bluuebunny/crossref_metadata_2025_split huggingface dataset:
The definition of sandstone-bearing formations in the Isle of Man and correlation with adjacent areas — evidence from sandstone chemistry
Authors: Barnes R. P. , Power G. M. , Cooper D. C. 
Published: April 2008

Abstract

The outcrop of Lower Palaeozoic rocks on the Isle of Man is dominated by thin- to medium-bedded sand-rich turbidites over most of the southeast side of the island (Lamplugh’s Lonan and Agneash Grits, comprising greywacke and quartz arenite, respectively, interbedded with mudstone) and on the northwest coast south of Peel (the Niarbyl Flags). Recent work has shown that the latter, the Niarbyl Formation, is Silurian in age and thus distinct from the otherwise early Ordovician sequences. The composition of the Niarbyl sandstone is also distinct, with comparatively low silica (SiO
2
60–66%) but elevated CaO, MgO and Cr, relative to the Ordovician sandstones.

The Ordovician sandstones fall into two compositional groups: a very mature, silica-rich (SiO
2
78–95%) quartz arenite (Agneash type) and a greywacke (Lonan type) with lower silica (SiO
2
65–78%). Most element contents vary with silica but there is a compositional hiatus. It is here inferred that the two sandstone groups represent material from separate source areas. The three tectonostratigraphical sequences distinguished in the southeast of the island all include sandstone of both compositional types in different proportions. These usually occur as units of one or other composition, but in one sequence the two are locally closely interbedded while remaining compositionally distinct. Sandstone in two possibly equivalent units may, however, vary gradationally between the two types, implying more intimate mixing. In the absence of biostratigraphical control, the geochemical data are used to constrain the various ways in which the tectonostratigraphical sequences might correlate.

The chemical signature of the Isle of Man sandstones also provides constraints on possible correlatives in adjacent areas. The Lonan type is very similar to mid-Arenig sandstone in the upper part of the Skiddaw Group of the English Lake District. The more siliceous Agneash type has no compositional comparative in the main Skiddaw Group outcrop, although sandstone comprising the enigmatic Redmain Formation is similar in composition. The Wenlock Niarbyl Formation is lithologically and chemically comparable with Wenlock turbidite sequences in the Southern Uplands terrane and in the Windermere Supergroup in the Lake District, and they may all be closely related. None provides a precise match but compositionally the Niarbyl sandstone closely resembles the sandstone of the same age in the Birk Riggs Formation of the Windermere Supergroup. Subject to a number of constraints, the chemical composition of sandstone can also provide information on the probable tectonic environment of the source rocks. On this basis, the Lonan and Niarbyl sandstones include substantial components of first- or second-cycle volcanic debris, whereas the Agneash type is dominated by mature debris reworked from older sedimentary rocks or derived from a granite/gneiss basement source.
The Silurian succession of the Isle of Man: the late Wenlock Niarbyl Formation, Dalby Group
Authors: Morris J. H. , Woodcock N. H. , Howe M. P. A. 
Published: April 2008

Abstract
Interpretation of the stratigraphy and structure of the Lower Palaeozoic Manx Group has been strongly influenced by the assumed equivalence of distinct sandstone sequences, the Niarbyl and Lonan Flags, exposed along the west and east coasts of the Isle of Man, respectively. However, new palaeontological evidence confirms an Arenig age for the Lonan Flags and indicates a mid-Silurian age for the Niarbyl Flags, thereby necessitating a complete revision of previous interpretations. The Niarbyl Flags are formally defined here as the Niarbyl Formation and are assigned to a new group, the Dalby Group. A previously unrecognized lithofacies in the formation, laminated hemipelagite, is also distinguished and described and this indicator of anoxic deposition is compared and contrasted with the Manx Group and other Lower Palaeozoic sequences. Combined turbidite facies, palaeocurrent and petrofacies analysis of the turbidite suite further serves to reinforce the distinction with the Manx Group, in particular palaeocurrent and petrofacies data that indicates provenance from a magmatic-arc source to the west-northwest. The turbidite sequence is interpreted as a mid-lower fan, slope-apron sequence of interlobe and sandy lobe packets. Finally, the regional correlation and significance of the formation in its Iapetus Ocean setting, as well as the significance of the Niarbyl Shear Zone that defines its lower contact with the Manx Group, is considered and compared.
Relationships between metamorphism and structure on the northern edge of eastern Avalonia in the Manx Group, Isle of Man
Authors: Power G. M. , Barnes R. P. 
Published: April 2008

Abstract

The early Ordovician rocks of the Isle of Man, comprising fine-grained clastic sedimentary rocks at low regional metamorphic grade, contain a range of variably developed porphyroblasts. These are used to establish the relationship between the metamorphism and early Devonian deformation. Evidence for pre-deformation mineral growth is limited to diagenetic chlorite-mica stacks which may occur in most lithostratigraphical units. The first deformation (D
1
) is marked by a pervasive cleavage, related to folding at various scales. Subsequent events formed crenulation cleavages in association with generally minor folding, including a gently dipping fabric developed relatively widely in response to the second phase of deformation (D
2
). The main metamorphic peak, represented by growth of ilmenite, Mn-rich garnet, chloritoid and cordierite in muddy facies in the Manx Group, occurred after D
1
and before the onset of D
2
. Local heating contributions are also recognized in restricted metamorphic aureoles around dioritic dykes and intermediate size granitic intrusions of syn-D
1
(Dhoon Granodiorite), syn-D
2
(Black Hut Dyke) and post-D
2
(Crosby and Foxdale Granite) ages.

Porphyroblast phases are best developed along the spine of the island and previous workers have suggested a metamorphic pattern related to underlying granitic intrusions. However, the timing of the growth of porphyroblasts within and outside the aureoles around exposed granites in this zone are very different, militating against any simple relationship between porphyroblast growth and igneous activity. Metamorphic mineral maps reveal a strong lithological control on the distribution of porphyroblasts. Chloritoid, in particular, is largely restricted to two prominent carbonaceous black mudstone units, the Barrule and Glen Rushen Formations, which strike northeast-southwest along the central part of the island. Cordierite is developed in the mudrocks of the Injebreck and Maughold Formations which crop out either side of the Barrule Formation. Further out across-strike, the absence of porphyroblasts (other than ilmenite) in the turbidite sandstone-rich parts of the sequence may again be, at least in part, related to composition. Here, however, low grades in the outermost tectonic tracts may be a real feature resulting from early D2 extensional reactivation and subsidence relative to the elevated central tracts.
Trans-Iapetus contrasts in the geological development of southern Scotland (Laurentia) and the Lakesman Terrane (Avalonia)
Authors: Barnes R. P. , Stone P. 
Published: April 2008

Abstract
The Iapetus Ocean was a major feature separating Laurentia and Avalonia in the early Ordovician. The early Palaeozoic, Laurentian margin of the ocean is preserved in the UK in inliers in the Midland Valley of Scotland and in the Southern Uplands Terrane. The oldest rocks, of similar age to the deep-marine facies of the Skiddaw and Manx Groups opposite on the Avalonian margin, form the fragmentary ophiolitic sequences preserved in the Ballantrae and Highland Border complexes. These, together with equivalents displayed more extensively in Newfoundland, show that a succession of volcanic arcs and back arc basins formed and were accreted onto the Laurentian margin as a result of subduction during the late Cambrian and early Ordovician. In contrast, a suprasubduction zone extensional regime may have dominated the Avalonian margin at that time.
Evidence for the progressive destruction of the ocean by northward directed subduction is preserved in the Caradoc-Wenlock rocks of the Southern Uplands. The tectonostratigraphic configuration, with fault-bound slices containing thick turbidite sandstone sequences, of individually restricted duration, resting southwards on progressively younger oceanic mudrocks, is suggestive of an accretionary complex, although the precise situation is debated. Interpretation of the structural complexity of the Southern Uplands is reliant upon extensive biostratigraphical data, prior to the availability of which the understanding was at a level comparable to that of the Manx Group at the present time.

The late Llandovery-Wenlock Hawick and Riccarton Groups in the Southern Uplands continue the general tectonostratigraphical pattern. These younger turbidites are, however, of distinctive lithological character and show similarities with Wenlock to Ludlow sandstone-dominated sequences in the Windermere Supergroup in the southern Lake District and the Niarbyl Formation on the Isle of Man. This correlation between the Laurentian and Avalonian margins confirms that the Iapetus Ocean was no longer a significant feature by the mid-Silurian. The Southern Uplands accretionary thrust front migrated southwards on to the Avalonian foreland during the late Silurian as the Avalonian plate was subducted beneath Laurentia. Deformation in the Southern Uplands was largely complete prior to emplacement of
c.
400 Ma granite plutons, whereas the Acadian deformation of the Skiddaw and Manx Groups was concentrated in the early Devonian at
c.
390 Ma. However, similarities in structural style in the two areas seem to arise from the operation of similar mechanisms.
Characterization of tephras using magnetic properties: an example from SE Iceland
Authors: Gonzalez Silvia , Jones Jennifer M. , Williams David L. 
Published: April 2008

Abstract
Mineral magnetic techniques have been applied to two different stratigraphic profiles excavated in the Oraefi Volcano area, SE Iceland. The profiles include sequences of soils and tephra layers of inferred age. Each profile includes the distinctive pumice tephra layer associated with the eruption of Oraefi in 1362, which is a stratigraphic marker for the area. Detailed magnetic measurements included: magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization (IRM) acquisition, back-field IRM’s and strong field thermomagnetic behaviour (Curie temperature). The results indicate that the most useful magnetic properties for distinguishing between soils and tephras are the back-field IRM’s and the Curie temperatures. Principal component analysis has been applied using all the measured magnetic properties. In this way it is possible to discriminate between different types of material in the sections, and even more importantly to correlate some tephras between the two sections. The potential of this technique to correlate tephras is promising, but further evaluation is required.
Inherited landscapes of the Sudetic Foreland (SW Poland) and implications for reconstructing uplift and erosional histories of upland terrains in Central Europe
Authors: Migoń Piotr 
Published: April 2008

Abstract
This paper provides evidence of the very varied denudation topography that had developed in the Sudetic Foreland by the end of the Palaeogene and which has survived up to the present day because of partial burial by Neogene sediments. The Sudetic Foreland comprised different landscape units and the range of relative relief within it may have been up to 600 m; 150–200 m seems to be a figure typical for the mid-Tertiary. This stands in apparent contrast to the widely held opinion that the landscape subjected to the Neogene uplift represented a planation surface. It is argued that much of the present-day topography of Central European uplands and mountains, including the adjacent Sudetes, may be inherited from the Early Cenozoic. In many cases there is generally no need to invoke complicated uplift histories, for which scarce independent geological evidence exists, to explain the origin of landsurfaces.
Palaeolandsurfaces and neotectonic analysis in the southern Sierras Pampeanas, Argentina
Authors: Costa Carlos H. , Giaccardi Aldo D. , González Díaz Emilio F. 
Published: April 2008

Abstract
The Sierras Pampeanas of northwestern Argentina are ranges underlain by crystalline basement rocks bounded on their western margins by N-S trending reverse faults along which uplift took place during the Andean orogeny. A pre-uplift regional erosion surface is commonly preserved on the eastern slopes which have been tilted in most cases towards the east. No stratigraphical units of Neogene age have been preserved on this surface. The remnants of this palaeolandsurface have been used in the southernmost Sierra de San Luis for reconstructing the palaeotopography, dismembered during Neogene tectonism. This analysis facilitated the identification of minor blocks and the calculation of the vertical component of neotectonic faults as well as a rough estimate of the rates and amplitudes of uplift along the range front. Simple geometrical techniques were applied for a preliminary balancing of cross-sections and for estimating shortening and the detachment depth of faults.
Cosmogenic isotope data support previous evidence of extremely low rates of denudation in the Dry Valleys region, southern Victoria Land, Antarctica
Authors: Summerfield M. A. , Sugden D. E. , Denton G. H. , Marchant D. R. , Cockburn H. A. P. , Stuart F. M. 
Published: April 2008

Abstract

Quantitative estimates of denudation rates in different tectonic and climatic environments are of fundamental importance to an understanding of long-term landscape development. Little quantitative information is currently available on minimum denudation rates, although this is important in placing constraints on the maximum survival potential of individual landforms or erosion surfaces in terrestrial environments. The persistence for up to >15 Ma of a hyper-arid, polar climate in the ice-free Dry Valleys area of southern Victoria Land, Antarctica, makes this a highly probable environment for minimum terrestrial denudation rates.
40
Ar/
39
Ar dating constraints on the mimimum formation ages of individual landforms indicates generally little modification of even minor features over the past few million years. Relatively, the highest rates of denudation occur at low elevations near the Ross Sea coast. By contrast, rates of landscape change are exceedingly slow at elevations above
c.
1500 m in the western Dry Valleys where landforms with a relief of a only a few metres have survived with minimal modification since the mid-Miocene. Measurements of
in situ
-produced cosmogenic isotopes indicate that even on rectilinear slopes maximum denudation rates may be only
c.
1 m Ma
−1
, with rates falling to <0.2m Ma
−1
at some locations on low relief surfaces at high elevation.
Source and fate of Chernobyl-derived radiocaesium on floodplains in Ukraine
Authors: Van Der Perk Marcel , Burrough Peter A. , Culling Adrian S. C. , Laptev Gennady V. , Prister Boris , Sansone Umberto , Voiteskhovitch Oleg V. 
Published: April 2008

Abstract
The accident in the Chernobyl nuclear power plant on 26 April 1986 has resulted in radiocaesium contamination in the Dnieper-Pripyat catchment in Ukraine, Belarus and Russia. As radiocaesium tends to be readily adsorbed by soil particles, by illitic clay minerals in particular, sedimentation and erosion of fine soil particles are the major radiocaesium redistribution processes that have occurred since initial deposition. A part of the eroded material is transported to and through the river channel. The seasonal character of fluvial transport causes deposition of this sediment on the river banks and floodplains. This is particularly relevant if floodplains are used for agriculture. The geochemical characteristics of the floodplain soils determine to what extent radiocaesium is taken up into food chains. In this paper, we try to identify the source and fate of radiocaesium on a floodplain along the Slučc River and its tributaries in the Dubrovitsa district, Ukraine, some 350 km west of the Chernobyl nuclear power plant. In July 1993, a major summer flood occurred, which inundated the floodplain for about 3 weeks. The observed provisional increase of radiocaesium contamination in soil and cow’s milk in this area after this flood is discussed in relation to soil type and proximity to the river channel.
Scientific and institutional constraints on the restoration of European floodplains
Authors: Adams W. M. , Perrow M. R. 
Published: April 2008

Abstract
Most river restoration (or often more appropriately rehabilitation) projects have focused on the river channel, in-stream and channel-edge environments. The desirability of extending restoration to the active floodplain is now widely recognized, because of the critical importance of the floodplain-riparian zone in river structure and function. However, the extension of river restoration to floodplain environments presents the environmental manager with complex scientific and institutional challenges. This paper considers the constraints on floodplain restoration as a result of scientific uncertainty, the ways in which scientific and technical knowledge are applied, the complexity of formal institutions of floodplain governance, and the complexity of informal institutions influencing floodplain environments.
Identification of an ecologically based floodway: the case of the Cosumnes River, California
Authors: Andrews Elizabeth S. 
Published: April 2008

Abstract
The opportunities for restoring natural floodplain function along the Cosumnes River in California, USA, were evaluated by integrating traditional methods of engineering floodplain analysis with geomorphological analysis. The specific goal for floodplain restoration was the reestablishment of physical processes that would lead to the creation of cottonwood forest, and ultimately the generation of riparian oak woodland, while preserving or reducing current off-site flood hazards. Long-term trends, current hydraulic conditions, anticipated ecological value, and expected future conditions were evaluated to identify an appropriate floodplain restoration goal for the river.
The use of floodplain sedimentation measurements to evaluate the effects of river restoration works
Authors: Asselman Nathalie E. M. 
Published: April 2008

Abstract
Over the past century, many rivers throughout Europe have been channelized. The channel of the River Rhine in the Netherlands was straightened, groynes were built, and minor river dykes were constructed to prevent inundation of parts of the embanked floodplain during minor floods. More recently, however, ecological rehabilitation of the rivers Rhine and Meuse and the reduction of flood risk have become major issues for river management in the Netherlands. Various projects for restoration of the embanked floodplains to a more natural state and for the improvement of the discharge capacity of the high-water floodway have been initiated. Proposed measures include the construction of side channels through the floodplain, lowering of the floodplain surface by several decimetres, removal of minor river dykes, and reintroduction of floodplain forests. These measures will alter floodplain sedimentation rates. The aim of this paper is to evaluate the possible effects of such river rehabilitation measures on sediment accumulation using the results of overbank sedimentation measurements. The measurements were carried out during several floods at different floodplain sections along the rivers Waal and Meuse in the Netherlands. Sediment traps made of artificial grass were used to collect the deposited sediment. By comparing amounts and patterns of sediment deposited at floodplain sections characterized by different topography, the possible effects of rehabilitation measures on floodplain sedimentation are assessed. The findings are compared with model predictions. Results indicate that removal of minor dykes and lowering of the floodplain surface will significantly enhance sedimentation, whereas the impact of changes in vegetation cover from grass to grass with clusters of trees will be small.
Island topography mapping for the Brahmaputra-Jamuna River using remote sensing and GIS
Authors: Hassan A. , Martin T. C. , Mosselman E. 
Published: April 2008

Abstract
The significance of river morphology and the need to develop reliable morphological prediction methods require better knowledge of river-bed and island topography. This study focuses on techniques for determining the topography of exposed chars (char is defined here as a vegetated island (island-char) or an area of vegetated land within the braid belt that is attached to the floodplain (attached-char)) within the braid belt of the Brahmaputra-Jamuna River, based on land cover and age of the land surface. Traditionally, char topography is assessed from widespread field surveys, which are both costly and time-consuming. In addition, the river is highly dynamic and the utility of field survey is limited beyond 1 year. This study explores the use of remote sensing as a cost-effective and rapid method of acquiring synoptic data on land elevations in the low relief of the Brahmaputra-Jamuna braid belt. The land elevations assessed indirectly by remote sensing are combined with ground surveys for calibration. The results indicate that the rate of char elevation growth is initially high, but decreases as the char matures. It appears that growth ceases after about 7 years, and that char elevation reaches a level that is maintained, provided the char is not subjected to erosion. A multitemporal satellite image database and field survey measurements at corresponding dates are required to develop the method. Extensive survey data are not available, hence verification of the method is limited. Despite this limitation the results give approximate char heights, which can be used for sediment budgeting and other morphological studies.
The contribution of a multiproxy approach in reconstructing floodplain development
Authors: Dinnin Mark , Brayshay Barbara 
Published: April 2008

Abstract
This paper discusses the results of palynological, fossil insect and sedimentological investigations of floodplain deposits in the lower reaches of the River Trent. The results demonstrate the value of using multiproxy records by enhancing the resolution of a model for the development of the Trent floodplain during Holocene time. In particular, these data provide evidence for ecological and hydrological process-response relationships within the catchment. The combined results highlight the role of anthropogenic disturbance in major changes in floodplain ecology and hydrology during the later prehistoric and historical periods. The results and their implications for nature conservation management of floodplain natural resources are discussed in their national contexts and with reference to the implications for habitat restoration.