Isotopic evidence for the magmatic and tectonic histories of the Carolina terrane: implications for stratigraphy and terrane affiliation

Establishing the age and crustal nature of exotic terranes and their underlying basements helps to determine their paleogeographic origin and tectonic histories. We present U–Pb ages of zircons and Sm–Nd whole rock isotopic data for volcanic and plutonic rocks of the Carolina terrane, one of several peri-Gondwanan terranes that were accreted to the margins of the circum-Atlantic continents during the Paleozoic. Volcanism in this subduction-related arc culminated in the eruption of the Morrow Mountain rhyolite, at ca. 540 Ma; thus, magmatism in the Carolina terrane ceased at the beginning of the Cambrian. The presence of inherited zircons and non-juvenile depleted mantle model ages of Carolina slate belt rocks favor a basement that is, at least in part, composed of evolved continental crust. Ages of inherited xenocrystic zircons cluster at ca. 1000, 2100 and 2500 Ma. These ages, in addition to volcanism at ca. 618–540 Ma, correlate best with well-known tectonic events in present-day northern South America. Specifically, the Orinoquian-Sunsas, the Trans-Amazonian and the Central Amazonian orogenic zones are likely candidates for potential basement correlatives to the Carolina terrane. Sm–Nd isotopic signatures vary significantly, but permit assimilation of Orinoquian age (1000 Ma) crust by magmas derived from the depleted mantle in a subduction (arc-related) setting. Our findings are also consistent with proposed correlations between the Carolina terrane and Avalonia which is likewise believed to have formed along the northern margin of present-day South America.     

Variations in ground surface temperature histories in the Thompson Belt, Manitoba, Canada: environment and climate changes

Several temperature–depth profiles recorded at Pipe Mine, 32 km southwest of Thompson, Manitoba, in central Canada, exhibit a marked departure from the equilibrium gradient. These profiles could be interpreted as indicating strong warming (up to 4.5 K) of the ground surface during the last 200 years. All the temperature profiles at Pipe Mine show perturbations stronger than at the others sites in the Thompson Nickel Belt. Temperature profiles recorded near the town of Thompson show a moderate warming (≈1–2 K) trend, while temperature profiles at Soab, 45 km southwest of Pipe Mine, indicate very moderate cooling (≈0.5 K). There was little human activity in this part of Manitoba before the development of the mining camp of Thompson in the late 1950s. Our study shows the variability of ground surface temperature histories at a very local scale (i.e. <1 km) with much stronger signals at some of the Pipe Mine drill holes than at others. These holes are located within 500 m of the highway and a power line built after 1955, at ≈3 km from the now abandoned open pit mine. The ground surface temperature history (GSTH) obtained by the inversion of Pipe Mine temperature profiles suggests that a recent (50 years) and strong (≈1–2 K) ground surface warming is superimposed on a 1–2 K warming trend that started 200 years ago, without any indication of a cold (little ice ages) episode before. The recent warming (40 years) at Pipe Mine is only a local effect and is likely to be related to the presence of the highway. Before 1960, the ground surface temperature history for Pipe is similar to other sites in the Thompson region. Ground surface temperature histories from other profiles within and near the city of Thompson seem less affected by environmental perturbations and their trends are parallel to that of the meteorological records in the Canadian Prairies.     

Ground temperature histories in eastern and central Canada from geothermal measurements: evidence of climatic change

Inverse and direct methods have been used to analyze a large number of borehole temperature logs in order to infer past climatic changes. Results indicate a warming of 1–2°C in eastern and central Canada during the past 150 years. A period of cooling between 500 and 200 years before present, corresponding to the time of the “Little Ice Age”, has also been identified in the same areas. A regional ground temperature history is estimated for eastern and central Canada from the simultaneous inversion of several temperature logs. The inferred temperature changes appear correlated with the concentration of atmospheric carbon dioxide as reported from a Greenland ice core, and agree with existing meteorological and dendrochronological records for the area.     

On the fluid and viscoelastic deformations of the planets

The shape of the Earth and of planets depends on the exciting forces and on the rheology of the medium. From the equilibrium equation, we present the main modelisations of the viscous and inviscid fluids and we essentially describe the characteristics of linear viscoelastic deformations, for the Maxwell viscoelastic model of rheology. We use the elastic, viscoelastic and fluid Love numbers in order to investigate the associated relaxation modes. For these various kinds of rheology of the planets interior, we compute the geoid and the topography induced by an internal mass distribution. Finally, we show the importance of this viscoelastic deformation calculations in the study of the celestial body rotations.     

Blaualgenliteratur aus den Jahren 1967 und 1968 mit Ergänzungen aus den Jahren 1960 bis 1966

Ohne Zusammenfassung     

An estimate of the Earth's induction effects on the vertical polarization of the Pc5 pulsations recorded in auroral regions

It is assumed that the generation mechanism of Pc5's is somehow related to oscillations of a current system whose ionospheric path is the westward (or the eastward) electrojet. The Earth induction effects on the vertical polarization of Pc5 pulsations recorded in auroral regions are then modelled as the response of a flat layered Earth to an overhead uniform band of current whose intensity oscillates in time with periods ranging from 2 to 10 min. It is shown that polarization ellipses are opened in the H-Z planes by induction alone with a maximum ellipticity of the order of 0.15 at distances from the centre of the electrojet comparable to its width.     

The polarization of public concern about climate change in Norway

This article contributes to the existing literature by investigating the importance of value orientations for the Norwegian public's climate change concern, by analysing data from a national Gallup Poll from 2003 to 2011. Logistic regressions were conducted to investigate the importance of individualistic and egalitarian values for climate concern, and whether the groups of different value orientations have polarized in their climate concern over time. Respondents who hold less individualistic values and those holding egalitarian values are found more likely to be concerned about climate change than are those holding individualistic and less egalitarian values. Furthermore, the analyses find polarization in climate concern in the period for both value orientations. Increased focus on policy instruments in the political debate may be one explanation for values being increasingly salient. Future research should focus on studying ways to formulate policies given variations in values. One way would be to develop solutions that have co-benefits across groups of different value orientations. However, not all mitigation policies have immediate co-benefits for everyone. Research on how changes in the institutional setting may enhance the logic of social responsibility seems crucial.

Policy relevance

It is an important social science contribution to increase our understanding of public positions on climate change for developing effective responses to this vexing problem. This study identifies polarization over time between subgroups of different value orientations in their climate change concern. This may have implications for policies, as political solutions may be increasingly dependent on the composition of political leadership. Society and politicians should look for mitigation policies that have co-benefits across groups of different value orientations when possible. However, not all mitigation policies have immediate co-benefits for everyone. One option then is to change the institutional settings from enhancing the logic of individual benefits to enhancing the logic of social benefits for behaviour crucial for mitigating climate change. Finally, narratives about a low-emitting society that are attractive for all groups of value orientations should be emphasized.     

The large peculiar velocity of the cD galaxy in Abell 3653

We present a catalogue of galaxies in Abell 3653 from observations made with the 2-degree field (2dF) spectrograph at the Anglo-Australian Telescope. Of the 391 objects observed, we find 111 are bona fide members of Abell 3653. We show that the cluster has a velocity of   cz = 32 214 ± 83  km s⁻¹ ( z = 0.10 738 ± 0.00 027)  , with a velocity dispersion typical of rich, massive clusters of  σ _cz = 880⁺⁶⁶₋₅₄  . We find that the cD galaxy has a peculiar velocity of  683 ± 96  km s⁻¹  in the cluster rest frame – some 7σ away from the mean cluster velocity, making it one of the largest and most significant peculiar velocities found for a cD galaxy to date. We investigate the cluster for signs of substructure, but do not find any significant groupings on any length scale. We consider the implications of our findings on cD formation theories.