eddies of different scales in this computational region.For example, there is a meso-scale stronger cyclonic eddy whose center is located at about 23°N, 124°20''E.  相似文献   

Hydroelectric Infrastructure and Potential Groundwater Contamination in the Brazilian Amazon: Altamira and the Belo Monte Dam     

Cristina Gauthier  Zihan Lin  Brad G. Peter  Emilio F. Moran 《The Professional geographer》2019,71(2):292-300

Heavy investments in hydroelectric development are occurring throughout the Amazon Basin, which holds 42.2 percent of Brazil’s hydroelectric potential. The Belo Monte dam is the most recent and largest project in this region. The prevalence of septic systems in the Amazon, coupled with the widespread use of water wells and rising water table from filling the reservoir, create sanitation and health concerns for upstream communities. Using spatial analytical data and terrain analyses, we identify high-risk locations within the most densely populated neighborhoods in Altamira, Belo Monte’s host city. The purpose of this research is to develop a heuristic for identifying areas susceptible to groundwater and well contamination in relation to existing and proposed hydroelectric projects. Altamira’s city center persists as a high-risk location for contamination of wells because of its population density and relatively low elevation compared to other parts of the city. The methods, tools, and analyses presented in this article provide a framework that can be used to identify vulnerability to groundwater and drinking well contamination. The results presented here can guide implementation of public health and sanitation efforts in areas affected by large hydroelectric projects to avoid future water quality crises. Key Words: Belo Monte, groundwater contamination, hydroelectric infrastructure, risk assessment, spatial and terrain analyses.  相似文献   

Assessing the Value of Scholarly Book Reviews among Geographers     

Jeffrey S. Smith 《The Professional geographer》2019,71(2):377-390

According to the latest data available, in 2013 a staggering 68,000 scholarly books reached print in North America alone. Book reviews have long served as an important tool to keep tabs on the content and quality of all of those books. In decades past, perusing book reviews was essential in conducting a literature review and a tool for authors to demonstrate the impact that their book has on a field of study. Most important, though, book reviews play a vital role in academic advancement by calling attention to books that successfully add to new knowledge and warn against books with defects and deficiencies. Despite their overwhelming importance, no one has systematically analyzed the value of scholarly book reviews. Moreover, in our current age of the Internet, e-mail, and social media, it is important to know the worth of book reviews. Drawing on the results of a 2018 survey sent to select members of the American Association of Geographers, this article assesses the value of scholarly book reviews among geographers. It answers these questions: Who writes and reads book reviews? What are the characteristics of a useful book review? Is writing a book review considered a valued scholarly activity? Does writing book reviews help advance a person’s career? Because geography is a microcosm of academia, this study has applicability across the social sciences and humanities. Do scholarly book reviews still matter? Key Words: human geography, monographs, promotion and tenure, scholarly book reviews.  相似文献   

Active tectonics of the Ortaköy fissure-ridge-type travertines: implications for the Quaternary stress state of the neotectonic structures of the Central Anatolia,Turkey     

B. Levent Mesci 《Geodinamica Acta》2013,26(1-2):12-25

Several geothermal fields are located in a NE-SW trend along a structural lineament around the Sivas basin; one of those is the Ortaköy travertines situated 83?km south-west of Sivas. There are eight fissure-ridge-type travertine localities in the area, although eroded-sheet-type travertines constitute many of the travertines of the region. By evaluating the rocks of the Late Miocene-Early Pliocene K?z?l?rmak Formation, it was determined that fissure axes developed within fissure-ridge-type travertines, and that the structural elements obtained from satellite images together with the fissures that form the fissure-ridge-type travertines are shear and tension fissures, and the NE-SW-oriented opening of the fissures, were a result of NW-SE-directed compression, which was also responsible for the formation of the Sivas Backthrust. Ground-penetrating radar studies have shown that the thickness of fissure fills within the fissure-ridge-type travertines of the Ortaköy geothermal field increase with depth, and that the hydrothermal fluids which brought about the formation of the travertines moved surfaceward via fissure systems. The results of U/Th radiometric dating indicate that the youngest travertine in the region is 17,761 (_?268/⁺²⁶⁹) years old and the oldest 128,286 (_?3537/⁺³⁶⁶²) years old. Using the widths of banded travertines within the fissure-ridge-type travertines as well as these age results, the opening rate of the Sivas Basin was determined to be .06 (_?.01/^+.05) mm/year.  相似文献   

(What Geographers Should Know About) The State of U.S. and Canadian Academic Professional Associations’ Engagement with Mental Health Practices and Policies     

《The Professional geographer》2012,64(1):37-53

The professional organizations to which geographers belong and by which they are represented have a civic duty and ethical responsibility to educate their members about mental health issues in their professions and, by default, their work environments. And yet national-level professional associations in North America are lagging behind universities in adopting initiatives, commissioning reports, and looking into best practices around the mental health of their members. A survey of the Web sites of sixty-six professional associations in the social sciences, geographical sciences, and humanities in the United States and Canada reveals an uneven presence of attention to mental health issues in terms of their members’ research on mental health issues, awareness of mental health as a professional development issue, and engagement in mental health advocacy and public outreach. In this article, we explore how geography’s professional organizations compare to others with respect to these issues and suggest ways in which they can develop their own mental health protocols to address the crisis of mental health in the academy. Key Words: Academic professional associations, American Association of Geographers, Canadian Association of Geographers, mental health, mental health practices and policies.  相似文献   

可编辑复杂线状符号库的设计与实现     

姜琦  周晓光  曾联斌  杨毛毛 《测绘软科学研究》2012,(2):75-80

针埘GDI＋绘制复杂线状符号存在符号不可编辑与遮捎等问题,设计了一种可编辑的复杂线状符号的组织方法,该方法将复杂线状符号分解为实线、虚线和点线蔓种基本单元,进而设计了基于这一种基本单元的复杂线状符号参数描述方法,解决了GDI＋绘制复杂线状符号存在符号不可编辑与遮挡等问题。采用C#实现了可编辑线状符弓库的设计与开发．建立了1：10000地形图符号库。最后,对本文方法与GDI＋方法的绘制效率进行了比较试验。试验表明本文方法不仅解决了GDI＋绘制复杂线状符号存在符号不可编辑与遮挡等问题．并且绘制效率也明显优于GDI＋方法．  相似文献   

Incomplete high P–T metamorphic transitions within the Kvamsøy pyroxenite complex, west Norway: a case study of disequilibrium     

MAI BRITT E. MØRK 《Journal of Metamorphic Geology》1985,3(3):245-264

Abstract The Kvamsøy pyroxenite complex consists of olivine websterite, olivine gabbro and leucogabbro-norite which have been subjected to regional high P-T (HPT) metamorphism. The metamorphism has resulted in a range of disequilibrium textures with the development of coronas and pseudomorphism of the igneous phases. Reactions between felsic and mafic mineral domains have been controlled by variable and selective diffusion of elements, resulting in a variety of local plagioclase-breakdown reactions and in significant compositional variations for the product garnet. Restricted diffusion favours transient reaction stages with garnet ± spinel ± corundum ± zoisite after calcic plagioclase in olivine gabbro and olivine websterite and garnet ± spinel ± kyanite ± quartz + sodic plagioclase in leucogabbro-norite. Complete HPT reaction has produced garnet pyroxenite which consists of garnet + diopside + hornblende + zoisite in gabbroic rocks, while amphibolitization continued during the cooling and uplift history. Grt + Ky + Pl + Qtz geobarometry suggests pressures in the range 13-16 kbar for T = 750°C, comparable with the regional eclogite-forming metamorphism.  相似文献   

Constraints on element mobility associated with the conversion of granulite to eclogite along fractures in an anorthositic complex on Holsnøy, Norway   总被引：1，自引：0，他引：1  

K. M. ROCKOW  L. A. HASKIN  B. L. JOLLIFF  & D. M. FOUNTAIN 《Journal of Metamorphic Geology》1997,15(3):401-418

On Holsnøy, an island off the coast of Western Norway, an anorthositic complex metamorphosed to granulite facies was partially overprinted by a later eclogite facies metamorphism. Eclogite facies rocks (containing omphacite, garnet, kyanite and hydrous phases such as mica and zoisite) occur in shear zones of various scales and adjacent to veins. Previous studies of shear zones on Holsnøy reported evidence for substantial element mobility (Jamtveit et al ., 1990; Mattey et al ., 1994). In this work, we compare chemical compositions of granulite and its undeformed eclogitized equivalent adjacent to veins in locations where a single band of granulite can be traced and sampled as it approaches the vein. This tracing is crucial because the pre-granulite rocks cover a substantial compositional range, indicative of a petrologically variable protolith consisting of anorthosite, gabbro and jotunite. We analysed multiple core samples collected across nine separate granulite-eclogite transition zones located at veins in anorthositic, jotunitic and gabbroic protoliths for major and trace elements. For each transition, no compositional difference between the average granulite and average eclogite composition was found at the 90% confidence level except for LOI (loss on ignition), which was consistently significantly higher in the eclogite samples. Although not significant at the 90% confidence level for any single traverse, the average eclogite concentrations of SiO₂ , Na₂O, Cs, As and Br exceed the average granulite concentrations for eight or all nine of the traverses. For most traverses, statistical analysis of the data limits any gain of SiO₂ in the eclogites to no more than a few relative per cent. Other than the introduction of volatile substances, presumably an H₂O-rich fluid, eclogitization associated with vein formation was essentially isochemical.  相似文献