2,976 research outputs found

    Stratigraphy of Tithonian (Ohauan-Puaroan ) marine beds near Port Waikato, New Zealand, and a redescription of Belemnopsis aucklandica (Hochstetter).

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    Some 1500 m of marine Ohauan and Puaroan strata in the Port Waikato region of New Zealand are restudied in an attempt to resolve lithostratigraphic and biostratigraphic anomalies in published works. New correlations are proposed for some units of the Apotu Group. A lower 650 m siltstone, previously correlated entirely with Kinohaku Siltstone, is here regarded as including the interval Kinohaku Siltstone to Lower Puti Siltstone (new member). The Waiharakeke Conglomerate is not represented in the area by coarse sediments. A thin sandstone unit overlying the Lower Puti Siltstone and previously correlated with Waiharakeke Conglomerate is here correlated with the Ruakiwi Sandstone. The overlying 400 m siltstone, regarded previously as the entire Puti Siltstone, is here recognised as a new member, the Upper Puti Siltstone. The Coleman Conglomerate is much thicker in the region than mapped, and located higher in the sequence. Biostratigraphy is a key element in correlating the sequence with named units to the south. The sequence is mostly siltstone, but sandstone units provide some lithostratigraphic control. Belemnites are almost the only fossils found in the Late Ohauan and Early Puaroan part of the sequence and are important in the Late Puaroan. Formal belemnite zones, based in part on their stratigraphic distributions in other parts of southwest Auckland, are erected. Occasional ammonites provide tie points that correlate the succession with the standard stratigraphic column for the Tethyan realm. Belemnopsis aucklandica (Hochstetter) is redescribed and considered to be of full specific status as is its former subspecies, Belemnopsis trechmanni Stevens. Many pre-adult Belemnopsis aucklandica differ in form from adults, some have been previously identified in the field as Hibolithes. Some earlier identifications of belemnites from the Late Puaroan of Port Waikato are incorrect, most are now included in Belemnopsis aucklandica

    Complex belemnites of the Puaroan (lower-? middle Tithonian) stage in the Port Waikato Region of New Zealand

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    Belemnite guards range through 2700 feet of Puaroan strata in the Port Waikato region. All are Belemnopsis of the uhligi-complex. Belemnopsis aucklandica aucklandica (Hochstetter) in its most typical form may be restricted to the lower 700 feet of the sequence. Three species are described, together with what may be transitional forms. The morphology of juvenile guards is in marked contrast with that of mature specimens, and development of the adult guard is revealed by examination of internal sections. Some aspects of belemnite paleoecology are discussed. Belemnite biostratigraphy of the area is outlined and the more important fossil localities are described

    Angels in the architecture - and devils in the detail: how the learning space impacts on teaching and learning

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    An innovative classroom design pioneered in the US, which aims to facilitate greater student engagement, has been piloted in a UK University for the first time. This case study reflects on some of the advantages and the challenges of this technology rich learning space and considers its impact on curriculum design in a module which aims to develop academic, research and digital skills in first year students on an undergraduate Health and Social Care course

    Comptonization of an isotropic distribution in moving media: higher-order effects

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    We consider the Comptonization of an isotropic radiation field by a thermal distribution of electrons with non-vanishing bulk velocity. We include all relativistic effects, including induced scattering and electron recoil, in the derivation of a kinetic equation which is correct to O(theta^2, beta theta^2, beta^2 theta), where beta is the bulk velocity (in units of c) and theta is the ratio of the electron temperature to mass. The result given here manifestly conserves photon number, and easily yields the energy transfer rate between the radiation and electrons. We also confirm recent calculations of the relativistic corrections to the thermal and kinematic Sunyaev-Zel'dovich effect.Comment: Minor revisions. To appear in the Astrophysical Journa

    CMB anisotropy science: a review

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    The cosmic microwave background (CMB) provides us with our most direct observational window to the early universe. Observations of the temperature and polarization anisotropies in the CMB have played a critical role in defining the now-standard cosmological model. In this contribution we review some of the basics of CMB science, highlighting the role of observations made with ground-based and balloon-borne Antarctic telescopes. Most of the ingredients of the standard cosmological model are poorly understood in terms of fundamental physics. We discuss how current and future CMB observations can address some of these issues, focusing on two directly relevant for Antarctic programmes: searching for gravitational waves from inflation via B-mode polarization, and mapping dark matter through CMB lensing.Comment: Invited science review for Proceedings of IAU Symposium 288, "Astrophysics from Antarctica". 11 pages, 5 figure

    Thermal and kinematic corrections to the microwave background polarization induced by galaxy clusters along the line of sight

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    We derive analytic expressions for the leading-order corrections to the polarization induced in the cosmic microwave background (CMB) due to scattering off hot electrons in galaxy clusters along the line of sight. For a thermal distribution of electrons with a kinetic temperature of 10 keV and a bulk peculiar velocity of 1000 km/s, the dominant corrections to the polarization induced by the primordial CMB quadrupole and the cluster peculiar velocity arise from electron thermal motion and are at the level of 10 per cent in each case, near the peak of the polarization signal. When more sensitive measurements become feasible, these effects will be significant for the determination of transverse peculiar velocities, and the value of the CMB quadrupole at the cluster redshift, via the cluster polarization route.Comment: 7 pages, 2 figures. Version accepted for MNRAS. Minor expansion of text in some section

    Weak lensing of the CMB

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    The cosmic microwave background (CMB) represents a unique source for the study of gravitational lensing. It is extended across the entire sky, partially polarized, located at the extreme distance of z=1100, and is thought to have the simple, underlying statistics of a Gaussian random field. Here we review the weak lensing of the CMB, highlighting the aspects which differentiate it from the weak lensing of other sources, such as galaxies. We discuss the statistics of the lensing deflection field which remaps the CMB, and the corresponding effect on the power spectra. We then focus on methods for reconstructing the lensing deflections, describing efficient quadratic maximum-likelihood estimators and delensing. We end by reviewing recent detections and observational prospects.Comment: 21 pages, 5 figures. Invited review for GRG special issue on gravitational lensin

    Notes on the belemnite content of the Heterian and Ohauan stages at Kawhia Harbour, New Zealand

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    The belemnite content of the Heterian and Ohauan stages at Kawhia Harbour is described. Six major species or groups are differentiated, each of which ranges through several hundred feet of strata. Other minor elements are also present. Belemnopsis keari Stevens is shown to be present in only a restricted group of beds in the upper part of the Waikutakuta Siltstone, and Belemnopsis alfurica (Boehm) may be present in the upper Waikutakuta Siltstone. A system of informal belemnite zones is suggested. The belemnite succession is well defined throughout most of the Heterian stage, but poorly defined in the Ohauan, and further work is required in the upper and lower parts of this stage
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