Biodiversity and Sequence of the Middle Triassic Panxian Marine Reptile Fauna, Guizhou Province, China

Abstract: The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction. Ten marine reptile taxa have been found from the 1.82–2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation, which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles. The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al., 2008 and Lariosaurus hongguoensis Jiang et al., 2006, the ichthyopterygians Xinminosaurus catactes Jiang et al., 2008 and Phalarodon cf. Phalarodon fraasi Merriam, 1910, associated with Mixosaurus panxianensis Jiang et al., 2006, representing a stage of predominance of durophagous taxa. In this bed, the large complete skeletons may reach up to 2.3 m in length, and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom, as well as a rising sea level. The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al., 2006 and the archosaur Qianosuchus mixtus Li et al., 2006, associated with Mixosaurus panxianensis Jiang et al., 2006. The fossils in this bed are characterized by its pincering dentition and large overall body size, with the largest possibly exceeding 3 m in length. This bed might represent a time of deepest basin with relatively anoxic condition near the bottom. The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al., 2008, Keichousaurus sp., the protorosaur Dinocephalosaurus orientalis Li, 2003, and the ichthyopterygian Mixosaurus panxianensis Jiang et al., 2006. In this bed, reptilian taxa characterized by suction feeding appeared, and most are less than 1 m long. This bed corresponds to a period of decreasing water depth.     

Morphology and sedimentary architecture of a beach‐ridge system (Anholt,the Kattegat sea): a record of punctuated coastal progradation and sea‐level change over the past ∼1000 years

Flakket on the island of Anholt in Denmark is a cuspate foreland facing the microtidal Kattegat sea. It is composed of a number of beach ridges typically covered by dune sand and separated by swales and wetlands. OSL dating indicates that the evolution of Flakket began c. AD 1000. Foreland growth was punctuated by a major episode of coastal reorganization leading to coastal retreat c. AD 1800. Coastal retreat led to the formation of an erosion surface that separates older and higher‐lying beach‐ridge and swale deposits from younger and lower‐lying deposits. The palaeo‐sea level is deduced from the architecture of the deposits, and interpretation of ground‐penetrating radar data and geomophological observations indicates that relative sea level was about 1.90±0.25 m above present sea level c. AD 1000, but about 0.00±0.25 m relative to present sea level c. AD 1830 and c. AD 1870. Anholt is situated at the margin of the uplifted Fennoscandian area; assuming uplift to be about 1.2 mm a^?1 it follows that absolute sea level was about +0.70±0.25 m at AD 1000, but around ?0.22±0.25 m at AD 1830 and around ?0.17±0.25 m at AD 1870. Within the uncertainties of the age control, the sea‐level indicators mapped by ground‐penetrating radar reflections and the variability of estimates of uplift found in the literature, the result obtained for AD 1000 is consistent with findings from the Stockholm area in Sweden and with a recently published global sea‐level curve.     

Black-body temperature of a closed Universe

In a closed gravitationally-bound Universe we are subject to an inward accelerationa ₀. One consequence of this acceleration is that matter will radiate and create a black-body spectrum throughout the Universe. Using the valuea ₀=7.623×10^–12 ms^–2 and a radiation formula from a previously-described cosmological model (Wåhlin, 1981), we obtain a black-body temperature of 2.766 K.     

A modelling study of the effects of land management and climatic variations on groundwater inflow to Lake St Lucia, South Africa

Over the past few years groundwater has been recognized as an important contributor of freshwater to Lake St Lucia, South Africa during periods of prolonged drought. This has led to a management strategy aiming at increasing the groundwater recharge and minimizing groundwater use through active manipulation of the vegetation. For the Eastern Shores on the edge of Lake St Lucia, the replacement of vast areas of pine (Pinus elliottii) plantations with grassland over the past decade, combined with a strict burning regime, has led to a general rise of the water table, which has increased the groundwater seepage to Lake St Lucia. A numerical groundwater model has been applied to assess the effects of local management strategies on the mass balance of a shallow aquifer and these are compared to the effects of predicted climate and sea-level change for this area. The simulations indicate that local management actions that are being applied to the Eastern Shores have positive effects on the groundwater flux into Lake St Lucia and that they outweigh potential negative effects of future climate and sea-level change predicted for this area.     

Morphological records of storm floods exemplified by the impact of the 1872 Baltic storm on a sandy spit system in south‐eastern Denmark

Beach‐ridge systems are important geo‐archives providing evidence for past wave climate including catastrophic storm flood events. This study investigates the morphological impacts of the 1872 Baltic storm flood on a beach‐ridge system (sandy spit) in south‐eastern Denmark and evaluates the frequency of extreme storm flood events in the area over a longer time perspective. This paper combines field studies of morphology and sedimentary deposits, studies of historical maps, digital terrain model, ground‐penetrating radar profiles, and luminescence dating. Sea water reached 2.8 m above mean sea level (amsl) during peak inundation and, based on studies of the morphological impacts of the 1872 storm flood, the event can be divided into four phases. Phase 1: increasing mean water levels and wave activity at the beach brought sediments from the beach (intertidal bars and normal berm) higher up in the profile and led to the formation of a storm‐berm. Phase 2: water levels further increased and sediment in the upper part of the profile continued to build up the storm‐berm. Phase 3: water levels now reached the top of the dune ridge and were well above the storm‐berm level. Sea water was breaching the dune ridge at several sites and wash‐over fans were generated until a level where the mean water level had dropped too much. Phase 4: the non‐vegetated wash‐over fans functioned as pathways for aeolian sand transport and relatively high dunes were formed in particular along the margins of the fan where aeolian sand was trapped by existing vegetation. The studied beach‐ridge system records about 4500 years of accumulation; the storm flood sediments described are unique suggesting that the 1872 Baltic storm flood event was an extreme event. Thus studies of beach‐ridge systems form a new source for understanding storm surge risk. Copyright © 2013 John Wiley & Sons, Ltd.     

Multidimensional thermal structure of magnetized neutron star envelopes

Recently launched X-ray telescopes have discovered several candidate isolated neutron stars. The thermal radiation from these objects may potentially constrain our understanding of nuclear physics in a realm inaccessible to terrestrial experiments. To translate the observed fluxes from neutron stars into constraints, one needs precise calculations of the heat transfer through the thin insulating envelopes of neutron stars. We describe models of the thermal structure of the envelopes of neutron stars with magnetic fields up to 10¹⁴ G. Unlike earlier work, we infer the properties of envelope models in two dimensions and precisely account for the quantization of the electron phase-space. Both dipole and uniformly magnetized envelopes are considered.     

A geoid solution for airborne gravity data

Airborne gravity data is usually attached with satellite positioning of data points, which allow for the direct determination of the gravity disturbance at flight level. Assuming a suitable gridding of such data, Hotine’s modified integral formula can be combined with an Earth Gravity Model for the computation of the disturbing potential (T) at flight level. Based on T and the gravity disturbance data, we directly downward continue T to the geoid, and we present the final solution for the geoid height, including topographic corrections. It can be proved that the Taylor expansion of T converges if the flight level is at least twice the height of the topography, and the terrain potential will not contribute to the topographic correction. Hence, the simple topographic bias of the Bouguer shell yields the only topographic correction. Some numerical results demonstrate the technique used for downward continuation and topographic correction.     

Unification of vertical datums by GPS and gravimetric geoid models using modified stokes formula

In general, neighboring vertical datums can be compared directly at one or more common points on the border between the datums. This direct method requires leveling and gravity measurements. Such a direct connection is not possible if the datums are separated by an ocean or another body of water. Then a rigorous mathematical model, an indirect approach, may be useful. In order to connect regional vertical datums, a rigorous mathematical model is derived based on a method by Rummel and Teunissen. In this study, two vertical datums are connected indirectly by means of a combination of precise geocentric positions of tide gauge sites and their geoid heights in one geocentric coordinate system and their height values in the respective height datums. This method is used to connect the Swedish and the Finnish height systems. The difference between Swedish RH70 and the Finnish N60 height systems is estimated to —12.1±2.7 cm. The results are mostly in good agreement with those of the direct approach by Sjöberg and by Ekman and the indirect approach by Pan and Sjöberg.     

Soil frost effects on soil water and runoff dynamics along a boreal transect: 2. Simulations

A physically based SVAT‐model was tested with soil and snow physical measurements, as well as runoff data from an 8600 m² catchment in northern Sweden in order to quantify the influence of soil frost on spring snowmelt runoff in a moderately sloped, boreal forest. The model was run as an array of connected profiles cascading to the brook. For three winter seasons (1995–98) it was able to predict the onset and total accumulation of the runoff with satisfactory accuracy. Surface runoff was identified as only a minor fraction of the total runoff occurring during short periods in connection with ice blocking of the water‐conducting pores. Little surface runoff, though, does not mean that soil frost is unimportant for spring runoff. Simulations without frost routines systematically underestimated the total accumulated runoff. The possibility of major frost effects appearing in response to specific combinations of weather conditions were also tested. Different scenarios of critical initial conditions for the winter, e.g. high water saturation and delayed snow accumulation leading to an increased frost penetration, were tested. These showed that under special circumstances there is potential for increased spring runoff due to soil frost. Copyright © 2001 John Wiley & Sons, Ltd.