Mineralogy and petrology of the Abee enstatite chondrite breccia and its dark inclusions

The Abee E4 enstatite chondrite breccia consists of clasts (many rimmed by metallic Fe, Ni), dark inclusions and matrix. The clasts and matrix were well equilibrated by thermal metamorphism, as evidenced by uniform mineral compositions, recrystallized chondrules, low MnO content of enstatite and high abundance of orthoenstatite. The clasts acquired their metal-rich rims prior to this metamorphic episode. The occurrence in Abee of relatively unmetamorphosed dark inclusions, clasts with nearly random magnetic orientations and a matrix with a uniform magnetic orientation [18,19] indicates that clast and matrix metamorphism occurred prior to the agglomeration of the breccia.The dark inclusions are an unusual kind of enstatite chondritic material, distinguished from the clasts and matrix by their relative enrichments in REE [21–23], low relative abundances of kamacite, total metallic Fe, Ni and silica, lower niningerite/(total sulfide) ratios, high relative abundances of oldhamite and martensite, smaller euhedral enstatite, more heterogeneous enstatite and metallic Fe, Ni, more calcic enstatite and more nickeliferous schreibersite.We propose the following model for the petrogenesis of the Abee breccia: The maximum metamorphic temperature of breccia parent material was?- 840°C (the minimum temperature of formation of Abee niningerite) and perhaps near 950–1000°C (the Fe-Ni-S eutectic temperature). Euhedral enstatite crystals in metallic Fe, Ni- and sulfide-rich areas grew at these metamorphic temperatures into pliable metal and sulfide. Breccia parent material was impact-excavated from depth, admixed with dark inclusions and rapidly cooled (700 to 200°C in about 2 hours) [15]. During this cooling, clast and matrix material acquired thermal remanent magnetization. Random conglomeration of clasts and unconsolidated matrix materials caused the clasts to have random magnetic orientations and the matrix areas to have net magnetic intensities of zero (due to the cancellation of numerous randomly oriented magnetic vectors of equal intensity in the matrix). A subsequent ambient magnetic field imparted a uniform net magnetic orientation to the matrix and caused the magnetic orientations of the clasts to be somewhat less random. The Abee breccia was later consolidated, possibly by shock or by shallow burial and very long-period/low-temperature (< 215°C) metamorphism.     

A new technique for determining the surface level of salt marshes and other uncompacted sedimentary environments

The method described involves the use of an electro-optical distance measurer mounted on a theodolite. Observations are taken onto a series of acrylic reflectors, aligned at right angles to the line of sight, and slope distances and vertical and horizontal angles are recorded. From these data it is possible to obtain surface heights to an accuracy of ±0·5 cm at 200 m and to avoid any direct disturbance of the site under investigation.     

The development of warehousing in England

Over the past decade there has been a growing recognition by the business community, central government and local planners of the economic importance of warehousing. This importance can be measured in terms of the value of stock held in warehouses, their very rapid growth relative to other types of commercial property and the employment they create. This article reviews changes in business and planning attitudes to warehousing, accounts for the recent growth of warehouse floorspace in England and examines the spatial distribution of this growth.     

Detection Time for Plausible Changes in Annual Precipitation, Evapotranspiration, and Streamflow in Three Mississippi River Sub-Basins

We use diagnostic studies of off-line variable infiltration capacity (VIC) model simulations of terrestrial water budgets and 21st-century climate change simulations using the parallel climate model (PCM) to estimate the time required to detect predicted changes in annual precipitation (P), evapotranspiration (E), and discharge (Q) in three sub-basins of the Mississippi River Basin. Time series lengths on the order of 50–350 years are required to detect plausible P, E, and Q trends in the Missouri, Ohio, and Upper Mississippi River basins. Approximately 80–160, 50, and 140–350 years, respectively, are needed to detect the predicted P, E, and Q trends with a high degree of statistical confidence. These detection time estimates are based on conservative statistical criteria (α = 0.05 and β = 0.10) associated with low probability of both detecting a trend when it is not occurring (Type I error) and not detecting a trend when it is occurring (Type II error). The long detection times suggest that global-warming-induced changes in annual basin-wide hydro-climatic variables that may already be occurring in the three basins probably cannot yet be detected at this level of confidence. Furthermore, changes for some variables that may occur within the 21st century might not be detectable for many decades or until the following century – this may or may not be the case for individual recording station data. The long detection times for streamflow result from comparatively low signal-to-noise ratios in the annual time series. Finally, initial estimates suggest that faster detection of acceleration in the hydrological cycle may be possible using seasonal time series of appropriate hydro-climatic variables, rather than annual time series.     

The impact of geographical indication on the revitalisation of a regional economy: a case study of 'Boseong' green tea

Geographical indications are legal signs which identify a good as originating in a specific country or region, where the reputation of the product is attributable to its geographical roots. South Korea has operated with a geographical indication system since 1999. This research analyses the regional impacts of geographical indications using the case study of 'Boseong' green tea. The results show that geographical indication has enhanced the image of the product, leading to increased production and the stimulation of tea-related industries. We argue that geographical indication can be used as an effective policy to cope with trade liberalisation.     

Significance of geomorphological and subsurface drainage controls on failures of peat‐covered hillslopes triggered by extreme rainfall

On 19 September 2003, 40 landslides of 140–18 000 m³ volume occurred within 2·5 km² on the slopes of Dooncarton Mountain (Republic of Ireland) during a storm that may have exceeded 90 mm within 90 minutes. The landslides were investigated to determine the reasons for such a high density of slope failures. All of the landslides were surveyed within four months, and nine of them were investigated in detail. The six largest landslides, all peat failures, accounted for 57% of the more than 100 000 m³ of material displaced during the event. A consistent sequence of superficial materials was found on the failed hillslopes, including an extensive iron pan at the base of a buried soil horizon 0·3 m below the base of the peat. Morphologically, almost all of the landslides occurred on steep planar slopes or around sharp convexities, with the latter failures developing retrogressively upslope. The only significant relationship found from analysis of 371 subsurface pipes and 142 seepage cracks (defined here as contiguous fissures conducting concentrated subsurface flow) across all the failures was that the thinner the peat cover, the deeper the pipes and seepage cracks occurred below the base of peat. It is concluded that most of the landslides were probably caused by a combination of excess water pressures in the buried soil horizon and the thinner overburden of peat or peaty soil associated with the steeper slope segments. Pipes and seepage cracks formed on the iron pan probably existed prior to the failure event and may have contributed to the high water pressures as rainwater inputs exceeded their discharge capacities. One large peat slide was probably triggered by excess water pressures developed within and between artificial tine cuts. The properties of the blanket peat were generally of little consequence in the occurrence of the landslides, but relict desiccation cracks and other structural weaknesses through the peat mass were probably highly significant. Although several aspects of the peat failures correspond to previously published examples, the context of these failures in terms of the topography and upland catena is distinctive. Copyright © 2007 John Wiley & Sons, Ltd.     

On the importance of non-hydrostatic processes in determining tidally induced mixing in sill regions

The importance of using a non-hydrostatic model to compute tidally induced mixing and flow in the region of a sill is examined using idealized topography representing the sill at the entrance to Loch Etive. This site is chosen since detailed measurements were recently made there. Calculations are performed with and without the inclusion of non-hydrostatic dynamics using a vertical slice model for a range of sill widths corresponding to typical sill regions. Initial non-hydrostatic calculations showed that the model could reproduce the observed flow characteristics in the region. However, when calculations were performed using the model in hydrostatic form, the significant artificial convective mixing that occurred in order to remove density inversions led to excessively high vertical mixing. This influenced the computed temperature field and the intensity of the current jet that separated from the sill on its lee side. In addition it affected the magnitude and spatial characteristics of the lee waves generated on the lee side of the sill. Calculations with a range of sill widths, showed that as the sill width decreased the difference between the solution computed with the non-hydrostatic and hydrostatic model increased.     

'Sediment'–cement relationships in a Pleistocene speleothem from Italy: a possible analogue for 'replacement' cements and Archaeolithoporella in ancient reefs

Ancient carbonate buildups may contain extraordinarily large amounts of early diagenetic precipitates. In some, host rock lamination may be traced into inclusion bands within the 'cement' crystals, suggesting that the crystals are replacive. By analogy with a Pleistocene speleothem from the Sorrento Peninsula, however, these relationships can be explained differently. In the speleothem, large, repeatedly split and dendritic calcite crystals occur within a laminated carbonate. Lamination consists of sub-mm alternations of micrite and microspar. Micritic laminae pass laterally into inclusion-rich growth bands in the dendritic calcite crystals, and have replaced an aragonitic cement, whereas the microspar laminae were primary calcite cements. Three types of inclusion-rich bands occur in the dendrite crystals: (1) with aragonite relicts, (2) 'ribbon calcite' and (3) with oriented micropores. When aragonite precipitated, the calcite dendrite branches were unable to keep growing as single crystals and split into crystallites (separated by micropores, some forming ribbon calcite), whereas during episodes of calcite lamina precipitation, the larger crystals were regenerated by crystallite coalescence. Calcite crystals are primary: they did not replace a micritic precursor. By analogy with the Italian speleothem, some ancient reefal sparry carbonates may not be replacements of earlier laminated sediments, but may have grown concurrently with them. It is also probable that some ancient laminated sediments were instead sea-floor precipitates, and that stromatolites containing cross-cutting crystal fabrics, and the alternating micrite-microspar laminae typical of Archaeolithoporella , could be largely abiotic crystal growths.