Coherent Unit Research Articles

Divergence in subduction zones and exhumation of high pressure rocks (Eocene Western Alps)

Exhumation of high-pressure rocks has long remained a controversial issue in the Earth sciences. In this article, we analyze the tectono-metamorphic, stratigraphic and plate-motion constraints from the Western Alps region, providing new insights on exhumation mechanisms and tectonic evolution during the earliest orogenic stages. Eocene eclogites of the Western Alps form a 20–25 km wide belt on the upper-plate side of the orogen (Eclogite belt), exposed beneath extensional shear zones at the rear of a lower-pressure accretionary wedge. Units of the Eclogite belt show the youngest peak-pressure assemblages within the subduction zone, and experienced superfast tectonic exhumation since 45–40 Ma. The role of erosion was negligible during the whole of this stage. Eocene foreland basins remained starved, and the massive arrival of axial-belt detritus began well after exhumation was completed. Tectonic reconstructions based on fixed-boundaries exhumation models (e.g. channel flow), and/or implying fast erosion at the surface (e.g. slab breakoff), are thus not consistent with geological evidence. In the lack of erosion, exhumation through the overburden requires divergence within the subduction zone. We demonstrate that this was not attained by rollback of the lower plate (Europe), but was instead attained by NNEward motion of the upper plate (Adria-Africa) away from the Western Alps trench. Such motion induced localized extension within the weak portion of the upper plate, at the rear of the accretionary wedge, and allowed tectonic emplacement of the Eclogite belt in the upper crust at rates much faster than subduction rates. Tectonic exhumation ceased in the Oligocene, when oblique-divergence along the Western Alps traverse changed into oblique-convergence. The onset of slow erosional unroofing was synchronously recorded by pressure–temperature paths in all major tectonic units of the Western Alps, and by arrival of orogenic detritus in sedimentary basins. This work demonstrates that divergence between upper plate and trench is a viable mechanism to exhume large and coherent eclogite units in continental subduction zones. Our exhumation model can be applied to other eclogite belts showing a similar exhumational record, including the Western Gneiss Region, the Dabie-Sulu, and eastern Papua New Guinea.

A reference model for deploying applications in virtualized environments.

Modern scientific research has been revolutionized by the availability of powerful and flexible computational infrastructure. Virtualization has made it possible to acquire computational resources on demand. Establishing and enabling use of these environments is essential, but their widespread adoption will only succeed if they are transparently usable. Requiring changes to applications being deployed or requiring users to change how they utilize those applications represent barriers to the infrastructure acceptance. The problem lies in the process of deploying applications so that they can take advantage of the elasticity of the environment and deliver it transparently to users. Here, we describe a reference model for deploying applications into virtualized environments. The model is rooted in the low-level components common to a range of virtualized environments and it describes how to compose those otherwise dispersed components into a coherent unit. Use of the model enables applications to be deployed into the new environment without any modifications, it imposes minimal overhead on management of the infrastructure required to run the application, and yields a set of higher-level services as a byproduct of the component organization and the underlying infrastructure. We provide a fully functional sample application deployment and implement a framework for managing the overall application deployment.

Multi-scale mineralogical characterization of the hypercalcified sponge Petrobiona massiliana (Calcarea, Calcaronea)

The massive basal skeleton of a few remnant living hypercalcified sponges rediscovered since the 1960s are valuable representatives of ancient calcium carbonate biomineralization mechanisms in basal Metazoa. A multi-scale mineralogical characterization of the easily accessible Mediterranean living hypercalcified sponge belonging to Calcarea, Petrobiona massiliana (Vacelet and Lévi, 1958), was conducted. Oriented observations in light and electron microscopy of mature and growing areas of the Mg-calcite basal skeleton were combined in order to describe all structural levels from the submicronic to the macroscopic scale. The smallest units produced are ca. 50-100nm grains that are in a mushy amorphous state before their crystallization. Selected area electron diffraction (SAED) further demonstrated that submicronic grains are assembled into crystallographically coherent clusters or fibers, the latter are even laterally associated into single-crystal bundles. A model of crystallization propagation through amorphous submicronic granular units is proposed to explain the formation of coherent micron-scale structural units. Finally, XRD and EELS analyses highlighted, respectively, inter-individual variation of skeletal Mg contents and heterogeneous spatial distribution of Ca ions in skeletal fibers. All mineralogical features presented here cannot be explained by classical inorganic crystallization principles in super-saturated solutions, but rather underlined a highly biologically regulated formation of the basal skeleton. This study extending recent observations on corals, mollusk and echinoderms confirms that occurrence of submicronic granular units and a possible transient amorphous precursor phase in calcium carbonate skeletons is a common biomineralization strategy already selected by basal metazoans.

Topological entropy of catalytic sets: Hypercycles revisited

The dynamics of catalytic networks have been widely studied over the last decades because of their implications in several fields like prebiotic evolution, virology, neural networks, immunology or ecology. One of the most studied mathematical bodies for catalytic networks was initially formulated in the context of prebiotic evolution, by means of the hypercycle theory. The hypercycle is a set of self-replicating species able to catalyze other replicator species within a cyclic architecture. Hypercyclic organization might arise from a quasispecies as a way to increase the informational containt surpassing the so-called error threshold. The catalytic coupling between replicators makes all the species to behave like a single and coherent evolutionary multimolecular unit. The inherent nonlinearities of catalytic interactions are responsible for the emergence of several types of dynamics, among them, chaos. In this article we begin with a brief review of the hypercycle theory focusing on its evolutionary implications as well as on different dynamics associated to different types of small catalytic networks. Then we study the properties of chaotic hypercycles with error-prone replication with symbolic dynamics theory, characterizing, by means of the theory of topological Markov chains, the topological entropy and the periods of the orbits of unimodal-like iterated maps obtained from the strange attractor. We will focus our study on some key parameters responsible for the structure of the catalytic network: mutation rates, autocatalytic and cross-catalytic interactions.

The molecular clock in terms of quantum information processing of coherent states, entanglement and replication of evolutionarily selected decohered isomers

Evolutionary pressures have selected quantum uncertainty limits -ΔxΔp ( x ) ≥ 1/2ħ-to operate on metastable amino DNA protons. This introduces a probability of molecular clock arrangement, keto-amino → enol-imine, where product protons are entangled and participate in coupled quantum oscillation at frequencies of ∼ 10(13) s(-1). The ket "seen by" the transcriptase, reading a coherent enol-imine G'-state, is |φ >= α| + + > +β|+- > +γ|-+ > +δ|-->. The transcriptase implements its measurement and generates an output qubit of observable genetic specificity information in an interval Δt ≪ 10(-13) s. These quantum measurements can specify the relative distribution of coherent G'-C' states at time of measurement. The ensuing quantum entanglement between coherent protons and transcriptase units is utilized as a resource to generate proper decoherence and introduce selected time-dependent substitutions, ts, and deletions, td. Topal-Fresco ts are G'202 → T, G'002 → C, *G020(0) → A and *C202(2) → T, whereas td are exhibited at coherent *A-*T sites. Variation in clock 'tic-rate' is a consequence of clock introduction of initiation codons - UUG, CUG, AUG, GUG - and stop codons, UAA, UAG, UGA. Using approximate quantum methods for times t < ∼ 100 y, the probability, P(t), of keto-amino → enolimine arrangement is P ( ρ )(t) = 1/2(γ ( ρ )/ħ)(2) t (2) where γ ( ρ ) is the energy shift. This introduces a quantum Darwinian evolution model which provides insight into biological consequences of coherent states populating human genes, including inherited (CAG)( n ) repeat tracts.

Testing for divergent transmission histories among cultural characters: a study using Bayesian phylogenetic methods and Iranian tribal textile data.

BackgroundArchaeologists and anthropologists have long recognized that different cultural complexes may have distinct descent histories, but they have lacked analytical techniques capable of easily identifying such incongruence. Here, we show how Bayesian phylogenetic analysis can be used to identify incongruent cultural histories. We employ the approach to investigate Iranian tribal textile traditions.MethodsWe used Bayes factor comparisons in a phylogenetic framework to test two models of cultural evolution: the hierarchically integrated system hypothesis and the multiple coherent units hypothesis. In the hierarchically integrated system hypothesis, a core tradition of characters evolves through descent with modification and characters peripheral to the core are exchanged among contemporaneous populations. In the multiple coherent units hypothesis, a core tradition does not exist. Rather, there are several cultural units consisting of sets of characters that have different histories of descent.ResultsFor the Iranian textiles, the Bayesian phylogenetic analyses supported the multiple coherent units hypothesis over the hierarchically integrated system hypothesis. Our analyses suggest that pile-weave designs represent a distinct cultural unit that has a different phylogenetic history compared to other textile characters.ConclusionsThe results from the Iranian textiles are consistent with the available ethnographic evidence, which suggests that the commercial rug market has influenced pile-rug designs but not the techniques or designs incorporated in the other textiles produced by the tribes. We anticipate that Bayesian phylogenetic tests for inferring cultural units will be of great value for researchers interested in studying the evolution of cultural traits including language, behavior, and material culture.

A Devonian to Carboniferous intra-oceanic subduction system in Western Junggar, NW China

The Devonian and Carboniferous rock assemblages in Western Junggar, southern Altaids, include ophiolitic mélanges and coherent units. At Baijiantan, Yeyagou and Dagun Devonian gabbros and one group of volcanic rocks (type I lava) generally crop out as blocks in a matrix of ultramafic rocks and/or mudstone. They have a depleted light rare earth element (LREE) and mid-oceanic ridge basalt (MORB)-like signature with a small negative Nb anomaly, suggesting formation in a back-arc basin. Another group of volcanic rocks (type II lava) from Baijiantan, Yeyagou, Western Karamay and Maliya includes alkaline basalt, basanite, andesite, dacite and trachyte that contain microphenocrysts of clinopyroxene–plagioclase, amygdales filled with chalcedony and calcite, and accessory pyrite and ilmenite. The type II lavas are further subdivided into five sub-types: (1) Type II1 lava is strongly enriched in LREE with incompatible trace element ratios similar to oceanic island basalt (OIB), suggesting derivation from enriched mantle. (2) Type II2 lava and tuff are slightly LREE-enriched, with a marked negative Nb anomaly and Th/Yb-enrichment indicating that they were generated in a supra-subduction zone (SSZ). (3) Type II3 lava is also moderately enriched in LREE suggesting derivation from a more-enriched MORB mantle. (4) Type II4 lava is enriched in LREE and has high Nb/Yb values close to those of OIB. It is extensively depleted in Nb suggesting a source containing a mixture of enriched and SSZ mantle. (5) Type II5 lava has MORB-like REE patterns, and Nb/Yb and Th/Yb ratios. Based on field structural data, and the contemporaneity of the Baogutu adakite, a high-Mg diorite dike and the Miaoergou charnockite, these enriched and depleted magmatic features suggest generation in an intra-oceanic subduction zone influenced by ridge-trench interaction. The Altaids in Western Junggar are characterized by multiple intra-oceanic subduction systems, which may have continued to operate to the late Carboniferous.

Some relationships between lithology, basin form and hydrology: a case study from the Thames basin, UK

AbstractThe role of lithology in influencing basin form and function is explored empirically by investigating correlations between a range of catchment variables, where the spatial unit of analysis is not surface catchments but lithologically coherent groundwater units. Using the Thames basin, UK, as a case study, nine groundwater units have been identified. Values for 11 hydrological and geomorphological variables, including rainfall, drainage density, Baseflow Index, aquifer porosity, storage coefficient and log‐hydraulic conductivity, aquifer and drainage elevation, river incision, and hypsometric integral have been estimated for each of the groundwater units in the basin, and Pearson correlation coefficients calculated for all pairs of variables. Seven of the correlation coefficients are found to be significant at a confidence level of &gt; 99%. Negative correlations between drainage density and log aquifer hydraulic conductivity, and between drainage density and river incision, and positive correlations between log‐hydraulic conductivity and river incision, log‐hydraulic conductivity and Baseflow Index, and between Baseflow Index and river incision are inferred to have consistent causal explanations. For example, incision of rivers into aquifers leads to relative increases in hydraulic gradients in the vicinity of rivers which, in turn, promotes the development of secondary porosity increasing both aquifer hydraulic conductivity and, hence, Baseflow Index. The implication of this interpretation is that the geomorphological evolution of basins is intimately linked to the evolution of hydraulic conductivity of the underlying aquifers. This is consistent with, and supports the notion of a coupled complexly evolving surface water‐groundwater system. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Tracing two orogenic cycles in one eclogite sample by Lu–Hf garnet chronometry

The Adula nappe, Central Alps, was thought to be a melange of rock fragments, some of which were subducted and then exhumed from the mantle. Lu–Hf dating of two populations of garnets in one rock sample instead indicates that the nappe twice experienced subduction and exhumation as one coherent unit.

Multiple Paradigm Research on Organisational Culture: An Introduction of Complexity Paradigm

Multiple Paradigm Research on Organisational Culture: An Introduction of Complexity Paradigm The author presents multiple paradigm research into the organisational culture of a birdwatching association, where he conducted his ethnographic research. On top of the functionalist, interpretive, radical structuralist and radical humanist paradigms as presented by Gibson Burrell and Gareth Morgan, he applies the fifth paradigm into the analysis of the organisation. The so-called complexity paradigm, which was formed in 1980's based on findings about complex systems and networks that emerged in natural and social sciences, summarizes all other paradigms, integrating them into a coherent unit. According to the author, the approach that exploits the benefits of each previously known paradigm illustrates comprehensively the complexity of organisational cultures, whereas the new paradigm upgrades our previous knowledge on organisations.

Slope–channel coupling in steepland terrain: A field-based conceptual model from the Tarndale gully and fan, Waipaoa catchment, New Zealand

Connectivity between an actively eroding gully complex and upper Waipaoa catchment via a steep, 1-km-long alluvial fan is assessed using digital elevation models (DEMs) of the Tarndale fan derived from 10 high resolution GPS surveys between 2004 and 2008. Repeat DEM analysis provides a means of assessing transfer of sediment supplied from the Tarndale gully through the fan to the Te Weraroa Stream and thus inferring connectivity between these landscape components from which a conceptual coupling model is derived. Analysis indicates the operation of two critical junction switches at the (i) gully–fan and (ii) fan–stream nexus, which contribute to considerable complexity in patterns of erosion and deposition on the fan as it responds to sediment supply or starvation from the Tarndale gully and evacuation to the Te Weraroa Stream (described in Fuller and Marden, 2010). The fan does not respond as a coherent unit. Each of six fan feeder tributaries behaves independently according to sediment supplied from six discrete source areas within the gully complex. This reflects sediment production within specific activity zones of Tarndale Gully. Mass movements, triggered by single rainstorm events and/or wet periods contingent upon sediment availability and intrinsic slope mechanics, frequently deliver sediment to the upper fan tributaries. This enhanced gully–fan coupling during storms or wetter periods promotes rapid fan aggradation, with each feeder tributary responding to its discrete source zone. Infilling may propagate down fan in response to upper fan incision once the gully–fan switch deactivates, transferring sediment as far as the Te Weraroa Stream, coupling the fan with the stream system. Floods generated in the Te Weraroa Stream may also activate the junction switch at the fan–stream nexus by trimming the lower fan, prompting up-fan incision via head-cutting in response to changed local base level. Slope–channel coupling in this environment is a function of a range of slope and channel processes responding to discrete storms and intrinsic gully dynamics. The high rates of geomorphic activity in this environment mean the Tarndale system provides a natural laboratory in which to assess key slope–channel coupling processes beyond the plot or discrete event scale.

Ultrahigh-pressure metamorphism and multistage exhumation of eclogite of the Luotian dome, North Dabie Complex Zone (central China): Evidence from mineral inclusions and decompression textures

The studied eclogite is located in the Luotian dome in the southwestern part of the North Dabie Complex Zone (NDZ), central China, and is a portion of deeply subducted mafic lower continental crust of the South China Block. Petrologic analysis suggests that the eclogite underwent ultrahigh-pressure (UHP) and high-pressure eclogite-facies metamorphism, and subsequent HP granulite-facies overprinting and amphibolite-facies retrogression during continental subduction and exhumation. As a result, multiple decompression textures were produced, suggesting a multistage exhumation history from eclogite-, to granulite-, to amphibolite-facies conditions. A striking feature of this eclogite is the widespread exsolution of different phases: oriented needles of rutile + clinopyroxene + amphibole + apatite in garnet; quartz + amphibole + hypersthene + sodic plagioclase in clinopyroxene, and pyrrhotite in apatite. Most importantly, we provide for the first time conclusive evidence of quartz pseudomorphs after coesite in garnet and relic coesite (confirmed by in situ Raman spectroscopy) in zircon. In addition, there are two groups of apatite: one is fluor (F)-apatite that occurs as inclusions in garnet or in matrix, which is rich in F (∼3 wt.%), lakes exsolution features and formed at UHP metamorphic conditions; the second is associated with the oriented pyrrhotite exsolution and formed during decompression. Microtextural and petrologic analysis suggests that the eclogites from the southwestern segment of the NDZ are similar to eclogites from the northern segment of the NDZ (e.g., Huangweihe and Baizhangyan) and underwent UHP metamorphism with a peak pressure >5–7 GPa. These results, combined with published geochronological data, imply that the NDZ experienced Triassic UHP metamorphism as a coherent unit.

The Rio Apa Craton in Mato Grosso do Sul (Brazil) and northern Paraguay: Geochronological evolution, correlations and tectonic implications for Rodinia and Gondwana

The Rio Apa cratonic fragment crops out in Mato Grosso do Sul State of Brazil and in northeastern Paraguay. It comprises Paleo-Mesoproterozoic medium grade metamorphic rocks, intruded by granitic rocks, and is covered by the Neoprotero- zoic deposits of the Corumbaand Itapocumi Groups. Eastward it is bound by the southern portion of the Paraguay belt. In this work, more than 100 isotopic determina- tions, including U-Pb SHRIMP zircon ages, Rb-Sr and Sm-Nd whole-rock determina- tions, as well as K-Ar and Ar-Ar mineral ages, were reassessed in order to obtain a complete picture of its regional geological history. The tectonic evolution of the Rio Apa Craton starts with the formation of a series of magmatic arc complexes. The oldest U-Pb SHRIMP zircon age comes from a banded gneiss collected in the northern part of the region, with an age of 1950 23 Ma. The large granitic intrusion of the Alumiador Batholith yielded a U-Pb zircon age of 1839 33 Ma, and from the southeastern part of the area two orthogneisses gave zircon U-Pb ages of 1774 26 Ma and 1721 25 Ma. These may be coeval with the Alto Tereremetamorphic rocks of the northeastern corner, intruded in their turn by the Bao´a das Garcas granitic rocks, one of them yielding a zircon U-Pb age of 1754 49 Ma. The original magmatic protoliths of these rocks involved some crustal component, as indicated by the Sm-Nd T DM model ages, between 1.9 and 2.5 Ga. Regional Sr isotopic homogenization, associated with tectonic deformation and medium-grade metamorphism occurred at approximately 1670 Ma, as suggested by Rb-Sr whole rock reference isochrons. Finally, at 1300 Ma ago, the Ar work indicates that the Rio Apa Craton was affected by widespread regional heating, when the temperature probably exceeded 350°C. Geographic distribution, age and isotopic signature of the lithotectonic units suggest the existence of a major suture separating two different tectonic domains, juxtaposed at about 1670 Ma. From that time on, the unified Rio Apa continental block behaved as one coherent and stable tectonic unit. It correlates well with the SW corner of the Amazonian Craton, where the medium-grade rocks of the Juruena-Rio Negro tectonic province, with ages between 1600 and 1780 Ma, were reworked at about 1300 Ma. Looking at the largest scale, the Rio Apa Craton is probably attached to the larger Amazonian Craton, and the actual configuration of southwestern South America is possibly due to a complex arrangement of allochthonous blocks such as the Arequipa, Antofalla and Pampia, with different sizes, that may have originated as disrupted parts of either Laurentia or Amazonia, and were trapped during later collisions of these continental masses.

LIQUID CRYSTALLINE WATER, QUANTUM MOLECULAR MACHINES &amp; THE LIVING STATE

It has been 18 years since the discovery in my laboratory suggesting that living organisms are dynamic liquid crystalline phases in which all the molecules in the cells and tissues of the body are aligned and moving coherently together, including especi- ally the water molecules that are intrinsic to the liquid crystalline matrix and essential to the function of macromolecules. In effect, the organism depends on a macroscopic quantum co- herence of individual molecular energy machines. Recent investigations using a range of sophisticated spectroscopic techniques have indeed revealed that the liquid crystalline (hydration) water forms dynamically coherent units with proteins and nucleic acids, and enables the macromolecules to function cohe- rently together. The same investigations also reveal that ions play their pivotal role in cellular meta- bolism and signalling through interactions with hydration water. Despite these major advances, the ultimate mystery of life remains tantalizingly beyond our grasp. Keywords: liquid crystalline organism, quantum coherence, molecular energy mac- hines, hydration water, two-states water, kosmotrope and chaotrope, Law of matching water affinities, microdomains.

Following the Leaf through Part of Dryden's Fables

Fables is a tightly unified collection of poems, but the poems also break down into smaller coherent units. For example, "The Flower and the Leaf" allegorically establishes the unfolding of the next four poems: in "Alexander's Feast," "The Twelfth Book of Ovid his Metamorphoses," and "The Speeches of Ajax and Ulysses" we see a world of the superficial values of the "Flower," identified with William's militaristic Court and those poets who sing its praise, run amuck; then, the whole section is resolved in "The Wife of Bath Her Tale," in which the eternal values of the "Leaf," a thinly veiled symbol for Dryden and Catholicism, prevail.

Pressure‐temperature history of titanite‐bearing eclogite from the Western Iratsu body, Sanbagawa Metamorphic Belt, Japan

AbstractEvidence for eclogite‐facies metamorphism is widespread in the Western Iratsu body of the oceanic subduction type Sanbagawa Belt, Southwest Japan. Previous studies in this region focused on typical mafic eclogites and have revealed the presence of an early epidote‐amphibolite facies metamorphism overprinted by a phase of eclogite facies metamorphism. Ca‐rich and titanite‐bearing eclogite, which probably originated from a mixture of basaltic and calc‐siliceous sediments, is also relatively common in the Western Iratsu body, but there has been no detailed petrological study of this lithology. Detailed petrographic observations reveal the presence of a relic early epidote‐amphibolite facies metamorphism preserved in the cores of garnet and titanite in good agreement with studies of mafic eclogite in the area. Thermobarometric calculations for the eclogitic assemblage garnet + omphacite + epidote + quartz + titanite ± rutile ± phengite give peak‐P of 18.5–20.5 kbar at 525–565°C and subsequent peak‐T conditions of about 635°C at 14–16 kbar. This eclogite metamorphism initiated at about 445°C/11–15 kbar, implying a significantly lower thermal gradient than the earlier epidote‐amphibolite facies metamorphism (∼650°C/12 kbar). These results define a P–T path with early counter‐clockwise and later clockwise trajectories. The overall P–T path may be related to two distinct phases in the tectono‐thermal evolution in the Sanbagawa subduction zone. The early counter‐clockwise path may record the inception of subduction. The later clockwise path is compatible with previously reported P–T paths from the other eclogitic bodies in the Sanbagawa Belt and supports the tectonic model that these eclogitic bodies were exhumed as a large‐scale coherent unit shortly before ridge subduction.

‘Communities of practice’: prospects for theory and action in participatory development

‘The myth of community’ permeates both the understanding and the practice of participatory development. Yet the idea that communities exist as coherent units of people who inhabit bounded geographic spaces and are ready to be mobilised for development restricts the very agency that participation promises. This article offers an alternative model of community: one that is more compatible with the ideal of people-centred, participatory development. Using Etienne Wenger's concept of ‘communities of practice’, and drawing on narrative theory and cognitive approaches to policy analysis, the article argues that community should be created and sustained around shared meanings.

Delineation of natural landscape units for Puerto Rico

We have classified the archipelago of Puerto Rico into a set of homogeneous and coherent natural landscape units. Such a classification may serve as the basic division of the territory for use in research or in planning and land management efforts. The landscape units defined in this work consist of homogeneous regions—in terms of their structural, functional and visual characteristics—which have been shaped by natural abiotic factors. Four variables were considered in the analysis: elevation, slope, life zones, and geology. The information from these variables was processed with non-linear Principal Component Analysis, which extracted two components. These components were used in a K-means cluster analysis to define nine landscape types (i.e., different groupings based on environmental characteristics). Two additional measures were obtained from this procedure and used in a subsequent analysis: cell membership values and the dissimilarity between landscape types. The strength of the grouping procedure was tested by using Multiple Discriminant Analysis, which found that 86 percent of the objects were correctly classified and that the whole classification process was significant. In addition, all variables were found to be significant during the classification process. The landscape types, the cell membership values, and the dissimilarity measure between landscape types were all used to delineate fourteen landscape units of the archipelago of Puerto Rico. The main island contains twelve units, while the island-municipalities of Vieques and Culebra make up two distinct units in themselves.

Discovering Structure in Auditory Input: Evidence From Williams Syndrome

We examined auditory perception in Williams syndrome by investigating strategies used in organizing sound patterns into coherent units. In Experiment 1, we investigated the streaming of sound sequences into perceptual units, on the basis of pitch cues, in a group of children and adults with Williams syndrome compared to typical controls. We showed that individuals with Williams syndrome were sensitive to the same pitch cues as typical children and adults when streaming these patterns. In Experiment 2, we evaluated differences in reliance on pitch and contour cues in unfamiliar melody perception in a group of adults with Williams syndrome relative to typical control children and adults. Unlike controls who demonstrated greater proficiency when contour cues were available, adults with Williams syndrome showed no such advantage.

Towards a complete magmatic barcode for the Zimbabwe craton: Baddeleyite U–Pb dating of regional dolerite dyke swarms and sill complexes

We present baddeleyite U–Pb ages of Neoarchaean to Palaeoproterozoic dyke swarms and the Mashonaland sill province in Zimbabwe. The 2575.0 ± 1.5 Ma age of the Umvimeela dyke is indistinguishable from the 2575.4 ± 0.7 Ma result (Oberthür et al., 2002) for a pyroxenite layer of the Great Dyke and testifies to synchronous emplacement of the Great Dyke and its satellites. Three samples of WNW- to NNW-trending dykes of the Sebanga swarm yielded ages of 2512.3 ± 1.8 Ma, 2470.0 ± 1.2 Ma and 2408.3 ± 2.0 Ma, the latter of which dates the Sebanga Poort Dyke of this swarm. These results suggest that emplacement took place over a protracted period which involved at least three generations of dykes within the swarm and, more importantly, invalidate previous inferences of a genetic link between the Sebanga swarm and the Mashonaland sills. Crystallisation ages of 1877 ± 2.2 Ma, 1885.9 ± 2.4 Ma and 1875.6 ± 1.6 Ma for three dolerite samples of the extensive Mashonaland sills from different parts of the Zimbabwe craton were also obtained. This is the oldest common igneous event that is recorded in the Zimbabwe and Kaapvaal cratons. Collectively with previous published geochronological and petrological evidence in favour of a major 2.0 Ga event within the Limpopo Belt, these results suggest that the Zimbabwe and Kaapvaal cratons did not form a coherent unit (Kalahari) until ca. 2.0 Ga. In the global barcode record for Archaean cratons, all the three generations of dykes within the Sebanga swarm match exactly events of dyke intrusion and LIPs (Large Igneous Provinces) in the Superior, Hearne and Kola-Karelia cratons, and corroborates the recognition of Superia as a supercontinent in the Neoarchaean. The 2408.3 ± 2.0 Ma result of the Sebanga Poort Dyke also provides a link to Western Australia, i.e. to the giant Widgiemooltha swarm of the Yilgarn craton. We conclude that in the context of the global barcode record, both the Zimbabwe and Yilgarn cratons fit into a Superia reconstruction.