Bicarbonate estimation from alkalinity determinations for neutral to acidic low alkalinity natural waters: theoretical considerations     

COLIN NEAL 《水文科学杂志》2013,58(6):619-623

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Low-pressure Granulites of the Lisov Massif, Southern Bohemia: Visean Metamorphism of Late Devonian Plutonic Arc Rocks     

JANOUSEK  VOJTECH; GERDES  AXEL; VRANA  STANISLAV; FINGER  FRITZ; ERBAN  VOJTECH; FRIEDL  GERTRUDE; BRAITHWAITE  COLIN J. R. 《Journal of Petrology》2006,47(4):705-744

The Liov Granulite Massif differs from neighbouring granulitebodies in the Moldanubian Zone of southern Bohemia (Czech Republic)in including a higher proportion of intermediate–maficand orthopyroxene-bearing rocks, associated with spinel peridotitesbut lacking eclogites. In addition to dominantly felsic garnetgranulites, other major rock types include quartz dioritic two-pyroxenegranulites, tonalitic granulites and charnockites. Minor bodiesof high-pressure layered gabbroic garnet granulites and spinelperidotites represent tectonically incorporated foreign elements.The protoliths of the mafic–intermediate granulites (quartz-dioriticand tonalitic) crystallized 360–370 Ma ago, as indicatedby laser ablation inductively coupled plasma mass spectrometryU–Pb ages of abundant zircons with well-preserved magmaticzoning. Strongly metamorphically recrystallized zircons giveages of 330–340 Ma, similar to those of other Moldanubiangranulites. For the overwhelming majority of the Liov granulitespeak metamorphic conditions probably did not exceed 800–900°Cat 4–5 kbar; the equilibration temperature of the pyroxenegranulites was 670–770°C. This is in sharp contrastto conditions of adjacent contemporaneous Moldanubian granulites,which are characterized by a distinct HP–HT signature.The mafic–intermediate Liov granulites are thought tohave originated during Viséan metamorphic overprintingof metaluminous, medium-K calc-alkaline plutonic rocks thatformed the mid-crustal root of a Late Devonian magmatic arc.The protolith resembled contemporaneous calc-alkaline intrusionsin the European Variscan Belt. KEY WORDS: low-pressure granulites; geothermobarometry; laser-ablation ICP-MS zircon dating; whole-rock geochemistry; Sr–Nd isotopes; Moldanubian Zone  相似文献   

The surface geometry of the Last Glacial Maximum ice sheet in the Andøya-Skånland region, northern Norway, constrained by surface exposure dating and clay mineralogy     

ATLE NESJE  SVEIN OLAF DAHL  HENRIETTE LINGE  COLIN K. BALLANTYNE  DANNY MCCARROLL  EDWARD J. BROOK  GRANT M. RAISBECK  FRANCOISE YIOU 《Boreas: An International Journal of Quaternary Research》2007,36(3):227-239

Blockfields, weathering boundaries and marginal moraines have been mapped along a longitudinal transect from northern Andøya to Skånland in northern Norway. The degree of rock-surface weathering above and below glacial trimlines, clay-mineral assemblages and surface exposure dating based on in situ cosmogenic ¹⁰Be have been used to reconstruct the vertical dimensions and timing of the Last Glacial Maximum (LGM) of the Scandinavian Ice Sheet in this region. The cosmogenic exposure dates suggest that the lower blockfield boundary/trimline along the Andøya-Skånland transect represents the upper limit of the Late Weichselian ice sheet, with an average surface gradient of c . 9.5 m/km. The surface exposure dates from Andøya pre-date the LGM, suggesting that the LGM ice sheet did not reach mountain plateaux at northwest Andøya. The results thus support evidence from lake sediment records that the northern tip of Andøya was not covered by the Scandinavian Ice Sheet during the LGM.  相似文献   

Transnational development networks: bringing development and postcolonial approaches into dialogue   总被引：2，自引：0，他引：2  

COLIN MCFARLANE 《The Geographical journal》2006,172(1):35-49

This paper explores some of the ways in which a dialogue between development and postcolonial scholarship might contribute to the theorizing of transnational networks in contemporary development. It does so through consideration of three inter-related themes: epistemologies, spatialities and ethico-politics. The discussion of epistemologies points to the potential benefit in reworking the analysis of the relationship between structure and agency in networks, whereas the discussion of spatialities focuses attention on the interface between the global and the local. Dialogue between development and postcolonial approaches also creates space for considering the politics and ethics of transnational development networks. In particular, this discussion prompts challenges around how to ethically research subaltern knowledge in transnational development networks, including how to trace the translation and redeployment of subaltern knowledge through networks. Consideration of these themes highlights not just overlaps and disjunctures between development and postcolonial approaches, but opportunities for further dialogue and future research on transnational development networks. To illustrate the points made in the paper, examples are drawn from Slum/Shack Dwellers International (SDI), a transnational network of civil society organizations working with urban poverty.  相似文献   

Late Quaternary glaciation and environmental change on St. Kilda, Scotland, and their palaeoclimatic significance   总被引：1，自引：0，他引：1  

DONALD G. SUTHERLAND  COLIN K. BALLANTYNE  MICHAEL J. C. WALKER 《Boreas: An International Journal of Quaternary Research》1984,13(3):261-272

On Hirta, the largest island of the St. Kilda archipelago near the western edge of the Scottish continental shelf, evidence has been found for four cold periods and one intervening mild period. During the most recent cold period (the Loch Lomond Stadial), two protalus ramparts were formed. Prior to this there occurred two periods of valley glaciation separated by a mild interval during which the local vegetation was dominated by grasses and sedges. For the most recent valley glaciation (= Late Devensian glacial maximum) a mean July temperature of 4°C is inferred. At this time intensive periglacial processes were operative down to present sea level. At some earlier, pre-Dcvensian, time St. Kilda was invaded by the Scottish ice sheet.  相似文献   

Petrology of Anorthite-bearing Gabbroic Anorthosite Dykes in northwest Skye     

DONALDSON  COLIN H. 《Journal of Petrology》1977,18(4):595-620

A group of gabbroic anorthosite dykes in northwest Skye containsmegacrysts of calcic plagioclase (An_93–87) and olivine(FO_87–78.5and plagioclase-rich xenoliths set in a matrixof low-alkali, high Ca olivine tholeiite. Field, mineralogicand petrochemical evidence indicates (1) that the dykes arefilled with crystals concentrated from magmas feeding lava flowsand (2) that, although the megacrysts crystallized from low-alkali,high Ca olivine tholeiite magmas at depths <4 km, the megacrystsand the matrix in each dyke are not cognate. The emplacementtemperature was less than 1230 °C. Low-alkali, high Ca olivinetholeiite is an abundant Hebridean magma type, resembling unfractionatedoceanic tholeiites from the Atlantic. The temporal change fromalkali olivine basalt to low-alkali, high Ca olivine tholeiitein the Hebridean proto-spreading centre may mimic compositionalchanges during initial development of the mid-Atlantic ridge.  相似文献   

MODELLING THE SENSITIVITY OF CHANNEL ADJUSTMENTS IN DESTABILIZED SAND-BED RIVERS     

STEPHEN E. DARBY  COLIN R. THORNE 《地球表面变化过程与地形》1996,21(12):1109-1125

Comprehensive empirical data of the response of unstable streams over a range of environmental conditions are unavailable. In this study, as a substitute for empirical data, a physically based numerical model of channel evolution is used in a range of numerical simulation experiments designed to predict the sensitivity of channel response to changes in control variables. The scope of the study is limited by the scope of the numerical model which applies to straight, sand-bed streams with cohesive bank materials that have been destabilized by sediment starvation and evolve towards equilibrium through bed degradation followed by channel widening. Results are presented for stable and unstable channel conditions. Stable channel depths are most sensitive to channel discharge, though the critical threshold shear stress for the entrainment of cohesive bank materials and discharge are both significant in determining the width. The sediment load, channel gradient, bank material cohesion, size of failed bank material aggregates and the initial bank height have sensitivities an order of magnitude smaller than discharge for both width and depth. Variations in bed material characteristics within the sand-size range are found to have little impact on simulated stable channel morphology. For unstable channels, the relative dominance of parameter sensitivities is examined in the context of an empirical-conceptual model of channel evolution proposed by Thorne and Osman (1988), to highlight the relationships between parameter dominance, time, and the processes and forms characterizing individual stages of channel evolution. Rates of change with time of width and depth sensitivity parameters for five tested independent variables (discharge, sediment supply, channel gradient, bank material cohesion and bed material size) are found to vary as a function of time, such that different stages of channel evolution are characterized by variations in the relative dominance of tested variables. The results support the hypothesis proposed by Thorne and Osman (1988) that the critical bank height required to initiate mass-wasting and widening may be regarded as a geomorphic threshold.  相似文献   

Cold climate landforms     

COLIN K. BALLANTYNE 《第四纪科学杂志》1996,11(2):168-169

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The local geologist 12: The roadshow     

COLIN G. R. REID 《Geology Today》1993,9(4):147-153

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Modelling Diverse Processes in the Petrogenesis of a Composite Batholith: the Central Bohemian Pluton, Central European Hercynides   总被引：6，自引：1，他引：5  

JANOUSEK  VOJTECH; BOWES  D. R.; ROGERS  GRAEME; FARROW  COLIN M.; JELINEK  EMIL 《Journal of Petrology》2000,41(4):511-543

The multiple intrusions making up the Central Bohemian Plutonin the Central European Hercynides have petrographic and geochemicalfeatures consistent with the presence of four main granitoidsuites. Major-element, trace-element and Sr–Nd isotopiccompositions are used to model their petrogenesis. Partial meltingof metabasic rocks or of a CHUR-like mantle source are interpretedto have produced melts parental to the most primitive calc-alkalineSázava suite. Interaction of basic with more acidic magmasfollowed by extensive amphibole–plagioclase-dominatedfractionation accounts for the production of trondhjemites.Alternatively, the trondhjemites correspond to small-degreemelts of a metabasic source. AFC (assimilation–fractionalcrystallization) modelling with a paragneiss as a contaminantand increasing D_Nd values simulates the characteristics of theBlatná suite. Closed-system fractionation of stronglyenriched mantle-derived magmas or their interaction with leucograniticmelts is deduced for the petrogenesis of the shoshonitic  相似文献