The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.

We consider infinite-dimensional diffusions where the interaction between the coordinates has a finite extent both in space and time. In particular, it is not supposed to be smooth or Markov. The initial state of the system is Gibbs, given by a strong summable interaction. If the strongness of this initial interaction is lower than a suitable level, and if the dynamical interaction is bounded from above in a right way, we prove that the law of the diffusion at any time t is a Gibbs measure with absolutely summable interaction. The main tool is a cluster expansion in space uniformly in time of the Girsanov factor coming from the dynamics and exponential ergodicity of the free dynamics to an equilibrium product measure.

Concept drift refers to a problem that is caused by a change in the data distribution in data mining. This leads to reduction in the accuracy of the current model that is used to examine the underlying data distribution of the concept to be discovered. A number of techniques have been introduced to address this issue, in a supervised learning (or classification) setting. In a classification setting, the target concept (or class) to be learned is known. One of these techniques is called “Ensemble learning”, which refers to using multiple trained classifiers in order to get better predictions by using some voting scheme. In a traditional ensemble, the underlying base classifiers are all of the same type. Recent research extends the idea of ensemble learning to the idea of using committees, where a committee consists of diverse classifiers. This is the main difference between the regular ensemble classifiers and the committee learning algorithms. Committees are able to use diverse learning methods simultaneously and dynamically take advantage of the most accurate classifiers as the data change. In addition, some committees are able to replace their members when they perform poorly. This thesis presents two new algorithms that address concept drifts. The first algorithm has been designed to systematically introduce gradual and sudden concept drift scenarios into datasets. In order to save time and avoid memory consumption, the Concept Drift Introducer (CDI) algorithm divides the number of drift scenarios into phases. The main advantage of using phases is that it allows us to produce a highly scalable concept drift detector that evaluates each phase, instead of evaluating each individual drift scenario. We further designed a novel algorithm to handle concept drift. Our Dynamic Committee for Concept Drift (DCCD) algorithm uses a voted committee of hypotheses that vote on the best base classifier, based on its predictive accuracy. The novelty of DCCD lies in the fact that we employ diverse heterogeneous classifiers in one committee in an attempt to maximize diversity. DCCD detects concept drifts by using the accuracy and by weighing the committee members by adding one point to the most accurate member. The total loss in accuracy for each member is calculated at the end of each point of measurement, or phase. The performance of the committee members are evaluated to decide whether a member needs to be replaced or not. Moreover, DCCD detects the worst member in the committee and then eliminates this member by using a weighting mechanism. Our experimental evaluation centers on evaluating the performance of DCCD on various datasets of different sizes, with different levels of gradual and sudden concept drift. We further compare our algorithm to another state-of-the-art algorithm, namely the MultiScheme approach. The experiments indicate the effectiveness of our DCCD method under a number of diverse circumstances. The DCCD algorithm generally generates high performance results, especially when the number of concept drifts is large in a dataset. For the size of the datasets used, our results showed that DCCD produced a steady improvement in performance when applied to small datasets. Further, in large and medium datasets, our DCCD method has a comparable, and often slightly higher, performance than the MultiScheme technique. The experimental results also show that the DCCD algorithm limits the loss in accuracy over time, regardless of the size of the dataset.

<p>Evolution by natural selection can occur at multiple biological scales. This is particularly the case for host-pathogen systems, where selection occurs both within each infected host as well as through transmission between hosts. Despite there being established mathematical models for understanding evolution at a single biological scale, fewer tractable models exist for multiscale evolutionary dynamics. Here I present mathematical approaches using tools from probability and stochastic processes as well as dynamical systems to handle multiscale evolutionary systems. The first problem I address concerns the antigenic evolution of influenza. Using a combination of ordinary differential equations and inhomogeneous Poisson processes, I study how immune selection pressures at the within-host level impact population-level evolutionary dynamics. The second problem involves the more general question of evolutionary dynamics when selection occurs antagonistically at two biological scales. In addition to host-pathogen systems, such situations arise naturally in the evolution of traits such as the production of a public good and the use of a common resource. I introduce a model for this general phenomenon that is intuitively visualized as a a stochastic ball-and-urn system and can be used to systematically obtain general properties of antagonistic multiscale evolution. Lastly, this ball-and-urn framework is in itself an interesting mathematical object which can studied as either a measure-valued process or an interacting particle system. In this mathematical context, I show that under different scalings, the measure-valued process can have either a propagation of chaos or Fleming-Viot limit.</p> / Dissertation

This thesis aims to investigate the influence of earnings news on stock liquidity and the relationship between information asymmetry cost component and Post Earnings Announcement Drift in different equity markets. The scope of this research includes 1821 firms from three leading countries in capital trading, the United States, United Kingdom, and France. The first part of empirical work, the univariate panel analysis, shows that price reaction, volume response and liquidity effect are profound during short term event window length and reduce over time when the news ceases, The second part, a multivariate regression analysis which uses Generalised Method of Movement to capture both the problems of a likely presence of endogeneity between the explanatory variables and cross-stock heterogeneity,shows that the impact of earnings announcement on stock liquidity can split in two directions. The immediate effect is the shock after the news, causing stock liquidity to decrease immediately by lifting the illiquidity function upward. After the event, from the new increased position of illiquidity function, stock liquidity improves over time due to the trading volume increases and shifts the slope of illiquidity function downward. The overall effects at a point of time will be the total impact of the two side effects. And as shown in the results, the overall impact on the US and UK markets are that stock liquidity decreases and that on Euronext Paris the stock liquidity increases. Given that in accounting there are two types of systems of which common law system includes the US, UK and others, and code law system includes France and the rest, the above results could suggest the difference between the two systems is that the information asymmetry component dominates the bid-ask spread in common law countries as in the US and UK markets while the cost of trading dominates the bid-ask spreads in code law countries such as France. Finally, it is shown that there are several determinants of the PEAD, of which stock liquidity is one. Earnings news changes the stock liquidity, and therefore stock liquidity plays a role in the market response. When earnings news is released, it initially creates a gap between the informed traders and the uninformed traders, increasing the bid ask spread. Over time, this information gap decreases, however in the meantime more information on the market increases trading volume and reduces trading cost, leading to another part of the bid ask spread decreasing or stock liquidity improving. After decomposing bid ask spread into information asymmetry cost and cost of trading components, the final part of empirical analysis shows that information asymmetry cost component provides a partial explanation for PEAD in the London Stock Exchange and Euronext Paris.

Inertial wearable sensors constitute a booming industry. They are self contained, low powered and highly miniaturized. They allow for remote or self monitoring of health-related parameters. When used to obtain 3-D position, velocity and orientation information, research has shown that it is possible to draw conclusion about issues such as fall risk, Parkinson disease and gait assessment. A key issues in extracting information from accelerometers and gyroscopes is the fusion of their noisy data to allow accurate assessment of the disease. This, so far, is an unsolved problem. Typically, a Kalman filter or its nonlinear, non-Gaussian version are implemented for estimating attitude â?? which in turn is critical for position estimation. However, sampling rates and large state vectors required make them unacceptable for the limited-capacity batteries of low-cost wearable sensors. The low-computation cost complementary filter has recently been re-emerging as the algorithm for attitude estimation. We employ it with a heuristic drift elimination method that is shown to remove, almost entirely, the drift caused by the gyroscope and hence generate a fairly accurate attitude and drift-eliminated position estimate. Inertial sensor data is obtained from the 10-axis SP-10C sensor, attached to a wearable insole that is inserted in the shoe. Data is obtained from walking in a structured indoor environment in Votey Hall.

This dissertation is focused on the research efforts to develop the growth, processing, and modeling technologies for GaN-based Heterojunction Field Effect Transistors (HFETs). The interest in investigating GaN HFETs is motivated by the advantageous material properties of nitride semiconductor such as large band gap, large breakdown voltage, and high saturation velocity, which make it very promising for the high power and microwave applications. Although enormous progress has been made on GaN transistors in the past decades, the technologies for nitride transistors are still not mature, especially concerning the reliability and stability of the device. In order to improve the device performance, we first optimized the growth and fabrication procedures for the conventional AlGaN barrier HFET, on which high carrier mobility and sheet density were achieved. Second, the AlInN barrier HFET was successfully processed, with which we obtained improved I-V characteristics compared with conventional structure. The lattice-matched AlInN barrier is beneficial in the removal of strain, which leads to better carrier transport characteristics. Furthermore, new device structures have been examined, including recess-gate HFET with n+ GaN cap layer and gate-on-insulator HFET, among which the insertion of gate dielectrics helps to leverage both DC and microwave performances. In order to depict the microwave behavior of the HFET, small signal modeling approaches were used to extract the extrinsic and intrinsic parameters of the device. An 18-element equivalent circuit model for GaN HFET has been proposed, from which various extraction methods have been tested. Combining the advantages from the cold-FET measurements and hot-FET optimizations, a hybrid extraction method has been developed, in which the parasitic capacitances were attained from the cold pinch-off measurements while the rest of the parameters from the optimization routine. Small simulation error can be achieved by this method over various bias conditions, demonstrating its capability for the circuit level design applications for GaN HFET. Device physics modeling, on the other hand, can help us to reveal the underlying physics for the device to operate. With the development of quantum drift-diffusion modeling, the self-consistent solution to the Schrödinger-Poisson equations and carrier transport equations were fulfilled. Lots of useful information such as band diagram, potential profile, and carrier distribution can be retrieved. The calculated results were validated with experiments, especially on the AlInN layer structures after considering the influence from the parasitic Ga-rich layer on top of the spacer. Two dimensional cross-section simulation shows that the peak of electrical field locates at the gate edge towards the drain, and of different kinds of structures the device with gate field-plate was found to efficiently reduce the possibility of breakdown failure.

Using a more reliable sampling system Aitik can have a greater control over the enrichment process and thus have a major prerequisite for increasing the profitability of the company. An increased production, according to the new production target, are putting an increased pressure on the analysis precision and process control to maintain the high quality of the copper concentrate. By reconstruction of the waste weir for separation of Mp and Mp Rep + S Rep is a further need to invest in a more reliable operation and a more well-devised maintenance of the sampling system. By taking the entire life-cycle thinking in procurement Aitik can save large resources and also increase the overall reliability of the equipment in long term. The project aims to increase the reliability of the analyzes in the concentration plant and the goal of the study is to provide a guide for how Aitik, in different ways, can obtain more representative samples and higher availability for sampling. With the help from experienced experts in the areas of operation, maintenance and analysis in Aitik, Boliden and Garpenberg improvement suggestions have been collected, and together with perspectives from a literature study, several potential solutions has been found for the sampling system. Redesign will make sampling more functional and easier to work with and an optimal sampling will require resources to optimize other parts of the system: from the test socket until the sampling equipment. To maintain the system functions for the entire sampling system preventive maintenance activities, primarily in the form of cleaning and replacement of wearing parts, is required. And by identifying the item number and 5S routines to the application Quicktag better conditions for their staff regard the maintenance of the equipment can be created. Additional responsibilities of the company to enable longer system life is to develop a detailed specification for the supplier containing drawings, exploded diagrams, maintenance manuals and maintenance instructions, warranty support and inventory management regarding the spare parts warranty, standard parts and recommendations for inventory planning. In addition, the company should look into the possibility of coordinating parts management within the koncern and enhance sharing information and experiences within the koncern and for staff in Aitik to jointly optimize both operations at large and to improve sampling systems in all concentration plants. To apply NBW (New Boliden Way) for work on the sampling equipment would also be a step towards Boliden's goal for NBW implementation of activities for continuous improvement of sustainable development, improved quality and greater competitiveness in the market. / Med hjälp av ett mer tillförlitligt provtagningssystem kan Aitik få en större kontroll över anrikningsprocessen och därmed ha en större förutsättning för att öka lönsamheten i företaget. En ökad produktion, enligt det nya produktionsmålet, sätter ökad press på analysprecision och processtyrning för att bibehålla hög kvalitet för kopparkoncentratet. I och med planen av ombyggnation av avfallsdammen för separation av Mp och Mp Rep + S finns ytterligare en anledning att satsa på en säkrare drift och ett mer välplanerat underhåll för provtagningssystemet. Genom att företaget tar hänsyn till hela livscykelperspektivet vid upphandling kan Aitik spara stora resurser och dessutom långsiktigt öka den totala driftsäkerheten för utrustningen. Syftet med projektet är att öka tillförlitligheten hos analyserna i anrikningsverket och målet med studien är att ge en vägledning för Aitik hur de, på olika sätt, kan få mer representativa prover och högre tillgänglighet för provtagningsutrustningen. Med hjälp från erfarna experter inom områdena drift, underhåll och analysering från Aitik, Boliden och Garpenberg har flertalet förbättringsförslag inhämtats och i samverkan med kunskap ur en litteraturstudie har flertalet potentiella lösningar hittats för provtagningssystemet. Omkonstruktion kommer att göra provtagningsutrustningen mer funktionell och lättare att arbeta med och för en optimal provtagning kommer det krävas resurser för optimering av övriga delar av systemet: från provuttag fram till provtagningsutrustningen. För att upprätthålla systemfunktionerna för hela provtagningssystemet krävs förebyggande underhållsåtgärder framför allt i form av rengöring och byte av förslitningsdelar, och genom att identifiera objektnummer och 5S-rutiner till applikationen Quicktag kan företaget skapa bättre förutsättningar för sin personal för underhållet av utrustningen. Ytterligare ansvar från företagets sida för att möjliggöra en längre systemlivslängd är att utforma en detaljerad kravspecifikation åt leverantören innehållande ritningar, sprängskisser, underhållsmanualer och underhållsrekommendationer, supportgaranti samt lagerhantering avseende reservdelsgarantier, standardiserade delar och rekommendationer för lagerplanering. Dessutom bör företaget se över möjligheten för att samordna reservdelshanteringen inom koncernen samt öka informations- och erfarenhetsutbytet inom både koncernen och inom Aitikpersonalen för att tillsammans optimera både verksamheterna i stort samt för att förbättra provtagningssystemen i alla anrikningsverk. Att kunna tillämpa NBW (New Boliden Way) för arbetet med provtagningsutrustningen skulle dessutom vara ett steg mot Bolidens mål för NBW-implementering i verksamheten för ständiga förbättringar avseende hållbar utveckling, ökad kvalitet och större konkurrenskraft på marknaden.

The Sun ionizes a small fraction of Earth's atmosphere above roughly 60 km, producing the plasma that constitutes the ionosphere. Radio signals passing through the ionosphere scatter off of plasma density structures created by the Farley-Buneman instability (FBI). While numerous studies have characterized the FBI's intrinsic nature, its evolution within the broader context of the surrounding plasma remains enigmatic. This dissertation answers two fundamental questions about the FBI: How does it interact with density gradients? How does its non-linear evolution depend on the background plasma? The fourth chapter examines the combined development of the FBI and the gradient drift instability (GDI) using a 2-D simulation of the equatorial ionosphere. A half-kilometer wave perturbs a plasma layer perpendicular to the ambient magnetic field, causing the perturbed layer to develop GDI waves along the gradient aligned with the ambient electric field, as well as FBI waves in a region where the total electric field exceeds a certain threshold. Early radar observations suggested that these two instabilities were distinct phenomena; the reported results illustrate their coupled nature. The fifth chapter presents 2-D simulations in which a one-kilometer plasma wave develops an electric field large enough to trigger meter-scale waves. Such large-scale waves arise via the GDI within the daytime ionospheric gradient around 100-110 km. Typical ionospheric radars only observe meter-scale irregularities but observations show meter-scale waves tracing out larger structures. Simulated meter-scale FBI in the troughs and crests of kilometer-scale GDI matches radar observations of the daytime equatorial ionosphere, answers a question about electric-field saturation raised by rocket observations in the 1980s, and predicts an anomalous cross-field conductivity important to magnetosphere-ionosphere (M-I) coupling. The sixth chapter of this dissertation presents 3-D simulations of the FBI at a range of altitudes and driving electric fields appropriate to the auroral ionosphere, where it plays a role in M-I coupling. Research has thoroughly established the linear theory of FBI but rigorous analysis of radar measurements requires an understanding of the turbulent stage. These simulations explain the change in instability flow direction with altitude, with regard to the direction of background plasma flow.

MSc., Faculty of Science, University of the Witwatersrand, 2011 / Granitoid intrusions are numerous in southwestern Rajasthan and are useful because they can provide geochronological constraints on tectonic activity and geodynamic conditions operating as the time of intrusion, as well as information about deeper crustal sources. The particularly voluminous Neoproterozoic felsic magmatism in the Sirohi region of Rajasthan is of particular interest as it may have implications for supercontinental (Rodinia and Gondwana) geometry. The Mt. Abu granitoid pluton is located between two major felsic suites, the older (~870-800 Ma) Erinpura granite and the younger (~751-771 Ma) Malani Igneous Suite (MIS). The Erinpura granite is syn- to lateorogenic and formed during the Delhi orogeny, while the MIS is classified as alkaline, anorogenic and either rift- or plume-related. This tectonic setting is contentious, as recent authors have proposed formation within an Andean-type arc setting. The Mt. Abu granitoid pluton has been mapped as partly Erinpura (deformed textural variant) and partly younger MIS (undeformed massive pink granite). As the tectonic settings of the two terranes are not compatible, confusion arises as to the classification of the Mt. Abu granitoid pluton. Poorly-constrained Rb-Sr age dating place the age of formation anywhere between 735 ± 15 and 800 ± 50 Ma. The older age is taken as evidence that the Mt. Abu intrusion was either a late phase of the Erinpura granite. However, U-Pb zircon geochronology clearly indicates that the Mt. Abu felsic pluton is not related to- or contiguous with- the Erinpura granite suite. The major results from this study indicate that the all textural variants within the Mt. Abu pluton were formed coevally at ~765 Ma. Samples of massive pink granite, mafic-foliated granite and augen gneiss from the pluton were dated using U-Pb zircon ID-TIMS at 766.0 ± 4.3 Ma, 763.2 ± 2.7 Ma and 767.7 ± 2.3 Ma, respectively. The simple Mt. Abu pluton is considered as an enriched intermediate I- to A-type intrusion. They are not anorogenic A-types, as, although these felsic rocks have high overall alkali and incompatible element enrichment, no phase in the Mt. Abu pluton contains alkali rich amphibole or pyroxene, nor do REE diagrams for the most enriched samples show the gull-wing shape typical of highly evolved alkaline phases. The alkali-enriched magma may be explained by partial melting of a crustal source such as the high-K metaigneous (andesite) one suggested by Roberts & Clemens (1993), not derivation from a mantle-derived mafic magma. The fairly restricted composition of Mt. Abu granitoids suggests that partial melting and a degree of assimilation/mixing may have been the major factors affecting the evolution of this granitoid pluton; fractional crystallization was not the major control on evolution of these granitoids. Revdar Rd. granitoids that are similar in outcrop appearance and petrography to Mt. Abu granitoids also conform to Mt. Abu granitoids geochemically and are classified as part of the Mt. Abu felsic pluton. Mt. Abu samples from this study have a maximum age range of 760.5-770 Ma, placing the Mt. Abu pluton within the time limits of the Malani Igneous Suite (MIS) as well as ~750 Ma granitoids from the Seychelles. Ages of the Sindreth-Punagarh Groups are also similar. These mafic-ultramafic volcanics are thought to be remnants of an ophiolitic mélange within a back-arc basin setting at ~750-770 Ma. The three Indian terranes are spatially and temporally contiguous. The same contiguity in space and time has been demonstrated by robust paleomagnetic data for the Seychelles and MIS. These similarities imply formation within a common geological event, the proposed Andean-type arc (Ashwal et al., 2002) on the western outboard of Rodinia. The implications are that peninsular India did not become a coherent entity until after this Neoproterozoic magmatism; Rodinia was not a static supercontinent that was completely amalgamated by 750 Ma, as subduction was occurring here simultaneous with rifting elsewhere. Pageiv The Mt. Abu pluton has undergone deformation, with much of the pluton having foliated or augen gneiss textures. The timing of some of the deformation, particularly the augen gneiss and shear zone deformation, is thought to have occurred during intrusion. The Mt. Abu and Erinpura granitoids have experienced a common regional metamorphic event, as hornblende (Mt. Abu) and biotite (Erinpura) give 40Ar/39Ar ages of 508.7 ± 4.4 Ma and 515.7 ± 4.5 Ma, respectively. This event may have reactivated older deformatory trends as well. The temperature of resetting of argon in hornblende coincides with temperatures experienced during upper-greenschist to lower-amphibolite facies metamorphism. These late Pan-African ages are the first such ages reported for the Sirohi region and southern part of the Aravalli mountain range. They offer evidence for the extension of Pan-African amalgamation tectonics (evidence from southern India) into NW India. The age of formation of the Erinpura augen gneiss magma is 880.5 ± 2.1 Ma, thus placing the Erinpura granitoids within the age limits of the Delhi orogeny (~900-800 Ma; Bhushan, 1995). Most deformation observed here would have been caused by compression during intrusion. The Erinpura granitoids are S-type granitoids due to their predominantly peraluminous nature, restricted SiO2-content, normative corundum and the presence of Al-rich muscovite and sillimanite in the mode. Weathered argillaceous metasedimentary material may also have been incorporated in this magma, while the presence of inherited cores suggests relatively lower temperatures of formation for these granitoids as compared to the Mt. Abu granitoids. The age of inheritance (1971 ± 23 Ma) in the Erinpura augen gneiss is taken as the age of the source component, which coincides with Aravalli SG formation. The Sumerpur granitoids differ from the Erinpura granitoids in terms of macroscopic and microscopic texture (undeformed, rarely megaporphyritic) but conform geochemically to the Erinpura granitoid characteristics and may thus be related to the Erinpura granitoid suite.The Revdar Rd. granitoids that are similar in macroscopic appearance to Erinpura granitoids also conform geochemically, and may similarly belong to the Erinpura granite suite. A Revdar Rd. mylonite gneiss with the Erinpura granitoids’ geochemical signature was dated at ~841 Ma, which does not conform to the age of the type-locality Erinpura augen gneiss dated here, but later intrusion within the same event cannot be ruled out because of the uncertainty in the age data (~21 Ma). The presence of garnet in one Revdar Rd. (Erinpura-type) sample implies generation of these granitoids at depth and/or entrainment from the source, similar to the S-type Erinpura granitoids. The Ranakpur granitoids differ significantly from both the Erinpura and Mt. Abu intrusives due to their low SiO2-content and steep REE profiles (garnet present in the source magma); they are thought to have been generated under higher pressures from a more primitive source. The deeper pressure of generation is confirmed by the absence of a negative Eu-anomaly. The Ranakpur quartz syenite dated at 848.1 ± 7.1 Ma is younger by ~30 m.y. than the Erinpura augen gneiss. It is within the same time range as numerous other granitoids from this region as well as the Revdar Rd. granitoid dated in this study. The prevalence of 830- 840 Ma ages may indicate that a major tectonic event occurred at this time. The Ranakpur quartz syenite may have been generated near a subduction or collision zone, where thickened crust allows for magma generation at depth. The deeply developed Nb-anomaly in the spider diagram also implies a larger subduction component to the magma. The Swarupganj Rd. monzogranite is interpreted to have formed by high degrees of partial melting from a depleted crustal source and is dissimilar to other granitoids from this study. More sampling, geochemical and geochronological work needs to be done in order to characterize this intrusion. Pagev The Kishengarh nepheline syenite gneiss is situated in the North Delhi Fold Belt and is the oldest sample dated within this study. The deformation in this sample is due to arc- or continental- collision during a Grenvillian-type orogeny related to the amalgamation of the Rodinia supercontinent (and peninsular India), dated by the highly reset zircons at ~990 Ma. This is considered a DARC (deformed alkaline rock and carbonatite) and represents a suture zone (Leelanandam et al., 2006). The primary age of formation of this DARC is older than 1365 ± 99 Ma, which is the age of xenocrystic titanites from the sample. The granitoid rocks from this study area (Sirohi region) range widely in outcrop appearance, petrography and geochemistry. Granitoids from the Sirohi region dated in this study show a range of meaningful ages that represent geological events occurring at ~880 Ma, ~844 Ma, ~817 Ma, ~789 Ma, ~765 Ma and ~511 Ma. Granitoid magmatism (age of formation) in this region is predominantly Neoproterozoic, and the number of events associated with each granitoid intrusion as well as diverse tectonic settings implies a complexity in the South Delhi Fold Belt that is not matched by the conventional and simplified view of a progression from collision and orogeny during Grenvillian times (Rodinia formation), through late orogenic events, to anorogenic, within-plate (rift-related) alkaline magmatism during Rodinia dispersal. Instead, it is envisaged that convergence and subduction during the formation of Rodinia occurred at ~1 Ga (Kishengarh nepheline syenite deformation), with a transition to continental-continental collision at ~880-840 Ma (Erinpura and Ranakpur granitoids). This was then followed by far-field Mt. Abu and MIS magmatism, related to a renewed period of subduction at ~770 Ma. The last deformatory event to affect this region was that associated with the formation of Gondwana in the late Pan-African (~510 Ma).