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1.
Daniel Hammett 《Geoforum》2012,43(5):937-947
South African human geographers have been largely silent in debates about Anglo-American disciplinary hegemony, hierarchies of knowledge, ir/relevance and myriad other debates about the academy and geographical knowledge. This paper offers a critical reflection on current tendencies within South African human geography towards parochialism, empiricism and disconnection from the international academy. Pointing to these developments as being rooted within the local geographical tradition, a call is made for greater critical self-reflection in order to re-engage international debates and advance local transformation. The tendency to bemoan the dominance of Anglo-American journals and academics, as well as contextual systematic constraints, is noted and established scholars gently chastised for failing to move beyond complaints towards measures that offer a way forward in these debates. 相似文献
2.
This paper describes the occurrence of dolomite and the mechanism of dolomitization of the Upper Triassic-Lower Jurassic K?z?loren Formation in the autochthonous Bolkardag? unit of the middle Taurus Mountains in south western Turkey. Dolomites were analyzed for geochemical, isotopic and crystallographic variation. Dolomites occur as a replacement of precursor carbonate and cement. The dolomite crystals range from <10 to ~1000 μm existing as both replacements and cements. Sr concentrations range between 84 and 156 ppm, and the molar Sr/Ca ratios of dolomitizing fluids are estimated to range between 0.0066 to 0.013 ratios. Dolomites are Ca-rich (with average CaCO3 and MgCO3 equal to 56.43 and 43.57 mol%, respectively) and they are non-stoichiometric, with an average Sr=116 ppm, Na=286 ppm, Mn=81 ppm, Fe=1329 ppm, and δ18O and δ13C ranges from –0.6‰ to –6.1‰ Pee Dee Belemnite [PDB], and +1.2 to +3.9‰ PDB. The North American Shale Composition [NASC]-normalized rare earth element (REE) values of the both limestone and dolomite sample groups show very similar REE patterns characterized by small positive Eu (mean=1.32 and mean=1.42, respectively) and slightly or considerably negative Ce (mean=0.61 and mean=0.72, respectively) anomalies and a clear depletion in all REE species. The K?z?loren Formation dolomites have been formed as early diagenetic from mixing zone fluids at the tidal-subtidal environment and at the late diagenetic from basinal brines at the shallow-deep burial depths. 相似文献
3.
Ali Bahad?r Yavuz 《Environmental Earth Sciences》2012,67(7):1909-1925
Ala?at? tuff has been used extensively as a source of building stone for outdoor and indoor decorations since the historical times in and around the tourist town of Ala?at? (western Turkey). The use of the Alacati tuff in buildings has been made compulsory by the Ala?at? municipality, for preserving the historical appearance of the buildings, after 2005 in Ala?at?. It has been noticed that, evident deteriorations developed in tuff surfaces of the stone buildings and garden walls within 5?C6?years of their emplacement. Durability properties of the Ala?at? tuff are evaluated by determining the mineralogical, chemical, and physico-mechanical properties of the fresh tuff samples obtained from the only operative quarry in the area. Ageing tests such as Na2SO4 and MgSO4 salt crystallization, freezing?Cthawing, and wetting?Cdrying were conducted on the fresh tuff samples to assess their durability. Additionally, the durability of the tuff is also evaluated by determining its average pore diameter, saturation coefficient, wet-to-dry strength ratio, static rock and slake-durability indices. Fresh Ala?at? tuff has high porosity and low unit weight and strengths and are classified to be very poor to moderately durable stone based on the test results of different durability assessment methods. Mineralogical and geochemical analyses have also been carried out on the deteriorated tuff samples collected from the surfaces of the stone buildings to determine the effect of weathering on tuff and the test results have been compared with those of the fresh tuff samples. There is no major difference observed between the mineralogy and chemistry of the fresh and weathered tuff samples thus, it has been concluded that physical weathering has been dominant in the area in deterioration of tuff. 相似文献
4.
《Geoforum》2017
In this article, we draw upon ongoing research in periurban Gurugram (formerly Gurgaon) in North–West India on the institutional dynamics around and conflicts over wastewater. Prevailing approaches to analysis of conflicts over natural resources pay scant attention to the role of the nature of the resource per se in shaping the possibilities of conflicts. Further, conflict researchers should pay attention to the difference between conflicts of interest and conflicts. In doing so, they should analyse the role of local norms that may prevent conflicts of interest from erupting into conflicts, while pushing people into situations of forced cooperation. 相似文献
5.
沿长江顺流而下,可以看到千山万谷,汹涌澎湃的三峡,也可以看到九曲回肠的荆江和潮平岸阔的江苏江段。在宜昌南津关,“山随平野尽,江入大荒流”(李白《渡荆门送别诗》)。长江就在这里由山区进入平原。一般说来,天然河流都可象长江一样,分为山区和平原两段。山区河流是水流改造山谷的产物。地壳运动,增加了河床演变的复杂性。山区河流具有下列特点:(1)河床纵比降大;(2)水流湍急紊乱;(3)山谷沿程宽窄不一,河道在平面上具有藕节状外形; 相似文献
6.
971349 Che;19 Jie(China Universityseienees,Beijing)The MammaljanShowjng ClimatieF盆uetuat应on—ExamPle of the Early Pleistoceneof Ge。FaunaS AS anMam-malian Faunas from Zhoukoudian,Beijing,China(ESI矛,ISSN 1 005一2321,CN 11一3370/P,4(2),1997,p·275一279,1 graph,1 table,10 ref) By analyses of the four local marnmalianfaunas from Zhoukoudian,Beijing,the EarlyPleistoeene elimatie and eeologieal environ-CN 11一1 905/Q1 53,1 graph,1735(2).1997,P.145一mental ehangespaper.One of1 .90M… 相似文献
7.
自然河流或者处于单向演变状态,或者处于准平衡状态。这是按平均概念而言。实际河床演变就是围绕这种均衡状态或正或负地交替进行。河流一旦受到外力干扰,均衡状态被破坏之后,河床演变过程也将随之改变。有的干扰、改变甚至破坏会很强烈。这种演变开始时都比较急剧,然后逐渐衰减,最终达到新的均衡状态。干扰河床演变均衡状态的途径有二:(1)改变河道的来水来沙条件。如河段以上的水土保持工程、拦沙工程、水库枢纽工程、分流堵汊工程和引水工程等的作用。它们增减水量、沙量,改变水流过程和输沙过程以及水沙搭配关系等。(2)改变河段河床形 相似文献
8.
The Guole biota contains common shelly fossils and some exceptionally well-preserved soft-bodied fossils. Stratigraphically, it is located in the mudstones and siltstones of the Sandu Formation near Guole Town, Jingxi County, Guangxi, South China. It is the first Furongian (late Cambrian) Burgess Shale-type biota found in the world, thereby filling the gap between middle Cambrian and Lower Ordovician Burgess Shale-type Lagerst?tten. Preliminary studies suggest that the Guole biota includes approximately seven metazoan groups as well as algae. These will provide important new evolutionary and ecological information. 相似文献
9.
In contrast to Solnhofen-type conservation Lagerstätten, the platy limestones of the Benkovac Stone of the Eocene of Croatia contains a variety of trace fossils. They belong to the Nereites ichnofacies, characterized by a suite of highly specialized ichnogenera, turbiditic preservation, and distinctive pre-event versus post-event communities. In siliciclastic rocks, this ichnofacies stands for turbiditic deep-sea sediments. Also unusual is the lack of body fossils. The only exceptions are occasional plant debris and Bencovacina concentrica. n. gen., n. sp., which is affiliated with xenophyophorian Foraminifera. These giant protozoans survive on present deep-sea bottoms, but they were also common on the shallow-marine biomats in Ediacaran times. These findings contradict the current shallow-marine interpretation, which is based on the regional geologic setting and sedimentary structures typical for tempestites. Thus, the Benkovac Stone would be an ideal place to test the reliability of ichnological versus sedimentological depth criteria in an entirely calcareous sequence. 相似文献
10.
11.
The Lower Cretaceous volcanic formations of Copiapó (Chile) host major stratiform, disseminated, vein, and stockwork mineral
deposits. Among these are the Punta del Cobre district (Cu-Fe) and the neighbouring, large Candelaria deposit (Cu-Fe-Au).
These deposits are likely to have formed during a major extensional event that was accompanied by granitoid emplacement that
triggered important contact metamorphism, metasomatic activity and mineralization processes. We suggest here that alteration-mineralization
processes developed within the upper-plate domain of a NNE-trending, ESE-dipping extensional system, while granitoids were
accomodated within the lower-plate. If this model prove to be right, `Candelaria-type' deposits may be hidden beneath the
present, higher structural position of the Punta del Cobre district.
Received: 13 May 1999 / Accepted: 2 August 1999 相似文献
12.
这是国际构造学委员会Lev Zonenshain写给国际构造委员会秘书Paul Hancock的一封信,提出“构造学向何处去?”这一重大问题,信中包合构造学领域一系列重大前沿课题,内涵深远.Paul Hancock将该信转发给各位委员征求意见.一贯关怀并寄于厚望于本刊的我校名誉教授马杏垣将Lev Zonenshai和Paul Hancock的两封信寄交本刊,现全文译出以飨读者. 相似文献
13.
The Late Cretaceous ükapili Granitoid including mafic microgranular enclaves intruded into metapelitic and metabasic rocks, and overlain unconformably by Neogene ignimbrites in the Ni de area of Turkey. It is mostly granite and minor granodiorite in composition, whereas its enclaves are dominantly gabbro with a few diorites in composition. The ükapili Granitoid is composed mainly of quartz, K-feldspar, plagioclase, biotite, muscovite and minor amphibole while its enclaves contain mostly plagioclase, amphibole, minor pyroxene and biotite. The ükapili Granitoid has calcalkaline and peraluminous (A/CNK= 1.0-1.3) geochemical characteristics. It is characterized by high LILE/HFSE and LREE/HREE ratios ((La/Lu) N = 3-33), and has negative Ba, Ta, Nb and Eu anomalies, resembling those of collision granitoids. The ükapili Granitoid has relatively high 87Sr/86Sr (i) ratios (0.711189-0.716061) and low εNd (t) values (-5.13 to -7.13), confirming crustal melting. In contrast, the enclaves are tholeiitic and metaluminous, and slightly enriched in LILEs (K, Rb) and Th, and have negative Ta, Nb and Ti anomalies; propose that they were derived from a subduction-modified mantle source. Based on mineral and whole rock chemistry data, the ükapili granitoid is H-(hybrid) type, post-collision granitoid developed by mixing/mingling processes between crustal melts and mantle-derived mafic magmas. 相似文献
14.
In this study uranium and thorium contents and depositional characteristics of ay rhan bituminous shales（ BS）, west of Ankara（central Anatolia）, are investigated. Samples used were collected from boreholes opened by Park Holding Ltd. A total of 25 samples were taken from bituminous shale levels in boreholes drilled at 6 different locations in the study area. The H rka formation which hosts bituminous shale deposits is a volcanosedimentary sequence and all lithofacies indicate that a lacustrine environment where the water level was continuously changed. In addition to hydrocarbon generation potential, bituminous shales also accumulate significant amount of radioactive elements such as uranium and thorium. The average uranium and thorium concentrations of BS（1.83/2.62 ppm） are much lower than averages of UC, NASK and PAAS（uranium： 2.70/2.66/3.10 ppm; thorium： 8.50/12.30/14.60 ppm）. Low uranium contents in comparison to those of similar lacustrine environments might be attributed to that waters of depositional environment of BS contain low concentration of dissolved uranium and redox conditions were of oxic and dioxic character. Correlation data indicate that U and Th have a similar source and are associated predominantly with clays and phosphates and dominantly with organic material. Radioactive elements in the basin might be derived from Paleozoic granites and metamorphites（e.g. gneiss, schist） which comprise the basement and volcanism which was active in the region throughout the Miocene period. These elements are probably associated with uraniferous phosphate minerals（e.g. autunite, torbernite） which occur in granite, gneiss and schist. BS with average TOC content of 10.96 % shows very good/perfect source rock potential. Positive correlations between Gamma-Ray values and U, Th and K concentrations imply that radioactivity might be originated from these three elements. 相似文献
15.
Predicting rainfall-induced landslides hinges on the quality of the rainfall product. Satellite rainfall estimates or rainfall reanalyses aid in studying landslide occurrences especially in ungauged areas, or in the absence of ground-based rainfall radars. Quality of these rainfall estimates is critical; hence, they are commonly crosschecked with their ground-based counterparts. Beyond their temporal precision compared to ground-based observations, we investigate whether these rainfall estimates are adequate for hindcasting landslides, which particularly requires accurate representation of spatial variability of rainfall. We developed a logistic regression model to hindcast rainfall-induced landslides in two sites in Japan. The model contains only a few topographic and geologic predictors to leave room for different rainfall products to improve the model as additional predictors. By changing the input rainfall product, we compared GPM IMERG and ERA5 rainfall estimates with ground radar–based rainfall data. Our findings emphasize that there is a lot of room for improvement of spatiotemporal prediction of landslides, as shown by a strong performance increase of the models with the benchmark radar data attaining 95% diagnostic performance accuracy. Yet, this improvement is not met by global rainfall products which still face challenges in reliably capturing spatiotemporal patterns of precipitation events.
相似文献16.
Peter Adamu Shivee Ranjanee Kaliappan Abdalla Sirag Ruth John Chenbap 《GeoJournal》2017,82(2):369-377
This study investigates the convergence of well-being between Sub Saharan Africa (SSA) and Organization for Economic Cooperation and Development (OECD) member countries during the period 1980–2014. The gap in living standard was examined from a steady state represented by the average income of OECD countries. Applying the unit root estimation technique to test for convergence with and without structural breaks, the result shows that; among a total of 43 countries studied, about 14 % are converging towards the average of OECD average. When the shock caused by the economic crisis of 2008 was factored into the analysis, the gains of about five countries out of the six converging disappeared. These results are disturbing owing to the fact that countries in the Asian region that started almost at the same level with SSA have converged to form a convergence club. Therefore, a lot more effort is needed from the government and stake holders in most countries in SSA to improve on the determinants of growth like good health care, quality institutions, better education and commitments to pursue developmental programmes which will boost the income of an average African to acquire better life. 相似文献
17.
Djamal Akziz Mostefa Guendouz Mohamed Said Guettouche Tahar Khelil 《Arabian Journal of Geosciences》2018,11(6):121
At the western Sahel of Algiers, the watercourse of the Mazafran river is perpendicular to the Sahel fold, forming a gorge that has developed in a tectono-eustatic context characteristic of the Sahel region. This gorge has formed in a regime of superimposition which involves the evolution of antecedence in relation to the Sahel uplift. This deduction is the result of multiple analyses that are based on a stratigraphic study which characterizes the succession of continental and marine deposits and the analyses of lineament map of tectonic evolution during the Quaternary which is marked by the Sahel folding. In order to correlate the chronology between the fluvial and marine sedimentary dynamics, a geomorphological study of the Mazafran alluvial terraces associated with the paleoshorelines was realized. The obtained results reveal that the development of the Mazafran river gorge is complex. 相似文献
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19.
Prokopyev Ilya R. Doroshkevich Anna G. Redina Anna A. Obukhov Andrey V. 《Mineralogy and Petrology》2018,112(2):257-266
Mineralogy and Petrology - The Ust-Chulman apatite ore body is situated within the Nimnyrskaya apatite zone at the Aldan shield in Russia. The latest data confirm the carbonatitic origin of the... 相似文献