bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstruction of continental margin architecture deformed by the contraction of the Lagonegro Basin, southern Apennines, Italy
Authors: MAZZOLI S. , BARKHAM S. , CELLO G. , GAMBINI R. , MATTIONI L. , SHINER P. , TONDI E.
Published: June 2010

Thrust propagation through previously rifted continental margins may result in fold and thrust belts whose structure is strongly controlled by the inherited basin architecture, as it occurs in southern Italy. The Lagonegro units of the southern Apennines comprise a deformed pelagic basin succession showing variable stratigraphic characteristics, mainly lateral variations in both facies and thickness, interpreted to be due to a complex basin topography related to a Triassic rifting event. In contrast to previous studies, cross-section balancing and restoration indicate that the Lagonegro units exposed in the high Agri Valley area suffered relatively limited internal shortening (8 km, i.e. 35%). Early deformation of these rocks, later incorporated into a large-displacement thrust sheet, was dominated by folding around (present-day) roughly north–south-trending axes. The attainment of a regional décollement level was favoured by an early
mild inversion
of the basin, producing a roughly similar structural elevation of both hanging-wall and footwall successions to Mesozoic faults. Most of the contractional deformation was accommodated by buckling of the Mesozoic syn-rift strata between synsedimentary faults, which represented major mechanical interfaces. Early strain localization in the Lagonegro Basin ahead of the active thrust front was most probably mechanically controlled by a faulted crustal segment which originally lay, within the continental margin, between two massive carbonate platforms.
Terrane evolution of the paratectonic Caledonides of northern Britain
Authors: ARMSTRONG H. A. , OWEN A. W.
Published: June 2010

A stratigraphically constrained re-evaluation of terrane amalgamation in the Caledonides of northern Britain allows the development of a new orogenic scenario which accounts for many of the outstanding problems in the paratectonic Caledonides and includes a new terrane template which correlates well with that proposed for Newfoundland. The Arenig Grampian Orogeny resulted from the accretion of two arc terranes to Laurentia: the Midland Valley (=Notre Dame Arc in Newfoundland) and a terrane of probable Avalonian/Gondwanan origin, here termed ‘Novantia’ (= Annieopsquotch Accretionary Tract
partim
), now hidden beneath the Southern Uplands allochthon. The Tyrone and Ballantrae ophiolites mark the northern boundary of Novantia within the composite Midland Valley Terrane. The Popelogan–Victoria Arc–Grangegeeth Terrane accreted to the amalgamated Midland Valley Terrane during the late Ordovician and initiated the Southern Uplands thrust duplex. A brief period of northward subduction during the Silurian followed, is ascribed to the northerly drift of the amalgamated Avalon–Baltica plate, and a final Wenlock (Scandian) collision and caused underplating of the Midland Valley Terrane. Caledonian deformation had ceased by the Emsian, the age of the undeformed Cheviot lavas that overlie the uplifted and peneplaned Southern Uplands.
U–Pb zircon ages from the Spontang Ophiolite, Ladakh Himalaya
Authors: PEDERSEN R. B. , SEARLE M. P. , CORFIELD R. I.
Published: June 2010

The Spontang Ophiolite in the Ladakh Himalaya consist of a thrust sheet of upper mantle and oceanic crustal rocks obducted onto the northern passive continental margin of India during the late Cretaceous. Precise isotopic ages of Himalayan ophiolites are presently unavailable. U–Pb dating of zircons from a dioritic segregation in the high-level gabbros of the Spontang ophiolite shows that the complex formed at 177±1 Ma (mid-Jurassic) and we suggest that it represents a fragment of Neo-Tethyan oceanic crust. This Jurassic age contrasts with late Cretaceous ages (91–95 Ma) previously reported for the formation of the Troodos and Oman ophiolite complexes further west along the Neo-Tethyan suture zone and also predates the early to mid-Cretaceous Masirah ophiolite (c. 150 Ma) and its alkaline volcanic seamounts (115–125 Ma). An andesitic rock from an arc sequence overlying the Spontang ophiolite was also dated using as 88±5 Ma. This Late Cretaceous age constrains the minimum age of initiation of subduction beneath the Spontang Ophiolite. The complex was emplaced during the Turonian–Maastrictian, some 80 Ma after its formation when the Indian continental margin collided with a Cretaceous arc about 25 Ma before the India–Asia collision. The lack of a sub-ophiolite metamorphic sheet beneath the Spontang mantle sequence may be explained by the fact that the ophiolite was old and cold at the time of obduction.
Petrogenesis of high Ba–Sr granites: the Rogart pluton, Sutherland
Authors: FOWLER M. B. , HENNEY P. J. , DARBYSHIRE D. P. F. , GREENWOOD P. B.
Published: June 2010

The Rogart pluton is a typical example of high Ba–Sr granitic magmatism, emplaced in northern Scotland towards the end of the Caledonian Orogeny. It consists of three granitoid facies (tonalite, granodiorite, granite) that are locally associated with large enclaves of coeval mafic appinite. The overall range of compositions is therefore extreme, with MgO from 11.6 to <0.1 wt%, SiO
2
from 47.50 to >73.0 wt%, with relatively high Na
2
O+K
2
O especially for the mafic rocks (up to 8.4 wt%), associated with K
2
O/Na
2
O≈1.5. Trace element abundances vary extensively and coherently, and the typical high Ba–Sr elemental signature of the pluton is also carried by the appinites. This is consistent with a genetic relationship throughout the suite. Sr, Nd and O isotope ratios are sufficiently similar to support this contention, but vary systematically with magma evolution. The appinites were derived from an enriched mantle source (
143
Nd/
144
Nd
400
≈0.51194,
87
Sr/
86
Sr
400
≈0.7061) with high δ
18
O (≈+8‰), probably related to active contemporaneous subduction. Quantitative elemental and isotopic modelling suggests that the granitoid magmas evolved from the appinites by crystal fractionation accompanied by minor crustal contamination. Early fractionation from appinite to tonalite was driven by crystallization of pyroxene plus biotite with minor plagioclase, replaced by a feldspar-dominated assemblage to produce granodiorite and granite. The total amount of crust assimilated was less than 25%, highlighting the juvenile nature of the high Ba–Sr granite class.
High- and low-K granites and adakites at a Palaeoproterozoic plate boundary in northwestern Australia
Authors: SHEPPARD S. , GRIFFIN T. J. , TYLER I. M. , PAGE R. W.
Published: June 2010

The Lamboo Complex is one of several Palaeoproterozoic terrains in northern Australia that is intruded by high-K, I-type granites. The oldest granites in the complex consist of the high-K 1865–1850 Ma Paperbark supersuite with initial ϵ
Nd
values between −2.7 and −4.0. Tonalite sheets of the
c
. 1850 Ma Dougalls suite have high Al
2
O
3
, Na
2
O, Sr, Sr/Y and La/Yb, and low Y and HREE, and initial ϵ
Nd
values between +1.4 and +0.7. The rocks have compositions similar to adakites that form by melting of mafic rocks in the deep crust with garnet in the residue. Granites of the 1835–1805 Ma Sally Downs supersuite range from high-K types through to crustally derived adakites, all with initial ϵ
Nd
values between +0.1 and −1.2. The two supersuites and the Dougalls suite were intruded into different tectonic settings. Previously all of the granites in the Lamboo Complex were interpreted as partial melts of a chemically and isotopically uniform underplate beneath a rifted Archaean craton. However, their spatial and temporal distribution, and their varied compositions, are best explained by large-scale horizontal plate motions and subduction of oceanic crust.
Onset of Late Palaeozoic glacio-eustasy and the evolving climates of low latitude areas: a synthesis of current understanding
Authors: WRIGHT V. P. , VANSTONE S. D.
Published: June 2010

Studies of depth sensitive carbonate successions in the UK indicate that regular, orbitally forced glacio-eustatic sea-level oscillations, which characterized the late Palaeozoic, started abruptly around 330 Ma (early Asbian). The Gondwanan ice sheet was highly sensitive to orbitally forced variations in solar insolation and the resultant sea-level oscillations had an approximate 100 ka periodicity. Studies of fossil soils and palaeokarst from low latitude settings suggest that pre-Asbian climates were relatively stable with infrequent changes. However, climatic changes became increasingly frequent in the Asbian and Brigantian, with regular fluctuations of a sub-100 ka periodicity occurring during glacial lowstand intervals.
Protracted felsic magmatic activity associated with the opening of the South Atlantic
Authors: KIRSTEIN L. A. , KELLEY S. , HAWKESWORTH C. , TURNER S. , MANTOVANI M. , WIJBRANS J.
Published: June 2010

Felsic magmatism is often observed in the final stages of the eruption of continental large igneous provinces. The occurrence of these felsic extrusive igneous rocks potentially provides key information on the complex interplay of magmatism and tectonics. In this paper we investigate the timing of eruption of Early Cretaceous felsic magmas associated with the Paraná–Etendeka flood basalt province using the
40
Ar/
39
Ar technique and interpret the results in terms of the recently proposed petrogenetic histories and dominant stress factors. There appears to be a link between lithospheric thinning and a change in the origin of the felsic magmas, from open system fractional crystallization to mid/lower crustal melting, particularly in southern Uruguay.
Emeishan Basalts, SW China: reappraisal of the formation’s type area stratigraphy and a discussion of its significance as a large igneous province
Authors: THOMPSON GARY M. , ALI JASON R. , SONG XIEYAN , JOLLEY DAVID W.
Published: June 2010

The late Permian Emeishan Basalt Formation of SW China is one of Earth’s LIPs (large igneous provinces), yet its basic geology remains poorly documented. Recent work on sections close to the type area in Sichuan Province enable us in part to rectify this. Descriptions of the formation and associated units at two areas, one on the lower flanks of Mt Emei and another from a series of outcrops in Ebian County, 50–70 km to the SW, are presented. The basalt pile is 180–270 m thick and in both areas comprises 12 flows that were erupted in relatively quick succession. It rests conformably upon shallow-marine limestones/lignites suggesting emplacement close to sea level. The upper half of the youngest basalt was intensively weathered, but not eroded, prior to it being conformably succeeded by complex body of rocks
c.
 30 m thick, that includes thin basalts, pyroclastic rocks, tuffs and organic-rich terrestrial sediments. This unit, which has previously been described as a sedimentary package, presumably because intense weathering has obscured the primary lithological fabric in key outcrops, is considered to mark the volcanic waning phase. Uppermost Permian and Triassic terrestrial sediments conformably overlie the terminal volcanic rocks. The sub-regional stratigraphy is compared, as best it can be, with that described from two sections 400 km to the SE; one section matches reasonably well, the other does not, indicating that regional correlations need to be developed carefully. The information is discussed in the context of LIP generator models; several key features of the Emeishan Basalt terrain are at odds with those commonly encountered in LIP’s. The most important conclusion is that the unit marks a prematurely terminated system in which full bloodied rifting leading to the development of an ocean basin never started.
Platiniferous chromitite and the tectonic setting of ultramafic rocks in Cabo Ortegal, NW Spain
Authors: MORENO TERESA , GIBBONS WES , PRICHARD HAZEL M. , LUNAR ROSARIO
Published: June 2010

High-Cr number (Cr#) chromitites with exceptional concentrations of platinum (up to 7000 ppb) and palladium (up to 4400 ppb) occur in sulphide-poor dunites exposed along the western side of the ultramafic Herbeira Massif at Cabo Ortegal, NW Spain. The Pt–Pd enriched chromitites are restricted to the exposed top of the
c.
 800 m thick Herbeira Layered Complex, which comprises two dunite-dominated units (lower and upper dunites) separated by a garnet-bearing pyroxenite-dominated unit. The Herbeira Layered Complex is interpreted as lower crustal and is underlain by high-Al spinel harzburgite interpreted as mantle tectonite. Dunite lenses within this underlying tectonized harzburgite also contain high-Cr# chromitites, but these are Pt–Pd depleted (Pt and Pd have been strongly fractionated into the overlying Herbeira Layered Complex). Highest Pt and Pd concentrations are restricted to the top of the upper dunite, where a negative Ru anomaly also becomes apparent. The Cabo Ortegal ultramafics form part of a high grade terrane with HP granulites, garnet pyroxenites and eclogites, and are similar to PGE-rich chromite concentrations in arc root complexes in Pakistan (Jijal) and Alaska (Talkeetna and Tonsina). The Cabo Ortegal chromitites are interpreted as having crystallized from a sulphide-poor, mantle-derived suprasubduction melt deep within an arc massif subsequently thrust over the Gondwanan continent during Variscan collision.
Metamorphism and exhumation of the NW Himalaya constrained by U–Th–Pb analyses of detrital monazite grains from early foreland basin sediments
Authors: WHITE NIKKI M. , PARRISH R. R. , BICKLE M. J. , NAJMAN Y. M. R. , BURBANK D. , MAITHANI A.
Published: June 2010

Single detrital monazite grains from the Dharamsala and Lower Siwalik Formations (early to mid-Miocene continental foreland basin sediments in NW India) have been dated by two techniques; isotope dilution thermal ionization multicollector mass spectrometry (ID-TIMS) and laser ablation plasma ionization multicollector mass spectrometry (LA-PIMMS). The results give U–Th–Pb isotopic ages of
c.
 400–1300 Ma and 28–37 Ma and suggest that the source of detritus shed from the uplifting Himalayan mountains and captured in the foreland basin included (1) the protolith to the High Himalayan Crystalline Series (HHCS), i.e. rocks unaffected by the Himalayan metamorphism, (2) Cambro-Ordovician granites and (3) HHCS affected by the M
1
phase of Barrovian metamorphism (Eo-Himalayan) related to the Indo-Asian collision. Deposition of the Dharamsala Formation was coeval with M
2
sillimanite grade Himalayan metamorphism and crustal melting.

The youngest monazite (
c.
 28–37 Ma) ages imply that Indian plate rocks, having experienced the earliest Himalayan metamorphic event which occurred within 10–20 Ma of collision were exhumed, eroded and deposited within
c.
 10–20 Ma of metamorphism. This indicates a minimum cooling rate of between 60 and 40°C Ma
−1
for the period 30–20 Ma. After 20 Ma our study suggests no change in source area and that this same sequence, comprising both metamorphosed and unmetamorphosed rocks, was supplying detritus and being progressively incised by erosion for at least a further 8 million years.
Tabular intrusion and folding of the late Archaean Murehwa granite, Zimbabwe, during regional shortening
Authors: BLENKINSOP TOM G. , TRELOAR PETER J.
Published: June 2010

The Murehwa granite belongs to the late Archaean Chilimanzi suite of granites that occupy more than 50% of the Zimbabwe craton. The granite has compositional layers on metre to tens of metre scales with generally shallow dips, and dip directions towards the centre of the granite near its margins. The layering is systematically folded about sub-horizontal east–west axes. Microcline phenocrysts are generally strongly aligned parallel to the layering, but locally crosscut the layering because they are axial planar to the folds. Crystals are not significantly deformed: fabrics are thus magmatic. The granite was intruded in a tabular sheet that may have been only about 6 km thick and fed by dykes, contrary to previous concepts of diapirism/ballooning for some Archaean granites of the Zimbabwe craton. The systematic orientation of magmatic folds and axial planar fabrics demonstrate that the granite was intruded during regional north-south shortening. This shortening is consistent with the orientation of cratonic-scale fractures that were intruded by the Great Dyke within 25 Ma of the intrusion of the Murehwa granite. The granite may have intruded in a relatively short interval of less than 1–26 Ma, within the longer duration of the entire Chilimanzi granite event.
Systematic destruction of K-feldspar in deeply buried rift and passive margin sandstones
Authors: WILKINSON M. , MILLIKEN KITTY L. , HASZELDINE R. STUART
Published: June 2010

Systematic patterns of detrital K-feldspar decline with increasing burial depth are revealed during deep burial (1.5–4.5 km) of sandstones in diverse sedimentary basins from three rift and two passive margin settings in the North Sea and USA Gulf Coast. K-feldspar destruction is predominantly by dissolution, though
in-situ
alteration to albite also occurs. Dissolution can remove up to 15% solid volume of the rock by 4.5 km, so that primary arkosic sandstones become diagenetic quartzarenites at depth, with increased secondary:primary porosity ratios. The quantity of K-feldspar destroyed during temperature increase is very variable: 0.05–1.0% solid volume/°C. Compaction continues during deep burial and petrographic textures diagnostic of secondary porosity are destroyed (so that many sandstones preserve <10% secondary porosity). Alternative explanations for K-feldspar reduction with depth, including changes in original sediment provenance controlling the observed variation of feldspar with depth, or that source areas changed during deposition, can be refuted. Deeply buried sandstones are not reliable records of depositional composition.

Exceptions to this scenario of detrital K-feldspar dissolution are noted. Proximity of K-rich evaporites, high SiO
2
and K
+
activity due to the breakdown of volcanic clasts or very low
P

CO
2

can stabilize both K-feldspar and a suite of K-rich cements.
Geochemistry of pelagic and hemipelagic carbonates: criteria for identifying systems tracts and sea-level change
Authors: JARVIS IAN , MURPHY AMANDA M. , GALE ANDREW S.
Published: June 2010

The elemental (Si, Ti, Al, Mn, Ca, Zr) and carbon stable-isotope (δ
13
C) geochemistry of a biostratigraphically well-constrained Cenomanian–Turonian (Upper Cretaceous) Chalk succession on the Isle of Wight, southern England, shows systematic variation that corresponds closely to a published sequence stratigraphic model for the Cenomanian. Six sequences and their constituent systems tracts, defined elsewhere using sedimentological criteria, are clearly distinguishable from bulk-sediment elemental profiles, and an additional Upper Cenomanian sequence previously identified in Spain is recognized in England from these geochemical data. The manganese curve is particularly instructive, exhibiting minima around sequence boundaries and through lowstands, rising values from the transgressive surfaces through transgressive systems tracts, maxima around maximum flooding surfaces, and declining values through highstands. Silica and trace-element (Ti, Zr) aluminium ratios peak around transgressive surfaces and maximum flooding surfaces, indicating pulses of increased siliciclastic input. Positive δ
13
C excursions are confirmed at the base of the Middle Cenomanian and spanning the Cenomanian–Turonian boundary but are not evident in other sequences. Variation in Mn is related to bulk sedimentation rate and detrital versus biogenic supply, which control the Mn flux and the efficiency of the diagenetic Mn ‘pump’ that leads to elevated Mn contents in sediments. Manganese peaks do not generally correlate with positive δ
13
C excursions, and although near-coincident Mn and δ
13
C peaks occur around the Cenomanian–Turonian boundary, the former is not necessarily linked to the oceanic anoxic event occurring at that time. The global oceanic Mn flux may have been enhanced during the Cenomanian as a result of hydrothermal activity during rapid sea-floor spreading and oceanic plateau formation. Elemental chemostratigraphy provides a new tool for developing sequence stratigraphic models in pelagic and hemipelagic carbonate successions.
Styles of sedimentation beneath Svalbard valley glaciers under changing dynamic and thermal regimes
Authors: GLASSER NEIL F. , HAMBREY MICHAEL J.
Published: June 2010

Glacier beds provide crucial information concerning past and present ice dynamics and thermal regime. In this paper we present structural and sedimentological data from four valley glaciers (Austre Lovénbreen, Midtre Lovénbreen, Vestre Lovénbreen and Austre Brøggerbreen) on Brøggerhalvøya, NW Spitsbergen. The main focus of this paper is Midtre and Austre Lovénbreen, two typical High-Arctic land-based polythermal valley glaciers; the former has a long record of documentation regarding its response to twentieth century climatic warming. Structural mapping on the glacier surface and analysis of sediments in the proglacial area of Midtre Lovénbreen indicate that the dynamic regime and thermal structure of the glacier have changed through time. Dynamically, Midtre Lovénbreen was once heavily crevassed and relatively fast moving, but now is virtually crevasse-free and slow moving. The sedimentary record indicates that extensive areas of this glacier were wet-based when it was in a more advanced state, probably at its Neoglacial maximum (late nineteenth/early twentieth centuries). During this advance, a thin deforming layer of diamicton, commonly fluted, was draped over the existing morphology in the presently exposed proglacial area. This morphology consisted of large streamlined ridges aligned parallel to ice flow. Erosion of the underlying bedrock appears to have been limited. Radio-echo soundings of the glacier show that, at present, it is characterized by a polythermal basal thermal regime, with wet-based subglacial conditions only beneath its thicker parts. Modification of the bed is limited under this thermal regime and, as a result, the supraglacial environment dominates modern sedimentation. Comparative studies on Austre Lovénbreen, which also is probably polythermal, indicate similar sedimentary characteristics and facies associations, although here there are much more extensive areas of striated bedrock indicative of former basal sliding. In contrast both Austre Brøggerbreen and, by analogy, Vestre Lovénbreen are known to be predominantly cold-based. Collectively, these four glaciers suggest a trend of glacier recession and thinning accompanied by a change in thermal regime from predominantly wet-based, through partly frozen, to completely frozen. This study suggests that Svalbard valley glaciers have several dynamic modes and that glaciers switch between these modes largely as a reaction to changes in mass balance.
Biodiversity and terrestrial ecology of a mid-Cretaceous, high-latitude floodplain, Alexander Island, Antarctica
Authors: FALCON-LANG H. J. , CANTRILL D. J. , NICHOLS G. J.
Published: June 2010

The biodiversity and terrestrial ecology of the Late Albian Triton Point Formation (Fossil Bluff Group), Alexander Island, Antarctica is analysed to improve our understanding of polar biomes during the mid-Cretaceous thermal optimum. This formation was deposited on a high-latitude (75°S) floodplain and consists of two facies associations, a lower braided alluvial plain unit and an upper coastal meander-belt unit. Analysis of fossil plants in well exposed palaeosols reveals the existence of spatially complex plant communities. Braidplains supported patchy, low-density (91 trees/ha) stands of podocarp and taxodioid conifers on floodbasin substrates, and conifer–cycadophyte–fern–angiosperm thickets in riparian settings. Coastal meander-belts supported medium density (568 trees/ha) podocarp–araucarian conifer forests on mature floodbasin soils, and fern–angiosperm–ginkgo thickets in riparian settings. Growth-ring analysis indicates plants experienced stressful growing conditions on the braidplain characterized by high-frequency flood events, but more favourable growing conditions on the coastal plain. Additional vegetation disturbances were caused by arthropod–fungal attack, frost and wildfire. In terms of structure, composition, ecology and productivity these predominantly evergreen, broad-leafed conifer forests bear similarities to the extant temperate rainforests of New Zealand.
SHRIMP U–Pb zircon dating of the exhumation of the Lizard Peridotite and its emplacement over crustal rocks: constraints for tectonic models
Authors: NUTMAN A. P. , GREEN D. H. , COOK C. A. , STYLES M. T. , HOLDSWORTH R. E.
Published: June 2010

On the Lizard Peninsula of Cornwall, UK, within the European Variscan orogenic belt, the Lizard Peridotite preserves evidence of high-temperature exhumation from
c.
 15 kbar, 1250–1300°C to <8 kbar, <900°C in marginal peridotite tectonite, and emplacement into mafic and pelitic rocks undergoing regional metamorphism. Following exhumation, the peridotite was intruded by troctolite and gabbro, and after cooling, by NNW–SSE-trending mafic dykes and shallow-dipping mafic sheets. Very shortly after this, the peridotite and associated rocks forming the Lizard Complex, were thrust over crustal rocks and intruded by granite and granitic injection gneiss, assumed to be derived from underlying continental crust. The Lizard Peridotite and associated gabbros have been interpreted as an ophiolite or having developed during extension to form a basin within, or at the margin of, continental crust. Using the ion-microprobe (SHRIMP) we address questions of these multiple events and histories recorded from complex, zoned zircons and their relevance to different tectonic models.

Zircons in an metagabbro marginal to peridotite in the NE of the complex (Landewednack or Traboe Hornblende Schists) yield a date of metamorphism of 387±7 Ma. In Landewednack Hornblende Schists structurally below the peridotite in the SW corner of the complex, low-U zircon grew at 379±25 Ma during ‘Barrovian’ amphibolite facies metamorphism. Two samples of Traboe Hornblende Schists, one in the amphibolite-granulite facies thermal aureole of the exhuming peridotite and the other one granulite within the marginal peridotite tectonite, have yielded metamorphic zircons dated at 393±6 Ma, and 386±7 Ma. One inherited old zircon core (two analyses—high U and
c.
 500 Ma) was detected in the Traboe Hornblende Schist sample from within the peridotite tectonite, and provides a link between them and the continental rocks of the Old Lizard Head Series (which are cut by granodioritic sheets which contain
c.
 500 Ma, high U, magmatic zircons) and the Landewednack Schists (which have biotite schist layers with
c.
 500 Ma zircons) in the south of the complex. Kennack Gneiss granite sheets intruded into the peridotite have been dated at 384±4 Ma, 396±10 Ma and 391±8 Ma by U–Pb zircon. Inherited Proterozoic zircons within Kennack Gneiss granites shows that source sialic (zircon-bearing) crust already (tectonically) underlay the peridotite by the time the granites were emplaced. Together with the date of 397±2 Ma on a ‘plagiogranite’ sheet the results show that exhumation of the peridotite, intrusion of gabbros into it and subsequent compression, detachment and stacking of the Lizard Peridotite over crust which melted to give the Kennack Gneiss granites occurred within a short interval between 380 and 400 Ma (Eifelian–Emsian).
Constraints on early sinistral displacements along the Great Glen Fault Zone, Scotland: structural setting, U–Pb geochronology and emplacement of the syn‐tectonic Clunes tonalite
Authors: STEWART M. , STRACHAN R. A. , MARTIN M. W. , HOLDSWORTH R. E.
Published: June 2010

Abstract:
Current tectonic models emphasize the role of crustal‐scale transcurrent faults in controlling the ascent and emplacement of plutons in orogenic belts. The Clunes Tonalite crops out adjacent to the transcurrent Great Glen Fault Zone within the Ordovician‐Silurian Caledonian orogenic belt of Scotland. The tonalite is characterized by a strong fabric defined by aligned plagioclase, hornblende and biotite that is interpreted to be a magmatic state deformation fabric formed during emplacement. Field and microstructural evidence derived from the tonalite and its Moine Supergroup country rocks supports an emplacement model that links intrusion directly to early sinistral displacements along the Great Glen Fault Zone. U–Pb zircon geochronology yields a crystallization age for the Clunes Tonalite of 427.8±1.9 Ma. The age is thus interpreted to date early sinistral displacements along the Great Glen Fault Zone and is identical within error to that of the Ratagain granite emplaced during sinistral displacement along the Strathconon Fault to the NW.
Annual to sub-annual resolution of multiple trace-element trends in speleothems
Authors: FAIRCHILD IAN J. , BAKER ANDY , BORSATO ANDREA , FRISIA SILVIA , HINTON RICHARD W. , McDERMOTT FRANK , TOOTH ANNA F.
Published: June 2010

This study aims to establish evidence for the widespread existence of preserved high-resolution trace element variations in speleothems that may have climatic significance. Ion microprobe analysis of speleothems reveals that annual to sub-annual variations in element chemistry exist at five, shallow western European cave sites (Crag Cave, County Kerry and Ballynamintra, County Waterford, Ireland; Uamh an Tartair, Sutherland, Scotland; Grotte Pere-Noël, Belgium; Grotta di Ernesto, NE Italy) with widely varying climatic, geomorphic and geological settings. The variations are not restricted to species (Mg, Sr and Ba) known to substitute directly for Ca in the calcite lattice, but include H, F, Na and P. Phosphorus (as phosphate) displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element. The technique allows estimation of growth rate of speleothems at any interval of interest, which is one of several possible uses in palaeoclimatology.
Phosphate homeostasis and the renal-gastrointestinal axis
Authors: Marks Joanne , Debnam Edward S. , Unwin Robert J.
Published: June 2010

Transport of phosphate across intestinal and renal epithelia is essential for normal phosphate balance, yet we know less about the mechanisms and regulation of intestinal phosphate absorption than we do about phosphate handling by the kidney. Recent studies have provided strong evidence that the sodium-phosphate cotransporter NaPi-IIb is responsible for sodium-dependent phosphate absorption by the small intestine, and it might be that this protein can link changes in dietary phosphate to altered renal phosphate excretion to maintain phosphate balance. Evidence is also emerging that specific regions of the small intestine adapt differently to acute or chronic changes in dietary phosphate load and that phosphatonins inhibit both renal and intestinal phosphate transport. This review summarizes our current understanding of the mechanisms and control of intestinal phosphate absorption and how it may be related to renal phosphate reabsorption; it also considers the ways in which the gut could be targeted to prevent, or limit, hyperphosphatemia in chronic and end-stage renal failure.
Indoxyl sulfate inhibits proliferation of human proximal tubular cells via endoplasmic reticulum stress
Authors: Kawakami Takahisa , Inagi Reiko , Wada Takehiko , Tanaka Tetsuhiro , Fujita Toshiro , Nangaku Masaomi
Published: June 2010

Uremic toxins can deteriorate renal function, but little is known about its mechanism. Because tubular injury is central to progression of chronic kidney disease (CKD), we investigated the effects of a representative uremic toxin indoxyl sulfate (IS) on tubular cells. IS induced endoplasmic reticulum (ER) stress in cultured human proximal tubular cells, demonstrated by the increase in C/EBP homologous protein (CHOP) in the immunoblots. Moreover, administration of an oral adsorbent AST-120 reduced serum IS concentration and decreased tubular expression of CHOP in immunohistochemistry in 5/6-nephretomized, CKD model, rats. Furthermore, we disclosed that IS inhibited proliferation of tubular cells in 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and 5-bromo-2′-deoxyuridine assay, whereas the results of trypan blue exclusion and lactate dehydrogenase assay showed that IS did not promote cell death. This inhibition was mitigated by small interfering (si) RNA against CHOP. Furthermore, IS increased the cyclin-dependent kinase inhibitor p21WAF1/CIP1(p21). Surprisingly, this was mediated by the inflammatory cytokine interleukin (IL)-6, the expression of which was decreased by siRNA against activating transcription factor 4, another ER stress marker; however, the induction of IL-6 and p21 by IS was not suppressed by siRNA targeted to CHOP, suggesting that they were downstream of ER stress, but independent of CHOP. Moreover, we found that their upregulation was dependent on ERK, using the ERK pathway inhibitor U-0126. Collectively, we demonstrated that IS induced ER stress in tubular cells and inhibited cell proliferation via two pathways downstream of ER stress, namely CHOP and ERK-IL-6-p21. These are possible targets for suppressing progression of CKD.
A Beta Oscillation Network in the Rat Olfactory System During a 2-Alternative Choice Odor Discrimination Task
Authors: Kay Leslie M. , Beshel Jennifer
Published: June 2010

We previously showed that in a two-alternative choice (2AC) task, olfactory bulb (OB) gamma oscillations (∼70 Hz in rats) were enhanced during discrimination of structurally similar odorants (fine discrimination) versus discrimination of dissimilar odorants (coarse discrimination). In other studies (mostly employing go/no-go tasks) in multiple labs, beta oscillations (15–35 Hz) dominate the local field potential (LFP) signal in olfactory areas during odor sampling. Here we analyzed the beta frequency band power and pairwise coherence in the 2AC task. We show that in a task dominated by gamma in the OB, beta oscillations are also present in three interconnected olfactory areas (OB and anterior and posterior pyriform cortex). Only the beta band showed consistently elevated coherence during odor sniffing across all odor pairs, classes (alcohols and ketones), and discrimination types (fine and coarse), with stronger effects in first than in final criterion sessions (>70% correct). In the first sessions for fine discrimination odor pairs, beta power for incorrect trials was the same as that for correct trials for the other odor in the pair. This pattern was not repeated in coarse discrimination, in which beta power was elevated for correct relative to incorrect trials. This difference between fine and coarse odor discriminations may relate to different behavioral strategies for learning to differentiate similar versus dissimilar odors. Phase analysis showed that the OB led both pyriform areas in the beta frequency band during odor sniffing. We conclude that the beta band may be the means by which information is transmitted from the OB to higher order areas, even though task specifics modify dominance of one frequency band over another within the OB.
Roles of Monkey Premotor Neuron Classes in Movement Preparation and Execution
Authors: Kaufman Matthew T. , Churchland Mark M. , Santhanam Gopal , Yu Byron M. , Afshar Afsheen , Ryu Stephen I. , Shenoy Krishna V.
Published: June 2010

Dorsal premotor cortex (PMd) is known to be involved in the planning and execution of reaching movements. However, it is not understood how PMd plan activity—often present in the very same neurons that respond during movement—is prevented from itself producing movement. We investigated whether inhibitory interneurons might “gate” output from PMd, by maintaining high levels of inhibition during planning and reducing inhibition during execution. Recently developed methods permit distinguishing interneurons from pyramidal neurons using extracellular recordings. We extend these methods here for use with chronically implanted multi-electrode arrays. We then applied these methods to single- and multi-electrode recordings in PMd of two monkeys performing delayed-reach tasks. Responses of putative interneurons were not generally in agreement with the hypothesis that they act to gate output from the area: in particular it was not the case that interneurons tended to reduce their firing rates around the time of movement. In fact, interneurons increased their rates more than putative pyramidal neurons during both the planning and movement epochs. The two classes of neurons also differed in a number of other ways, including greater modulation across conditions for interneurons, and interneurons more frequently exhibiting increases in firing rate during movement planning and execution. These findings provide novel information about the greater responsiveness of putative PMd interneurons in motor planning and execution and suggest that we may need to consider new possibilities for how planning activity is structured such that it does not itself produce movement.
Surface-Based Information Mapping Reveals Crossmodal Vision–Action Representations in Human Parietal and Occipitotemporal Cortex
Authors: Oosterhof Nikolaas N. , Wiggett Alison J. , Diedrichsen Jörn , Tipper Steven P. , Downing Paul E.
Published: June 2010

Many lines of evidence point to a tight linkage between the perceptual and motoric representations of actions. Numerous demonstrations show how the visual perception of an action engages compatible activity in the observer's motor system. This is seen for both intransitive actions (e.g., in the case of unconscious postural imitation) and transitive actions (e.g., grasping an object). Although the discovery of “mirror neurons” in macaques has inspired explanations of these processes in human action behaviors, the evidence for areas in the human brain that similarly form a crossmodal visual/motor representation of actions remains incomplete. To address this, in the present study, participants performed and observed hand actions while being scanned with functional MRI. We took a data-driven approach by applying whole-brain information mapping using a multivoxel pattern analysis (MVPA) classifier, performed on reconstructed representations of the cortical surface. The aim was to identify regions in which local voxelwise patterns of activity can distinguish among different actions, across the visual and motor domains. Experiment 1 tested intransitive, meaningless hand movements, whereas experiment 2 tested object-directed actions (all right-handed). Our analyses of both experiments revealed crossmodal action regions in the lateral occipitotemporal cortex (bilaterally) and in the left postcentral gyrus/anterior parietal cortex. Furthermore, in experiment 2 we identified a gradient of bias in the patterns of information in the left hemisphere postcentral/parietal region. The postcentral gyrus carried more information about the effectors used to carry out the action (fingers vs. whole hand), whereas anterior parietal regions carried more information about the goal of the action (lift vs. punch). Taken together, these results provide evidence for common neural coding in these areas of the visual and motor aspects of actions, and demonstrate further how MVPA can contribute to our understanding of the nature of distributed neural representations.
Anodal Transcranial Direct Current Stimulation Enhances Procedural Consolidation
Authors: Tecchio Franca , Zappasodi Filippo , Assenza Giovanni , Tombini Mario , Vollaro Stefano , Barbati Giulia , Rossini Paolo Maria
Published: June 2010

The primary motor cortex (M1) area recruitment enlarges while learning a finger tapping sequence. Also M1 excitability increases during procedural consolidation. Our aim was to investigate whether increasing M1 excitability by anodal transcranial DC stimulation (AtDCS) when procedural consolidation occurs was able to induce an early consolidation improvement. Forty-seven right-handed healthy participants were trained in a nine-element serial finger tapping task (SFTT) executed with the left hand. Random series blocks were interspersed with training series blocks. Anodal or sham tDCS was administered over the right M1 after the end of the training session. After stimulation, the motor skills of both trained and a new untrained sequential series blocks were tested again. For each block, performance was estimated as the median execution time of correct series. Early consolidation of the trained series, assessed by the performance difference between the first block after and the last block before stimulation normalized by the random, was enhanced by anodal and not by sham tDCS. Stimulation did not affect random series execution. No stimulation effect was found on the on-line learning of the trained and new untrained series. Our results suggest that AtDCS applied on M1 soon after training improves early consolidation of procedural learning. Our data highlight the importance of neuromodulation procedures for understanding learning processes and support their use in the motor rehabilitation setting, focusing on the timing of the application.
Effect of Trandolapril on Regression of Retinopathy in Hypertensive Patients with Type 2 Diabetes: A Prespecified Analysis of the Benedict Trial
Authors: Ruggenenti Piero , Iliev Ilian , Filipponi Marco , Tadini Stefano , Perna Annalisa , Ganeva Maria , Ene-Iordache Bogdan , Cravedi Paolo , Trevisan Roberto , Bossi Antonio , Remuzzi Giuseppe
Published: June 2010

Background. The effect of angiotensin converting enzyme inhibitors (ACEi) on regression of retinopathy in type 2 diabetics is still ill defined.Methods. We compared the incidence of retinopathy regression in 90 hypertensive type 2 diabetics randomized to at least 3-year blinded ACEi with trandolapril (2 mg/day) or non-ACEi therapy who had preproliferative or proliferative retinopathy at baseline.Results. Over a median (interquartile range) follow-up period of 35.8 (12.4–60.7) months, retinopathy regressed in 27 patients (30.0%). Regression occurred in 18 of 42 patients (42.9%) on ACEi and in 9 of 48 (18.8%) on non-ACEi therapy (adjusted for predefined baseline covariates HR (95% CI): 2.75 (1.18–6.42),P=.0193). Concomitant treatment with or without Non-Dihydropyridine Calcium Channel Blockers (ndCCBs) did not appreciably affect the incidence of retinopathy regression.Conclusions. Unlike ndCCB, ACEi therapy may have an additional effect to that of intensified BP and metabolic control in promoting regression of diabetic retinopathy.
Some Nonunique Fixed Point Theorems of Ćirić Type on Cone Metric Spaces
Authors: Karapınar Erdal
Published: June 2010

Some results of (Ćirić, 1974) on a nonunique fixed point theorem on the class of metric spaces are extended to the class of cone metric spaces. Namely, nonunique fixed point theorem is proved in orbitally T complete cone metric spaces under the assumption that the cone is strongly minihedral. Regarding the scalar weight of cone metric, we are able to remove the assumption of strongly minihedral.
Lyapunov‐Based PD Linear Control of the Oscillatory Behavior of a Nonlinear Mechanical System: The Inverted Physical Pendulum with Moving Mass Case
Authors: Aguilar-Ibáñez Carlos Fernando , Gutiérrez-Frías Oscar Octavio , Martínez-García Juan Carlos , Garrido-Moctezuma Rubén , Gómez-González Bernardo
Published: June 2010

This paper concerns active vibration damping of a frictionless physical inverted pendulum with
a radially moving mass. The motion of the inverted pendulum is restricted to an admissible set.
The proposed Proportional Derivative linear controller damps the inverted pendulum (which is
anchored by a torsion spring to keep it in a stable upright position), exerting a force on the
radially moving mass. The controller design procedure, which follows a traditional Lyapunov‐based
approach, tailors the energy behavior of the system described in Euler‐Lagrange terms.
Current Hypotheses on How Microsatellite Instability Leads to Enhanced Survival of Lynch Syndrome Patients
Authors: Drescher Kristen M. , Sharma Poonam , Lynch Henry T.
Published: June 2010

High levels of microsatellite instability (MSI‐high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI‐high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.
Supporting Family Carers of Community-Dwelling Elder with Cognitive Decline: A Randomized Controlled Trial
Authors: Schoenmakers Birgitte , Buntinx Frank , Delepeleire Jan
Published: June 2010

Objective. Caring for a patient with cognitive decline has an important impact on the general well-being of family caregivers. Although highly appreciated, interventions in dementia home care remain mainly ineffective in terms of well-being. Consequently, in spite of an extensive support system, abrupt ending of home care remains more rule than exception. Method. The hypothesis was that the intervention of a care counselor, coordinating care in quasi-unstructured way during one year, will alleviate caregivers' feelings of depression. The study population was composed of community-dwelling patients with cognitive decline. A care counselor was at the exclusive disposal of the intervention group. Primary outcome measure was caregiver depression. Results. Finally, depression was 6.25 times less frequent in the intervention group. The actual intervention appeared minimal with only ten applications for more support followed by only three interventions effectively carried out. Although caregivers felt burdened and depressed, formal support remained stable. On the other hand, the availability of the care counselor made caregivers feel less depressed with the same amount of support. Conclusion. Carers do not always need to be surrounded with more professionals, but they want to feel more supported. In terms of policy, this could have some important implications.
Potential of Nonlinear Ultrasonic Indicators for Nondestructive Testing of Concrete
Authors: Payan C. , Garnier V. , Moysan J.
Published: June 2010

In the context of a growing need for safety and reliability in Civil Engineering, acoustic methods of nondestructive testing provide answers to a real industrial need. Linear indicators (wave speed and attenuation) exhibit a limited sensitivity, unlike nonlinear ones which usually have a far greater dynamic range. This paper illustrates the potential of these indicators, and evaluates its potential for in situ applications. Concrete, a structurally heterogeneous and volumetrically, mechanically damaged material, is an example of a class of materials that exhibit strong multiple scattering as well as significant elastic nonlinear response. In the context of stress monitoring in pre-stressed structures, we show that intense scattering can be applied to robustly determine velocity changes at progressively increasing applied stress using coda wave interferometry and thereby extract nonlinear coefficients. In a second part, we demonstrate the high sensitivity of nonlinear parameters to thermal damage as regard with linear ones. Then, the influence of water content and porosity on these indicators is quantified allowing to uncouple the effect of damage from environmental or structural parameters.