bluuebunny/crossref_metadata_2025 huggingface dataset:
Eclogites of the Ojén nappe: a record of subduction in the Alpujárride complex (Betic Cordilleras, southern Spain)
Authors: TUBIA J. M. , GIL IBARGUCHI J. I.
Published: December 2007

Eclogites interlayered with amphibolites and migmatites occur in an upper unit (OjCn nappe) of the Alpujarride complex (Betic Cor- dilleras). Estimates of P-T conditions reveal a retrograde meta-morphic path from an edogitic stage at >15 kbar and c. 730 °C, to amphibolite-facies conditions at 5-8 kbar or less and c. 650 °C. The Ronda peridotites belonging to the uppermost Alpujarride nappe (Los Reales nappe) structurally overlie the eclogite-bearing unit. It is suggested that eclogitic metamorphism and overthrusting of the peridotites reflect dfierent stages of the same convergent episode.
Hercynian transpressional tectonics at the southern margin of the Central Iberian Zone, west Spain
Authors: SANDERSON D. J. , ROBERTS S. , McGOWAN J. A. , GUMIEL P.
Published: December 2007

The boundary between the Central Iberian and Ossa-Morena zones, in south-central Spain, occurs within the Badajoz–Cordoba shear zone. The spatial and temporal relationships of structures across the La Codosera syncline, located within the Central Iberian zone just to the north of the shear zone, demonstrate a progressive increase in strike-slip shear towards the Badajoz shear zone.

Within the region of the La Codosera syncline, Precambrian to Cambrian rocks were subject to pre-Ordovician tilting and open folding, accompanied by local faulting and veining, but no cleavage. These, together with overlying Palaeozoic rocks were subsequently affected by Hercynian ductile deformation, which produced steeply inclined folds, cleavage and faulting. Intense left-lateral shearing on the southern limb of the La Codosera syncline produced augen, shear bands, sub-horizontal stretching lineation, boudinage, variably oriented folds and steep faults, whereas the northern limb of the syncline is characterized by folding and thrusting in a transpressional regime, with limited net northward transport.

Late Hercynian faulting produced N–S and NE–SW faults which overprint the early structures and granites. These rotate to a NW-SE trend and increase in right-lateral displacement as a result of domino or bookshelf faulting which can be attributed to continued left-lateral motion along the Badajoz shear zone.
Quaternary uplift and sea-level change at an active plate boundary, Cyprus
Authors: POOLE A. J. , ROBERTSON A. H. F.
Published: December 2007

A combination of northward underthrusting of the African plate and serpentinite diapirism resulted in progressive uplift of Cyprus during the Quaternary. The uplift was associated with the development of succession of alluvial fans and marine terraces. Marine terraces in coastal southern Cyprus are developed at 350–360 m, 110–100 m, 60–50 m, 11–8 m and 2–3 m above present sea-level. The terraces display sequences of regressive, deltaic, carbonate and siliciclastic sub-littoral, to littoral and sub-aerial type. Alluvial fans of the Fanglomerate Group crop out on the northern flanks of the Troodos Massif, forming extensive, dissected, peneplaned terraces. Later uplift resulted in the formation of channel fans and river terraces. Proximal sheetflood conglomerates pass distally into channelized braid-plain environments. On the southern margin of the Troodos Massif the Fanglomerate Group comprises braided, channelized and floodplain sequences, which pass laterally into littoral facies. Provenence studies indicate that uplift and resulting erosion of Cyprus was centred on the Troodos Massif (Mount Olympus). Radiometric dates indicate that uplift was rapid in the early and mid-Pleistocene. In the late Pleistocene—Holocene, eustatic sea-level changes and anthropogenic effects dominated, while the rate of uplift was reduced, with local submergence of southern coastal areas.
Tethyan Workshop 1991
Authors: SHARP I. , USTAOMER T.
Published: December 2007

Report of a meeting of the Tethyan Working Group, held at the University of Edinburgh, on 25–26 April 1991. The conveners were I. R. Sharp, T. Ustaomer, P. Degnan, A. H. F. Robertson and J. E. Dixon.

The latest in a long established series of Tethyan Workshops took place over a two day period in The Grant Institute at Edinburgh University. The purpose of the workshop was to provide a forum for the presentation of recent and ongoing work in the Tethyan realm, with postgraduate research being particularly featured. The Workshop was attended by about 60 geologists and geophysicists, with a strong input from foreign institutes, ensuring a good level of discussion on the evolution of the complex Tethyan region. Over the years it has become apparent that only by combining a number of geological disciplines and techniques can major progress be made in the Tethyan realm and this was reflected in the talks presented at the meeting.

G. S. Boulton opened the Workshop and introduced the first chairman,
R. Hall
(University College London). The first talk of the day was presented by
A. H. F. Robertson
(Edinburgh University) who outlined the work that has been carried out at Edinburgh over the last decade or so and its contribution towards solving some of the longstanding problems of Tethyan geology in the Mediterranean region. The main points arising from this talk were: (a) evidence from the Pontides (Turkey) suggests that Palaeotethys closed along a zone of northwards subduction-accretion; (b) no
Ion-probe zircon dating of a mid-Early Cambrian tuff in South Australia
Authors: COOPER J. A. , JENKINS R. J. F. , COMPSTON W. , WILLIAMS I. S.
Published: December 2007

Ion microprobe U-Pb dating of zircons extracted from a narrow tuff band in the Lower Cambrian Heatherdale Shale of South Australia produced an age of 526 ± 4 Ma (95% confidence limits). Local and regional trilobite and archaeocyathan evidence indicates that the tuff ìs latest Atdabanian or Botomian. The tuff shortly predates the onset of the Delamerian Orogeny.
Footwall involvement during arc-continent collision, Ungava orogen, northern Canada
Authors: LUCAS S. B. , BYRNE T.
Published: December 2007

Geological evidence and theoretical models are presented to illustrate deformation paths followed by continental crust during underthrusting, subduction and collision. Fieldwork in an early Proterozoic collisional orogen indicates that a thrust belt and its autochthonous footwall basement are obliquely exposed in a crustal cross-section with significant structural relief. The collisional orogen records an evolution in the style and extent of involvement of the Archaean footwall from: (1) underthrusting without evidence of internal deformation; (2) limited thrusting and ductile deformation of footwall rocks; to (3) folding of the entire thrust belt and its footwall into cuspate-lobate, long wavelength structures. The structural evolution occurred during hydration of basement rocks coeval with collision-related metamorphism. Lithospheric strength profiles, constrained by simple numerical heat conduction models, suggest that the observed deformation path for the footwall crust was controlled by weakening due to heating of basement rocks, and by changes in the relative strengths of different crustal layers. The profiles predict a very weak lower crust and upper mantle at the time of footwall-involved folding, suggesting that the lower crust and upper mantle deformed by ductile flow concomitant with buckling of the stronger upper crust.
Late Cretaceous to early Tertiary subduction history of the Antarctic Peninsula
Authors: McCARRON JOE J. , LARTER ROBERT D.
Published: December 2007

Quantitative estimates of the rates and azimuths of Phoenix plate convergence with the Antarctic Peninsula have been derived from plate rotation calculations for two periods in the Late Cretaceous and early Tertiary (83.0–67.7 and 61.1–53.4 Ma). Published marine magnetic anomaly identifications and ‘flow lines’ interpreted from gravity anomaly maps were used in simple spherical geometry calculations to derive Phoenix–Pacific stage rotations. These were combined with published Pacific–Antarctic rotation data to determine contemporaneous Phoenix–Antarctic stage rotations. The results indicate a significant change in azimuths of relative motion between the Late Cretaceous and early Tertiary. Late Cretaceous, and perhaps earlier, oblique subduction probably caused migration of fore-arc slivers along the margin, resulting in variations in width of the accretionary prism. Comparison between synthetic magnetic profiles and a 900 km long magnetic profile across ocean floor produced at the Antarctic–Phoenix ridge during the early Tertiary establishes the time of a major decrease in spreading rate, and hence also in convergence rate, as chron C23r (52.3 Ma). The associated change in subduction dynamics may have caused the dextral transtensional deformation observed in the George VI Sound region and initiated uplift of blueschist facies rocks now exposed on Smith Island. The calculated convergence history does not provide a simple explanation for the occurrence of high-Mg# andesite lavas on Alexander Island, which were erupted more than 20 Ma before the Antarctic–Phoenix ridge arrived at the margin. The existence of these lavas implies either earlier subduction of another ridge or slab break-up beneath Alexander Island.
Tectonic and geochronological constraints on late Archaean and Palaeoproterozoic stratigraphic correlation within and between the Kaapvaal and Pilbara Cratons
Authors: MARTIN D. McB. , CLENDENIN C. W. , KRAPEZ B. , McNAUGHTON N. J.
Published: December 2007

Recent radiometric dating of carbonates and banded iron-formations on the Kaapvaal Craton, southern Africa, has suggested that late Archaean and Palaeoproterozoic carbonate sedimentation was diachronous across the craton. We present new SHRIMP U–Pb zircon ages of 2583±5 Ma and 2588±7 Ma for two samples of a tuff bed, 320 km apart in the upper Oak Tree Formation, Transvaal Supergroup. These ages, in conjunction with published data, support previously established sequence stratigraphic correlations that show the temporal equivalence of late Archaean carbonates in the region. A review of the sequence stratigraphy and geochronology of the Mount Bruce Megasequence Set on the Pilbara Craton, Western Australia, and the newly named Highveld Megasequence Set on the Kaapvaal Craton, indicates a remarkably similar geohistory. Both cratons are characterized by a divergent megacycle (Hamersley Range and Vaal Megasequences) followed by a convergent megacycle (Chichester Range and Drakensberg Megasequences). Our data show that the megasequence boundary is marked by drowning of both cratons at approximately the same time (
c.
2590 Ma), which permits more meaningful geotectonic correlations between them.
The recognition of multiple hydrocarbon generation episodes: an example from Devonian lacustrine sedimentary rocks in the Inner Moray Firth, Scotland
Authors: MARSHALL J. E. A.
Published: December 2007

Burmah well 12/27-1, drilled on a structural high in the Inner Moray Firth, penetrated over 3000 ft (914 m) of Lower Devonian, organic-rich sedimentary rocks. These have been analysed for source-rock potential, and contain a substantial proportion of oil-prone, thermally mature kerogen. A decompacted vitrinite reflectivity profile shows that the lower part of the Devonian section has a steeper thermal maturity gradient, which is interpreted as indicating a high Devonian geothermal gradient associated with basin extension. Solid bitumen reflectivities and organic petrography show that the most recent hydrocarbon generation occurred in the upper part of the Devonian interval during maximum Tertiary burial. Vitrinite reflectivity data from the Jurassic rocks in the Beatrice Field and onshore East Sutherland enable the position of the oil generation window to be predicted in relation to the depth of the top of the Devonian sequence. The main controls on Devonian source rock potential in the Inner Moray Firth are not the depth of Mesozoic and Tertiary burial but the distribution of source rocks, their degree of Permian truncation, and the pre-Permian thermal maturity level.
The role of the Indian summer monsoon and the mid-latitude westerlies in Himalayan glaciation: review and speculative discussion
Authors: BENN D. I. , OWEN L. A.
Published: December 2007

New dates for late Quaternary glaciations in the Himalayas show that, during the last glacial cycle, glaciations were not synchronous throughout the region. Rather, in some areas glaciers reached their maxima at the global glacial maximum of
c.
18–20 ka
bp
, whereas in others glaciers were most extensive at
c.
60–30 ka
bp
. Comparison of these data with palaeoclimatic records from adjacent regions suggest that, on millennial timescales, Himalayan glacier fluctuations are controlled by variations in both the South Asian monsoon and the mid-latitude westerlies.
Granite rheology: magma flow and melt migration
Authors: BAGDASSAROV N. , DORFMAN A.
Published: December 2007

Granite magma rheology has long been studied by rock physicists, petrologists and experimentalists. New data on viscosity of dry and H
2
O-bearing melts and glasses in a wide range of temperatures and H
2
O content changed drastically the general view on the Arrhenian behaviour of granitic melts. Recent studies on the deformation of partially molten granite rocks at up to 50 vol% of melting show the failure of the RCMP (rheologically critical melt percentage) concept for granites. We present new direct measurements of melt migration from a combination of centrifuge experiments, falling sphere viscometry of partially molten granites assisted by a centrifugal field and viscoelastic behaviour of partially molten granites in torsion oscillation apparatus. The results suggest that the extrapolation of the Einstein–Roscoe equation for the viscosity of partially molten rocks does not give adequate results for granites with 50 vol% of melt phase. Rheology of granite magmas is very sensitive to chemical composition, and viscosity of the melt phase. Adding H
2
O to partially molten granites results in a decrease in the viscosity of the melt phase, as well as dissolution of quartz crystals. In turn, this produces more felsic and viscous melt. Thus, these factors smear out the contrast between partially and completely molten granites, and between anhydrous and H
2
O-bearing magmas at moderate H
2
O contents (1 to 2 wt%).
Granular flow and viscous fluctuations in low Bagnold number granitic magmas
Authors: PETFORD N. , KOENDERS M. A.
Published: December 2007

Recent thermal and fluid dynamical models have shown that density-driven ascent of isoviscous granitic melt through the crust in narrow dykes is geologically instantaneous, provided the role of suspended crystals is ignored. However, it is well known that solids in suspension can aVect significantly the rheology and hence flow properties of magmas, leading to the subjective criticism that granite ascent and emplacement rates based on simple dyke transport models may be unrealistic. By estimating the magnitude of shear stresses developed during continuous flow in a 6 m wide granitic dyke, we show yield strengths in excess of 10
4
pascals are required to stop flow entirely if the pressure gradient driving the flow is high. Using granular flow theory, we show how fluctuations in particle velocity in the shear field can be used to predict the rheological behaviour of magmas with crystal contents (solidosity) in the range 0.1<Φ<0.25.

Specimen calculations for the solidosity and fluctuation on particle velocity for ascending granitic magmas show that the energy associated with these irregular movements is much greater than that expected on purely Brownian grounds. We find no clear correlation between viscosity ì and the yield strength, and while it is possible that magma has curious, unexpected bonding properties, magmatic suspensions where the grain size is on the scale of centimetres (e.g. some coarsely porphyritic magmas), low estimated Bagnold numbers (
c.
10
"
8
) render Bingham flow models inappropriate. Self-organization of the flow into a crystal-poor margin and crystal-rich core (flow differentiation) by
diffusion
of particles towards the region of minimal shear results in the familiar plug-type flow profiles traditionally associated with an inherent yield strength. Shear-enhanced diffusion is an inevitable consequence of granular flow that leads to flow differentiation, providing a simple mechanistic explanation for high concentrations of pheoncrysts in the cores of porphyritic dykes (Bagnold effect). Deviation from simple Newtonian flow is unlikely to be significant until the magma has stopped ascending and emplacement begins.
The Pangong Injection Complex, Indian Karakoram: a case of pervasive granite flowthrough hot viscous crust
Authors: WEINBERG R. F. , SEARLE M. P.
Published: December 2007

In the Karakoram Range of NW India, the Tangtse gorge cuts across deep crustal rock sexhumed by transpression along two strands of the dextral Karakoram fault. Crustal leucogranitic magmas pervasively intruded amphibolites and migmatites in the form of sheets that locally coalesced and expanded to form kilometre-scale plutons. Sheets resulted from slow seeping of granite into foliation planes (magma wedging) rather than from dyking, driven by magma buoyancy and possibly syn-intrusive tectonic deformation. High temperature of the country rocks at the time of intrusion is inferred from similar crystallization ages of the intrusive leucogranite and
in situ
partial melt in the migmatites, and reflected in the ductile structures developed. Whereas low country rock viscosity inhibited dyking, high temperature freed the magma from the constraints of freezing and permitted pervasive intrusion. The injection complex exposed along the Tangtse gorge, rather than representing the final emplacement structures, represent transient structures of the granite pathways on their upward journey to build the Karakoram batholith, which crops out a few kilometres north, at structurally shallower levels. We suggest that pervasive magma flow is a transitional step between magma segregation at the source and later rise through cold crust and it may be one of several factors controlling whether dyking or diapirism becomes dominant during late ascent.
Neotectonics of western India: evidence from deformed Quaternary fluvial sequences, Mahi River, Gujarat
Authors: JAIN MAYANK , WOODCOCK NIGEL H. , TANDON SAMPAT K.
Published: December 2007

A Quaternary fluvial sequence along the Mahi River, Gujarat, western India, shows evidence for a discrete episode of normal faulting and related surface slumping. Four mapped NW-striking faults have throws ranging from 1 m to over 3 m, and have related growth folds in synchronous sediment units. A slump sheet moved tens of metres northeastward down the 0.7° dip slope of one tilt block during displacement on its bounding fault. The exposed part of the internally folded sheet is probably one side of a lobate slump mass, several hundred metres in width.

Fault activity began after deposition of a lower gravel, which regional correlations suggest is about 300 ka old. Faulting ended just before deposition of an upper gravel-sand complex dated by luminescence techniques in correlated sections at no younger than about 60 ka. The Mahi River section shows that neotectonic activity in Peninsular India, exemplified by the 1993 Killari (Latur) earthquake, has a mid- to late Pleistocene component.
Rb–Sr and U–Pb geochronology of migmatitic gneisses from the Góry Sowie (West Sudetes, Poland): the importance of Mid–Late Devonian metamorphism
Authors: BRÖCKER MICHAEL , ŻELAŹNIEWICZ ANDRZEJ , ENDERS MICHAEL
Published: December 2007

The Góry Sowie Block, West Sudetes, SW Poland consists of a gneiss–migmatite complex with minor amphibolites, calc-silicate rocks, ultrabasic rocks and granulites. Migmatitic gneisses underwent a complex polyphase history of deformation and metamorphism, each deformation phase (D1 to D5) being associated with synkinematic amphibolite-facies metamorphism (M1 to M5). For a better understanding of the
P–T–t
-deformation path three types of gneisses, which represent distinct stages of deformation and metamorphism (D2–M2, D3–M3 and D5–M5), have been studied by means of the Rb–Sr and U–Pb isotopic systems. U–Pb monazite and xenotime ages of
c.
380 Ma for rocks migmatized and deformed during the D3–M3 and D5–M5 stages constrain the timing of the last metamorphic–migmatitic event in the Góry Sowie Block. Rb–Sr thin-slab and mica–whole-rock dating for samples with D2, D3 and D5 characteristics provide ages between 362 and 375 Ma which overlap within error (2ó). No correlation between deformational characteristics and apparent Rb–Sr ages was recognized. The Rb–Sr data are interpreted as time constraints for post-peak metamorphic cooling. The new geochronological data indicate the significance of Devonian high-temperature metamorphism in the Sudetes and support a similar interpretation of earlier studies. The isotopic results are also consistent with the interpretation, based on field, structural and petrological data, that at least four (D2–D5) structural episodes occurred in Devonian times within a very short time interval, the details of which cannot be further resolved with the methods used.
The Menderes Massif of western Turkey and the Cycladic Massif in the Aegean—do they really correlate?
Authors: RING U. , GESSNER K. , GÜNGÖR T. , PASSCHIER C. W.
Published: December 2007

Based on lithostratigraphic comparisons the Menderes Massif has been correlated with the Cycladic Massif, thereby implying that the eastern Mediterranean consists of a narrow pre-Alpine basement belt which is laterally continuous over a long distance and which experienced a similar Alpine orogenic history. Our work indicates that the architecture, the age of basement and the pre-Alpine and Alpine tectonometamorphic history of both massifs differ fundamentally from each other. The Menderes Massif consists of remnants of the Cycladic Massif which overly an exotic unit, the Menderes nappes. Both massifs do not represent lateral continuations which has implications for palaeogeographic reconstructions.
Polyphase deformation and metamorphism in the Llyn Ogwen area of Snowdonia, North Wales
Authors: BAIRD A. W. , McCAFFREY K. I W.
Published: December 2007

Structural mapping of Upper Ordovician (Caradoc) volcaniclastic rocks around Llyn Ogwen, North Wales has revealed a hitherto unrecorded, kilometre-scale, Ramsay 'type-3' refold pattern. Each phase of folding is associated with an axial planar low grade, metamorphic fabric. The Caradoc aged, sub-volcanic Ogwen microgranite, contains two fabrics which are contiguous with those in the metasedimentary rocks. Recognition of two tectono-metamorphic events may simply explain the discrete Late Silurian and Early Devonian isotopic ages for deformation in North Wales and has implications for models of Acadian tectonics and the use of K/Ar and
40
Ar/
39
Ar dating techniques in slate belts.
Late Vendian-?Cambrian glacially influenced deep-water sedimentation, Macduff Slate Formation (Dalradian), NE Scotland
Authors: STOKER M. S. , HOWE J. A. , STOKER S. J.
Published: December 2007

The deep-water metasedimentary rocks of the late Dalradian Macduff Slate Formation preserve a record of distal glaciomarine sedimentation in the form of ice-rafted dropstones and related bedding-deformation structures, glaciogenic debris-flow diamictites and an allochthonous slump unit. The input of ice-rafted debris was cyclical and probably related to periodic disintegration of the marine margin of an ice sheet. Downslope resedimentation processes, typical of glaciated continental margins, were responsible for the diamictites and slump deposits which were probably derived from the adjacent outer shelf and upper slope, in common with Pleistocene analogues off NW Britain. The uppermost diamictite bed is an integral part of the deep-marine succession, in contrast to the previously proposed lodgement-till hypothesis.
Instantaneous sediment deposition rates deduced from climbing-ripple cross-lamination
Authors: Allen John Robert Lawrence
Published: December 2007

A mathematical analysis is made showing how the geometrical properties of climbing-ripple cross-lamination, a common sedimentary structure in fluviatile and turbidity current deposits, depend on the ripple height and the prevailing rates of sediment deposition and bed load transport. This structure is very commonly found in the field in vertical association with parallel laminated sand-grade deposits. The orientation of the ripple structures and of the parting lineations and/or grain fabric associated with the parallel laminae can be accounted for only if the two kinds of deposit were formed during consecutive stages in the change of a single current. Because the hydraulic conditions attending the transition between current ripples (giving cross-lamination) and a plane bed (giving parallel laminations) are known, the sediment deposition rate at the moment of transition can be calculated, from field measurements of ripple height, angle-of-climb and sediment size. Examples of deposition rates calculated in this way are discussed from the Old Red Sandstone and the Aberystwyth Grits of Wales.
A note on the structural evolution of Alaska
Authors: Stoneley Robert
Published: December 2007

Considerable
progress in the mapping and geological understanding of Alaska has been made in recent years through the efforts of the United States Geological Survey, petroleum companies and academic institutions. Sufficient reliable data now seem to be available to attempt, very tentatively, a synthesis of its geological history in the light of modern tectonic theories.

Distribution of major tectonic elements

A.
Southern Alaska

East central Alaska is divided fundamentally along the line of the Tintina Trough (Fig. 1), a feature which lies on approximately the same general trend as the homologous Rocky Mountain Trench of western Canada. It separates unmetamorphosed Palaeozoic and early Mesozoic miogeosynclinal rocks to the north from a series of eugeosynclinal belts to the south, and may have marked the edge of the continental platform in early Palaeozoic times. The Tintina Trough cannot be traced with certainty for more than 300 kms westwards into Alaska, and the continental margin then appears to have degenerated into a narrow welt along the Ruby Geanticline.

The Ruby Geanticline, which consists of rocks as yet poorly dated, also bounds the eugeosynclinal belts to the south: but, interposed between it and the miogeosyncline, there is now the Koyukuk Geosyncline, a middle Mesozoic feature with associated ophiolites, that was compressed during the Cretaceous. This possibly represented a deep ocean basin during the Palaeozoic and the Ruby Geanticline an island arc, analogous perhaps to the modern Bering Sea and Aleutian Arc.

The various tectonic belts of southern Alaska seem to represent a history of
Conductive faults and sealing fractures in the West Sole gas fields, southern North Sea
Authors: Barr D.
Published: December 2007

Understanding the distribution and geometry of sealing faults and conductive natural fractures is important at all stages of field development and infill drilling. Sealing faults or fractures reduce contacted hydrocarbon volume per well by compartmentalizing the reservoir and reduce rate by locally impairing permeability. Open fractures or conductive faults enhance well productivity and contacted volume, but cause drilling difficulties and may lead to early aquifer influx or injection water breakthrough. With their lengthy drilling and production history, the West Sole area gas fields provide a natural laboratory for the study of sealing and conductive fractures and their inter-relationships. Conductive fractures were recognized early in field life, but the poor performance of some wells indicated that fractures were not uniformly distributed. As development continued, entire field segments were found to be unfractured. Subsequent appraisal drilling identified undepleted and partially depleted compartments, demonstrating that sealing faults or fractures are also present. More recent development of the satellite fields Newsham and Hoton has confirmed the presence in a single field of both conductive and sealing fractures, although there is a general inverse spatial relationship between the two. The structural history of the reservoirs provides an explanation for this phenomenon. Faulting at high pressures and temperatures during Jurassic rifting gave rise to sealing lithified cataclasite fault rocks. Inversion to form the hydrocarbon traps took place at lower pressures and temperatures. The associated brittle deformation breached sealing faults and generated open fractures.
Fracture intensity from geomechanical models: application to the Blue Forest 3D survey, Green River Basin, Wyoming, USA
Authors: Wilkins S. J.
Published: December 2007

A geomechanical method is presented for the prediction of subseismic fracture intensity associated with faulting using a boundary element model conditioned from 3D seismic interpretation within the Green River Basin, Wyoming, USA. Seismic data indicate two major phases of deformation: (1) an early phase of approximately ESE‐verging contraction accommodated along a NNE–SSW striking system of basement-involved reverse faults and associated drape folds; and (2) a later phase of transtension accommodated by ENE–WSW-trending normal faults that are preferentially located in the hanging wall, above the crest of the drape fold.

The models predict different spatial patterns of fracture intensity for each phase of deformation. For D
1
, enhanced probability for shear failure develops in the upper quadrant of the footwalls along the reverse faults (i.e. forelimb) and the greatest magnitudes occur adjacent to regions with the largest component of observable dip-slip displacement along the faults. During D
2
, enhanced probability for joint and fault formation occurs along-strike of the normal faults and in a general NE trend. Seismic velocity anisotropy data support the geomechanical predictions for both phases of deformation in that the location and azimuth of large anisotropies correlate with regions of predicted enhancement in joint and fault intensity.
Spontaneous myogenic differentiation of Flk-1-positive cells from adult pancreas and other nonmuscle tissues
Authors: Di Rocco Giuliana , Tritarelli Alessandra , Toietta Gabriele , Gatto Ilaria , Iachininoto Maria Grazia , Pagani Francesca , Mangoni Antonella , Straino Stefania , Capogrossi Maurizio C.
Published: December 2007

At the embryonic or fetal stages, autonomously myogenic cells (AMCs), i.e., cells able to spontaneously differentiate into skeletal myotubes, have been identified from several different sites other than skeletal muscle, including the vascular compartment. However, in the adult animal, AMCs from skeletal muscle-devoid tissues have been described in only two cases. One is represented by thymic myoid cells, a restricted population of committed myogenic progenitors of unknown derivation present in the thymic medulla; the other is represented by a small subset of adipose tissue-associated cells, which we recently identified. In the present study we report, for the first time, the presence of spontaneously differentiating myogenic precursors in the pancreas and in other skeletal muscle-devoid organs such as spleen and stomach, as well as in the periaortic tissue of adult mice. Immunomagnetic selection procedures indicate that AMCs derive from Flk-1+ progenitors. Individual clones of myogenic cells from nonmuscle organs are morphologically and functionally indistinguishable from skeletal muscle-derived primary myoblasts. Moreover, they can be induced to proliferate in vitro and are able to participate in muscle regeneration in vivo. Thus, we provide evidence that fully competent myogenic progenitors can be derived from the Flk-1+ compartment of several adult tissues that are embryologically unrelated to skeletal muscle.
Ontogeny of Ca2+-induced Ca2+ release in rabbit ventricular myocytes
Authors: Huang Jingbo , Hove-Madsen Leif , Tibbits Glen F.
Published: December 2007

It is commonly accepted that L-type Ca2+ channel-mediated Ca2+-induced Ca2+ release (CICR) is the dominant mode of excitation-contraction (E-C) coupling in the adult mammalian heart and that there is no appreciable CICR in neonates. However, we have observed that cell contraction in the neonatal heart was significantly decreased after sarcoplasmic reticulum (SR) Ca2+ depletion with caffeine. Therefore, the present study investigated the developmental changes of CICR in rabbit ventricular myocytes at 3, 10, 20, and 56 days of age. We found that the inhibitory effect of the L-type Ca2+ current ( ICa) inhibitor nifedipine (Nif; 15 μM) caused an increasingly larger reduction of Ca2+ transients on depolarization in older age groups [from ∼15% in 3-day-old (3d) myocytes to ∼90% in 56-day-old (56d) myocytes]. The remaining Ca2+ transient in the presence of Nif in younger age groups was eliminated by the inhibition of Na+/Ca2+ exchanger (NCX) with the subsequent addition of 10 μM KB-R7943 (KB-R). Furthermore, Ca2+ transients were significantly reduced in magnitude after the depletion of SR Ca2+ with caffeine in all age groups, although the effect was significantly greater in the older age groups (from ∼40% in 3d myocytes up to ∼70% in 56d myocytes). This SR Ca2+-sensitive Ca2+ transient in the earliest developmental stage was insensitive to Nif but was sensitive to the subsequent addition of KB-R, indicating the presence of NCX-mediated CICR that decreased significantly with age (from ∼37% in 3d myocytes to ∼0.5% in 56d myocytes). In contrast, the ICa-mediated CICR increased significantly with age (from ∼10% in 3d myocytes to ∼70% in 56d myocytes). The CICR gain as estimated by the integral of the CICR Ca2+ transient divided by the integral of its Ca2+ transient trigger was smaller when mediated by NCX (∼1.0 for 3d myocytes) than when mediated by ICa (∼3.0 for 56d myocytes). We conclude that the lower-efficiency NCX-mediated CICR is a predominant mode of CICR in the earliest developmental stages that gradually decreases as the more efficient L-type Ca2+ channel-mediated CICR increases in prominence with ontogeny.
Defective trafficking and localization of mutated transferrin receptor 2: implications for type 3 hereditary hemochromatosis
Authors: Wallace Daniel F. , Summerville Lesa , Crampton Emily M. , Subramaniam V. Nathan
Published: December 2007

Transferrin receptor 2 (TfR2), a homologue of transferrin receptor 1 (TfR1), is a key molecule involved in the regulation of iron homeostasis. Mutations in TfR2 result in iron overload with similar features to HFE-associated hereditary hemochromatosis. The precise role of TfR2 in iron metabolism and the functional consequences of disease-causing mutations have not been fully determined. We have expressed wild-type and various mutant forms of TfR2 that are associated with human disease in a mouse liver cell line. Intracellular and surface analysis shows that all the TfR2 mutations analyzed cause the intracellular retention of the protein in the endoplasmic reticulum, whereas the wild-type protein is expressed in endocytic structures and at the cell surface. Our results indicate that the majority of mutations that cause type 3 hereditary hemochromatosis are a consequence of the defective localization of the protein.
Cyclosporine increases ischemia-induced endothelial progenitor cell mobilization through manipulation of the CD26 system
Authors: Wang Chao-Hung , Cherng Wen-Jin , Yang Ning-I , Hsu Chia-Ming , Yeh Chi-Hsiao , Lan Yii-Jenq , Wang Jong-Shyan , Verma Subodh
Published: December 2007

Cyclosporin A (CsA) improves the success rate of transplantation. The CD26/dipeptidylpeptidase IV (DPP IV) system plays a critical role in mobilizing endothelial progenitor cells (EPCs) from bone marrow. This study investigated whether CsA manipulates CD26/DPP IV activity and increases EPC mobilization. C57BL/6 mice were divided into control and CsA-treated groups. Before and after hindlimb ischemia was induced, circulating EPC number and serum levels of different cytokines were measured. Compared with the controls, CsA treatment significantly increased the blood levels of stroma-derived factor-1α and stem cell factor after ischemic stress ( P < 0.001). The CsA group displayed a significant increase in the number of circulating EPCs (sca-1+KDR+ and c-kit+CD31+ EPCs, both P < 0.05). In vivo, CsA caused a significant increase in the numbers of EPCs incorporated into the Matrigel and ischemic limbs ( P < 0.05). In the peripheral blood, CsA significantly decreased CD26+ cell numbers and attenuated the plasma CD26/DPP IV activity ( P < 0.001). Furthermore, short-term CsA treatment significantly improved the perfusion of ischemic limbs and decreased the spontaneous digital amputation rate. In summary, CsA manipulates the mobilization of EPCs into the circulation via the CD26/DPP IV system. Short-term CsA treatment has beneficial effects on angiogenesis of ischemic tissues.
Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest
Authors: Trappe Scott , Creer Andrew , Minchev Kiril , Slivka Dustin , Louis Emily , Luden Nicholas , Trappe Todd
Published: December 2007

The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE + RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n = 7), nutrition (BRN; n = 8), and exercise (BRE; n = 6) group. Single muscle fiber diameter (Dia), peak force (Po), contractile velocity, and power were studied. BR decreased ( P < 0.05) MHC I Dia (−14%), Po(−38%), and power (−39%) with no change in contractile velocity. Changes in MHC I size (−13%) and contractile function (∼30%) from BRN were similar to BR. BRE decreased ( P < 0.05) MHC I Dia (−13%) and Po(−23%), while contractile velocity increased ( P < 0.05) 26% and maintained power. These soleus muscle data show 1) the AE + RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus.
Role of AQP2 in activation of calcium entry by hypotonicity: implications in cell volume regulation
Authors: Galizia L. , Flamenco M. P. , Rivarola V. , Capurro C. , Ford P.
Published: December 2007

We previously reported in a rat cortical collecting duct cell line (RCCD1) that the presence of aquaporin 2 (AQP2) in the cell membrane is critical for the rapid activation of regulatory volume decrease mechanisms (RVD) (Ford et al. Biol Cell 97: 687–697, 2005). The aim of our present work was to investigate the signaling pathway that links AQP2 to this rapid RVD activation. Since it has been previously described that hypotonic conditions induce intracellular calcium ([Ca2+]i) increases in different cell types, we tested the hypothesis that AQP2 could have a role in activation of calcium entry by hypotonicity and its implication in cell volume regulation. Using a fluorescent probe technique, we studied [Ca2+]iand cell volume changes in response to a hypotonic shock in WT-RCCD1(not expressing aquaporins) and in AQP2-RCCD1(transfected with AQP2) cells. We found that after a hypotonic shock only AQP2-RCCD1cells exhibit a substantial increase in [Ca2+]i. This [Ca2+]iincrease is strongly dependent on extracellular Ca2+and is partially inhibited by thapsigargin (1 μM) indicating that the rise in [Ca2+]ireflects both influx from the extracellular medium and release from intracellular stores. Exposure of AQP2-RCCD1cells to 100 μM gadolinium reduced the increase in [Ca2+]isuggesting the involvement of a mechanosensitive calcium channel. Furthermore, exposure of cells to all of the above described conditions impaired rapid RVD. We conclude that the expression of AQP2 in the cell membrane is critical to produce the increase in [Ca2+]iwhich is necessary to activate RVD in RCCD1cells.
Proteomic Profiling Identifies Afamin as a Potential Biomarker for Ovarian Cancer
Authors: Jackson David , Craven Rachel A. , Hutson Richard C. , Graze Ina , Lueth Paul , Tonge Robert P. , Hartley Joanne L. , Nickson Janice A. , Rayner Steve J. , Johnston Colin , Dieplinger Benjamin , Hubalek Michael , Wilkinson Nafisa , Perren Timothy J. , Kehoe Sean , Hall Geoffrey D. , Daxenbichler Guenter , Dieplinger Hans , Selby Peter J. , Banks Rosamonde E.
Published: December 2007

Purpose: To discover and validate serum glycoprotein biomarkers in ovarian cancer using proteomic-based approaches.

Experimental Design: Serum samples from a “discovery set” of 20 patients with ovarian cancer or benign ovarian cysts or healthy volunteers were compared by fluorescence two-dimensional differential in-gel electrophoresis and parallel lectin-based two-dimensional profiling. Validation of a candidate biomarker was carried out with Western blotting and immunoassay (n = 424).

Results: Twenty-six proteins that changed significantly were identified by mass spectrometric sequencing. One of these, confirmed by Western blotting, was afamin, a vitamin E binding protein, with two isoforms decreasing in patients with ovarian cancer. Validation using cross-sectional samples from 303 individuals (healthy controls and patients with benign, borderline, or malignant ovarian conditions and other cancers) assayed by ELISA showed significantly decreased total afamin concentrations in patients with ovarian cancer compared with healthy controls (P = 0.002) and patients with benign disease (P = 0.046). However, the receiver operating characteristic areas for total afamin for the comparison of ovarian cancer with healthy controls or benign controls were only 0.67 and 0.60, respectively, with comparable figures for CA-125 being 0.92 and 0.88 although corresponding figures for a subgroup of samples analyzed by isoelectric focusing for afamin isoform 2 were 0.85 and 0.79. Analysis of a further 121 samples collected prospectively from 9 patients pretreatment through to relapse indicated complementarity of afamin with CA-125, including two cases in whom CA-125 was noninformative.

Conclusions: Afamin shows potential complementarity with CA-125 in longitudinal monitoring of patients with ovarian cancer, justifying prospective larger-scale investigation. Changes in specific isoforms may provide further information.
Modulation of Reactive Oxygen Species in Pancreatic Cancer
Authors: Teoh Melissa L.T. , Sun Wenqing , Smith Brian J. , Oberley Larry W. , Cullen Joseph J.
Published: December 2007

Purpose: The aim of the present study was to compare the effects of the three different forms of the antioxidant enzyme superoxide dismutase [i.e., manganese superoxide dismutase (MnSOD), copper zinc superoxide dismutase (CuZnSOD), and extracellular superoxide dismutase (EcSOD)] on the malignant phenotype of human pancreatic cancer.

Experimental Design: Human pancreatic cancer cell lines were infected with adenoviral vectors containing the cDNAs for three different forms of the antioxidant enzyme SOD. Intratumoral injections of the adenoviral vectors were used in nude mice with human tumor xenografts.

Results: Increases in immunoreactive protein and enzymatic activity were seen after infections with the AdMnSOD, AdCuZnSOD, or AdEcSOD constructs. Increased SOD activity decreased superoxide levels and increased hydrogen peroxide levels. Increasing SOD levels correlated with increased doubling time. Cell growth and plating efficiency decreased with increasing amounts of the adenoviral constructs, with the AdCuZnSOD vector having the greatest effect in decreasing in vitro tumor growth. In contrast, inhibiting endogenous SOD with small interfering RNA increased superoxide levels and promoted tumor growth. Of the three SODs, tumors grew the slowest and survival was increased the greatest in nude mice injected with the AdEcSOD construct.

Conclusions: Scavenging plasma membrane–generated superoxide may prove beneficial for suppression of pancreatic cancer growth.
HLA Tetramer–Based Artificial Antigen-Presenting Cells Efficiently Stimulate CTLs Specific for Malignant Glioma
Authors: Jiang Xiaobing , Lu Xiaoling , Liu Ruen , Zhang Fangcheng , Zhao Hongyang
Published: December 2007

Purpose: The interleukin-13 receptor α2 (IL-13Rα2) is a glioma-restricted cell-surface epitope not otherwise detected within the central nervous system. Here, we report a novel approach for targeting malignant glioma with IL-13Rα2–specific CTLs.

Experimental Design: Artificial antigen-presenting cells (aAPC) were made by coating human leukocyte antigen (HLA)-A2/pIL-13Rα2345-354 tetrameric complexes, anti-CD28 antibody, and CD83 molecules to cell-sized latex beads, and used to stimulate IL-13Rα2–specific CTLs from the peripheral blood mononuclear cells of HLA-A2+ healthy donors. After multiple stimulations, the induced CTLs were analyzed for tetramer staining, IFN-γ production, and CTL reactivity.

Results: Tetramer staining assay showed that the induced CTLs specifically bound HLA-A2/pIL-13Rα2345-354 tetramers. The CTLs specifically produced IFN-γ in response to the HLA-A2/pIL-13Rα2345-354-aAPCs and exhibited specific lysis against T2 cells pulsed with the peptide pIL-13Rα2345-354 and HLA-A2+ glioma cells expressing IL-13Rα2345-354, whereas HLA-A2− glioma cell lines that express IL-13Rα2345-354 could not be recognized by the CTLs. The peptide-specific activity was inhibited by anti–HLA class I monoclonal antibody.

Conclusion: The induced CTLs specific for IL-13Rα2345-354 peptide could be a potential target of specific immunotherapy for HLA-A2+ patients with malignant glioma.
The Roles of Therapy-Induced Autophagy and Necrosis in Cancer Treatment
Authors: Amaravadi Ravi K. , Thompson Craig B.
Published: December 2007

Metabolic and therapeutic stresses activate several signal transduction pathways that regulate cell death and cell survival in cancer cells. Although decades of research unraveled the pathways that regulate apoptosis and allowed the development of novel diagnostic and therapeutic modalities in cancer treatment, only recently has the regulation and significance of tumor cell autophagy and necrosis become the focus of investigations. Necrosis is an irreversible inflammatory form of cell death. In contrast, autophagy is a reversible process that can contribute both to tumor cell death and survival. This review describes recent advances in understanding the regulation of autophagy and necrosis and their implications for cancer therapy. Currently available methods to measure autophagy and necrosis are highlighted. The effect of tumor cell autophagy and necrosis on host immunity is explored. Finally, therapeutic approaches that target autophagy and necrosis in cancer are described.