Permeability Structure of the Lava-Dike Transition of 15 My Old Oceanic Crust Formed at the East Pacific Rise

The permeability structure of oceanic crust controls both the spatial and temporal extent of hydrothermal circulation, but the detailed geometry of fractures in seafloor rocks is not well known. We apply an equivalent channel model to veins, joints, faults, and breccias preserved in recovered cores from ODP-IODP Hole 1256D to calculate paleo-permeability. In the ~250 m transition between dikes and lavas, paleo-permeability is 10-13~10-14 m2 with narrow zones of >10-9 m2 that presumably act as conduits for the largest volume of fluids. Most of these high permeability zones are oriented vertically as a result of diking events into a significant thickness of lavas outside of the neovolcanic zone. After an increase in permeability due to off-axis diking events, fluid temperatures drop, pathways are sealed, and the permeability of the upper oceanic crust drops significantly

Geophysical imaging unveils the largest pull-apart basin in East Antarctica

West Antarctica hosts one of the largest continental rift systems on Earth, the West Antarctic Rift System (WARS) that forms the lithospheric cradle for the West Antarctic Ice Sheet. The WARS is known to have experienced several stages of extension starting with distributed/wide mode extension in the Cretaceous, followed by narrower mode and variably oblique extension in the Cenozoic, the latter potentially triggered by the onset of oceanic seafloor spreading in the Adare Basin (Davey et al., 2016, GRL). However, the extent and impact of Cenozoic extension and transtension within the Transantarctic Mountains sector of East Antarctica is much less well understood. Here we present results from a new project (REGGAE) that by analysing aeromagnetic, aerogravity and land-gravity and bedrock topography images and models provides key new geophysical constraints on the form, extent and kinematics of the largest Cenozoic pull-apart basin recognised so far in East Antarctica, the Rennick Graben (RG). Potential field imaging reveals the extent of part of a Jurassic tholeiitic Large Igneous Province preserved within the RG and helps delineate the inherited structural architecture of the underlying Ross-age basement in northern Victoria Land, including highly magnetic arc basement in the northern Wilson Terrane and the subglacial extent of a thrust fault belt located between the western flank of the RG and the eastern margin of Wilkes Subglacial Basin (WSB). We show that the RG is a major composite right-lateral pull-part basin that extends from the Oates Coast to the Southern Cross Mountains crustal block and propose that it is kinematically connected with both the western edge of the WARS and the eastern margin of the WSB. More cryptic evidence for an earlier phase of left-lateral strike slip deformation is also emerging from our recent geological field work in the study region and relatively subtle offsets in aeromagnetic anomaly patterns. Our findings suggest that the RG is part of a distributed region of the continental lithosphere in East Antarctica that was preferentially deformed in response to Cenozoic transtensional stresses that likely also facilitated propagation of accelerated oceanic transform faulting in the adjacent oceanic lithosphere located between southeastern Australia and Tasmania

Capturing player enjoyment in computer games

The current state-of-the-art in intelligent game design using Artificial Intelligence (AI) techniques is mainly focused on generating human-like and intelligent characters. Even though complex opponent behaviors emerge through various machine learning techniques, there is generally no further analysis of whether these behaviors contribute to the satisfaction of the player. The implicit hypothesis motivating this research is that intelligent opponent behaviors enable the player to gain more satisfaction from the game. This hypothesis may well be true; however, since no notion of entertainment or enjoyment is explicitly defined, there is therefore no evidence that a specific opponent behavior generates enjoyable games.peer-reviewe

Intraplate strike-slip faulting in East Antarctica: new geophysical views from the Rennick Graben and Wilkes Subglacial Basin

Intraplate strike-slip faulting can occur in association with different geodynamic settings, ranging from subduction-related to collision and extension. Geological and geophysical research in Northern Victoria Land (NVL) in East Antarctica, has led to the interpretation that major fault systems that were active during the early Paleozoic Ross Orogen were reactivated much later as right-lateral intraplate strike-slip fault systems from ca 48 Ma, and that these faults may have accomodated differential shear along evolving oceanic transform faults located between southeastern Australia and Tasmania. One of the main structures in NVL that has been inferred to relate to this unusual geodynamic process is the Rennick Graben (RG), but its age, extent and kinematics have remained both poorly constrained and controversial. Even less well-understood are the potential tectonic linkages between the RG and the deep sub-basins that lie within the much broader Wilkes Subglacial Basin (WSB), in the hinterland of the Transantarctic Mountains. Here, we present new interpretations of enhanced potential field images derived from aeromagnetic and airborne and land-gravity observations to help constrain the extent and architecture of the RG and the sub-basins within the WSB. We show that the RG is a composite pull-part basin that extends from the Oates Coast towards the margin of the Ross Sea Rift, part of the West Antarctic Rift System. We suggest that the more cratonic WSB region was also affected by extensional and transtensional processes, the latter potentially linked to an evolving and distributed left-lateral Paleogene(?) strike-slip plate boundary between East Antarctica and Australia

Landsat-8, advanced spaceborne thermal emission and reflection radiometer, and WorldView-3 multispectral satellite imagery for prospecting copper-gold mineralization in the northeastern Inglefield Mobile Belt (IMB), northwest Greenland

© 2019 by the authors. Several regions in the High Arctic still lingered poorly explored for a variety of mineralization types because of harsh climate environments and remoteness. Inglefield Land is an ice-free region in northwest Greenland that contains copper-gold mineralization associated with hydrothermal alteration mineral assemblages. In this study, Landsat-8, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and WorldView-3 multispectral remote sensing data were used for hydrothermal alteration mapping and mineral prospecting in the Inglefield Land at regional, local, and district scales. Directed principal components analysis (DPCA) technique was applied to map iron oxide/hydroxide, Al/Fe-OH, Mg-Fe-OH minerals, silicification (Si-OH), and SiO2 mineral groups using specialized band ratios of the multispectral datasets. For extracting reference spectra directly from the Landsat-8, ASTER, and WorldView-3 (WV-3) images to generate fraction images of end-member minerals, the automated spectral hourglass (ASH) approach was implemented. Linear spectral unmixing (LSU) algorithm was thereafter used to produce a mineral map of fractional images. Furthermore, adaptive coherence estimator (ACE) algorithm was applied to visible and near-infrared and shortwave infrared (VINR + SWIR) bands of ASTER using laboratory reflectance spectra extracted from the USGS spectral library for verifying the presence of mineral spectral signatures. Results indicate that the boundaries between the Franklinian sedimentary successions and the Etah metamorphic and meta-igneous complex, the orthogneiss in the northeastern part of the Cu-Au mineralization belt adjacent to Dallas Bugt, and the southern part of the Cu-Au mineralization belt nearby Marshall Bugt show high content of iron oxides/hydroxides and Si-OH/SiO2 mineral groups, which warrant high potential for Cu-Au prospecting. A high spatial distribution of hematite/jarosite, chalcedony/opal, and chlorite/epidote/biotite were identified with the documented Cu-Au occurrences in central and southwestern sectors of the Cu-Au mineralization belt. The calculation of confusion matrix and Kappa Coefficient proved appropriate overall accuracy and good rate of agreement for alteration mineral mapping. This investigation accomplished the application of multispectral/multi-sensor satellite imagery as a valuable and economical tool for reconnaissance stages of systematic mineral exploration projects in remote and inaccessible metallogenic provinces around the world, particularly in the High Arctic regions

New Zinc-Based Active Chitosan Films: Physicochemical Characterization, Antioxidant, and Antimicrobial Properties

The improvement of the antioxidant and antimicrobial activities of chitosan (CS) films can be realized by incorporating transition metal complexes as active components. In this context, bioactive films were prepared by embedding a newly synthesized acylpyrazolonate Zn(II) complex, [Zn(QPhtBu)2(MeOH)2], into the eco-friendly biopolymer CS matrix. Homogeneous, amorphous, flexible, and transparent CS@Znn films were obtained through the solvent casting method in dilute acidic solution, using different weight ratios of the Zn(II) complex to CS and characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), Raman, and scanning electron microscopy (SEM) techniques. The X-ray single-crystal analysis of [Zn(QPhtBu)2(MeOH)2] and the evaluation of its intermolecular interactions with a protonated glucosamine fragment through hydrogen bond propensity (HBP) calculations are reported. The effects of the different contents of the [Zn(QPhtBu)2(MeOH)2] complex on the CS biological proprieties have been evaluated, proving that the new CS@Znn films show an improved antioxidant activity, tested according to the DPPH method, with respect to pure CS, related to the concentration of the incorporated Zn(II) complex. Finally, the CS@Znn films were tried out as antimicrobial agents, showing an increase in antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus) with respect to pure CS, when detected by the agar disk-diffusion method

Identification of phyllosilicates in the antarctic environment using aster satellite data: Case study from the mesa range, campbell and priestley glaciers, northern Victoria land

In Antarctica, spectral mapping of altered minerals is very challenging due to the remote-ness and inaccessibility of poorly exposed outcrops. This investigation evaluates the capability of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite remote sensing imagery for mapping and discrimination of phyllosilicate mineral groups in the Antarctic environment of northern Victoria Land. The Mixture-Tuned Matched-Filtering (MTMF) and Constrained Energy Minimization (CEM) algorithms were used to detect the sub-pixel abundance of Al-rich, Fe -rich, Fe -rich and Mg-rich phyllosilicates using the visible and near-infrared (VNIR), short-wave infrared (SWIR) and thermal-infrared (TIR) bands of ASTER. Results indicate that Al-rich phyllosilicates are strongly detected in the exposed outcrops of the Granite Harbour granitoids, Wilson Metamorphic Complex and the Beacon Supergroup. The presence of the smectite mineral group derived from the Jurassic basaltic rocks (Ferrar Dolerite and Kirkpatrick Basalts) by weathering and decomposition processes implicates Fe -rich and Fe -rich phyllosilicates. Biotite (Fe -rich phyllosilicate) is detected associated with the Granite Harbour granitoids, Wilson Metamorphic Complex and Melbourne Volcanics. Mg-rich phyllosilicates are mostly mapped in the scree, glacial drift, moraine and crevasse fields derived from weathering and decomposition of the Kirkpatrick Basalt and Ferrar Dolerite. Chlorite (Mg-rich phyllosilicate) was generally mapped in the exposures of Granite Harbour granodiorite and granite and partially identified in the Ferrar Dolerite, the Kirkpatrick Basalt, the Priestley Formation and Priestley Schist and the scree, glacial drift and moraine. Statistical results indicate that Al-rich phyllosilicates class pixels are strongly discriminated, while the pixels at-tributed to Fe -rich class, Fe -rich and Mg-rich phyllosilicates classes contain some spectral mixing due to their subtle spectral differences in the VNIR+SWIR bands of ASTER. Results derived from TIR bands of ASTER show that a high level of confusion is associated with mafic phyllosilicates pixels (Fe -rich, Fe -rich and Mg-rich classes), whereas felsic phyllosilicates (Al-rich class) pixels are well mapped. Ground truth with detailed geological data, petrographic study and X-ray diffraction (XRD) analysis verified the remote sensing results. Consequently, ASTER image-map of phyllosilicate minerals is generated for the Mesa Range, Campbell and Priestley Glaciers, northern Victoria Land of Antarctica. 3+ 2+ 3+ 2+ 2+ 3+ 2+ 3+ 2

IODP Expeditions 309 and 312 drill an intact section of upper oceanic basement into gabbros

The Integrated Ocean Drilling Program's (IODP) Expeditions 309 and 312 successfully completed the first sampling of an intact section of upper oceanic crust, through lavas and the sheeted dikes into the uppermost gabbros. Hole 1256D, which was initiated on the Ocean Drilling Program's (ODP) Leg 206, now penetrates to >1500 mbsf and >1250 m sub-basement. The first gabbroic rocks were encountered at 1407 mbsf. Below this, the hole penetrates 3c100 m into a complex zone of fractionated gabbros intruded into contact metamorphosed dikes