Discourses of regeneration in early twentieth-century Britain: from Bedlam to the Imperial War Museum

This article calls for greater attention to be paid to the way that sex and sexuality impact on geographical fieldwork. By concentrating in particular on cross–cultural fieldwork, the article focuses on the ways in which attention to these questions has the potential to bring about greater self–reflexivity and to expose the contingency of the researcher's sexuality.     

Bamus volcano,Papua New Guinea: Dormant neighbour of Ulawun,and magnesian-andesite locality

Bamus and Ulawun are more than 400 m higher than all other major composite volcanoes in the 1000-km-long Bismarck volcanic arc. The two cones are immediately adjacent to each other and have partly coalesced. This close proximity, their similarity of form, and their positions over the same depths (70–160 km) to the New Britain Benioff zone, could be indications that Bamus and Ulawun have had related, or at least similar, eruptive histories. But there are important differences between the two volcanoes. Bamus is thought to have last erupted some time between 1878 and 1894, whereas Ulawun has erupted at least 17 times since the late nineteenth century. In addition, the rocks of Bamus are distinctly different from those of Ulawun. Mafic rocks are found in the older part of Bamus (including a boninite-like, or magnesian-andesite, lava flow), and the younger rocks of Bamus are low-MgO andesites (the most recent products have the highest SiO₂ contents of all the analysed rock samples). In contrast, Ulawun appears to be a uniform pile of basalts and some andesites that have consistently lower amounts of CaO and Zr compared to Bamus rocks. Ulawun basalts are unlikely to represent the parental magmas from which Bamus andesites were derived by simple crystal fractionation, judging by the results of least-squares mixing calculations and the relatively high Zr contents of the Bamus andesites. The magmatic histories of Bamus and Ulawun appear to be unrelated, but because both volcanoes are the highest of all volcanoes in the Bismarck volcanic arc, both may now be susceptible to large-scale gravitational slumping or cauldron subsidence. North- and east-trending lineaments and escarpments on both volcanoes may represent the tectonically controlled scars of former gravitational collapses. Ulawun, in particular, may be at a critical stage because of its great height and steep slopes, and because eruptions in 1978 took place from a new, east-trending (possibly tectonically controlled) fissure low on the eastern flank of the volcano.

---

Zusammenfassung Bamus und Ulawun überragen mit mehr als 400 m alle anderen Hauptvulkane im 1000 km langen Bismarck-Vulkanbogen. Beide Kegel liegen sich unmittelbar gegenüber und sind teilweise miteinander verbunden. Die enge Nachbarschaft, die Ähnlichkeit in der Morphologie und die gleiche Entfernung (70–160 km) von der New Britain Benioff-Zone können Anzeichen dafür sein, daß Bamus und Ulawun in Beziehung miteinanderstehen oder letztendlich die gleiche eruptive Geschichte haben. Aber es gibt wichtige Unterschiede zwischen beiden Vulkanen. Man nimmt an, daß Bamus zum letzten Mal zwischen 1878 und 1894 ausgebrochen ist, im Gegensatz dazu brach Ulawun 17 mal im späten neunzehnten Jahrhundert aus. Darüber hinaus sind die Gesteine von Bamus deutlich unterschieden von denen Ulawuns. Mafische Gesteine findet man im älteren Teil von Bamus (einschließlich eines Boninit-ähnlichen Gesteins oder magnesiumreiche Andesite und Lavaausflüsse). Die jüngeren Gesteine von Bamus sind magnesiumarme Andesite (die meisten der jüngsten Produkte haben die höchsten SiO₂-Gehalte aller analysierten Gesteinsproben). Im Gegensatz dazu scheint Ulawun eine einheitliche Anhäufung von Basalten und einigen Andesiten zu sein, diese haben durchgehend geringere Gehalte an CaO und Zr verglichen mit den Bamus-Gesteinen. Es gilt als unwahrscheinlich, daß Ulawun-Basalte ursprünglich Magma repräsentieren, von dem die Bamus-Andesite durch einfache Kristallfraktionierung stammen, bei der Beurteilung der Ergebnisse von least squares Mischungsberechnungen und den relativ hohen Zr-Gehalten der Bamus-Andesite. Die magmatische Geschichte von Bamus und Ulawun scheint beziehungslos, aber da beide Vulkane die höchsten im Bismarck-Vulkanbogen sind, mögen beide für einen weiträumigen gravitativen Kollaps oder für ein calderaartiges Einsinken empfänglich sein. Nord- und ostverlaufende Lineamente und Steilhänge an beiden Vulkanen können tektonisch kontrollierte Merkmale früherer gravitativer Zusammenbrüche sein. Besonders Ulawun könnte in einem kritischen Stadium sein wegen seiner Höhe und seiner steilen Hänge, und aufgrund jener Ausbrüche, die 1978 von einer neuen ostverlaufenden (möglicherweise tektonisch kontrolliert) Kluft tief an der östlichen Flanke des Vulkans stattfanden.

---

Résumé Les monts Bamus et Ulawun s'élèvent à plus de 400 m d'altitude au-dessus de tous les autres volcans importants composites de l'archipel volcanique de Bismarck, qui s'étend sur plus de 1000 km en long. Les deux cônes sont contigus et en partie se confondent. Leur contiguité, leur conformation semblable et leur position à l'aplomb de la même profondeur (70–160 km) de la zone de Benioff de la Nouvelle-Bretagne pourraient indiquer que le Bamus et l'Ulawun ont eu une histoire éruptive apparentée ou au moins semblable. Mais il existe des differences importantes entre les deux volcans. On croit que la dernière éruption du Bamus a eu lieu entre 1878 et 1894, tandis que l'Ulawun a fait éruption au moins 17 fois depuis les dernières années du 19ème siècle. De plus, les roches du Bamus sont de composition nettement differénte de celles de l'Ulawun. On trouve des roches mafiques dans la partie plus ancienne du Bamus (y compris une coulée volcanique qui ressemble à une boninite ou andésite magnésienne) et les roches les plus récents du Bamus sont des andésites à faible teneur en MgO (les produits les plus récents contiennent plus de SiO₂ que tous les échantillons jusqu'ici analysés). Par contre, l'Ulawun parait être un amas uniforme de basaltes avec quelques andésites qui contiennent regulièrement moins de CaO et de Zr en comparaison avec les roches du Bamus. Il est peu probable que les basaltes de l'Ulawun représentent les magma-mères d'ôu proviennent les andésites du Bamus par une simple cristallisation fractionnée, à en juger par les calculs du mélange des «moindres carrés» et la quantité relativement élevée de Zr dans les andésites du Bamus. Il n'y a apparemment aucun lien de parenté entre les histoires du magmatisme du Bamus et de l'Ulawun; mais étant donné qu'ils sont les deux volcans les plus hauts de l'archipel volcanique Bismarck, il est possible qu'ils soient maintenant susceptibles d'effondrements par gravité de grande dimension ou de subsidences en caldera. Les linéaments et les escarpements qui s'étendent vers le nord et l'est des deux volcans représentent peut-être les sutures contrôlées par la tectonique d'anciens effondrements par gravité. Surtout l'Ulawun a peut-être atteint une phase critique à cause de sa hauteur et de ses pentes raides, et parce que l'éruption de 1978 dans le flanc inférieur du volcan est sortie d'une fissure en direction de l'est (peut-être sous une influence tectonique).

---

Bamus Ulawun , 400 , , 1000 . . , (70– 160) , , , , , . . , Bamus 1878 1894 , a Ulawun 17 19- . Ulawun'a. — , — Bamus. — ; . Ulawun, , , , , . , , Ulawun , Bamus . , , , , . . , , , , . , , . , . , 1978 , .

     

Laboratory simulation of salt weathering processes in arid environments

The equipment and techniques being used at Bedford College, London to simulate salt weathering processes in deserts are described in the context of a general discussion of the nature of salt weathering processes and approaches to studying them. An experiment based on the equipment and techniques is described: it is designed to test the durability of three building stones in the presence of several different saline solutions under conditions of surface temperature and relative humidity that are considered typical of hot deserts. The experiment, the first of a series, shows that Na₂SO₄ is the most effective of the salts used, and that susceptibility of the rocks to weathering is related to such rock properties as porosity, microporosity and water absorption capacity.     

Iron oxide from a seasonally anoxic lake

The ferric oxide formed by oxidation of Fe(II) in Esthwaite Water, U.K., during the lake's seasonal thermal stratification and deep-water anoxia consists of amorphous particles which are approximately spherical or ellipsoidal, with diameters in the range 0.05–0.5 μm. Concentrations in the lake are 10¹¹–10¹² particles per litre, corresponding to 3 mg l^?1 Fe. Unlike iron oxides of similar chemical composition formed by oxidative mechanisms in soil-borne waters, the particles do not appear to be composed of small primary particles. This is possibly because in the lake they form slowly, at low supersaturation. The particles contain 30–40% by weight Fe. The carbon content is uncertain because of contamination but is in the range 4–18%. Humic carbon contributes at least 4–7% of the total weight. Other major elements present are P, N, Mn, Si, S. Ca and Mg, comprising between them up to 8% of the total weight.The particles are negatively charged probably because of adsorbed humic substances, and also phosphate and silicate. Their electrophoretic mobility-pH dependence is similar to those of synthetic iron oxides added to samples of surface Esthwaite Water. The calculated zeta potential is ? 27 mV, which is sufficiently high to make flocculation slow under lake conditions. The low flocculation rate partially accounts for the formation of a well-defined peak of particulate iron in the water column of the lake.     

Laboratory simulation of rock weathering by salt crystallization and hydration processes in hot,arid environments

The results of a series of experiments are reported in this paper which were designed to differentiate between the forces of crystal growth and hydration in salt weathering, using a single salt-hydrate system (sodium sulphate), five contrasting rock types, and several diurnal temperature-relative humidity cycles which permitted or inhibited these processes and simulated ground surface climates in hot, arid environments. It was shown that hydration of sodium sulphate is an effective mechanism of rock disintegration but that it is significantly less destructive than crystal growth pressure. Crystallization of thenardite (Na₂SO₄) is, in turn, more effective in rock weathering than the crystal growth of mirabilite (Na₂SO₄.10H₂O). In general, rates of disintegration were most rapid where the diurnal temperature range was extreme and relative humidity lowest.     

Pleistocene chronology: Long or short?

European geologists, in general, have tended to favor a “short” chronology for the glacial Pleistocene, with four major glacial cycles in the past 500,000 or 600,000 yr. Interpretation of ocean floor sediments by Emiliani and others has accorded with this view, in contrast to the “long” chronology of Ericson and Wollin and their followers, who spread the four North American glacial episodes over a 2-m.y. period. An examination of the available radiometric dates and age estimates from paleomagnetic polarity zones serves to confirm Richmond's view that the four major European glacials do not equate with the four North American glacials in a simple one-to-one manner, but that the Illinoian matches the Elster (Mindel) rather than the Saale (Riss). The Alpine Günz is then equated broadly with the Kansan and overlaps in time with the Jaramillo normal polarity event at about 900,000 y.a. The Nebraskan is older than 1.2 m.y. and is thus coeval with the European Upper Villafranchian, within which the Donau and Biber glacial events may be traced. Montane glaciation certainly extended back into the Tertiary but cold pulses of sufficient duration to produce continental glaciation were more marked through the past 1.5 m.y. More critical studies of the terrestrial record are needed before firm correlations can be made.     

Multimillion year thermal history of a porphyry copper deposit: application of U–Pb, 40Ar/39Ar and (U–Th)/He chronometers, Bajo de la Alumbrera copper–gold deposit, Argentina

Application of multiple chronometers (including U–Pb and ⁴⁰Ar/³⁹Ar geochronology and zircon and apatite (U–Th)/He thermochronology) to porphyry intrusions at the Bajo de la Alumbrera porphyry copper–gold deposit, Argentina, reveals a complex history of reheating that spans millions of years. Previous U–Pb geochronology, combined with our new ⁴⁰Ar/³⁹Ar data, shows that the multiple porphyritic intrusions at Bajo de la Alumbrera were emplaced during two episodes, the first at about 8.0 Ma (P2 and associated porphyries) and the second about a million years later (Early and Late P3 porphyries). Complex overprinting alteration events have obscured the earliest hydrothermal history of the deposit. By contrast, ⁴⁰Ar/³⁹Ar data reveal the close temporal relationship of ore-bearing potassic alteration assemblages (7.12 ± 0.13 Ma; biotite) to the emplacement of the P3 intrusions. Consistent with low closure temperatures, younger ages have been determined for associated hydrothermal alkali feldspar (6.82 ± 0.05 Ma and 6.64 ± 0.09 Ma). The temperature-sensitive Ar data also record an unexpected prolonged cooling history (to below 200°C) extending to 5.9 Ma. Our data suggest that the Bajo de la Alumbrera system underwent protracted cooling, after the collapse of the main hydrothermal system, or that one or more low-temperature (~100–200°C) reheating events occurred after emplacement of the porphyritic intrusions at Bajo de la Alumbrera. These have been constrained in part by our new ⁴⁰Ar/³⁹Ar data (including multidomain diffusion modeling) and (U–Th)/He ages. Single-grain (U–Th)/He ages (n = 5) for phenocrystic zircon from P2 and P3 intrusive phases bracket these thermal events to between 6.9 (youngest crystallization of intrusion) and 5.1 Ma. Multidomain modeling of alkali feldspar data (from both igneous and hydrothermal crystals) is consistent with the deposit cooling rapidly from magmatic temperatures to below about 300°C, with a more protracted history down to 150°C. We conclude that the late-stage low-temperature (150 to 200°C) thermal anomaly localized at Bajo de la Alumbrera resulted from radiation of heat and/or fluids sourced from deeper-seated magma bodies, emplaced beneath the deposit. To produce the observed thermal longevity of the porphyry system, magma bodies underlying the Bajo de la Alumbrera deposit must have been repeatedly replenished by new magma batches. Without replenishment, crystallization of the source magma will occur, and heat release will stop, leading to rapid cooling (in less than ten thousand years). The influx of deep-seated magma may have caused the development of late low-temperature hydrothermal alteration assemblages at Bajo de la Alumbrera, at the same time that mineralization formed at Agua Rica, some 25 km away. All available chronologic data for the Bajo de la Alumbrera deposit suggest that the hydrothermal system was active episodically over at least a three-million and possibly up to a four-million-year period. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.