Extensional Part Research Articles

The Pondosa fault zone: A distributed dextral-normal-oblique fault system in northeastern California, USA

Abstract The tectonic domains of Basin and Range extension, Cascadia subduction zone contraction, and Walker Lane dextral transtension converge in the Mushroom Rock region of northeastern California, USA. We combined analysis of high-resolution topographic data, bedrock mapping, 40Ar/39Ar geochronology, low-temperature thermochronology, and existing geologic and fault mapping to characterize an extensive dextral-normal-oblique fault system called the Pondosa fault zone. This fault zone extends north-northwest from the Pit River east of Soldier Mountain, California, into moderately high-relief volcanic topography as far north as the Bartle (California) townsite with normal and dextral offset apparent in geomorphology and fault exposures. New and existing 40Ar/39Ar and radiocarbon dating of offset lava flows provides ages of 12.4 ka to 9.6 Ma for late Cenozoic stratigraphic units. Scarp morphology and geomorphic expression indicate that the fault system was active in the late Pleistocene. The Pondosa fault zone may represent a dextral-oblique accommodation zone between north-south–oriented Basin and Range extensional fault systems and/or part of the Sierra Nevada–Oregon Coast block microplate boundary.

Numerical Study on Performance of Prefabricated RCS Joint under Normal Temperature and Fire

To study the mechanical behavior and fire resistance of the prefabricated reinforced concrete column and steel beam (RCS) joints with endplate, this paper presented a numerical investigation on the joints under normal temperature and fire. The full 3D solid finite element models were implemented in ABAQUS. The simulated results show that under normal temperature, the yield moment and initial rotation stiffness increase with the increase of the endplate thickness, the failure mode changes from deformation of the endplate to yield of the extensional part. Increasing the thickness of stiffeners and changing the form of stiffeners can effectively improve the yield moment of the joint, but the initial rotational stiffness keeps invariant basically. Under fire condition, the load ratio has a significant effect on the fire resistance of the prefabricated RCS joint; the thickness of the endplate and stiffener, the stiffener form have less influence on the fire resistance of the joint.

Safety Mechanisms in Relational Database as Part of the IT System of the Enterprise

Abstract The work examines the effectiveness of the replication mechanism of the X production company database. In order to extend the functionality of the computer database of the enterprise, a model of its resource flow was created and an intensional and extensional part was created for a test database based on real enterprise resources. The model has been simplified to 3-rd normal form. The implementation was done in the MySQL database system. Two different operating systems were selected for testing: Windows and Linux. The database management system (DBMS) is working under the GPL license. MySQL DBMS offers many security mechanisms, and to secure the database, system of users permissions to objects have been selected and also an encryption of access passwords for users and connections to servers was used. A replication engine based on the binary log and the model “main server and backup server” was used to create a copy of the enterprise data.

Novel viscoelastic model for predicting the synthetic polymer’s viscoelastic behavior in porous media using direct extensional rheological measurements

High molecular weight, flexible polymers used for heavy oil recovery exhibits viscoelasticity that causes the thickening of apparent viscosity which could not be predicted by the conventional shear thinning rheological models. Unified apparent viscosity model (UVM) developed at UT-Austin based on the postulation that the apparent viscosity of polymer solutions is the sum of shear and elongational viscosity accounts for the viscoelastic thickening in the extensional part through relaxation time, maximum elongational viscosity and strain hardening index. Although UVM addresses the other limitation of the previous viscoelastic models, its dependence on the core flood data to predict maximum elongational viscosity and strain hardening index limits its commercial independent usage for preliminary screening.These limitations are addressed in our novel viscoelastic model named as Azad Trivedi Viscoelastic Model (AT-VEM), which could predict the apparent viscosity in the shear thickening region using the extensional parameters measured by capillary breakup extensional rheometer (CaBER) through the combination of Upper Convected Maxwell (UCM), finite extensible nonlinear elasticity (FENE) and power law theories. CaBER set up uses a step-strain to stretch the drop of polymeric liquid placed between the two plates and monitor its midpoint diameter during filament drainage. The relaxation time is determined by fitting the filament diameter from the region representing the balance between the elastic stress and surface tension into UCM. As per FENE theory, fluid relaxes at the rate two-third of its strain rate and the extensional viscosity around the critical Deborah number of 0.66 corresponds to the maximum elastic limit and would be the maximum elongational viscosity. Filament during drainage gets strained and the corresponding increment in extensional viscosity is fitted with power law to determine the strain hardening index.A series of core flood data (performed using partially hydrolyzed polyacrylamide (HPAM) polymers) from the UT-Austin that validated the UVM model was used extensively. Other reported literature data were also used. Extensional rheology was performed on those polymers at the similar conditions to determine the relaxation time, maximum elongational viscosity, and strain hardening index. These parameters along with the shear parameters were used to match the reported apparent viscosity. All the experiments fairly match well with the average downscaling power factor of 0.35 to the maximum elongational viscosity and subtrahend of 1.2 to the strain hardening index. Downscaling and subtrahend factor is essential to scale down the pure elongation in the extensional bulk field to the combination of shear and elongation experienced in the porous media.AT-VEM can be incorporated into commercial numerical simulators for predicting the injectivity and recovery due to viscoelastic thickening independently and thereby assist in quick screening polymers for oil recovery applications.

Maar-diatreme volcanism relating to the pyroclastic sequence of a newly discovered high-alumina basalt in the Maroa Volcanic Centre, Taupo Volcanic Zone, New Zealand

Diatreme sequences have previously been described from drill holes within the Taupo Volcanic Zone. The newly discovered Te Hukui Basalt exhibits deep excavation of country rocks that do not appear elsewhere at the surface. The basalt is characterized by proximal deposition of pyroclastic deposits relating to phreatomagmatism. The geochemical composition classifies these rocks as high-alumina basalts. They erupted along the Orakeikorako Fault at the same location where rhyolitic activity of Puketerata occurred at a later point in time. The petrological characteristics of the basalts indicate the mixing of mafic melt with crystalline mush relating to more evolved magmas. The new basaltic occurrence supports frequent mafic recharge of shallow magma reservoirs, inducing basaltic eruptions, in this case the mafic magma intruding into highly crystallized mush zones. This may explain why basaltic eruptions mostly occur on the edge of the central extensional part of the Taupo Volcanic Zone.

A Linear Category of Polynomial Functors (extensional part)

We construct a symmetric monoidal closed category of polynomial endofunctors (as objects) and simulation cells (as morphisms). This structure is defined using universal properties without reference to representing polynomial diagrams and is reminiscent of Day's convolution on presheaves. We then make this category into a model for intuitionistic linear logic by defining an additive and exponential structure.

Modes of orogen-parallel stretching and extensional exhumation in response to microplate indentation and roll-back subduction (Tauern Window, Eastern Alps)

The Tauern Window exposes a Paleogene nappe stack consisting of highly metamorphosed oceanic (Alpine Tethys) and continental (distal European margin) thrust sheets. In the eastern part of this window, this nappe stack (Eastern Tauern Subdome, ETD) is bounded by a Neogene system of shear (the Katschberg Shear Zone System, KSZS) that accommodated orogen-parallel stretching, orogen-normal shortening, and exhumation with respect to the structurally overlying Austroalpine units (Adriatic margin). The KSZS comprises a ≤5-km-thick belt of retrograde mylonite, the central segment of which is a southeast-dipping, low-angle extensional shear zone with a brittle overprint (Katschberg Normal Fault, KNF). At the northern and southern ends of this central segment, the KSZS loses its brittle overprint and swings around both corners of the ETD to become subvertical, dextral, and sinistral strike-slip faults. The latter represent stretching faults whose displacements decrease westward to near zero. The kinematic continuity of top-east to top-southeast ductile shearing along the central, low-angle extensional part of the KSZS with strike-slip shearing along its steep ends, combined with maximum tectonic omission of nappes of the ETD in the footwall of the KNF, indicates that north–south shortening, orogen-parallel stretching, and normal faulting were coeval. Stratigraphic and radiometric ages constrain exhumation of the folded nappe complex in the footwall of the KSZS to have begun at 23–21 Ma, leading to rapid cooling between 21 and 16 Ma. This exhumation involved a combination of tectonic unroofing by extensional shearing, upright folding, and erosional denudation. The contribution of tectonic unroofing is greatest along the central segment of the KSZS and decreases westward to the central part of the Tauern Window. The KSZS formed in response to the indentation of wedge-shaped blocks of semi-rigid Austroalpine basement located in front of the South-Alpine indenter that was part of the Adriatic microplate. Northward motion of this indenter along the sinistral Giudicarie Belt offsets the Periadriatic Fault and triggered rapid exhumation of orogenic crust within the entire Tauern Window. Exhumation involved strike-slip and normal faulting that accommodated about 100 km of orogen-parallel extension and was contemporaneous with about 30 km of orogen-perpendicular, north–south shortening of the ETD. Extension of the Pannonian Basin related to roll-back subduction in the Carpathians began at 20 Ma, but did not affect the Eastern Alps before about 17 Ma. The effect of this extension was to reduce the lateral resistance to eastward crustal flow away from the zone of greatest thickening in the Tauern Window area. Therefore, we propose that roll-back subduction temporarily enhanced rather than triggered exhumation and orogen-parallel motion in the Eastern Alps. Lateral extrusion and orogen-parallel extension in the Eastern Alps have continued from 12 to 10 Ma to the present and are driven by northward push of Adria.

Geochemistry and zircon U–Pb–Hf isotopes of the late Paleoproterozoic Jianping diorite–monzonite–syenite suite of the North China Craton: Implications for petrogenesis and geodynamic setting

The late Paleoproterozoic Jianping diorite–monzonite–syenite suite (JDMSS), in the Western Liaoning Province (WLP) along the northern margin of the North China Craton (NCC), is composed mainly of magnetite diorites, clinopyroxene monzonites, syenites, and quartz syenites. LA-ICP-MS zircon U–Pb isotopic dating indicates that this complex emplaced between 1696 and 1721Ma, almost synchronously with the 1680–1750Ma anorthosite–mangerite–alkali granitoid–rapakivi granite suite (AMGRS) in northern Hebei Province. The JDMSS in the WLP is the eastwards extensional part of the AMGRS in northern Hebei Province along the northern margin of the NCC. All samples from the JDMSS are characterized by a wide and continuously variable geochemical spectrum of 46.3–64.9wt.% SiO2 and 0.528–4.14wt.% MgO, with high K2O (1.080–7.01wt.%) and total alkalis (Na2O+K2O, 5.08–12.55wt.%). These rocks are enriched in LREEs and LILEs but depleted in HFSEs (Nb, Ta, and Ti), and they show negative zircon εHf(t) values of −12.6 to −0.3 and a low whole-rock initial 87Sr/86Sr value of 0.703564. These geochemical features, together with trace element modeling, suggest that all the rocks of the JDMSS were generated chiefly by fractional crystallization of a common parental magma that was derived by partial melting of an amphibole-bearing enriched subcontinental lithospheric mantle source (mixed EMI and HIMU mantle), and that the magma assimilated crustal materials during ascent and emplacement. Integrating our data with those of previous studies of the contemporaneous magmatic rocks throughout the NCC (mafic dykes, volcanic rocks, and AMGRS; 1680–1780Ma), we propose that both the northern and southern margins of the NCC, as well as the TNCO (Trans-North China Orogen), evolved under a post-collisional tectonic setting during the late Paleoproterozoic, postdating the final amalgamation of the NCC, and that the NCC at this time was probably located between Laurentia (North America and Greenland) and Siberia within the interior of the Columbia supercontinent.

Flat-topped mounds in western Ross Sea: Carbonate mounds or subglacial volcanic features?

Detailed multibeam bathymetry data in the western Ross Sea, Antarctica, delineate a field of unusual flat-topped seafloor mounds located ∼50 km west of Franklin Island and an arcuate zone of pockmarks to the northwest and west of Franklin Island. Sixteen mounds occur in an area about 30 km square at a depth of ∼500 m, within the Terror Rift, the active extensional part of the Victoria Land Basin. The mounds tend to be circular in the east and linear in the west, with their steepest slope to the southeast, and shallowest slope to the northwest, consistent with erosion by northwest ice-sheet movement. The largest mound is ∼4 km across and 100 m high. Five similar features were delineated to the south and east of Franklin Island at depths of 400–650 m. Seismic, gravity, and magnetic data indicate that the mounds are largely low-density, nonmagnetic bodies overlying a largely nondisrupted sedimentary section, but some mounds have an associated small (∼50 nT), short-wavelength, normal or reversed magnetic anomaly, indicating a magnetic core to the mounds. Their proximity to inferred subsurface gas hydrates suggests they may be carbonate banks, but they also occur close to volcanic centers including Franklin Island. Our preferred interpretation is that they are of volcanic origin, erupted during a geomagnetic reversal and under a grounded ice sheet forming hyaloclastite edifices, previously unknown under the Ross Sea. The pockmarks range from 200 m to 500 m in diameter.

Miocene emplacement and rapid cooling of the Pohorje pluton at the Alpine-Pannonian-Dinaridic junction, Slovenia

New laser ablation-inductive coupled plasma-mass spectrometry U-Pb analyses on oscillatory-zoned zircon imply Early Miocene crystallization (18.64±0.11 Ma) of the Pohorje pluton at the southeastern margin of the Eastern Alps (northern Slovenia). Inherited zircon cores indicate two crustal sources: a late Variscan magmatic population (∼270–290 Ma), and an early Neoproterozoic one (850–900 Ma) with juvenile Hf isotope composition close to that of depleted mantle. Initial ∈Hf of Miocene zircon points to an additional, more juvenile source component of the Miocene magma, which could be either a juvenile Phanerozoic crust or the Miocene mantle. The new U-Pb isotope age of the Pohorje pluton seriously questions its attribution to the Oligocene age ‘Periadriatic” intrusions. The new data imply a temporal coincidence with 19–15 Ma magmatism in the Pannonian Basin system, more specifically in the Styrian Basin. K-Ar mineral- and whole rock ages from the pluton itself and cogenetic shallow intrusive dacitic rocks (∼18–16 Ma), as well as zircon fission track data (17.7–15.6 Ma) gave late Early to early Middle Miocene ages, indicating rapid cooling of the pluton within about 3 Million years. Medium-grade Austroalpine metamorphics north and south of the pluton were reheated and subsequently cooled together. Outcrop-and micro scale structures record deformation of the Pohorje pluton and few related mafic and dacitic dykes under greenschist facies conditions. Part of the solidstate fabrics indicate E-W oriented stretching and vertical thinning, while steeply dipping foliation and NW-SE trending lineation are also present. The E-W oriented lineation is parallel to the direction of subsequent brittle extension, which resulted in normal faulting and tilting of the earlier ductile fabric at around the Early/Middle Miocene boundary; normal faulting was combined with strike-slip faulting. Renewed N-S compression may be related to late Miocene to Quaternary dextral faulting in the area. The documented syn-cooling extensional structures and part of the strike-slip faults can be interpreted as being related to lateral extrusion of the Eastern Alps and/or to back-arc rifting in the Pannonian Basin.

Numerical modelling of fault generation in the extensional tectonic regime of the Gulf of Corinth

AbstractThe aim of this work is to investigate the extent to which a relatively simple mechanical model (both at constitutive and boundary conditions levels) can reproduce the main features of a typical extensional part of European continent such as the Gulf of Corinth (or Korinthos). A second step is performed here for the investigation of this problem, following a first one consisted of appropriate downscaled sandbox model tests and continuum mechanics numerical modelling. A more suitable numerical method, namely the distinct element method implemented in Universal Distinct Element Code (UDEC), is employed in this second attempt to study faulting and the associated deformations in extensional tectonic regimes. The hypothesis that an inherited listric normal fault with high dip angle ( ∼ 60°) at the surface transforming into a gently dipping normal fault at larger depths ( ∼ 10° ) subjected to extensional strain rate may reproduce the major structural features of the Gulf is herein investigated. This study shows that sliding on the listric fault produces a second high‐angle antithetic normal fault that initiates at the point of change of curvature of the initial listric fault and propagates upwards until it reaches the surface. A second model that takes into account both listric and antithetic faults as boundary conditions, produces under extension, a third normal fault dipping as the first master listric fault and initiating close to the root of the antithetic fault, ultimately propagating upwards up to the free surface. Finally, a third model that starts with the three faults, results in a system of conjugate normal faults lying between the master listric fault and the first antithetic fault. This structure of normal faults resembles closely both the structure of normal faults observed at the Gulf of Corinth and the history of their formation, indicating that the Gulf is a half‐graben. Copyright © 2007 John Wiley & Sons, Ltd.

Answering Queries Addressed to Several Databases According to a Majority Merging Approach

The general context of this work is the problem of merging data provided by several sources which can be contradictory. Focusing on the case when the information sources do not contain any disjunction, this paper first defines a propositional modal logic for reasoning with data obtained by merging several information sources according to a majority approach. Then it defines a theorem prover to automatically deduce these merged data. Finally, it shows how to use this prover to implement a query evaluator which answers queries addressed to several databases. This evaluator is such that the answer to a query is the one that could be computed by a classical evaluator if the query was addressed to the merged databases. The databases we consider are made of an extensional part, i.e. a set of positive or negative ground literals, and an intensional part i.e. a set of first order function-free clauses. A restriction is imposed to these databases in order to avoid disjunctive data.

Querying several conflicting databases

This paper addresses the problem of querying several databases considered as a whole. Assuming that the different databases share a common data description language, the problem that arises is to consistently answer queries even if the database contents are contradictory. The main contribution of this paper is the specification of a query-evaluator for answering closed and open general queries addressed to several databases and for providing explanations about the results. For doing so, we first specify a query-evaluator, in logic, which assumes that the databases are propositional ones and do not contain disjunctions. Then we extend it to first-order databases defined by an extensional part (sets of positive or negative facts) and an intensional part (sets of first order clauses). We also show that the query-evaluator corresponds to a majority merging of the databases.

Compression molding of glass reinforced thermoplastics: Modeling and experiments

AbstractThe shearing and extensional behavior of glass mat‐thermoplastic (GMT) material under compression molding was investigated with a special model being developed for the case of non‐lubricated mold‐plate surfaces. Mathematical expressions for the radial and through‐thickness flow velocities were derived that enabled the derivation of extensional and shear strain rates. The GMT non‐lubricated (no‐slip wall conditions) compression molding was modeled as a combination of extensional and shearing flow and the two extensional and shear viscosities were determined. Scott's approach was used in this work to determine the radial velocit in the r‐direction, which depends on the shear power‐law expression. The velocity component in the z‐direction was then calculated using the continuity equation. The velocity profiles were used to calculate the shear and extensional strain rates. Scott's shear viscosity did not satisfy the constitutive equation for the extensional part, but a power‐law expression with new parameters depending on the deformation tensors was successfully used to calculate an independent extensional viscosity using the same non‐lubricated squeezing experiment. Lubricated squeezing flow was carried out for the same material to achieve a pure extensional flow, and the extensional viscosity calculated using this approach agreed with the extensional viscosity determined using the non‐lubricated experiment. GMT material used in this study is confirmed to have two layers of continuous long fibers orientated randomly inplane, separated by short chopped fibers in the middle, which suggests that the material can be treated as an isotropic material, and the fiber‐matrix separation is seen to be high at the extremities of the flow.

Incorporating pore geometry and fluid pressure communication into modeling the elastic behavior of porous rocks

Inclusion‐based formulations allow an explicit description of pore geometry by viewing porous rocks as a solid matrix with embedded inclusions representing individual pores. The assumption commonly used in these formulations that there is no fluid pressure communication between pores is reasonable for liquid‐filled rocks measured at high frequencies; however, complete fluid pressure communication should occur throughout the pore space at low frequencies. A generalized framework is presented for incorporating complete fluid pressure communication into inclusion‐based formulations, permitting elastic behavior of porous rocks at high and low frequencies to be described in terms of a single model. This study extends previous work by describing the pore space in terms of a continuous distribution of shapes and allowing different forms of inclusion interactions to be specified. The effects of fluid pressure communication on the elastic moduli of porous media are explored by using simple models and are found to consist of two fundamental elements. One is associated with the cubical dilatation and governs the effective bulk modulus. Its magnitude is a function of the range of pore shapes present. The other is due to the extensional part of the deviatoric strain components and affects the effective shear modulus. This element is dependent on pore orientation, as well as pore shape. Using sandstone and granite models, an inclusion‐based formulation shows that large differences between high‐ and low‐frequency elastic moduli can occur for porous rocks. An analysis of experimental elastic wave velocity data reveals behavior similar to that predicted by the models. Quantities analogous to the open and closed system moduli of Gassmann‐Biot poroelastic theory are defined in terms of inclusion‐based formulations that incorporate complete fluid pressure communication. It was found that the poroelastic relationships between the open and closed system moduli are replicated by a large class of inclusion‐based formulations. This connection permits explicit incorporation of pore geometry information into the otherwise empirically determined macroscopic parameters of the Gassmann‐Biot poroelastic theory.

Intensional query answering by partial evaluation

Intensional query answering aims at providing a response to a query addressed to a knowledge base by making use of the intensional knowledge as opposed to extensional. Such a response is an abstract description of the conventional answer that can be of interest in many situations, for example it may increase the cooperativeness of the system, or it may replace the conventional answer in case access to the extensional part of the knowledge base is costly as for Mobile Systems. In this paper we present a general framework to generate intensional answers in knowledge bases adhering to the logic programming paradigm. Such a framework is based on a program transformation technique, namely Partial Evaluation, and allows for generating complete and procedurally complete (wrt SLDNF-resolution) sets of intensional answers, treating both recursion and negation conveniently.

Deformation of the northern circum-Pacific margin: Variations in tectonic style and plate-tectonic implications

During mid- to Late Cretaceous time, the northern paleo–Pacific Ocean was characterized by subduction for >6000 km along strike. The associated magmatic and orogenic belt now comprises parts of the U.S. and Canadian Cordillera, Alaska, and the Russian Far East. Crustal shortening in the northwestern Cordillera sector of the belt was contemporaneous with extension in northern and interior Alaska and the Bering Strait region, while extensional to neutral tectonics prevailed in the Sea of Okhotsk region, Russian Far East. The along-strike continuity of magmatism during the ≈120–80 Ma time interval resulted from subduction beneath the northern circum-Pacific margin, even beneath the broadest parts of the belt in the Alaska and Bering Strait region, which we suggest were modified by large-magnitude crustal extension. Variations in deformational style along strike of the orogenic belt may be related to changes in the nature of the mechanical coupling between the subducting oceanic and overriding continental plates, where the central extensional part of the belt developed above a part of the slab characterized by southward retreat or rollback of the subduction zone.

New semantics for the extensional but hyper-intensional part $\scr L_\alpha$ of the modal sense language ${\scr S}{\scr L}^\nu_\alpha$.

New semantics for the extensional but hyper-intensional part $\scr L_\alpha$ of the modal sense language ${\scr S}{\scr L}^\nu_\alpha$.

Geochemistry of bimodal basalt-subalkaline/peralkaline rhyolite provinces within the Southern British Caledonides

Bimodal associations of basalt and rhyolite of Upper Ordovician age which were erupted in a submarine environment occur within the Caledonian orogenic belt of South Britain at Parys Mountain (Anglesey), in Snowdonia (North Wales) and at Avoca (SE Ireland). The volcanic rocks have experienced hydrothermal alteration and low-grade metamorphism, and therefore immobile elements (e.g. Ti, Zr, Nb, Y) have been used to identify the original geochemical characteristics. The basalts have characters transitional between volcanic ‘arc’ and ‘within plate’ types consistent with eruption on an extensional part of an active continental margin. Two groups of rhyolites have been identified. A low-Zr group (Zr<500ppm), represented at all three locations, is interpreted as originally of high-K, subalkaline type. A high-Zr group (Zr>500ppm), represented at Snowdonia and Avoca, is interpreted as originally being peralkaline in composition; their high Zr/Nb ratios (>10) are typical of peralkaline rhyolites erupted above subduction zones. The bimodal nature of the associations and the peralkaline character of some rhyolites indicates magma production in a complex tectonic setting, transitional between an active continental margin/island arc and an extensional environment. Associated sulphide mineralization is volcanogenic and probably syn-sedimentary. High-level, rhyolitic magma chambers are thought to have driven convection of the hydrothermal fluids from which the sulphides precipitated.

西南日本における三畳―ジュラ紀のプレート境界の移動について

Igneous activity characteristic of island arc did not take place in the Triassic Southwest Japan. Very thin chert has been widely deposited surrounding the Hida-Sangun island arc formed in the Late Permian. On the contrary, arc volcanism occurred in the Hida and the southern part of Korea during Jurassic time. Coarse-grained sediments and olistostrome are common in the island slope of the Hida-Sangun arc. This geologic change may be due to consumption of the Triassic oceanic plate to the north of the Hida-Sangun arc, and subsequent collision of southwest Japan with eastern extensional part of Korea.