Genesis of mafic-ultramafic inclusions in sublayer and inclusion quartz diorite and implications for the formation of associated NICU-PGE mineralization in the Sudbury igneous complex

The lowermost, discontinuous units of the impact-generated Sudbury Igneous Complex (SIC), Sublayer, Footwall Breccia (FWBX), and Inclusion Quartz Diorite (IQD), are distinguished from overlying Main Mass norite rocks by the presence of abundant inclusions and Ni-Cu-PGE (PGE – platinum group element) mineralization. The majority of the felsic-mafic inclusions appear to be derived from exposed country rocks, but volumetrically important mafic-ultramafic inclusions have only rare equivalents in the surrounding country rocks and appear to be preferentially associated with sulfide mineralization. Establishing the petrogenesis of the mafic-ultramafic inclusions and the nature of their association with the Ni-Cu-PGE mineralization are therefore critical to understand the evolution of the impact melt, genesis of Sublayer, FWBX, and IQD, and the formation of one of the world’s largest accumulations of Ni-Cu-PGE mineralization. Petrographic, mineralogical, geochemical, and Sm-Nd and Re-Os isotopic data indicate three origins for the olivine-bearing mafic-ultramafic inclusions: (1) Anteliths, comprising olivine melanorites and olivine melagabbronorites in the Whistle and Levack embayments on the North Range, which are characterized by igneous textures, Zr/Y, Zr/Nb, Nb/U, and Zr/Hf ratios similar to igneous-textured Sublayer matrix (ITSM), unradiogenic εNd1850 Ma values (-8 to -5), and slightly unradiogenic to radiogenic γOs1850 Ma values (-8 to +94). They likely crystallized from a local mixture of SIC impact melt and a more mafic melt derived by melting of the widespread Huronian volcanic and subvolcanic units in the region. (2) Local xenoliths, comprising wehrlites and olivine clinopyroxenites in the Levack embayment and olivine melanorites in the Foy Offset on the North Range, which are characterized by shock mosaic and recrystallized textures, and trace element patterns (e.g., negative Th-U, Nb-Ta-(Ti), Sr, and Zr-Hf anomalies) similar to and Nb/U ratios overlapping with a layered mafic-ultramafic intrusion in the footwall of the Levack and Fraser deposits. They were likely derived from local mafic-ultramafic protoliths that were petrogenetically-related to the layered mafic-ultramafic intrusion in the footwall of the Levack and Fraser deposits. (3) Exotic xenoliths, comprising phlogopite/feldspar lherzolites in the Trill, Levack, and Bowell embayments and the Foy Offset dike on the North Range, which are characterized by variably igneous, tectonic-metamorphic, and shock-metamorphic textures, and orthopyroxene reaction rims against igneous-textured Sublayer matrix (ITSM), indicating disequilibrium with the impact melt. One composite inclusion exhibits igneous layering of feldspar lherzolite and olivine gabbro, suggesting derivation from an unexposed older layered mafic-ultramafic intrusion. The calculated parental magma for one particularly well-preserved feldspar lherzolite inclusion is similar to continental arc basalt formed by up to 5% partial melting of garnet peridotite. Ol-Cpx-Pl thermobarometry of several exotic inclusions indicate equilibration at 900o C – 1120o C and 210 – 300 MPa, suggesting emplacement into upper-middle crust (7.7 – 10.9 km), prior to being incorporated into the lower parts of the proto-SIC during impact excavation and/or thermomechanical erosion of target rocks. Most analyzed inclusions, ITSM, and Main Mass lithologies are enriched in highly incompatible elements with negative Nb-Ta-Ti anomalies, unradiogenic Nd, and radiogenic Os isotopic signatures. These features suggest that the impact sampled rocks that were derived from subduction-metasomatized mantle, including the widespread Huronian volcanic and intrusive rocks adjacent to the SIC. Melting of these volcanic and intrusive rocks and the underlying Neoarchean Superior Province upper-middle crustal rocks would produce the observed geochemical characteristics of the SIC lithologies and inclusions. The Main Mass has a very homogeneous Hf isotopic composition, indicating that the impact melt sheet was well mixed. However, Sublayer, IQD, and overlying basal Main Mass norites vary widely in terms of Pb-S-(Os) isotopic compositions. Most mafic-ultramafic inclusions, except for anteliths, contain no sulfides and exhibit no signatures of Ni-Cu-PGE depletion caused by prior sulfide saturation, which suggest that the association between mafic-ultramafic inclusions and NiCu-PGE sulfide mineralization is attributable to the hydrodynamic equivalence of less dense but larger silicate inclusions and denser but smaller sulfide melt droplets during transport and/or settling. Anteliths, locally-derived inclusions, and local variations in Pb-S-(Os) isotopes must have been generated in situ, requiring significant degrees of assimilation of footwall rocks via thermomechanical erosion, whereas most exotic inclusions other than shocked feldspar lherzolite were derived from deeper mafic-ultramafic protoliths, generated during impact excavation and/or thermomechanical erosion, and physically transported into their current locations. Thus, thermomechanical erosion played an important role in the generation of embayments, incorporation of xenoliths and sulfide xenomelts from the mineralized country rocks (e.g., EBLINipissing-Huronian), and formation of isotopic heterogeneity in the basal parts of the SIC. Convective- and gravity-driven mass flow contributed to the horizontal transportation of inclusions and sulfide xenomelts into the embayment when the impact melt contained <45% inclusions, but became less significant as proto-Sublayer incorporated more inclusions.Doctor of Philosophy (Ph.D.) in Mineral Deposits and Precambrian Geolog

Pre-trained transformer for adversarial purification

With more and more deep neural networks being deployed as various daily services, their reliability is essential. It's frightening that deep neural networks are vulnerable and sensitive to adversarial attacks, the most common one of which for the services is evasion-based. Recent works usually strengthen the robustness by adversarial training or leveraging the knowledge of an amount of clean data. However, in practical terms, retraining and redeploying the model need a large computational budget, leading to heavy losses to the online service. In addition, when adversarial examples of a certain attack are detected, only limited adversarial examples are available for the service provider, while much clean data may not be accessible. Given the mentioned problems, we propose a new scenario, RaPiD (Rapid Plug-in Defender), which is to rapidly defend against a certain attack for the frozen original service model with limitations of few clean and adversarial examples. Motivated by the generalization and the universal computation ability of pre-trained transformer models, we come up with a new defender method, CeTaD, which stands for Considering Pre-trained Transformers as Defenders. In particular, we evaluate the effectiveness and the transferability of CeTaD in the case of one-shot adversarial examples and explore the impact of different parts of CeTaD as well as training data conditions. CeTaD is flexible, able to be embedded into an arbitrary differentiable model, and suitable for various types of attacks

A framework of lightweight deep cross-connected convolution kernel mapping support vector machines

Deep kernel mapping support vector machines have achieved good results in numerous tasks by mapping features from a low-dimensional space to a high-dimensional space and then using support vector machines for classification. However, the depth kernel mapping support vector machine does not take into account the connection of different dimensional spaces and increases the model parameters. To further improve the recognition capability of deep kernel mapping support vector machines while reducing the number of model parameters, this paper proposes a framework of Lightweight Deep Convolutional Cross-Connected Kernel Mapping Support Vector Machines (LC-CKMSVM). The framework consists of a feature extraction module and a classification module. The feature extraction module first maps the data from low-dimensional to high-dimensional space by fusing the representations of different dimensional spaces through cross-connections; then, it uses depthwise separable convolution to replace part of the original convolution to reduce the number of parameters in the module; The classification module uses a soft margin support vector machine for classification. The results on 6 different visual datasets show that LC-CKMSVM obtains better classification accuracies on most cases than the other five models

RSSI-Based Smooth Localization for Indoor Environment

Radio frequency (RF) technique, for its better penetrability over traditional techniques such as infrared or ultrasound, is widely used for indoor localization and tracking. In this paper, three novel measurements, point decision accuracy, path matching error and wrong jumping ratio, are firstly defined to express the localization efficiency. Then, a novel RSSI-based smooth localization (RSL) algorithm is designed, implemented, and evaluated on the WiFi networks. The tree-based mechanism determines the current position and track of the entity by assigning the weights and accumulative weights for all collected RSSI information of reference points so as to make the localization smooth. The evaluation results indicate that the proposed algorithm brings better localization smoothness of reducing 10% path matching error and 30% wrong jumping ratio over the RADAR system

A Compact and Low Profile Loop Antenna with Six Resonant Modes for LTE Smart phone

In this paper, a novel six-mode loop antenna covering 660-1100 MHz, 1710-3020 MHz, 3370-3900 MHz, and 5150-5850 MHz has been proposed for the application of Long Term Evolution (LTE) including the coming LTE in unlicensed spectrum (LTE-U) and LTE-Licensed Assisted Access (LTE-LAA). Loop antennas offer better user experience than conventional Planar Inverted-F Antennas (PIFA), Inverted-F Antennas (IFA), and monopole antennas because of their unique balanced modes (1?, 2?, …). However, the bandwidth of loop antennas is usually narrower than that of PIFA/IFA and monopole antennas due to these balanced modes. To overcome this problem, a novel monopole/dipole parasitic element, which operates at an unbalanced monopole-like 0.25? mode and a balanced dipole-like 0.5? mode, is first proposed for loop antennas to cover more frequency bands. Benefiting from the balanced mode, the proposed parasitic element is promising to provide better user experience than conventional parasitic elements. To the authors’ knowledge, the balanced mode for a parasitic element is reported for the first time. The proposed antenna is able to provide excellent user experience while solving the problem of limited bandwidth in loop antennas. To validate the concept, one prototype antenna with the size of 75×10×5 mm3 is designed, fabricated and measured. Both simulations and experimental results are presented and discussed. Good performance is achieved

All Things Considered: Detecting Partisan Events from News Media with Cross-Article Comparison

Public opinion is shaped by the information news media provide, and that information in turn may be shaped by the ideological preferences of media outlets. But while much attention has been devoted to media bias via overt ideological language or topic selection, a more unobtrusive way in which the media shape opinion is via the strategic inclusion or omission of partisan events that may support one side or the other. We develop a latent variable-based framework to predict the ideology of news articles by comparing multiple articles on the same story and identifying partisan events whose inclusion or omission reveals ideology. Our experiments first validate the existence of partisan event selection, and then show that article alignment and cross-document comparison detect partisan events and article ideology better than competitive baselines. Our results reveal the high-level form of media bias, which is present even among mainstream media with strong norms of objectivity and nonpartisanship. Our codebase and dataset are available at https://github.com/launchnlp/ATC.Comment: EMNLP'23 Main Conferenc