Stable Block Research Articles

Detrital zircon lineages of late Neoproterozoic and Cambrian strata, NW Laurentia

The Phanerozoic tectonic evolution of the Arctic is a field of escalating scientific interest. Detrital zircon provenance studies provide vital contributions to clarify the region’s tectonic evolution. Northwest Laurentia exposes a broad expanse of Proterozoic and Paleozoic sedimentary strata for which detrital zircon populations are poorly characterized. Moreover, the significance of sedimentary recycling is becoming better appreciated in light of detrital zircon studies. As more data become available, our understanding of the detrital zircon character of NW Laurentia improves, providing an increasingly reliable baseline at subcontinental resolution against which potentially allochthonous terranes, such as Arctic Alaska, can be assessed. Sandstones of late Neoproterozoic and Cambrian age from NW Canada yield detrital zircon signatures dominated by zircon grains recycled from Proterozoic sedimentary strata. Two Neoproterozoic sandstones from the northern Mackenzie Mountains yield zircon populations sourced from the Mackenzie Mountains Supergroup. Two Lower Cambrian sandstones sourced from the Yukon stable block and deposited in Richardson Trough have zircon populations nearly identical to those of the upper Wernecke Supergroup, locally exposed across the southern Yukon stable block, where they are unconformably overlain by Cambrian strata. Comparisons with similar studies from NW Canada permit generalizations of the patterns of zircon recycling. Four provenance lineages are described that characterize Laurentia-derived successions in NW Canada.

Late Mesozoic compressional folds in Dongsha Waters, the northern margin of the South China Sea

Once considered as a component part of the Cenozoic Pearl River Mouth Basin (PRMB), Dongsha Waters was found with distinct tectono-stratigraphic style, in which the upper structural layer comprises only thin (usually 0.5-1 km) sediments of mid-Miocene to Quaternary, whereas the lower layer consists of Early Cretaceous terrestrial, Jurassic marine and possibly Triassic sedimentary rocks, totaled 4-9 km thick. The major sedimentary hiatus between them corresponds to the Late Cretaceous to mid-Miocene Epoch, well during the continental rifting to oceanic spreading stage. Faulting and magmatism during the opening of the South China Sea are basically weak over the central part of Dongsha Waters where the crustal thickness is mostly around 25 km thick, reflecting a relatively stable block. All these indicate less influence exerted by the Cenozoic rifting, strikingly contrasting to the neighboring areas where thick rift-to-drift sediments have accumulated. With the recognition of Mesozoic strata in this and the previous study, a relict Mesozoic basin is proposed to be existed over Dongsha Waters and named as Dongsha Basin. There are two generations, Late Neogene and Late Jurassic to Early Cretaceous, of compressions featuring seafloor and blind folds, respectively. The former presents only in few localities in east to Dongsha Island. The later distributes widely as individuals in north and as trains in south. They are characterized mostly by gentle growth folds inside which only a few minor upthrust faults with offsets in the order of a few tens to hundreds of meters. The upthrust faults dipped mostly southeastward against to the northwestward subduction of paleo-Pacific as suggested in a previous study. They featured more like back-thrust growth tectonics, formed a broad NNE-SSW trending belt oblique to the northern margin of the South China Sea, and thus are inferred to have been the far-field impact of the Late Mesozoic subduction of the proto-Pacific. (C) 2014 Elsevier B.V. All rights reserved.

A family of highly stable second derivative block methods for stiff IVPs in ODEs

This paper considers a class of highly stable block methods for numerically solving initial value problems (IVPs) in ordinary differential equations (ODEs). The boundary locus of the proposed parallel one-block, r-output point algorithms shows that the new schemes are A-stable for output points r = 2(2)8 and A(α)-stable for output points r = 10(2)20, where r is the number of processors in a particular block method in the family. Numerical results of the block methods are compared with the second derivative linear multistep method in [8].

Distribution of the crustal magnetic field in Sichuan-Yunnan region, southwest China.

Based on the new and higher degree geomagnetic model NGDC-720-V3, we have investigated the spatial distribution, the altitude decay characteristics of the crustal magnetic anomaly, the contributions from different wavelength bands to the anomaly, and the relationship among the anomaly, the geological structure, and the geophysical field in Sichuan-Yunnan region of China. It is noted that the most outstanding feature in this area is the strong positive magnetic anomaly in Sichuan Basin, a geologically stable block. Contrasting with this feature, a strong negative anomaly can be seen nearby in Longmen Mountain block, an active block. This contradiction implies a possible relationship between the magnetic field and the geological activity. Completely different feature in magnetic field distribution is seen in the central Yunnan block, another active region, where positive and negative anomalies distribute alternatively, showing a complex magnetic anomaly map. Some fault belts, such as the Longmen Mountain fault, Lijiang-Xiaojinhe fault, and the Red River fault, are the transitional zones of strong and weak or negative and positive anomalies. The corresponding relationship between the magnetic anomaly and the geophysical fields was confirmed.

George Frampton's homes and studios in St John's Wood: a sculptor's architectural ideal realized

A remarkable, though late, example of architecture stemming from the AEsthetic and Arts and Crafts Movements has been overlooked to the extent that it is not even mentioned in the relevant volume of Buildings of England.1 This complex of house and two studios at 92-96 Carlton Hill, St John's Wood, London, has the added interest for historians of sculpture that it was largely conceived by its owner, the sculptor Sir George Frampton, for his own use and that of his wife, the painter Christabel Frampton (nee Cockerell). It was designed in 1908, in the same year that Frampton received his knighthood, and was completed in 1910. This customized house and studio complex noteworthily departed from the exotic and historicist display exemplified in Lawrence Alma Tadema's Roman-style villa in nearby Grove End Road, or more famously in Leighton House. Its residential quarters, if not its workspaces, are noticeably more restrained than those of Frampton's previous residence at Queen's Road (now Queen's Grove), in another part of St John's Wood. What Frampton aimed at in his property was, he declared, 'not a so-called artistic house, but a house that an artist would like to live in'.2 As for the adjoining sculpture studio, it was a severely practical space, 'with no pretence of adornment'.3 Demonstratively rejecting the resplendent theatricality of the Victorian masters, the Carlton Hill buildings have much more in common with the houses and studios designed in the early 1900s by Joseph Maria Olbrich for the artists' colony in Darmstadt, though they remain very recognizably English.Viewed from the street, the complex is somewhat deceptive in its air of suburban normality, at least judging by standards set for us in the 1930s and later (figs. 1 and 2). The bay windows of the central block, with their multiplicity of mullions and glazing bars, produce a countrified, vernacular effect. The deep, unmodulated cornices of all three blocks, as well as the extensive overhang of the roofs, punctuated by flat-ended brackets, give a generous feeling of horizontality. At the same time, the plunging screen wall linking the central to the side blocks at first-floor level counters the predominant rectilin- earity. The smaller size of the subsidary block on the north-east side provides a slight element of asymmetry, hardly noticeable, since the house is generally approached from up or down hill. The overall effect is of imposing symmetry, lent a picturesque aspect by the sloping site. That anything so homogeneous was achieved may come as a surprise when we learn that the house and the block adjoining it to the south-west (the block on the other side, containing Frampton's studio was a totally new addition) were make-overs to already existing structures (fig. 3). The original house, with its free-standing stable block, had been built in 1873 by a pub architect, James Miller, for a publican named George Speedy, and had already had three owners by the time Frampton purchased it.4 The sculptor, on becoming its owner, was not prepared to settle for what was later described as 'a mid-Victorian suburban house of a commonplace and ugly type'.5 Miller's elevations were those of a Venetian renaissance palazzo, tamed and cut down to size, and hardly conformed to Frampton's idea of a home. For the practical implementation of his idea, he had the sense to bring in the already eminent architect Guy Dawber, at that time living close by. Dawber signed the drawings and was responsible for negotiations with the London County Council, but the building's exterior bears little resemblance to Dawber's other works. An article for The Studio of April 1910 proclaims that, for its owner, the building was 'the fulfillment of a long cherished plan of building for himself a residence in which he could embody his own ideas of construction and decoration'. For the author of this article, 92-96 Carlton Hill was Frampton's own brainchild, and nowhere in the quite considerable space given to describing it is the name of Dawber once mentioned, whereas it is stated that 'the new house shows naturally, in numberless details the impress of the mind of the original and gifted artist by whom it was projected'. …

Polymeric Micelle Assembly for the Direct Synthesis of Platinum-Decorated Mesoporous TiO2 toward Highly Selective Sensing of Acetaldehyde

Platinum-decorated mesoporous TiO2 is synthesized by the self-assembly of polymeric micelles of an asymmetric triblock copolymer with three chemically distinct units in an acidic tetrahydrofuran solution. The strong hydrophobic interaction of platinum(II) 2,4-pentanedionate with a polystyrene core and electrostatic interaction of titanium tetraisopropoxide with a poly(vinylpyridine) shell enable us to directly synthesize crystalline mesoporous TiO2 with platinum nanoparticles. A thermally stable block copolymer prevents collapse of the ordered mesostructure during the calcination process. The platinum source is in situ reduced to form the platinum nanoparticles on the TiO2 walls. The sensing performance of platinum-decorated mesoporous TiO2 is studied in detail using a quartz crystal microbalance technique, and it is found that it shows excellent sensitivity for acetaldehyde.

Study on Comprehensive Measures of Long-Term Stable Dense Oil Reservoir

water injection development is an effective means of tight reservoir to maintain formation energy, and high formation pressure is the basis of reservoir maintain a long-term and stable, therefore, give enough water injection, so as to maintain high pressure is the key to maintain the long-term stability of the reservoir. Liu Maoyuan block Changqing Oilfield is a typical part of tight sandstone reservoir, water injection wells long is not up to the demand of injection, after fracturing, acidizing by invalid injection measures, is not conducive to long-term and stable block. Therefore, research on comprehensive countermeasures of long-term stability of dense oil reservoir. Through the research and development of new antihypertensive drag reduction agent for the overall pressure on block; select suitable for dense reservoir single well stimulation measures and local boosting measures, measures ineffective wells and local abnormal pressure injection is difficult to solve the problem of the cause, to maintain formation pressure. A good result has been obtained by field test, effectively solve the tight reservoir by high-pressure injection resulted in not long-term stability problems, and provides a new idea and reference for solving dense reservoir long-term stability problem.

Apoptosis and neutrophils in the regulation of Ph-positive myeloid cell proliferation and differentiation ex vivo

Ex vivo proliferation and differentiation of Philadelphia chromosome-positive (Ph+) human myeloid cells (Ph+ cells) from chronic myeloid leukemia (CML) proceed via alternation stages of cell proliferation and neutrophil maturation. To regulate them, apoptosis is alternately blocked or induced with the help of neutrophils and expression of bcr/abl, bax, and bcl2. The regulation of apoptosis in main types of Ph+ cells depends on the alternation of (1) Ph+ cell proliferation and (2) neutrophil maturation and may follow two pathways. One consists in alternating blockages and inductions of apoptosis with initial maturation and subsequent proliferation under alternation stages as (2)-(1)-(2) and has not been described as yet. Neutrophil accumulation blocks apoptosis. As neutrophils are depleted, apoptosis is induced again. Its block accelerates proliferation with a new accumulation of neutrophils, which is followed by regular neutrophil death and a new induction of apoptosis. The way optimizes the proliferation efficiency (P/D index) with a regular alternation of maturation and proliferation, allowing the cycle of proliferation and differentiation to be completed. In another way, the alternation starts with proliferation as (1)-(2)-(1) at a lower neutrophil content) and leads to resistant decrease of the maximal apoptosis level by a factor of 3–8 as compared with (2)-(1)-(2) alternation. A stable block of apoptosis is observed in cells with prolonged stages of proliferation and maturation, leading to an accumulation of blasts and myelocytes with elevated bcr/abl expression and expression of bcl2 > bax. A stable block of apoptosis is associated with CML progression and in Ph+ cell lines. Cells follow the first pathway of the apoptotic regulation in chronic-phase CML. Ex vivo cultivation of Ph+ cells from individual CML patients was assumed to provide for a more exact diagnosis of the CML phase and optimizing the treatment.

Evolution of the South Atlantic passive continental margin in southern Brazil derived from zircon and apatite (U–Th–Sm)/He and fission-track data

The area between São Paulo and Porto Alegre in southeastern Brazil plays a key area to understand and quantify the evolution of the South Atlantic passive continental margin (SAPCM) in Brazil. In this contribution, we present new thermochronological data attained by fission-track and (U–Th–Sm)/He analysis on apatites and zircons from metamorphic, sedimentary and intrusive rocks. The zircon fission-track ages range between 108.4 (15.0) and 539.9 (68.4) Ma, the zircon (U–Th–Sm)/He ages between 72.9 (5.8) and 525.1(2.4) Ma, whereas the apatite fission-track ages range between 40.0 (5.3) and 134.7 (8.0) Ma, and the apatite (U–Th–Sm)/He ages between 32.1 (1.5) and 93.0 (2.5) Ma. The spatial distribution of these ages shows three distinct blocks with a different evolution cut by old fracture zones. While the central block exhibits an old stable block, the Northern and especially the Southern block underwent complex post-rift exhumation. The sample of the Northern block shows two distinct cooling phases in the Upper Cretaceous and the Paleogene to Neogene. After sedimentation of the Permian sandstones the samples of the Central block were never heated up over 100 °C with a following moderate to fast cooling phase in Cretaceous to Eocene time and a fast cooling between Oligocene to Miocene. The five thermal models obtained in the Southern block indicate a complex evolution with three cooling phases. The exhumation events of the three blocks correspond with the Paraná–Etendekka event, the alkaline intrusions due to the Trinidad hotspot, and the evolution of the continental rift basins in SE Brazil and are, therefore, most likely to be the major force for the post-rift evolution of the passive continental margin in SE Brazil, which therefore corresponds to the three main phases of the Andean orogeny.

Size distribution of Parkfield's microearthquakes reflects changes in surface creep rate

AbstractThe nucleation area of the series of M6 events in Parkfield has been shown to be characterized by low b-values throughout the seismic cycle. Since low b-values represent high differential stresses, the asperity structure seems to be always stably stressed and even unaffected by the latest main shock in 2004. However, because fault loading rates and applied shear stress vary with time, some degree of temporal variability of the b-value within stable blocks is to be expected. We discuss in this study adequate techniques and uncertainty treatment for a detailed analysis of the temporal evolution of b-values. We show that the derived signal for the Parkfield asperity correlates with changes in surface creep, suggesting a sensitive time resolution of the b-value stress meter, and confirming near-critical loading conditions within the Parkfield asperity.

Learning from the Past: A Review of Treatments carried out to Clunch in 1985

Clunch has been widely used as a building stone in the south and east of England since the fourteenth century; it can be subject to significant and severe deterioration principally through a characteristic lamination of the surface. In August 1985 a series of comparative consolidation treatments was undertaken on the clunch of the west elevation of the south stable block at Woburn Abbey. Half of this elevation had been dressed back to behind the decay zone and the other had not; the same treatments were applied to both types of surface. It is rare that the opportunity arises to carry out an assessment of such a variety of treatments, but in 2011 a thorough investigation of the elevation was undertaken. Simple field techniques such as drill resistance, permeability measurements and decay mapping were used to provide some objective measurements of the effect of treatments. This paper describes the results and places them in a wider context of past, current and possible future treatments of clunch.

A new Late Cretaceous to Present APWP for Asia and its implications for paleomagnetic shallow inclinations in Central Asia and Cenozoic Eurasian plate deformation

Based on a compilation of 533 Cretaceous to present-day palaeomagnetic poles obtained from both sedimentary and igneous rocks, we present a new analysis of the so-called 'Asian inclination anomaly' and demonstrated the anomaly to be twofold: a 2nd-order anomaly, characterized by high palaeolatitudes in Indochina and low palaeolatitudes over Tibet and Central Asia, is superimposed on a 1st-order anomaly, characterized by Cenozoic low palaeolatitudes found all over northeastern Asian stable blocks. The analysis herein convincingly shows that the Europe Apparent Polar Wandering Path (APWP) can no longer be used to interpret palaeomagnetic data East of the Urals, including interpretation of Asian Tertiary deformation related to the India-Asia Collision. We, thus, construct a new APWP for East Asia, based on palaeopoles from blocks assumed to be stable. This new APWP is consistent with and reinforces previous analyses of Asian tectonics, such as the age (∼55 Ma) and locus (∼5-10°N) of the Indo-Asian collision, the lateral extrusion of SE Asian continental blocks and the intracontinental shortening in Central Asia. Possible origins of the 1st-order palaeolatitude anomaly are: (1) a geomagnetic origin, due to long-lasting non-dipolar contribution to the magnetic field and (2) a tectonic hypothesis, in which a newly defined East Asia Plate was located ∼10° farther south than expected from the current Europe APWP. Based on a set of six new reconstructions from 90 Ma to present, we show that our tectonic model reconciles geophysical, geological and tectonic observations throughout Eurasia, from Siberia to Europe, including kinematics in the Arctic Ocean, up to northwestern Arctic Alaska. Beyond possible occurrences of non-dipolar field contribution and/or local inclination flattening in the sedimentary data, our model leads us to conclude that Cenozoic tectonics is the dominant contributor to the observed 1st-order ∼10° low palaeolatitude anomaly over Asia during the Tertiary.

Active Deformation Measurements at Mishmi Complex of Eastern Himalayan Syntaxis

We focus the geodynamic status of Eastern Himalayan Syntaxis with reference to Tibetan Plateau,Chinaand Burmese Arc using the crustal deformation constraints with GPS observation. We have used the GPS data, surface geomorphic constraints and compared the existing Pn velocity and Anisotropy [1], determined the crustal velocity of Tibetan Block and North andEast Chinablock as 2 - 8 mm/yr and 6 - 11 mm/yr considering the EHS as stable block. The lack of crustal deformation studies in EHS poses a gap in its geodynamic setup. The present attempt is first time in EHS to estimate crustal deformation by GPS. We presented GPS results from 10 stations along with one permanent station covering the EHS 2 - 3 mm/yr with an azimuth of N460. It reveals that the EHS is moving very slow rates, which accommodates the maximum strain (after Great Earthquake of8.7 M, Arunachal China Border 1950). The neotectonic activities are recorded along the major rivers traversing EHS follow the major thrusts and faults.

42 Computer folding of RNA tetraloops? Are we there yet?

The tetraloops (Tls) are basic and unusually stable building blocks of RNA structure that often participate in a variety of biochemical processes – including nucleation in RNA, folding and formation of tertiary contacts. Moreover, they are known to play roles in transcription and translation as well as serving as recognition sites for RNA-binding proteins. Understanding the folding of small RNA hairpins is a critical first step in understanding the folding of larger RNA molecules. In present study, we investigate the folding and unfolding of two RNA Tls at the atomic level based on replica exchange molecular dynamics (MD) simulations. Using the most recent reparametrisation of the Amber family of RNA force fields (ff99bsc0OL3 (Banáš et al. 2010, Zgarbová et al. 2011)), we have, for the first time, folded tetraloop structures to within 2 Å all-atom RMSD of the native structure involving all signature interactions of native fold, starting from fully unfolded conformations. The most native-like structures reported by previous studies were only ∼4 Å from native; due to force field deficiencies, Tl structures degraded even in short MD simulations initiated from folded (Banáš et al. 2010). We described the folding pathway, which is very similar for both tetraloops, and it is comparable with experimental results. Further, we can use our results to address several questions related to the biological function of tetraloops. For example, an open question is whether the antibiotic restritocin induces the conformational change of the GNRA TL or binds to a transiently unstructured GNRA TL. We observed the misfolded state of UUCG Tl recently suggested by mutation experiments, which most likely acts as a kinetic trap during UUCG folding. We can also relate our results to ultrafast spectrosopy experiments that identified some features of misfolded states of GNRA TLs reminiscent of the misfolded-compact GAGA structure identified in this study. Nevertheless, our simulations show that despite REMD technique being powerful tool which significant increases the sampling, obtaining an equilibrium between the unfolded, misfolded and folded states is still very challenging.

Interblock zones in the crust of the southern regions of East Siberia: tectonophysical interpretation of geological and geophysical data

Interblock zones in the crust of the southern regions of East Siberia: tectonophysical interpretation of geological and geophysical data

Velocity structure of the uppermost mantle beneath East Asia from Pn tomography and its dynamic implications

AbstractEast Asia is one of the most tectonically active regions on Earth's surface due to the collision from the India plate and the suctions induced by the subduction of the Pacific and Philippine plates. To better understand the complicated deformation and active seismicity of the area, we conducted a Pn traveltime tomography to estimate the compressive wave speed of the uppermost mantle beneath East Asia. We collected a total of 296,334 Pn arrivals recorded by 1354 stations from 27,777 earthquakes in a rectangular area from 60°E to 145°E in longitude, 15°N to 60°N in latitude. The data set was carefully integrated from three different catalogs after examining potential systematic biases in the catalogs. The inversion results revealed a large‐scale velocity perturbation in the study area. Pn velocity in the region west to ~108°E is approximately 10% higher than that in the east. In each region, stable blocks tend to have high Pn velocity while the boundary regions, which show a high level of seismicity and surface deformation, appear to have low Pn velocity. We further computed the Benioff strain rate in the two regions and found it correlates negatively with the averaged Pn velocity. Our observations here suggest that Pn velocity, which is predominantly determined by Moho temperature, is a good indicator of lithosphere strength.

Pn wave velocity and anisotropy beneath Pamir and its adjacent regions

As the western end point of continental collision between the Indian and Eurasian plates, Pamir is an ideal place to research uplifting mechanisms in the Tibetan plateau. In this study, 141 644 Pn arrivals were used to obtain seismic wave velocities and anisotropy in the uppermost mantle beneath Pamir and its adjacent regions by performing tomographic inversion of Pn travel times. The data were selected from multiple databases, including ISC/EHB, the Annual Bulletin of Chinese Earthquakes, and regional bulletins of Xinjiang. The tomography results reveal significant features with high resolution and correlate well with geological structures. The main results are as follows: (1) The Pn wave velocities are particularly high in the old stable blocks such as Tarim basin, Indian plate and Tajik basin, while the low Pn velocities always lie in tectonically active regions like the western Tibetan plateau, Pamir, Tianshan and Hindu Kush. (2) Strong Pn anisotropy is found beneath the Indian-Eurasian collision zone; its direction is parallel to the collision arc and nearly perpendicular to both the direction of maximum compression stress and relative crustal movement. The result is probably caused by the pure shear deformation in the uppermost mantle of the collision zone. (3) A geodynamic continent-continent collision model is proposed to show anisotropy and collision mechanisms between the Indian plate and the Tarim and Tajik basins.

An improved lower bound on a positive stable block triangular preconditioner for saddle point problems

In this paper, a new lower bound on a positive stable block triangular preconditioner for saddle point problems is derived; it is superior to the corresponding result obtained by Cao [Z.-H. Cao, Positive stable block triangular preconditioners for symmetric saddle point problems, Appl. Numer. Math. 57 (2007) 899–910]. A numerical example is reported to confirm the presented result.

A note on the positive stable block triangular preconditioner for generalized saddle point problems

In this paper, we give a sharp eigenvalue bound for the positive stable block triangular preconditioned matrix presented in a recent paper by Cao [Z.-H. Cao, Positive stable block triangular preconditioners for symmetric saddle point problems, Appl. Numer. Math. 57 (2007) 899–910]. The intervals containing these eigenvalues of the preconditioned matrix remove the origin, which is benefit for further study. Numerical experiments of a model Stokes problem are presented to show the estimate and the effectiveness of the positive stable block triangular preconditioners.

Termination of the northwestern Basin and Range province into a clockwise rotating region of transtension and volcanism, southeast Oregon

New data indicate that northeast-directed extensional faulting characterizes slip across the Brothers fault zone (BFZ), which marks the northern limit of the northwestern Basin and Range (NWBR) extensional province in southeastern Oregon. Structural separation across individual north-northeast striking NWBR faults decreases to zero south of the BFZ. Field relationships and cross-sections demonstrate limited kinematic linkage and independent evolution of the two fault systems since ∼7 Ma. West-directed extension accumulated on NWBR faults at 0.01 mm/yr and lengthened northward after 7.05 Ma. BFZ faults accumulated northeast-directed extension at rates of 0.01 mm/yr since 5.68 Ma. Deformation coincides with periods of heightened basaltic magmatism in the High Lava Plains, implying that volcanism weakened the crust and promoted extension in the BFZ. In a new model, we reconcile the observed northward diminishing rate and clockwise motion of the modern NWBR deformation field with regional geology. The BFZ defines a small circle about the pole of rotation and separates a stable block to the NE from the extending region to the south. Faults to the south are growing northward, consistent with the northward decrease in rate and magnitude of extension in the NWBR.