Search

Mafic-ultramafic subvolcanic intrusive complexes, at the 1–10-km scale, constitute favorable environments for the formation of orthomagmatic Ni-Cu-PGE sulfide deposits. Within 100–1000-km scale large igneous provinces (LIPs), the most favorable economic target areas may be difficult to identify using a traditional regional exploration approach. We report results of field and laboratory studies focused on an integrated geochemical-architectural model for the Ni-Cu-PGE sulfide potential of the High Arctic large igneous province (HALIP) of Canada, the largest and best-exposed portion of this circum-arctic LIP. Previous lithogeochemical studies of the Canadian HALIP (130–80 Ma) concluded that subalkaline mafic units located on Axel Heiberg Island were more prospective than younger, alkalic igneous rocks (alkaline basalts to basanites) exposed on northern Ellesmere Island. Mapping carried out for this study revealed the presence of abundant subalkaline igneous rocks on western Ellesmere Island. We interpret these units as an extension of the Schei Sills, a stratigraphically bound sequence of intrusions exposed along a ~ N-S belt on eastern Axel Heiberg Island. Samples from the Schei Sills and from the Middle Fiord Intrusive Complex (~ 20 km2, central Axel Heiberg Island) show Cu/Zr values above and below unity, consistent with complementary sulfide enrichment and removal, respectively, within these intrusive systems. The spatial association of the Schei Sills with the post-emplacement Eocene Stolz Thrust is noteworthy, as later thrusting associated with the Paleogene Eurekan Orogeny caused the uplift of deeper parts of the HALIP subvolcanic feeder system and associated wall-rock stratigraphy. Absolute Ir-group PGE contents are low throughout the HALIP; however, Pt-group PGE contents range widely among analyzed tholeiitic intrusive rocks. For example, relatively elevated Pt + Pd values of 10–30 ppb in samples from the Middle Fiord Intrusive Complex and the Schei Sills suggest heightened prospectivity in these two areas. In contrast, tholeiitic flood basalts in the Strand Fiord Formation and associated intrusions exposed in western Axel Heiberg Island (~ 95 Ma) exhibit Cu/Zr < 1 and low Pt + Pd contents (below 10 ppb). The ca. 120 Ma magmatic event associated with the Schei Sills and Middle Fiord Intrusive Complex appears to have generated magmas that are more prospective than those of the younger (ca. 95 Ma) magmatic pulse associated with the flood basalts of the Strand Fiord Formation. This work demonstrates that not all architectural elements of a LIP are equal in terms of metallogenic potential, and that nested zones of higher prospectivity can be identified through the integration of several geological constraints. [ABSTRACT FROM AUTHOR]

Gossans resulting from the oxidation of sulphide-rich bedrock occur sporadically across Canada, and these features are routinely indicated on geological maps published by the Geological Survey of Canada (GSC). In the Canadian Arctic Islands, some gossans display reactive zones in permafrost characterized by specific textures and mineralogical facies. In poorly-vegetated areas of the High Arctic, gossans can easily be detected on high-resolution satellite imagery. However, the mechanisms leading to their formation are poorly known. For this study, two reactive gossans located in the early Neoproterozoic Minto Inlier of Victoria Island, Northwest Territories, were investigated to determine if the deposits constitute (1) analogues of mine waste in permafrost and (2) vectors to economic resources. Mineralogy was determined in situ using a portable spectroradiometer, with follow-up laboratory measurements. Site 1, Gossan Hill, is a 75-m topographic high capped by a poorly consolidated, rust-coloured layer overlying pyrite-rich sands, and resembles a classic gossan. Site 2, Gossan Sill, underlies a mineralized gabbroic sill consisting of sulphide-rich veins and pods but appears to be inverted morphologically. Visible–Near Infrared–Short Wave Infrared spectral analyses of surficial materials at Gossan Hill indicate gypsum, goethite and jarosite, and X-ray diffraction (XRD) confirms their presence as well as quartz, illite and feldspar. At Sill Gossan, spectral analyses show gypsum and jarosite; XRD indicates variable amounts of goethite, hematite, pyrite, chlorite, calcite and feldspar. The positive relief and presence of concentric alteration zones at Gossan Hill suggest that cryogenic processes, typical of Arctic regions, are active. Water becomes expelled during the freezing cycle forcing material outwards and along with oxidation of the sulphides, forms variably coloured zones in gossanous material. The inverted stratigraphy at Sill Gossan is more problematic. Constant weathering and mass wasting from the overlying sill and pyrite-rich breccia provide fresh pyrite to the gossan on a regular (seasonal) basis. [ABSTRACT FROM AUTHOR]

Gossan Hill is located within the Minto Inlier in central Victoria Island, Northwest Territories (N 71.36697°, W 114.95155°). A study of the mineralogical associations and geological setting of this deposit indicates that it is an arrested hydrothermal system frozen in permafrost. From above, the hill stands out because of the topographic relief of 75 m and the orange-brown color of the surficial material. The surface of the hill is marked by areas of concentric color zonation up to 3 m across, with light gray centers surrounded by a yellow–orange ring that is surrounded by an orange–brown color that covers the rest of the surface of the hill. Trenches dug into these areas reveal that the central zone contains quartz and pyrite native sulfur in a loose aggregate of sand-sized grains. This central area is surrounded by a zone dominated by gypsum and quartz with some jarosite. Beyond this, the surrounding surface consists of quartz, hematite, and amorphous iron oxides. The radial arrangement of the mineral assemblage indicates an increase in oxidation of sulfur from the center outward. Analysis of isotopic composition of the sulfur indicates the source of sulfur could be the underlying strata. The hill is underlain by inter-bedded carbonate and sulfate-evaporite sedimentary rocks of the Kilian formation in the upper part of the Neoproterozoic Shaler Super group. The sedimentary rocks were intruded by diabase sills of the 720 Ma Franklin igneous event, which crop out 2 km to the south of Gossan Hill. The soft friable nature of the deposit and the topographic relief of the hill indicate a post-glacial (Pleistocene) age of formation. Permafrost has maintained the disequilibrium mineral assemblage since the cessation of fluid flow. Extraction of the permafrost ice from the central zone yields a liquid with a pH of 2.3. The observed long-term persistence of pyrite encased within the acidic permafrost indicates that oxidation and dissolution reactions common in mine waste are slowed, if not stopped, in such an environment. The predicted rise of Arctic temperatures will cause the active layer to move deeper and result in the release of the acidic solutions frozen in the permafrost. Water ice or frozen CO2 just below the Martian surface would also preserve such mineral disequilibrium for very long periods of time. No region exists on Earth where ice has existed continuously for millions of years, but the Gossan Hill deposit is an excellent terrestrial analogue. On Mars, the subsurface ice may be very old. Ancient reactive Martian mineral assemblages and the fluids associated with them will reflect conditions that existed in the past. [ABSTRACT FROM AUTHOR]

Terrestrial ilmenite has been assessed for its suitability in the preparation of a simulant of lunar high-Ti mare regolith, which is needed to test oxygen production on the lunar surface during future missions. Petrographic observations using optical and electron microscopes revealed that ilmenite grains in the Mirepoix, Sanford Lake, and Degrosbois Fe-Ti oxide deposits from Grenvillian anorthosite massifs contain hercynite in their rims but that hematite exsolution is absent in three of eight studied samples. Electron microprobe analyses showed that the ilmenite grains vary in TiO2 from 38.82 to 52.34 wt.%; in FeO from 33.15 to 45.88 wt.%; in Fe2O3 (calculated from stoichiometry) from 2.18 to 27.03 wt.%; in MgO from 0.05 to 2.49 wt.%; and in MnO from 0.26 to 1.51 wt.% and are thus comparable in composition to lunar ilmenite. Ilmenite, free of hematite, in two samples was homogeneous in composition (e.g., sample SL1: 50.4-51.4 wt.% TiO2). Two sub-solidus reactions occurred amongst the oxide minerals in the studied deposits: ( i) exsolution of hercynite in magnetite; and ( ii) reaction between the hematite component in the ilmenite and the ulvöspinel component of the magnetite, forming new ilmenite, which includes the hercynite. The reaction between the hematite component in the ilmenite and the ulvöspinel component of the magnetite, when conditions are favorable for diffusion, produces ilmenite grains that are homogenous in composition and free of hematite exsolution. Ilmenite with little or no Fe3+ may occur in massive, fine-grained, and metamorphosed Fe-Ti oxide deposits and provide a terrestrial analogue source of ilmenite useful for the production of lunar mare simulant. [ABSTRACT FROM AUTHOR]

The first Special Issue published by the Canadian Journal of Earth Sciences in the field of planetary sciences consists of a collection of nine papers on astromaterials, planetary geology, and Earth-based analogues. We describe the milestones that led to the development of the planetary geology and geophysics (PG&G) community in Canada over the past 5 years, which culminated in record-breaking attendance at a special session of the 2011 GAC-MAC-SEG-SGA Joint Annual Meeting held in Ottawa. The idea of a Special Issue was met with enthusiasm by delegates from coast to coast. By connecting the fields of earth and planetary sciences, the Canadian Journal of Earth Sciences pioneers a new vision for geoscience that expands the options available to Canadians who wish to publish their research at home. [ABSTRACT FROM AUTHOR]

This Special volume published by the Canadian Journal of Earth Sciences consists of a collection of six papers on the petrology, geochemistry, and metallogeny of igneous rocks emplaced in large igneous provinces (LIPs). The papers provide a snapshot of results presented at a Special Session of the 2017 Geological Association of Canada – Mineral Association of Canada Joint Annual Meeting held in Kingston, Ontario, by members of the vibrant geoscience community dedicated to the study of LIPs. Participants applauded the idea of a joint session on these topics and as a result, the session fostered animated discussions and new collaborations. The scope of magmatic and metallogenic studies of LIPs often precludes the type of brainstorming that took place during the meeting. This Special volume demonstrates that a robust understanding of magmatic processes represents the essential first step towards the search for mineral deposits in LIPs worldwide. [ABSTRACT FROM AUTHOR]

The article discusses large igneous provinces (LIPs) have characterized by massive outpourings of predominantly mafic magma in the continental and oceanic domains. Topics include geoscientists have studied the stratigraphy, volcanology, petrology, and geochemistry of continental flood basalts emplaced in LIPs; and the relative contributions of asthenospheric versus lithospheric mantle sources to LIP basalt genesis have a topic of debate.

The Alpha–Mendeleev ridge complex is a prominent physiographic and geological feature ofthe Arctic Amerasia Basin. The Alpha and Mendeleev ridges are, respectively, the eastern andwestern components of a continuous seafloor high that is approximately 2000 km long and200–400 km wide. A surge of interest in the tectonic evolution of Arctic submarine featureshas led to a wealth of new geophysical data collected from the Alpha Ridge. Currentinterpretations of its origin vary but there is compelling evidence that the Alpha Ridge mayhave formed as an oceanic plateau during the Late Cretaceous. Geological samples are rarebut most samples recovered indicate a genetic link with the High Arctic Large IgneousProvince (HALIP). In August 2016, Canada&#x2019;s Extended Continental Margin-United Nations Convention onthe Law of the Sea Program dredged approximately 100 kg of volcanic rocks from the AlphaRidge. The large size and pristine state of the samples enabled the first comprehensive studyof a single eruptive event in the volcanic record of the Alpha Ridge. The dredgesample is a lapilli tuff containing vitric and basaltic clasts. Textural evidence and thecoexistence of juvenile and cognate clasts suggest a phreatomagmatic eruption. Thevitric fragments consist of sideromelane glass with abundant plagioclase microlites.Texturally, these basaltic glass lapilli display a fresh glassy core surrounded byFe- and Ti-rich zones and a palagonite rim. Major and trace element analyses ofglassy cores indicate remarkably uniform, mildly alkaline basaltic compositions. Theplagioclase-bearing glass yielded a 40Ar/39Ar plateau age of 90.40 ± 0.26 Ma (2σ error)which included 89% of 39Ar released. We interpret this result to represent the eruption age ofthe plagioclase microlites and consequently, of the host basaltic glass lapilli inthe tuff. Volatile species analyses by infrared spectroscopy on the fresh basalticglass suggests that the melt was effectively degassed to shallow level. Assumingequilibrium degassing, the homogeneous resulting values of H2Ototal in the range0.1 to 0.19 wt.% (1σ error) indicate subaerial or shallow eruption (surface to 80m). The new 40Ar/39Ar age for the sample is consistent with a 40Ar/39Ar age of 89 ± 1 Maobtained for a sample of tholeiitic basalt dredged from the central part of the Alpha Ridge,and with the range of ages reported for HALIP igneous rocks exposed onshore in theCanadian Arctic Archipelago (130-80 Ma). Our new data provide evidence for localemergence of the Alpha Ridge in the Late Cretaceous. A comparison of the Alpha Ridge andKerguelen Plateau–Broken Ridge Large Igneous Province (LIP) provides new insights on theepisodic nature of LIP magmatism and variations in eruptive style through time. [ABSTRACT FROM AUTHOR]

The Canadian Space Agency (CSA) is involved in several space exploration research projects carried out through the Canadian Analogue Research Network (CARN). All these projects require the visualization, manipulation, analysis, and interpretation of geospatial terrestrial information for comparison with the existing planetary databases. The large amount of data gathered through these projects require easy access and processing ability for principal investigators and their students at Canadian universities, CSA staff, and stakeholders in government, industry, and at space agencies worldwide. We present the results of a project in development to create an Internet-based Geographic Information System (WebGIS) for terrestrial analogue research and planetary databases at the CSA The project has three objectives: (1) to promote and facilitate research at analogue sites in Canada; (2) forge stronger links with the international earth and planetary science community by sharing geospatial information and (3) give visibility to the CSA in the field of analogue and planetary database management. For this project, we are testing an OpenGIS architecture made available on the Internet and built according to the international standards developed by the Open Geospatial Consortium. In addition to reducing costs, this approach allows: (1) flexibility in database management, (2) interoperability with a Web Map Service (WMS), (3) the ability to create multilayered databases and queries for comparative studies, and (4) regular updates to include data from ongoing terrestrial analogue and planetary missions. Similar solutions already exist but are largely dedicated to terrestrial databases except in a few cases for global planetary information. The particular feature of the proposed WebGIS solution will be to focus on a detailed comparison of terrestrial and planetary geospatial databases using a list of specific queries developed in collaboration with experts from the scientific community in Canada and internationally. [ABSTRACT FROM AUTHOR]

Geochemical data, from the Mars Meteorite Compendium web site, for 13 basaltic meteorites, possibly from only four localities on Mars, are used to study Martian petrogenetic processes. To achieve this goal, an exploratory data analysis technique, multidimensional scaling (MDS), is used to quantitatively assess the relative behavior (measured with correlation coefficients) of 160 incompatible element ratios involving 25 'trace' elements. The ratios behave as in Earth basalts, suggesting that relative element incompatibility is similar in both planets. Because mineralogy controls incompatibility, the mineralogy of Earth and Mars mantles appears similar. In addition, results suggest that ratios involving elements with highly different incompatibility (e.g., La/Yb) are dominantly controlled by % melting. Plots of SiO2 (pressure proxy; decreases with increasing pressure) versus La/Yb and Nb/Y (decrease as melting increases) imply that Mars basalts, like Earth tholeiites, reflect high percentages of melting, but opposite to Earth, % melting appears to increase with increasing pressure. The moderately correlated, positive, SiO2-La/Yb Mars relationship parallels highly correlated Lunar KREEP data and contrasts with Earth's negative correlation. The positive relationships may reflect restricted mantle convection in some (Mars and the Moon are smaller) planetary bodies. Using similarly incompatible element ratios that are sensitive to source composition, to compare Mars and Earth with MDS, Mars sources most resemble depleted Earth mantle. Additionally, these ratios group Mars sources into enriched, depleted, and intermediate types. The groupings are the same as those suggested by isotopes, and we conclude that trace element data support the hypothesis that chemical variation in Mars may reflect crystallization of a Mars magma ocean. The natural patterns in ratios and samples revealed using MDS, which has no a priori information about relationships, support integrity of the geochemical data set, despite potential shortcomings such as small sample sizes, alteration, and weathering. However, whether the meteorites are representative of Mars as a whole is unknown. [ABSTRACT FROM AUTHOR]

An association of Nb-enriched basalts (NEB), high-MgO andesites (HMA), and flows with adakitic characteristics are interlayered with tholeiitic pillow basalts in the 2.7 Ga Penakacherla greenstone belt of eastern Dharwar craton. Two populations of basalt are present, a high-Mg# Ni (0.65-0.56, 106-52 ppm) and low-Mg# Ni (0.45-0.34, 32-13 ppm) counterpart; Nb spans 6.3-18 ppm relative to 'normal' arc tholeiitic basalts, where Nb ∼3 ppm, and hence qualify as NEB. Basalts plot on the low-Ce/Yb trend of intraoceanic arcs, and have fractionated heavy rare-earth elements (HREE) indicative of melting with residual garnet at >90 km. Ratios of Nb/Ta (7.6 ± 0.7), Zr/Hf (44 ± 0.8), and Zr/Sm (27 ± 2.4) are systematically low, high, and similar to respective primitive mantle ratios of 17, 36, and 25, consistent with a mid-ocean ridge basalt-like mantle source in the sub-arc mantle wedge. Intermediate compositions are divided into high-K but low-Na (K2O 1.8-5.3; Na2O 0.5-2.1 wt.%) and low-K but high-Na (K2O 0.10-1.5; Na2O 4.1-5.6 wt.%) populations defining distinct magma series; accordingly, these are termed K-adakitic and Na-adakitic rocks, respectively. The Na-type has SiO2 ≥56 wt.%, MgO <3 wt.%, Mg# ∼0.5, Na2O ≥3.5 wt.%, K2O ≤3 wt.%, Yb ≤1.9 ppm, Cr ≥30 ppm, with slightly lower limits of Al2O3 ≥15 wt.% and La/Yb 7.5-8.2 versus ≥20, thus conforming to most criteria for Na-adakites. NEB are interpreted as melts of mantle wedge hybridized by adakitic melts having residual garnet; and Na-adakites are slab melts of low-Mg basalt in the garnet-amphibolite facies. K-adakitic flows are melts of mafic lower crust, or melts of lower crust delaminated into mantle wedge asthenosphere. [ABSTRACT FROM AUTHOR]

Modern mineral exploration strategies should take into account nontraditional metallogenic models for a given geological environment. Here we document the first detailed study of a massive sulphide showing associated with the High Arctic Large Igneous Province (HALIP) and Sverdrup Basin and in fact, only the second example of mineralization described from Axel Heiberg Island, Queen Elizabeth Islands, Canadian Arctic Archipelago. The Between Lake showing (western Axel Heiberg Island) is a small massive sulphide occurrence within scree/talus below a large ridge of gabbro. It was originally described by explorationists as an orthomagmatic sulphide occurrence hosted within a dioritic dyke. New petrographic and mineralogical analyses indicate that the showing consists predominantly of pyrrhotite with lesser pyrite, trace chalcopyrite, and rare sphalerite. No Ni- or Pb-bearing sulphide minerals were detected. Geochemically, the showing contains some Co and Cu, rare Zn, and generally very low Ni contents (<9 ppm). Sulphur isotope ratios of sulphide minerals range from +3.6 to + 6.6‰, somewhat heavier than expected for magmatic-derived S but isotopically lighter than S associated with local evaporite diapirs (+5.8‰ to +12.2‰). Orthomagmatic sulphides hosted in the diorite typically exhibit even lighter isotopic ratios of –3.9‰ to –1.00‰. The data are consistent with potential mafic–siliciclastic volcanogenic massive sulphide mineralization, or the like, the first documented in the HALIP. High heat flow associated with extensive HALIP magmatism was likely the driving force for such mineralization. Mineral prospectivity in Canada's High Arctic had been predicated upon the potential presence of magmatic Ni – Cu – platinum group element sulphide mineralization. Rather than negating this potential, our findings provide evidence for additional metallogenic potential for this region of Nunavut. [ABSTRACT FROM AUTHOR]

The article discusses large Igneous Provinces has linked, directly or indirectly, to several metallogenic systems. Topics include sedimentary units of the Sverdrup Basin have deformed, at localities, by structures associated with syndepositional episodic flow related to diapirism of Otto Fiord Formation evaporites; and the area exhibits a complex and unique fold interference pattern.

The Cretaceous geological evolution of the Canadian Arctic was marked by voluminous magmatism comprising Canada's portion of the High Arctic large igneous province (HALIP) that is thought to have resulted from a mantle plume head. This magmatism is largely recorded as extensive Early Cretaceous lavas of the Isachsen Formation, Late Cretaceous continental flood basalts of the Strand Fiord Formation, and an extensive network of dykes and sills forming their plumbing systems. Axel Heiberg Island near South Fiord contains a small, structurally complex portion of the overall network of HALIP tabular intrusions, from which samples from the South Fiord intrusions and Isachsen Formation basaltic lavas were analysed to better understand their petrogenesis. Specifically, we apply trace-element ratios together with Sm-Nd isotope systematics in order to identify processes that shaped the chemical evolution of the South Fiord intrusions and Isachsen Formation lavas, to identify (1) mantle source chemistries and (2) the role of crustal assimilation. On the basis of Sm-Nd isotopic results, South Fiord intrusion magmas were derived from a homogeneous mantle source whereas a more heterogeneous source is invoked for the Isachsen Formation lavas. Furthermore, modelling with Th/ La, Nb/U, Ba/Th and Ba/Nb suggests that South Fiord intrusive magmatism was contaminated by sedimentary rocks from the Sverdrup Basin. Conversely, a trend towards high Ba/Th in Isachsen Formation lavas suggests a subducted sediment component derived from extinct subduction zones. We surmise that (1) South Fiord intrusive rocks are geochemically distinct from the Isachsen Formation lavas and (2) the HALIP mantle plume head intersected and incorporated sediments from ancestral subduction zones to the present-day Aleutian and Alaska subduction zones to produce the Isachsen Formation flows, whereas the South Fiord intrusions (and correlated Strand Fiord magmatism) were generated from plume material that interacted with upper crustal sedimentary rocks. [ABSTRACT FROM AUTHOR]

Mafic and ultramafic rocks crop out as decimetre- to centimetre-sized bodies of talc-antigorite-olivine (±orthopyroxene) and chlorite-amphibole schists interleaved in the pelitic Kluane Schist of southwestern Yukon. The metamorphic assemblages in ultramafic rocks exposed at Doghead Point overprint two generations of cleavage and are consistent with metamorphism reaching >550 °C (talc + olivine) and >750 °C (olivine + enstatite) in the contact aureole of the Eocene Ruby Range batholith. The bulk rock major and trace element patterns in the ultramafic schists (>40 wt.% MgO, Mg/(Mg + Fe) > 0.90) are unlike residual mantle from partial melting (i.e., ophiolite, orogenic massif, abyssal ocean floor) but are similar to peridotite or pyroxenite cumulates from arc magmas. Identical trace element concentrations and patterns are observed in several late Triassic basalts, pyroxenites, and websterites occurring to the southeast in Stikinia (present coordinates). A highly discordant U-Pb zircon date for one antigorite-talc-olivine schist sample (200-210 Ma) is within the range of U-Pb zircon ages for the late Triassic Lewes River - Stuhini arc in northwestern Stikinia (200-208 Ma, 216-220 Ma). When combined with other published age information, the ultramafic rocks in the Kluane Schist are interpreted as fragments of deeper arc-related mafic and ultramafic intrusive rocks introduced to the Kluane forearc basin between 95 and 82 Ma by exhumation along shear zones in northwestern Stikinia, most likely the Wann River or Llewellyn Faults. The Kluane Schist represents a west-facing forearc basin bordered to the east by arc-parallel strike-slip fault(s) that served to exhume and imbricate large knockers into the accretionary prism. [ABSTRACT FROM AUTHOR]

The Paint Pots are a natural Fe-SO4 acid spring system along the Kicking Horse Rim, a major geological feature that has controlled fluid flow and mineralization over geologic time. The very low pH (∼3) and extremely high trace metal concentrations of the springs are anomalous and greatly exceed health limits (Zn = 35.8 mg/L, Pb = 0.461 mg/L, As = 82.7 ppb). Sulphur isotopes (δ34S and δ18O in sulphate equal to +11.4 and -12.1 ‰, respectively) are consistent with sulphide oxidation. Mass balance calculations indicate that the springs must have derived their acidity and metal content from natural weathering of a pyrite-rich ore deposit in the vicinity. Several ore deposit types occur along the Kicking Horse Rim, with the Mississippi Valley Type (MVT) style being the most consistent with the source of the spring waters. At the spring outlet, Fe-rich waters oxidize, forming large cone features of Fe-O precipitates, predominantly goethite. A diverse microbial community has been identified in the site that is distinct from those found at acid mine drainage sites. At one site, there was a high proportion of the bacterial candidate division WPS-2, the first time that this group has been detected as the predominant phylum in a community. Compared with anthropogenically influenced acid mine drainage sites that have been studied to date as Mars analogues, the unique uncultured organisms found in the Paint Pots provide a distinct analogue site that can offer insights into the diversity of extremophilic organisms in more natural environments. [ABSTRACT FROM AUTHOR]

Abstract: Polygonal terrain is found in a variety of polar environments on Earth and Mars. As a result, many areas of northern Canada may represent ideal terrestrial analogues for specific regions of Mars – in particular the northern plains. In the Canadian Arctic, polygon troughs are commonly underlain by wedges of massive ice, with rare examples of other wedge types. If the same is true for Mars, this raises interesting implications for the processes that concentrate H2O at the Martian poles. This study uses an electromagnetic induction sensor to investigate the electromagnetic characteristics of terrestrial polar ice-wedge polygons. Surveys were conducted in two regions of the Canadian Arctic using a DUALEM-1S dual-geometry electromagnetic induction sensor, which measures electrical conductivity in the first 1.5–2m of the subsurface. At locations where strong geomorphological evidence of ice was found, polygon troughs corresponded to local conductive anomalies. Trenching confirmed the presence of ice wedges at one site and allowed ground-truthing and calibration of the geophysical data. Previously unknown bodies of massive ice were also identified through the use of this geophysical technique. This study shows that an electromagnetic induction sounder is a useful instrument for detecting and mapping out the presence of subsurface ice in the Canadian Arctic. Taking together with its small size, portability and ruggedness, we suggest that this would also be a useful instrument for any future missions to Mars’ polar regions. [Copyright &y& Elsevier]

Gossans are surficial deposits that form in host bedrock by the alteration of sulphides by acidic and oxidizing fluids. These deposits are typically a few meters to kilometers in size and they constitute important vectors to buried ore deposits. Hundreds of gossans have been mapped by field geologists in sparsely vegetated areas of the Canadian Arctic. However, due to Canada's vast northern landmass, it is highly probable that many existing occurrences have been missed. In contrast, a variety of remote sensing data has been acquired in recent years, allowing for a broader survey of gossans from orbit. These include band ratioing or methods based on principal component analysis. Spectrally, the 809 gossans used in this study show no significant difference from randomly placed points on the Landsat 8 imageries. To overcome this major issue, we propose a deep learning method based on convolutional neural networks and relying on geo big data (Landsat-8, Arctic digital elevation model lithological maps) that can be used for the detection of gossans. Its application in different regions in the Canadian Arctic shows great promise, with precisions reaching 77%. This first order approach could provide a useful precursor tool to identify gossans prior to more detailed surveys using hyperspectral imaging. [ABSTRACT FROM AUTHOR]