Cleaved microgranite dykes of the Shap swarm in the Silurian of NW England

Felsite-microgranite dykes, chemically comparable with the Shap swarm and associated with the Shap intrusion, are present in Silurian sediments of the southern Lake District. They were emplaced after the country rocks had undergone Acadian (late Caledonian) folding and cleavage-formation but are themselves weakly cleaved. This confirms a ‘flattened buckle’ model for the Acadian deformation in NW England, which in turn establishes the link between sinistral transpression in this region and the clockwise transection of the folds by cleavage. The evidence also shows that the Acadian cleavage developed episodically, and that the Shap-Skiddaw magmatism occurred during one or more stress-relief episodes. The emplacement age of these intrusions thus constrains the age of the Acadian orogeny in NW England which was late in the Lower Devonian (according to currently available isotopic evidence), significantly later than the Silurian deformation of the Southern Uplands.     

Intraspecific cleaning by juvenile Cape white seabream Diplodus capensis (Sparidae) off eastern South Africa

Juveniles of the Cape white seabream Diplodus capensis were observed cleaning adult conspecifics in a large tidepool off Sodwana Bay, South Africa. Although nine other tropical fish species were present and interacted with a nearby pair of Labroides cleaner wrasses, only adults of D. capensis posed for and were cleaned by the D. capensis juveniles. Such cleaning interactions have not been reported previously for this species or among marine fishes off South Africa, and thus add to the growing list of facultative cleaners globally.     

Skolithos pipes as strain markers in mylonites

It is argued that mylonite zones result from translatory movements between rock masses and that the deformation mechanism is one of simple shear. Evidence is adduced to show that the mylonite zones in the Moine Thrust Belt of northwestern Scotland were developed in association with the inverted limbs of early Caledonian folds which trend parallel to the thrust front. On this basis a method is developed for the determination of shear strain from parameters which can be measured in mylonites which contain deformed Skolithos worm burrows. Very large strains are indicated (γ - 10). Some general implications are discussed.     

Biostratigraphic ages of tertiary basalts on the East Greenland continental margin and their relationship to plate separation in the Northeast Atlantic

Palynological evidence indicates that the 4?5 × 10⁵ km³ pile of tholeiitic basalts on the central east Greenland coast was erupted in latest Palaeocene (late Landenian) and earliest Eocene (early Ypresian) time. Assignment of a precise numerical age of this interval is not yet possible, but it is evident that the eruptive episode was completed within about 3 m.y. The effusion rate was at least an order of magnitude faster than the current Icelandic rate. Marine horizons at the base and top of the pile show that its build-up was accompanied by concomitant crustal depression. It is argued that this major volcanic episode marks the initiation of plate separation between Greenland and northwest Europe. Implications with regard to spreading chronology and the magnetic polarity time scale are discussed.     

Primordial non-Gaussianity from LAMOST surveys

The primordial non-Gaussianity (PNG) in the matter density perturbation is a very powerful probe of the physics of the very early Universe. The local PNG can induce a distinct scale-dependent bias on the large scale structure distribution of galaxies and quasars, which could be used for constraining it. We study the detection limits of PNG from the surveys of the LAMOST telescope. The cases of the main galaxy survey, the luminous red galaxy (LRG) survey, and the quasar survey of dif- ferent magnitude limits...     

Generalized electromagnetic torque on a vacuum pulsar model

The Deutsch solution to the electromagnetic field in a vacuum surrounding a perfectly conducting obliquely rotating sphere with a dipolar distribution of magnetic flux is extended to the oblique rotator with a general axisymmetric surface flux. It is shown that the torque component perpendicular to the rotation axis is always of opposite sign to the decelerating component parallel to the rotation axis. It is emphasized that this unambiguous result may not apply to more realistic pulsar models with magnetospheres containing charges.     

Phylogeny of the Sepia officinalis species complex in the eastern Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region

Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue samples from the currently presumed distributions of S. vermiculata and S. hierredda (from South Africa and Ghana/Angola, respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome and then compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades, corresponding to S. officinalis, S. hierredda and S. vermiculata, were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. The sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. These results indicate that the range of S. vermiculata extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer-scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks.     

Lithostratigraphy of the Windermere Supergroup,Northern England

A formal lithostratigraphy is erected for the Late Ordovician and Silurian rocks of northern England. The scheme presented herein emphasizes natural depositional sequences within the supergroup and defines new type sections or cites existing definitions where appropriate. It is intended to be sufficiently flexible and comprehensive to apply to all the inliers, and to bear some rational relationship to lithostratigraphical usage in other British Lower Palaeozoic inliers.     

Observing the reconnection region in a transequatorial loop system

A vertical current sheet is a crucial element in many flare/coronal mass ejection (CME) models. For the first time, Liu et al. reported a vertical current sheet directly imaged during the flare rising phase with the EUV Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO). As a follow-up study, here we present the comprehensive analysis and detailed physical interpretation of the observation. The current sheet formed due to the gradual rise of a transequatorial loop system. As the l...     

Dusky dolphin movement patterns: short-term effects of tourism

Cetacean-oriented tourism has experienced rapid growth in the last two decades, accompanied by increasing concerns about the effects of tourism on target species. Here, we used shore-based observations of dusky dolphin (Lagenorhynchus obscurus) groups near Kaikoura, New Zealand, and generalised additive models to quantify changes in group speed, reorientation and linearity relative to natural and anthropogenic factors. Summer months were characterised by slower speeds and more changes in direction than winter months. Group speeds were higher at the beginning and end of the day, with slower speeds at midday. Speeds were slower when vessels were present, and dolphin groups changed direction more often when aircraft circled overhead. Effects were positively correlated with number of vessels present within 300 m. Short-term changes have potential to lead to long-term impacts, and further acoustic and energetic studies are proposed to elucidate whether these effects are likely to reduce individual fitness.