bluuebunny/crossref_metadata_2025 huggingface dataset:
NEW METHOD FOR YEAST IDENTIFICATION USING BURROWS–WHEELER TRANSFORM
Authors: POKRZYWA RAFAL
Published: May 2008

The explosive growth in biological data in recent years has led to the development of new methods to identify DNA sequences. Many algorithms have recently been developed that search DNA sequences looking for unique DNA sequences. This paper considers the application of the Burrows–Wheeler transform (BWT) to the problem of unique DNA sequence identification. The BWT transforms a block of data into a format that is extremely well suited for compression. This paper presents a time-efficient algorithm to search for unique DNA sequences in a set of genes. This algorithm is applicable to the identification of yeast species and other DNA sequence sets.
KNOWLEDGE-BASED VERSUS EXPERIMENTALLY ACQUIRED DISTANCE AND ANGLE CONSTRAINTS FOR NMR STRUCTURE REFINEMENT
Authors: CUI FENG , JERNIGAN ROBERT , WU ZHIJUN
Published: May 2008

Nuclear Overhauser effects (NOE) distance constraints and torsion angle constraints are major conformational constraints for nuclear magnetic resonance (NMR) structure refinement. In particular, the number of NOE constraints has been considered as an important determinant for the quality of NMR structures. Of course, the availability of torsion angle constraints is also critical for the formation of correct local conformations. In our recent work, we have shown how a set of knowledge-based short-range distance constraints can also be utilized for NMR structure refinement, as a complementary set of conformational constraints to the NOE and torsion angle constraints. In this paper, we show the results from a series of structure refinement experiments by using different types of conformational constraints — NOE, torsion angle, or knowledge-based constraints — or their combinations, and make a quantitative assessment on how the experimentally acquired constraints contribute to the quality of structural models and whether or not they can be combined with or substituted by the knowledge-based constraints. We have carried out the experiments on a small set of NMR structures. Our preliminary calculations have revealed that the torsion angle constraints contribute substantially to the quality of the structures, but require to be combined with the NOE constraints to be fully effective. The knowledge-based constraints can be functionally as crucial as the torsion angle constraints, although they are statistical constraints after all and are not meant to be able to replace the latter.
SEMIPARAMETRIC CLUSTERING METHOD FOR MICROARRAY DATA ANALYSIS
Authors: YUAN AO , HE WENQING
Published: May 2008

Clustering is a major tool for microarray gene expression data analysis. The existing clustering methods fall mainly into two categories: parametric and nonparametric. The parametric methods generally assume a mixture of parametric subdistributions. When the mixture distribution approximately fits the true data generating mechanism, the parametric methods perform well, but not so when there is nonnegligible deviation between them. On the other hand, the nonparametric methods, which usually do not make distributional assumptions, are robust but pay the price for efficiency loss. In an attempt to utilize the known mixture form to increase efficiency, and to free assumptions about the unknown subdistributions to enhance robustness, we propose a semiparametric method for clustering. The proposed approach possesses the form of parametric mixture, with no assumptions to the subdistributions. The subdistributions are estimated nonparametrically, with constraints just being imposed on the modes. An expectation-maximization (EM) algorithm along with a classification step is invoked to cluster the data, and a modified Bayesian information criterion (BIC) is employed to guide the determination of the optimal number of clusters. Simulation studies are conducted to assess the performance and the robustness of the proposed method. The results show that the proposed method yields reasonable partition of the data. As an illustration, the proposed method is applied to a real microarray data set to cluster genes.
CLePAPS: FAST PAIR ALIGNMENT OF PROTEIN STRUCTURES BASED ON CONFORMATIONAL LETTERS
Authors: WANG SHENG , ZHENG WEI-MOU
Published: May 2008

Fast, efficient, and reliable algorithms for pairwise alignment of protein structures are in ever-increasing demand for analyzing the rapidly growing data on protein structures. CLePAPS is a tool developed for this purpose. It distinguishes itself from other existing algorithms by the use of conformational letters, which are discretized states of 3D segmental structural states. A letter corresponds to a cluster of combinations of the three angles formed by Cα pseudobonds of four contiguous residues. A substitution matrix called CLESUM is available to measure the similarity between any two such letters. CLePAPS regards an aligned fragment pair (AFP) as an ungapped string pair with a high sum of pairwise CLESUM scores. Using CLESUM scores as the similarity measure, CLePAPS searches for AFPs by simple string comparison. The transformation which best superimposes a highly similar AFP can be used to superimpose the structure pairs under comparison. A highly scored AFP which is consistent with several other AFPs determines an initial alignment. CLePAPS then joins consistent AFPs guided by their similarity scores to extend the alignment by several "zoom-in" iteration steps. A follow-up refinement produces the final alignment. CLePAPS does not implement dynamic programming. The utility of CLePAPS is tested on various protein structure pairs.
Plant-insect relationships in Palaeozoic and later time
Authors: Hughes Norman Francis , Smart John
Published: May 2008

Events in the history of land plants and of insects are discussed, with particular reference to fossil evidence from Palaeozoic rocks. Some possible relationships are suggested, although it is acknowledged that evidence on many points is as yet insufficient.
Problems of the relationship between surface structure and deep displacements illustrated by the Zagros Range
Authors: Falcon N. L.
Published: May 2008

The object of this paper is to discuss some of the unknown or little-known relationships between surface structure and deep displacements in the well-exposed Zagros orogenic belt of south-west Iran, which can be divided into three major structural belts. The subjective nature of all inferences about deep structure in the absence of seismic data supported by deep borehole evidence is accentuated. Only at relatively shallow depths where the rock succession is well known can concealed structure be predicted with confidence from surface geology alone.
Sedimentary thicknesses in orogenic belts
Authors: Stoneley R.
Published: May 2008

The evidence provided by certain examples of thick sedimentary sequences, both deformed and undeformed, suggests that at least some of the geotectonic processes can be isolated whereby they are accommodated. These are (
a
) isostatic depression of oceanic crust by sedimentary loading, (
b
) down-dragging and compressional warping due to tangential crustal and sub-crustal displacements and (
c
) crustal foundering resulting from vertically acting changes in the mantle and/or lower crust. All three of these factors must be involved to some extent during the evolution of an orogenic belt but some features, such as the subsidence of a miogeosyncline under tension, are still difficult to explain. Within many Alpine orogenic zones, large thicknesses of sediment are found in miogeosynclines, eugeosynclines, flysch troughs and molasse basins but these four environments are not recognizable in all orogenic belts, particularly the older ones. Comparisons between different belts are not always meaningful in the framework of existing geosynclinal concepts and terminology, but it is expected that a new and comprehensive terminology, based on geotectonic considerations, may shortly become possible.
8. The climatic sequence in cores from the Mediterranean Sea, Indian Ocean and Antarctic Ocean
Authors: Evans Percy
Published: May 2008

Among the earliest cores examined by Emiliani (1955B) was the Swedish core 189 taken in the western Mediterranean. Radiometric evidence in limited to a single radiocarbon date, but correlation with Atlantic cores is clear (Emiliani 1958, fig. 2). The
14. East Anglia and Essex
Authors: Evans Percy
Published: May 2008

In this Section of the review discussion will be mainly concerned with fitting into the suggested time-scale those portions of the Eats Anglian succession that have an important bearing on the stratigraphy of other parts of England. It is convenient to begin with the younger beds.

The Hunstanton Till is assigned to the Weichselian because of the freshness of the associated land-forms; a variety of gravels (fluviatile and marine) can be placed in this stage through radiocarbon dating, direct correlation, or relation to the Ipswichian (Eemian). But the numerous problems of the East Anglian Weichselian seem to be mostly of a local nature.

The Ipswichian warm-climate deposits are securely correlated with the Eemian by their pollen diagrams. Their age is ioo to 7 ~ t.y., half-cycle 3 w. The Gipping glaciation is older, and since it is post-Hoxnian (Holsteinian) it must belong to some part of the Saale, either Drenthe or Warthe. The Drenthe glaciation (of 5 c) was the only terrestrial glaciation known to have invaded the Netherlands and the eastward prolongation of the general line of the Drenthe ice-front would bring it to Essex, whereas the Warthe ice-front was IOO to 2oo km farther north. Such a geographical correlation seems to have some merit in connexion with the later glaciations, but must have less force with earlier ice-sheets developed when topographical conditions were less like those of the present time. This
prima facie
evidence for the correlation of the Gipping is strongly upheld by the gradual uninterrupted passage
18. Summary and conclusions
Authors: Evans Percy
Published: May 2008

The aim of this review was to bring together all the more important data bearing on the assignment of definite ages to the events of the past two or three million years. Five main chronological controls together provide the framework for the dates wh
Occurrence, origin and significance of mechanically transported sulphide ores at Buchans, Newfoundland
Authors: Thurlow J. G.
Published: May 2008

The Buchans orebodies are high-grade Kuroko-like massive sulphide deposits associated with Silurian (?) felsic volcanism of the northern Appalachians. Since 1928, 17 000 000 tons of ore has been mined, of which approximately one-half consists of mechanically transported sulphide breccia accumulations. Most of the transported ores occur as discrete orebodies composed of angular (competent) and wispy (plastic) sulphide fragments intimately mixed with a large variety of angular to rounded lithic fragments. Abundant evidence exists to suggest that these ores were fragmented by surface volcanic explosions and transported as rapidly moving sub-aqueous density flows. Fragmentation of the
in-situ
orebodies occurred intermittently throughout massive sulphide deposition and thus the zonation of the
in-situ
deposits is mimicked by zonation of the transported ores. These ores were preferentially deposited in palaeotopographic depressions along the path of density flow and maintain economic grade for distances in excess of 2 km from their source. Other deposits appear to have moved as slowly advancing ‘mud glaciers’.

The direction of transport can be determined from imbrication of ore fragments, direction of elongation of the ore zones and clast fabric, and from increasing ore grades, clast size and individual bed thickness in more proximal areas. Limited data on the distribution of disorganized, inverse to normally graded and normally graded beds yield transport directions compatible with those obtained from the other parameters. On the basis of the above criteria, as well as stratigraphic considerations and comparison of metal ratios in transported and
in-situ
deposits, the source of most transported ores can be identified as one of the two major
in-situ
massive sulphide deposits. At least one far-travelled sub-economic prospect has, however, no known source orebody.

In terms of exploration the Buchans orebodies are significant in that economic sulphide accumulations may occur as discrete transported orebodies well beyond the limits of stockwork mineralization and significant alteration.
Seismic constraints on the deep geology of the Caledonides of northern Britain
Authors: Bamford David
Published: May 2008

Interpretation of compressional and shear wave data from the 1974 L.I.S.P.B. seismic experiment has resulted in a detailed crustal cross-section across the Caledonian orogenic belt of northern Britain. This section provides clear evidence of lateral variations in deep structure comparable with the gross geological variations: in particular crustal structure is asymmetric across the orogenic belt. The axis of this asymmetry seems to vary with depth within the central part of the belt but the evidence suggests that any Caledonian destructive plate boundary was located south of the Southern Uplands fault.
Basement-cover relations in Shetland
Authors: Flinn Derek , Frank P. L. , Brook Maureen , Pringle I. R.
Published: May 2008

The relationship between basement and cover can be studied in two places in Shetland. In NW Shetland, orthogneisses with a minimum age of 2900 Ma are followed to the east and southeast by Caledonian metasediments and greenschists and these in turn by schists and gneisses with a minimum age of 860 Ma. The metasediments contain bands of mylonite and blastomylonite. Wide belts of superposed schistosity occur in the schist and gneiss unit and also at the junction of the orthogneisses with the metasediments. This area is interpreted as including the Caledonian front. In NE Shetland, two nappes of ultramafic and basic rocks, one above the other, have been thrust over the surface of the earth onto Caledonian (lower Dalradian?) schists and gneisses. During transport the nappes have suffered erosion, and sediments, including nappe detritus, have been deposited on and in front of them and subsequently been over-ridden and metamorphosed by the nappes. The occurrence forms a typical obducted ophiolite complex.
Regional geochemistry of the Northern Highlands of Scotland
Authors: Johnstone G. S. , Plant Jane , Watson Janet V.
Published: May 2008

The distribution of trace-elements between the Lewisian basement and the Caledonian cover-formations can be assessed from regional geochemical maps based on stream-sediment sampling. The Lewisian basement is characterised by depletion in heat-producing elements, U, K, Rb, and in Pb, Be and by high values of Sr, Mg and first row transition elements. The range of Zr, Ba, B and Y levels are comparable with those over the Moine. Regional variations relate to crustal level and to the presence of zones of high deformation. Anomalies for Mo, Zr and U are associated with granite and pegmatites in some of these zones. Within the Moine nappe the zone of tectonically emplaced Lewisian slices divides an area where the bulk geochemistry is consistent with that of continental arkoses—the Morar Division—from the Glenfinnan and Loch Eil divisions which have geochemical characteristics closer to those of greywacke facies. No other geochemical discontinuity has been recognised in the Moine but the boundary with the Dalradian is marked by an increase in boron. Clear misfits of element distribution across the Great Glen fault are apparent but the data so far available could be interpreted in terms of either sinistral or dextral displacement.
New evidence for a Central Highland Root Zone
Authors: Thomas Peter R.
Published: May 2008

The major nappe structures of the west Central Highlands of Scotland have been found to diverge from the upward facing Ossian-Geal Charn steep belt, trending NE-SW through the Ben Alder Forest. As the deep equivalent of the Loch Awe synclinal complex to the southwest, it more probably represents a root zone than the Tummel steep belt which is largely controlled by later deformational events. A structural synthesis of the west Central Highlands describes how the large elongated Drumochter-Dochard dome influences at least three subsequent phases of deformation.
The tectonic evolution of the lower Palaeozoic rocks of extreme SE Ireland
Authors: Shannon Patrick M.
Published: May 2008

Five deformation phases (D
0
–D
4
) and four metamorphic events (M
0
–M
3
) are recognised in the lower Palaeozoic rocks of an extensive area lying to the south of the Leinster granite. D
0
and M
0
features are interpreted as being the result of post diagenetic burial metamorphism. The main regional deformation (D
1
) preceded the intrusion of the Leinster granite and produced tight folds and an axial-planar slaty cleavage. D
2
and D
3
deformations produced more brittle linear and planar structures. They show a localised development which is interpreted as being due to late stage movements of unexposed granite bodies at relatively shallow depths.
A metamorphic map of the British and Irish Caledonides
Authors: Fettes D. J.
Published: May 2008

The metamorphic rocks of the British and Irish Caledonides fall into two groups. The first group constitutes the northern belt. These rocks have been subjected to a lower Ordovician metamorphism (Grampian event of Lambert & McKerrow 1976) which was probably, in part at least, diachronous. The metamorphic pattern ranges from the low- to the intermediate-pressure facies series and from the low greenschist- to the upper amphibolite-facies groups. The distribution of facies within the belt is complex and may relate to a depth-controlled metamorphism with locally induced thermal highs. The second group constitutes the southern belt. Here the rocks have been subjected to a late-Silurian event which, in general, causes slight crystallisation but very locally rises to upper greenschist facies.
The pattern of three-dimensional metamorphism in the Killin area, Inverness-shire: a direct method of determining the thickness of metamorphic zones in the Caledonides
Authors: Winchester J. A. , Whittles K. H.
Published: May 2008

The mineral assemblages in calc-silicates from the Killin area suggest an eastward increase in metamorphic grade. By comparing the chemistry and mineral assemblages of the calc-silicates, the isograd surfaces were defined. They were found to dip 13° west, to the east of Glen Brein, and approximately 4° east in the western part of the area. Thus a metamorphic synform is defined. The interval measured between the isograd surfaces shows that the combined thickness of the hornblende and bytownite zones is less than 1400 m, and therefore, by correlation, the kyanite zone in the Killin area cannot exceed this thickness.
Lower Palaeozoic soft-sediment deformation structures in the western end of the Longford-Down inlier, Ireland
Authors: Morris J. H.
Published: May 2008

Two types of interrelated soft-sediment deformation (D
0
) structures are described, disturbed bedding and folds. Disturbed bedding varies from pinch-and-swell bed(s) to lenticular boudins. Folds are variable in style and scale; one fold is associated with a welded contact, two with décollement zones. All structures are stratabound. The structures are considered to be the product of dewatering of channel infill deposits combined with slope instabilities caused by channeling and/or penecontemporaneous volcanism. Packages of beds of alternating, opposed younging direction are also present and predate tectonic folds and cleavage. These structures may correlate with either D
0
or represent an intermediate stage between D
0
and post-lithification D
1
tectonic structures.
Tremadoc to Llanvirn volcanism on the southeast side of the Harlech dome (Rhobell Fawr), N Wales
Authors: Kokelaar B. P.
Published: May 2008

A volcanic episode, initiated in the late Tremadoc and persisting into the lower Llanvirn, is represented around Rhobell Fawr (SH 7825) by basaltic lavas and their breccias (the Rhobell Volcanic Group), by dolerite, microdiorite and microtonalite intrusions, by a rhyolite tuff and by the basic and intermediate constituents of certain sedimentary rocks. Initially basalts were erupted, at a variable rate, subaerially from fissures. This effusive phase was followed by eruptions of andesite and dacite, which, in turn, were followed by explosive eruption of rhyolite. A dyke regime in the west of the area represents the sub- and intravolcanic parts of a major site of eruption and was the source of the volcanic group. The rocks of the Rhobell episode are genetically related by amphibole-dominated fractional crystallisation of mantle-derived basaltic magma and are similar to those of modern destructive plate margin environments. The Rhobell fractionation series, from silica-undersaturated to quartz-normative, is closely paralleled by that at Grenada, at the southern end of the Lesser Antilles island arc. The tectonovolcanic evolution of the area is consistent with the development of a N-S basement fracture situated beneath the eastern margin of the Harlech Dome.
Ignimbrite volcanism in the Ordovician Borrowdale volcanics of the English Lake District
Authors: Millward David
Published: May 2008

Ignimbrites within the Borrowdale Volcanic Group predominantly occur in two situations; thick dacitic sheets associated with lavas of similar composition, and thin dacitic-to-andesitic units interbedded with basic-to-andesitic pyroclastic fall deposits. Mapping and examination of samples from the units has revealed petrological and chemical variations which can be attributed to the variations in components (crystals, fiamme and lithic fragments) and to post emplacement processes including crystallisation, ion-exchange with vapour phases and leaching by groundwater.
Geochemistry of the appinite suite
Authors: Wright A. E. , Bowes D. R.
Published: May 2008

The suite is highly enriched in many of the trace elements, both those typical of basaltic rocks (Co, Ni, Cr) and those more frequently richer in calc alkaline suites (Ba, Sr). The suite is rich in these elements and in K in all the members of the suite and the geochemical characters are indicative of normal igneous differentiation of a volatile, K and trace element-rich basaltic magma. The suite is not similar to any of the more widespread basaltic or andesitic suites although the rocks mostly vary in composition from a rather ultramafic basalt to a silica-poor andesite. There are also abundant acidic and alkaline differentiates but these do not show any more extreme enrichment in major or trace elements than the more basic rocks.
The strain profile above a major thrust fault, Finnmark, N Norway
Authors: Milton N. J. , Williams G. D.
Published: May 2008

The base of the Laksefjord Nappe, Finnmark, N Norway consists of a strained conglomerate. Field studies of the deformation suggest a simple strain profile, with strain depending on height above the basal thrust within the Nappe. A combination of simple shear deformation, related to movement on, or initiation of, the basal thrust, with a relatively constant flattening component is proposed. A mathematical model based on down surface slope stress and the steady state flow law is suggested for the simple shear component of the strain.
The 3D propagation of décollement in the Jura
Authors: Laubscher H. P.
Published: May 2008

The sequence of instabilizations leading to the formation of shallow nappes may be illustrated by the kinematics of the embryonic Jura Nappe. On the first order arc, due to regional boundary conditions, are superposed second and third order arcs that developed around more local irregularities in the distribution of strength. Successive instabilization of the Rheintal part of the Jura Décollement Nappe generally proceeds from S to N. Location of ramps where décollement climbs to the surface is largely influenced by pre-existing Rhinegraben structures. These also convey a certain anisotropy to the sedimentary cover which seems to be responsible, at least partly, for a different aspect of sinistral and dextral shear zones. Whereas sinistral shears are usually along discrete faults, mostly reactivated Rhinegraben faults, the dextral shears commonly are diffuse zones. Arcuate elements, convex to the N, connect the sinistral and dextral shear zones frontally. Regionally, the shear zones accommodate the divergence of movement, with lateral elongation, within the overall Jura Arc. More locally, they bound arcuate segments of ever smaller dimensions, and also seem to ease diverging movements in these smaller arcs.
Wrench related thrusting along a Mesozoic-Cenozoic continental margin: Antalya Complex, SW Turkey
Authors: Woodcock N. H. , Robertson A. H. F.
Published: May 2008

An imbricate thrust belt and a geometrically related wrench-fault terrain are reported from the Antalya Complex, SW Turkey. The deformation occurred between late Cretaceous and Miocene time along a former Mesozoic rifted continental margin. The thrusting appears to have been temporally and mechanically related to at least the early stages of wrench tectonics.
An overview of thrusts and nappes of western Himalaya
Authors: Thakur V. C.
Published: May 2008

The Shali-Deoban Parautochthon, Krol Berinag Nappes and Outer Crystallines Nappes are the main lithostructural units of the Lesser Himalaya of Kumaun, Garhwal and eastern Himachal. Two thrust sheets, the Chail Nappe and the Jutogh Nappe are recognized in the Outer Crystallines Nappes. The Chail Nappe forms a separate thrust sheet, and the Jutogh Nappe overlying it represents a southward extension of the Central Crystallines Nappe of the Higher Himalaya. The Chail Nappe rocks constitute the base of the Palaeozoic-Mesozoic sequence of the Kashmir-Chamba Parautochthon, whereas the Central Crystallines Nappe forms the basement for the late Precambrian-Cretaceous sequence of the Tethyan Zone in the Kumaun, Spiti and Zaskar regions. The Central Crystallines Nappe shows a progressive regional metamorphism, chlorite to sillimanite grade, whereas the metamorphism of the Chail Nappe is mainly confined to the greenschist facies. Metamorphic inversion is a characteristic feature of the Jutogh Nappe which occurs as crystalline klippen in the Lesser Himalaya Zone. The ophiolite suite of rocks of the Indus-Tsangpo suture occurs also as klippen above the sediments of the Tethys Himalaya and metamorphics of the Tso Morari Dome. They appear to have resulted from squeezing out from the root zone and subsequent gravity gliding. The Indus Suture Zone is unique with regard to its thrust tectonics, in that, whereas all the principal thrusts elsewhere in the Himalaya are directed towards the S, within this zone they are directed only toward the N.
Thrust nappes in the Rocky Mountain Foothills near Mountain Park, Alberta
Authors: Charlesworth H. A. K. , Kilby W. E.
Published: May 2008

In 200 km
2
of W central Alberta, the thrusts associated with seven nappes cut up section to the NE at about 5° through 1000 m of Upper Jurassic and Lower Cretaceous strata whose overall dip is gentle and to the SW. The thrusts, whose horizontal spacing ranges from 0 to 4 km, have a combined displacement of about 12 km. Most folds affecting the nappe assemblage originated through bending over steps in the thrusts against which they end downwards. Up plunge to the NW the upper nappes, most of which involve older strata, are apparently truncated by the McConnell Nappe, whereas three of the thrusts underlying the lower nappes appear to run into the Miette thrust which to the NW replaces the McConnell as the SW boundary of the Foothills. Down plunge to the SE the thrusts merge in an Upper Cretaceous décollement zone whose 15 km of movement are dissipated in the Foothills to the NE by low-angle thrusts splaying into the overlying strata. The décollement and associated thrusts are cut by a younger generation of faults that include the McConnell, Nikanassin and Folding Mountain.
Deformational styles in two Mesozoic fault zones, western Washington, USA
Authors: Cowan D. S. , Miller R. B.
Published: May 2008

The Navaho Divide and Lopez fault zones record sub-greenschist facies, brittle fragmentation and tectonic mixing at an active Mesozoic continental margin. Displacement directions across these zones are interpreted as partly or wholly dip-slip, although unambiguous criteria in these and many other Cordilleran fault zones are lacking. The moderate to high-angle Navaho Divide zone, which is part of the ophiolitic Ingalls Complex, contains variously sized elongate fragments of serpentinized ultramafic rocks, gabbro, and related rock types set in a voluminous matrix of foliated, scaly serpentinite. The moderately dipping Lopez zone comprises larger slices of turbidites, pebbly mudstone, and minor mafic metavolcanic rocks separated by faults and narrow fault zones locally filled with mudstone that apparently flowed during thrusting. In both complexes, the elongate slices and subparallel faults define an imbricate or schuppen structure geometrically similar to the macroscopic fabric of intracratonic, Rocky Mountain-type imbricate zones. However, the Navaho Divide and Lopez zones are fundamentally different in that they both juxtapose and contain rock units that are difficult, or impossible, to restore palinspastically to a pre-faulting configuration.
Mechanisms for basement shortening in the Andean foreland fold belt of southern South America
Authors: Winslow Margaret A.
Published: May 2008

A mechanism for basement shortening underneath allochthonous foreland fold and thrust belts is reverse faulting along inherited normal faults. Normal faulting of basement rocks beneath much of southernmost South America indicates that up to 30–40% extension occurred before sedimentation in a subsiding foredeep. The basement is divided into blocks of similar dimensions to those in the Basin and range of Nevada, U.S.A. Post-depositional reverse motion along some of these high-angle block boundaries under the foreland can account for the 20–40 km of shortening observed in the cover rocks, without showing upthrust wedges of basement rocks.

The folds in the cover rocks of the foreland fold-belt are asymmetric, open to closed with over-steepened to overturned limbs which are frequently truncated by high-angle reverse faults. These faults attain a shallower dip with depth toward a décollement plane above a basal volcanic section. Basement involvement in thrusts (0.5–1.5 km vertical displacement) is suggested where basal volcanics are involved in thrust wedges, as revealed by drilling and seismic reflection data. Block faults have been observed beneath many forelands and have always been assumed to be pre-orogenic and passive with respect to deformation of the cover. The block dimensions, fault angles, vertical displacements and other parameters from the southern Andes are inserted to calculate pre-depositional extension and syn-orogenic shortening that can occur without producing obvious basement upthrusting. The results are compared with data from the Appalachians and Canadian Rockies.
Sedimentation across the Japan Trench off northern Honshu Island
Authors: von Huene Roland , Arthur Michael A.
Published: May 2008

The convergent margin along the International Program of Ocean Drilling (IPOD) Japan Trench transect was sampled by dredging, piston coring, and drilling by the Deep Sea Drilling Project (DSDP). This sampling was within an extensive network of single-and multichannel seismic reflection records. The Quaternary uplift of northern Honshu Island, climatic change, and lowered sea-levels, provided coarser grained sediment during the Quaternary than during the late Miocene and Pliocene. Within the Quaternary sediments, those in the forearc basin, in a slope basin, and on the trench floor are coarser grained and accumulated more rapidly than the clayey sediment from the trench slope. But overall, the sediment sampled from all environments is mainly clay and silt. Rates of accumulation varied greatly and prior to 3 Ma ago they were higher in trench slope basins than in the forearc basin. Tectonism along the Japan Trench transect must have changed the Miocene-Pliocene morphology by tilting some of the former trench slope basins; this may have actually triggered slumping and erosion rather than allowing sediment deposition.

The lower slope has a relatively large number of channels and a greater amount of slumped material then is found elsewhere; thus it may contain vertical and lateral changes of facies in sediments deposited over relatively short periods of time. Morphological features and sedimentation patterns on the lower slope are greatly affected by local tectonic structure which has changed significantly in the past 2–3 Ma. Slope basin and trench-floor deposits are distinguished from those of the main forearc basin by the relative abundance of material deposited by mass movement. Channels commonly cross the forearc basin and trench slope and provide the transport paths for coarse sediment to any part of the margin. No specific characteristics appear exclusively in a given environment, but the relative abundance of features can help identify broad environments of deposition.
Structural evolution of coherent terranes in the Ghost Rocks Formation, Kodiak Island, Alaska
Authors: Byrne Tim
Published: May 2008

The Late Cretaceous to Palaeocene Ghost Rocks Formation, Kodiak Island, Alaska, comprises two structural styles: multiply deformed mélange and relatively coherent terranes of turbidite deposits which together constitute a probable ancient accretionary complex. The mélange consists almost exclusively of orientated, elongate sandstone boudins which lie in a foliated pelitic matrix. In the coherent terranes, structural histories, rock types and hornfels metamorphism delineate two NE trending units: Unit A, and a probably younger Unit B. Unit A can be subdivided into two gradational structural belts, a seaward conjugate fold belt and a landward spaced cleavage belt. The conjugate fold belt contains ‘S’ and ‘Z’ type kink folds that often intersect to form conjugate fold sets. The folds of this fold belt are hornfelsed by a sill which intruded partially lithified sediments; the fold belt therefore also formed when the sediments were partially lithified. Analyses of the fold axial surfaces indicate a shortening direction of 319°, when later folding is removed. Sill emplacement and hornfels metamorphism interrupted the conjugate fold deformation and resulted in a change in style of deformation in Unit B to broad, open to tight folds associated with a spaced cleavage. The cleavage strikes 046° and dips approximately vertically, fanning divergently about fold axial surfaces. The approximately coaxial conjugate folding and folding with cleavage in unit A constitute D
1
. Unit B generally contains sub-horizontal beds except for a large-scale, overturned, thrusted fold, which emplaced mélange to the NW and above Unit B. Slickenlines, fold axes and poles to bedding indicate this unit was shortened along a trend of 334°. This deformation is termed D
2
and is correlated elsewhere in the Ghost Rocks Formation to thrust faults which place mélange to the NW and under the coherent terranes.

The structural histories of the coherent terranes in the Ghost Rocks Formations show that accretionary prism deformation can involve coaxial deformations and the tectonic deformation of partially lithified sediments. The structural histories also show that the Palaeocene deformation axes in the Ghost Rocks Formation have not rotated out of their original sub-horizontal orientations.
Sedimentation in the Sunda Trench and forearc region
Authors: Moore Gregory F. , Curray Joseph R. , Emmel Frans J.
Published: May 2008

Sedimentation in the Sunda Trench and forearc region is dominated by the transport of terrigenous detritus from orogenic and volcanic terranes around the margins of the north-eastern Indian Ocean. Quartzose Himalayan detritus is transported into the Bay of Bengal and down the trench axis as far south as the Sunda Strait. Prior to development of the outer-arc ridge, the majority of arc-derived sediment bypassed the forearc basin and was deposited in the trench. Nearly all sediment derived from the arc terranes of Java and Sumatra during the Neogene has been trapped in the forearc basin and has not reached the trench.

Hemipelagic sedimentation dominates on the lower part of the inner trench slope. Calcareous microfossils and volcanic ash are the dominant constituents of these hemipelagic deposits. Higher on the slope, terrigenous and hemipelagic sediments accumulate in large trench-slope basins.

The Sunda forearc basin is a series of smaller individual basins separated from each other by transverse highs, isolating the respective sedimentary sequences. Off north Sumatra, quartzose detritus accumulates, whereas off Java, volcaniclastic sediments predominate.

Long-distance transport of sediment down the trench axis, damming of sediments behind the outer-arc ridge, and the segmented nature of the forearc basin leads to the juxtaposition of sediment bodies with different provenances.
Development of the North Island Subduction System, New Zealand
Authors: van der Lingen Gerrit J.
Published: May 2008

Subduction of the Pacific plate underneath the North Island of New Zealand began near the beginning of the Neogene, when the Tonga-Kermadec Subduction System propagated southwards into the New Zealand continental crustal block, together with the southwards migration of the relative pole of rotation between the Pacific and Australian plates. Many geological and geophysical aspects of the North Island, both on land and offshore, are in agreement with models of subduction systems from elsewhere. Several NE-trending zones can be distinguished: Taupo Volcanic Zone (volcanic arc), Axial Ranges (exposed part of arc massif), East Coast Depression (forearc basin), Coastal Ranges (structural high of subduction complex), continental shelf and slope (trough-inner-slope of subduction complex). A west-dipping Benioff zone underlies the volcanic arc and arc massif. A negative gravity anomaly coincides with the surface extension of the Benioff zone. However, no subduction trench exists below the negative gravity anomaly.
Sensu stricto
, The Hikurangi Trough, to the east of the subduction complex, is not a subduction trench.

The forearc basin and subduction complex are riding passively on top of the Pacific plate to the east of the Benioff zone. The forearc basin initially was shallow marine, but subsequently was filled with coarse debris shed from the rising arc massif, and is now above water. The subduction complex consists of highly deformed autochthonous Cretaceous-Palaeogene strata, possibly deposited in a pre-subduction continental borderland. Accreted oceanic sediments have not been recorded, but may be present in the lower part of the subduction complex, or, to a large degree, may have been subducted. During the formation of the subduction complex, small basins were created by elongate narrow structural ridges parallel to the trough-inner-slope. Several are now exposed in the Coastal Ranges structural high. Their sedimentary fills comprise sediment gravity flow deposits, hemipelagic muds, and arc-derived ash. Similar sedimentary facies have been cored in present-day offshore slope basins. Some sediment gravity flows reach the Hikurangi Trough via submarine canyons, bypassing the slope.

A directional, morphological and geophysical break exists between the North Island and Kermadec subduction systems, probably caused by the Vening Meinesz Fracture Zone.

Early-upper Miocene rhyolitic tuff beds in trough-inner-slope flysch basins are the first sign of volcanic arc activity. They cannot have come from the Quaternary Taupo Volcanic Zone, but were probably derived from the upper Miocene Coromandel Arc further to the NW. As subduction is oblique, strike-slip movement has moved the forearc region east of the Axial Ranges from a position closer to the Coromandel Arc to its present situation.
The Late Cretaceous-Cenozoic history of western Baluchistan Pakistan—the northern margin of the Makran subduction complex
Authors: Arthurton Russell S. , Farah Abul , Ahmed Wahiduddin
Published: May 2008

The study area lies some 400 km N of the Makran coast, and extends westwards for some 450 km from the Chaman Fault, a major sinistral transform fracture zone which marks the suture between the Eurasian and Indian plates. It lies to the north of the Makran ranges of Tertiary flysch, and flanks the southern margin of a stable, aseismic area known as the Dashi-i-Margo block.

The Makran region as a whole has been interpreted as an accretionary prism of Late Cretaceous to Holocene age, resulting from the northward subduction of oceanic lithosphere. The geological record of the study area is consistent with such an interpretation, for the period Late Cretaceous-Palaeocene at least.

Rapid northward subduction during the Late Cretaceous gave rise to profuse andesitic volcanism on the sub-parallel, ENE-trending arc massifs of the Chagai Hills and Ras Koh geanticlines. The waning of this volcanism during the Maestrichtian coincided with the accumulation and deformation of flysch sediments in a trench which extended from Mirjawa to the south of Ras Koh; also with thick forearc sedimentation in the Dalbandin Trough, between the geanticlines.

In late Palaeocene times, deformed flysch—interpreted as a subduction complex—was elevated to form a structural high in the Mirjawa range. In the western Ras Koh, the flysch, along with ultramafic slices, became emplaced against the arc massif to form a new landmass. This emplacement may have been a result of a late Palaeocene collision between the northward-migrating Indian continental plate and the continental lithosphere of the Dasht-i-Margo block, the Ras Koh flysch belt taking the brunt of the initial impact.

The principal forearc faults have regular, arcuate traces which, in the south-west, parallel the structural grain of the Mirjawa flysch belt. Movement on the faults influenced sedimentation in the forearc, particularly during the Eocene and Miocene. There is evidence of tensional transform movement in Eocene times. The forearc faults were especially active during the Pliocene. Movement across them during this period was compressional and associated with major folding, particularly in the Dalbandin Trough. The trend of this folding may imply dextral transform displacement within the trough.
The Coastal Belt of the Franciscan: youngest phase of northern California subduction
Authors: Bachman Steven B.
Published: May 2008

The Coastal Belt of the Franciscan complex represents the latest Cretaceous to middle Tertiary part of the accretionary prism of an arc-trench system in northern California. On the Mendocino coast, both deformed slope and trench deposits and much less deformed slope basin deposits are recognized. Deformation increases with depth in the slope deposits, towards the contact with the accretionary prism. In the accretionary prism, bands of deformed rocks from tens of metres to kilometres in width suggest major zones of shearing. Stratigraphic tops of beds face eastward, yet palaeontological ages young westward; imbricate stacking is suggested by these relationships. Stratigraphical tops and palaeontological ages indicate that the slope basin deposits are in normal stratigraphic sequence.

Facies in the accretionary prism may represent trench fill, abyssal plain, feeder channel, and small fan deposits that were accreted to the leading edge of the continent and may also include slope deposits that were deformed during progressive deformation of the accretionary prism. The less deformed slope deposits may have been deposited as slope basin turbidites, small fans, and channels. South- and south-westward-directed palaeocurrent indicators and sandstone petrology suggest sediment transport from the Klamath Mountains and Oregon across the shelf and down the slope and/or along the trench axis.
Composition of modern deep-sea sands from arc-related basins
Authors: Maynard J. Barry , Valloni Renzo , Yu Ho-Shing
Published: May 2008

Petrographic and chemical examination of modern deep-sea sands shows a clear distinction between active and passive plate-tectonic settings. Among active settings, sands from forearc basins of island arcs and basins from strike-slip continental margins can be distinguished, but those from other arc-related settings overlap considerably in composition. In particular, sands from continental margin subduction zones and those from the backarc of island arcs appear to be indistinguishable.

Chemically, arc-related sands are very close in composition to ancient greywacke sandstones. For instance, sodium almost always exceeds potassium. Thus it is not necessary for sodium to be added to sands diagenetically to make greywackes, as has been suggested.
Initiation of subduction zones: implications for arc evolution and ophiolite development
Authors: Karig D. E.
Published: May 2008

The initial location of trenches with respect to continental margins is a critical factor in the nature of the forearc region and its subsequent evolution, as well as for the interpretation of ophiolites. Although recent studies of ancient margins and highly evolved arcs suggest that wide strips of oceanic crust are commonly trapped between the trench and volcanic arc, review of young active arcs does not support this conclusion. Neogene trenches have formed predominantly very close to the crustal interface between oceanic crust and continental or older island arc crust. A few arcs have developed along transform zones, but none can be identified as having formed by breakage within an oceanic plate. Apparently the high strength of normal oceanic lithosphere causes the initial fracture to utilize pre-existing zones of weakness or pre-stressing, such as the downbowed and fractured crustal interfaces along passive margins. There seems to be no physical basis for the initial rupture to form smooth, large radius arcs, thereby trapping oceanic crust in re-entrants. Moreover, oceanic crust or ophiolites originating adjacent to a continental or arc margin ought to betray that heritage by a high terrigenous or volcaniclastic component in their overlying sediment. Large ophiolite sheets that can be interpreted as forearc slabs may develop in areas with relatively unusual plate geometries, as where oceanic spreading zones cut diagonally across the forearc. Disrupted ophiolites could, in many cases, represent slices of oceanic crust and upper mantle accreted to and responsible for the growth of oceanic arcs. Evidence for accreted slices in the Mariana arc and the range of forearc geometries among oceanic arcs allow construction of an evolutionary sequence in which an initial steep and narrow trench shape is differentiated into upper and lower sections by intermittent accretion of oceanic crustal slices. As a result, the slope apron on the upper section rotates arcward and can rise to form a basin as is displayed in the southern Middle America arc.
Base metal concentrations in kaolinised and silicified lavas of the Central Burma volcanics
Authors: Marshall T. R. , Amos B. J. , Stephenson D.
Published: May 2008

Detailed mapping and limited geochemical sampling of a Lower Pliocene trachyandesite-sediment-tuff sequence reveals two juxtaposed but distinct kaolinised sequences caused by tropical weathering and hydrothermal activity. The stratigraphy and sequence of alteration in the lower Taungni section is difficult to establish. The kaolinised rocks are characterized by high lead and arsenic content and contain large irregular masses of silica. Kaolinisation resulted either directly from metalliferous hydrothermal activity or from acidic fluids released by oxidation of sulphides. The upper, well-bedded Kyauktaga section shows regular redistribution of silica resembling that of the silcrete profile and vertical base metal zoning attributable to groundwater movement.