The Jeffers Brook diorite–granodiorite pluton: style of emplacement and role of volatiles at various crustal levels in Avalonian appinites,Canadian Appalachians

International Journal of Earth Sciences - Small appinite plutons ca. 610 Ma outcrop in the peri-Gondwanan Avalon terrane of northern Nova Scotia, with different structural levels exposed....     

Palaeomagnetism of Caledonian intrusive suites in the Northern Highlands of Scotland: Constraints to tectonic movements within the Caledonian orogenic belt

To evaluate the scale of tectonic movements within the northern sector of the 500-400 Ma Caledonian orogenic belt and its Precambrian foreland zone between the Great Glen Fault (GGF) zone to the southeast and the Laurentian Block to the northwest, we have studied the palaeomagnetism of minor intrusive rocks within the Northern Highlands terrain. These rocks include

1. (1) amphibolites and other metamorphic rocks predating deformation,

2. (2) microdiorities, dolentes and related suites emplaced, and probably magnetised, between 450 and 420 Ma, and

3. (3) Lower-Middle Devonian lamprophyres.

A range of predominantly NNE negative and SSW positive components are resolved by cleaning treatment with a dispersion of declinations towards a minority WNW-ESE axis; isolated southerly negative directed hematite-held components suggests limited, but no widespread, remagnetisation in Devonian-Carboniferous times.Comparison is made with data from other tectonic divisions in the Caledonian orogenic belt and the bordering forelands. Palaeopoles from the Northern Highlands closely conform in part with North American Ordovician poles and in part with the post-Ordovician palaeopoles from Britain south of the GGF. The definitive motions of the British Caledonides to emerge from the palaeomagnetic analysis are an anticlockwise rotation of the Caledonian terrain in early Ordovician times, small relative motions during the remainder of Ordovician times followed by large clockwise and then anticlockwise rotations during late Ordovician to early Silurian times contemporary with the last major movements on the Moine Thrust (ca. 430 Ma). Late Silurian-Devonian movements along the GGF were probably below the limits of palaeomagnetic detectability. The collective data require that apparent polar wander movements and concomitant continental movements have currently been incompletely recovered by North American studies and the path for Lower Palaeozoic times is more complex than recognised hitherto.     

Palaeomagnetism of Ketilidian metamorphic rocks of SW Greenland,and 1850-1600 m.y. apparent polar movements

Proterozoic supracrustal rocks of southwest Greenland and amphibolite dykes intruding the basement possess a thermal remanent magnetisation acquired during slow regional uplift and cooling between 1800 and 1600 m.y. following the Ketilidian mobile episode. Most samples from amphibolite dykes (mean palaeomagnetic pole 214°E, 31°N) possess a stable remanence associated with development of hematite during regional thermal metamorphism. Metavolcanics from the eastern part (eight sites, palaeomagnetic pole 230°E, 60°N, A₉₅ = 15°) and western part (twelve sites, 279°E, 59°N, A₉₅ = 17°) of Ars?k Island have magnetisations postdating folding and are related to KAr ages dating regional cooling (1700-1600 m.y.); magnetic properties are highly variable and partially stable remanence resides predominantly in pyrrhotite.These results agree in part with other palaeomagnetic results from the northern margin of the same craton, and currently available palaeomagnetic results assigned to the interval 1850-1600 m.y. are evaluated to define apparent polar wander movements. Two large polar movements are recognised during this interval with the possibility of a third at ca. 1800 m.y. It is concluded that apparent polar wander movements in Proterozoic times are most accurately described in terms of closed loops.     

Unpacking race,party and class from below: Surveying citizenship in the Msunduzi municipality

On the basis of a 2008 survey conducted in the Msunduzi municipality in the KwaZulu-Natal province, the paper begins an exploration of the character of popular politics and citizenship in South Africa. Embracing a ‘citizen-centred’ methodology informed by participation literatures, and sensibilities to the ‘work in progress’ character of African cities from urban studies debates, the paper interrogates the mainstream liberal-participatory model of citizenship in South Africa, and the critiques of current South African politics informed by these notions, specifically the ‘racial census’ and ‘dominant party syndrome’ analyses. Taken together these views can be read as characterising South African politics as a game for individual citizens governed by liberal rules, but played by racial and/or partisan groups in exclusionary ways, thus distorting liberal democratic mechanisms of representation and accountability. The paper also examines evidence for an alternative class-based analysis of one aspect of citizenship, namely, protest against poor local governance.The paper looks to unpack this ‘liberal model versus racialised communitarian practice’ imaginary by, on the one hand, demonstrating the ways in which citizenship is not racialised, or is asymmetrically racialised. Indeed, other than party allegiances and trust in key offices, very little by way of what citizens do, believe or think of themselves follows discrete racial lines. Similar points hold for partisanship too. On the other hand, the paper does not redeem the liberal-democratic model as there is also evidence of trust in government when it is not deserved based on performance, but more importantly, evidence that citizens embrace ‘informal’ means to secure their rights. A good example of this is protestors who are also more likely to vote than non-protestors. Taken together, these findings affirm both the way in which the racial and partisan legacy of the past is being undone by new institutions and practices, and suggest the complex intersection of these with networks of personal relations which characterise the local politics of most African cities.     

U-Pb geochronology of Late Palaeozoic plutons,Cobequid Highlands,Nova Scotia,Canada: evidence for Late Devonian emplacement adjacent to the Meguma-Avalon terrane boundary in the Canadian Appalachians

The Cobequid Highlands in the Canadian Appalachian orogen lie within Avalonia adjacent to the Meguma Terrane. U-Pb (zircon) data show that the age range of voluminous bimodal plutonism in the highlands is from 358 to 363 Ma (late Devonian). This age range is much narrower than that previously suggested by Rb/Sr geochronology and confirms that the Cobequid Highlands preserve the youngest large-scale plutonic event in the Canadian Appalachians. Late Palaeozoic tectonic history of the Appalachian orogen is profoundly influenced by predominantly dextral motion on the Avalon-Meguma terrane boundary. This age of plutonism is coeval with previously published ⁴⁰Ar/³⁹Ar (muscovite) plateau ages derived from shear zones in the Meguma terrane adjacent to the terrane boundary, which is defined by the Minas fault zone. The NNE trending structural grain of the Appalachian orogen is disturbed in this area by the E-W Minas fault zone and pluton emplacement may have been associated with motion along this terrane boundary.     

Gender and Migration Policies in Southeast and East Asia: Legal Protection and Sociocultural Empowerment of Unskilled Migrant Women

This paper is concerned with how existing migration policies affect individual migrant women's choices, in particular, with the advancement, or consolidation, of a migrants' rights perspective. The focus is thereby on those migrants classified as unskilled, who constitute the largest and most vulnerable category among migrants. The analysis of migration policies has conventionally been approached from a state/government‐centred viewpoint that sees states as the key actors. This paper, however, emphasises a larger number of actors ‐ governmental and non‐governmental ‐ as well as the power relations among them to argue that protection through “legal regulation” in the absence of actual implementation is an incomplete solution to alleviate unfair labour conditions that migrants in general, and migrant women specifically, experience. Measures designed to “protect” migrants must be accompanied by measures that empower them, a role that has largely been taken on by existing migrant worker non‐governmental organisations (NGOs). Focussing on intra‐Asian migration flows in which Southeast Asia is the main labour sender and East Asia the receiver of Southeast Asian migrants, the paper explores the nexus between law and civic activism in the specific subject area of international labour migration and its gender implications.     

Palaeomagnetic study of the Kepezdağ and Yamadağ volcanic complexes, central Turkey: Neogene tectonic escape and block definition in the central-east Anatolides

The Anatolian accretionary collage between Afro-Arabia and Eurasia is currently subject to two tectonic regimes. Ongoing slip of Arabia relative to Africa along the Dead Sea Fault Zone in the east is extruding crustal blocks away from the indenter by a combination of strike-slip and rotation. This zone of compression gives way to an extensional province in western Turkey, which also includes the eastern sector of Aegean Province. Although it is now well established that rotational deformation throughout Anatolia is distributed and differential, the sizes of the blocks involved are poorly understood. As a contribution towards evaluating this issue in central-east Turkey, we report palaeomagnetic study of the mid-Miocene Kepezda? and Yamada? volcanic complexes in central-south Anatolia (38–39.5°N, 37.5–39°E). A distributed sample through the Yamada? complex identifies eruption during an interval of multiple geomagnetic field reversals (40 normal, 36 reversed, 8 intermediate sites) with a selected mean defined by 63 sites of D/I = 335.4/51.1° (α₉₅ = 4.4°). The smaller Kepezda? complex (8 reversed, 4 normal and 1 intermediate site) yields a comparable mean direction from 12 sites of 338.7/49.8° (α₉₅ = 14.1°). In the context of a range of radiometric age evidence, two thick normal polarity zones within the Yamada? succession probably correlate with zones C5ACn and C5ADn of the Geomagnetic Polarity Time Scale and imply that the bulk of the volcanic activity took place between ∼15 and 13.5 Ma. Comparison of the palaeomagnetic results with the adjoining major plate indenters shows that the Yamada? complex has rotated CCW by 29.3 ± 5.2° relative to Eurasia; the much smaller dataset from the Kepezda? complex indicates a comparable CCW rotation of 26.0 ± 11.8° with respect to Eurasia. The Arabian Indenter has also been rotating CCW since mid Miocene times, and the block incorporating these two volcanic complexes north of the East Anatolian Fault Zone (EAFZ) is determined to have rotated 18.2 ± 6.0° CCW relative to the northern perimeter of Arabia. Comparison with data to the north identifies quasi-uniform rotation across a ∼200 km wide block extending from the Central Anatolian Fault Zone in the northwest to close to the East Anatolian transform fault zone in the south east. Although absence of suitable younger rocks does not permit the timing of this rotation to be determined in the study area, analogies with results from the Sivas Basin suggest that it is young, and followed establishment of the major transform faults. Rotation has evidently taken place around bounding arcuate faults and accompanied westward expulsion as the accretionary collage north of Arabia has been subject to ongoing post-collisional indentation.     

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

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.