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The global extent of the Late Cretaceous oceanic anoxic event 3 (OAE 3) remains uncertain. It is not considered to have extended into the Boreal Realm. To test this, we examined Late Cretaceous organic- and metal-rich black mudstones of the Smoking Hills Formation in Arctic Canada. New high-precision U-Pb zircon ages indicate that deposition of the Smoking Hills Formation (88.535-78.230 Ma) was temporally coincident with OAE 3, indicating a much broader global expression of this event than previously thought. OAE 3 was likely manifest throughout the proto-Arctic Ocean (now Arctic Canada). Abundant bentonite layers and cryptotephra within the Smoking Hills Formation have rare earth element (REE) patterns that are consistent with ashfall derived from Cretaceous arc volcanism. Anomalously high organic matter content in the Smoking Hills Formation, as compared to underlying and overlying units, suggests that ocean fertilization led to enhanced productivity and metal drawdown. A peak in arc volcanism may have been a key driver of the OAE 3 event. We also explored the potential use of cadmium as a geochemical marker of volcanism and show that high volcanogenic metal loading could affect the use of Cd and other proxies for marine productivity (e.g., Zn, Cu). [ABSTRACT FROM AUTHOR]

The Permian-Triassic mass extinction (PTME) interval is marked by major excursions in both inorganic and organic carbon (C) isotopes. Carbon cycle models predict that these trends were driven by large increases in productivity, yet organic C-rich rocks are not recorded in most PTME shelf sedimentary successions. Anomalous C-rich facies have been reported from rare abyssal plains records now exposed in Japan and New Zealand, where black shales at the PTME are extraordinarily organic-rich units. We examined organic matter at the Waiheke, New Zealand, section, and results show that these deposits are dominated by lamalginites composed of unicellar solitary or colonial phytoplankton produced during algal blooms that falls as "marine snow." We modeled the impact of ash fall from eruptions in the Siberian Traps large igneous province and argue that they fertilized the Panthalassa Ocean with P and Fe, leading to a marine "snowstorm" and significant C drawdown marking this major biobloom during the PTME. [ABSTRACT FROM AUTHOR]

The timing and ecological impacts of the Deccan Traps large igneous province eruption are vigorously debated. Pre--Cretaceous-Paleogene (KPg) boundary impacts of Deccan volcanism have been widely identified in marine sediments, but direct evidence of terrestrial impacts remains rare. We used mercury concentrations and isotopic compositions, a proxy for volcanic activity, to assess impacts on terrestrial environments. We studied two drill cores across the KPg boundary in eastern China that represent two different depositional environments: clastic deposits in the Jiaolai Basin and carbonate deposits in the Pingyi Basin. Both drill cores exhibit strong Hg enrichment prior to the KPg boundary. Near consistent massindependent fractionation (MIF) of odd-Hg isotopes (odd-MIF) in the Jiaolai Basin likely indicates a volcanogenic source of Hg spikes below the KPg boundary. Odd-MIF isotopes in the Pingyi Basin likewise suggest a volcanogenic Hg source but with a terrestrial Hg signature of lower Δ199Hg values before and after the Hg spike interval. The Hg enrichment level can be stratigraphically correlated to the beginning of the Latest Maastrichtian warming event (LMWE) and is consistent with a strong, negative carbon-isotope excursion (CIE) in both δ13Corg (organic matter) and δ13Ccarb (carbonate), suggesting a disturbance of the global carbon cycle induced by a major pulse of Deccan Traps volcanism. Our discovery of a terrestrial record of pre-KPg boundary Deccan volcanism provides robust evidence of global influence of the Deccan Traps large igneous province during the LMWE. [ABSTRACT FROM AUTHOR]

Land surface temperature (LST) from satellite images contains meaningful signatures of geothermal heat flux (GHF) for geothermal exploration. However, the signal is mixed with solar radiation dominated features, making it difficult to identify GHF anomaly. Here we propose a novel method to tackle this problem that removes the time variant solar component based on principles of energy balance. Through an iteration process examining multiple LST maps from different seasons, the temporally invariant GHF component can be revealed. We tested this method by examining the Mount Meager Volcanic Complex area in British Columbia, Canada where data of known geothermal prospects are publicly accessible for validation. Seventy-two Landsat-8 cloud-free LST maps acquired in the last 10 years, were employed to extract the GHF component. Four high GHF anomalies are identified and two are consistent with areas of known hot spring swarms that occur above identified geothermal prospects. A third anomaly is spatially coincident with an active landslide site where warm seeps from the sliding surface and faults/fractures within the moving land mass are responsible for the anomalies. The anomalies in the fourth one are predominately anthropogenic, related to heat emission from hydropower facilities. The proposed method provides an efficient way to extract non-solar sourced LST anomalies, adding a cost-effective tool for geothermal exploration, and environmental/geohazard monitoring. • A novel method for detecting geothermal components from solar energy dominated LST. • Using LST time series to eliminate temporal variant solar energy input. • Uncertainty in anomaly identification quantified by probability measure. • Capable of revealing LST anomalies caused by geothermal, anthropogenic and surface processes. [ABSTRACT FROM AUTHOR]

The Carnian Pluvial Event (CPE) was an interval marked by global climatic and environmental change, along with biotic turnover, which occurred during the early Late Triassic. Although the causes and consequences of this event remain unclear, one possible scenario is enhanced volcanism injecting greenhouse gases into the atmosphere, perturbing the global carbon cycle, and negatively impacting the global environment. However, there is an underlying challenge in showing a true causeand-effect relationship between volcanism and the CPE, as both the sedimentary and volcanic records are difficult to date accurately enough to demonstrate temporal correspondence. However, mercury (Hg) can be used to fingerprint catastrophic volcanism in the sedimentary record. We examined two sections that record the CPE at Laishike and Wayao in Guizhou Province, southwest China, which display high Hg contents along with spikes of Hg/total organic content (TOC), Hg/Al, Hg/total sulfur (TS), and Hg/(Mo/Al) during the CPE that indicate a shift to excess Hg loading. These Hg anomalies are correlative with the global negative excursion in d13Ccarb values at the CPE, which suggests that increased volcanism injected both massive amounts of Hg and isotopically light carbon into the atmosphere, and these were ultimately recorded in marine sediments. This interpretation is supported by slightly negative or near-zero 199Hg values that are consistent with a volcanic Hg source. Our study supports the hypothesis that enhanced volcanism played a major role in the evolution of biota and the environment during the CPE. [ABSTRACT FROM AUTHOR]

Large spikes in mercury (Hg) concentration are observed globally at the latest Permian extinction (LPE) horizon that are thought to be related to enhanced volcanic emissions of the Siberian Traps large igneous province (LIP). While forming an effective chemostratigraphic marker, it remains unclear whether such enhanced volcanic Hg emissions could have generated toxic conditions that contributed to extinction processes. To address this, we examined the nature of enhanced Hg emissions from the Siberian Traps LIP and the potential impact it may have had on global ecosystems during the LPE. Model results for a LIP eruption predict that pulses of Hg emissions to the atmosphere would have been orders of magnitude greater than normal background conditions. When deposited into world environments, this would have generated a series of toxic shocks, each lasting >1000 yr. Such repeated Hg loading events would have had severe impact across marine trophic levels, as well as been toxic to terrestrial plant and animal life. Such high Hg loading rates may help explain the co-occurrence of marine and terrestrial extinctions. [ABSTRACT FROM AUTHOR]

The Ordovician saw major diversification in marine life abruptly terminated by the Late Ordovician mass extinction (LOME). Around 85% of species were eliminated in two pulses 1 m.y. apart. The first pulse, in the basal Hirnantian, has been linked to cooling and Gondwanan glaciation. The second pulse, later in the Hirnantian, is attributed to warming and anoxia. Previously reported mercury (Hg) spikes in Nevada (USA), South China, and Poland implicate an unknown large igneous province (LIP) in the crisis, but the timing of Hg loading has led to different interpretations of the LIP-extinction scenario in which volcanism causes cooling, warming, or both. We report close correspondence between Hg, Mo, and U anomalies, declines in enrichment factors of productivity proxies, and the two LOME pulses at the Ordovician-Silurian boundary stratotype (Dob's Linn, Scotland). These support an extinction scenario in which volcanogenic greenhouse gases caused warming around the Katian-Hirnantian boundary that led to expansion of a preexisting deepwater oxygen minimum zone, productivity collapse, and the first LOME pulse. Renewed volcanism in the Hirnantian stimulated further warming and anoxia and the second LOME pulse. Rather than being the odd-one-out of the "Big Five" extinctions with origins in cooling, the LOME is similar to the others in being caused by volcanism, warming, and anoxia. [ABSTRACT FROM AUTHOR]

The largest extinction in Earth history, in the latest Permian, was followed throughout most of the Early Triassic by a prolonged period of ecologic recovery. What factors delayed biotic recovery are still under debate and partly revolve around impacts of global warming on primary marine productivity. We examined N isotope records from the Festningen section on Spitsbergen, Arctic Norway, to examine changes in nutrient availability through the Early to Middle Triassic along the northern margin of Pangea. Our results show progressive decline in N availability throughout the Griesbachian, leading to severe nutrient limitations through the remainder of the Early Triassic, until returning to a highly productive continental margin in Middle Triassic time. These results are consistent with other studies from northern and western Pangea and thus show regional nutrient limitations occurred in what should have been the main zone of marine primary productivity. Such nutrient limitation likely stressed primary production and consequently contributed to prolonged marine recovery. We suggest this was driven by high ocean temperatures depressing the marine nutricline. [ABSTRACT FROM AUTHOR]

The Permian-Triassic mass extinction is widely attributed to the global environmental changes caused by the eruption of the Siberian Traps. However, the precise temporal link between marine and terrestrial crises and volcanism is unclear. Here, we report anomalously high mercury (Hg) concentrations in terrestrial strata from southwestern China, synchronous with Hg anomalies in the marine Permian-Triassic type section. The terrestrial sediments also record increased abundance of fossil charcoal coincident with the onset of a negative carbon isotope excursion and the loss of tropical rainforest vegetation, both of which occurred immediately before the peak of Hg concentrations. The organic carbon isotope data show an ~5‰-6‰ negative excursion in terrestrial organic matter (bulk organic, cuticles, and charcoal), reflecting change in atmospheric CO2 carbon-isotope composition coincident with enhanced wildfire indicated by increased charcoal. Hg spikes provide a correlative tool between terrestrial and marine records along with carbon isotope trends. These data demonstrate that ecological deterioration occurred in tropical peatlands prior to the main marine mass extinction. [ABSTRACT FROM AUTHOR]

Low efficiency of turbines used in geothermal power production, along with large power demand for geothermal fluid pumping, limits use of geothermal resources for power production in the Canadian low to mid enthalpy basins. Much larger areas of Canadian sedimentary basins have potential for geothermal direct heating, but use will be dependent on the amortization period of the installation cost as well as the parasitic power demand to maintain large flow rates in injection and production wells. Maximum exergy (kJ/kg) potential for the most perspective geothermal resources in the deeper parts of Canadian basins (150 kJ/kg (0.15 MJ/kg)), are compared to exergy contained by the intrinsic chemical energy in oil, gas and coal (30–35 MJ/kg) that is required to be replaced in order to reduce carbon emissions. The calculated number of geothermal producing doublet well systems, at very high assumed flows of 0.08 m3/s (80 L/s), required to replace an average oil producing well in Alberta –WCSB will be > 10. But, such high exergy is available only in the deepest northern parts of the WCSB. • Huge difference in exergy of geothermal and fossil fuels. • Geothermal can provide a clean energy supply to offset portion of hydrocarbons. • Power production restricted to deep basins with high geothermal gradients. [ABSTRACT FROM AUTHOR]

Abstract The October 28, 2012 magnitude 7.8 Haida Gwaii earthquake disrupted flow of the only thermal springs in the Haida Gwaii archipelago of western Canada. Springs of the Gandll K'in Gwaay.yaay geothermal system ceased discharge at existing outlets and spring pools drained empty. Subsequent visits to the remote site documented return of flow at the lowest elevation discharge points, although at a greatly reduced discharge rate. Over time thermal water discharge was renewed at higher elevations and the total discharge rate increased. To understand better how seismic activity affected the spring flow, at a site ∼30 km distant from the epicentre, a study was initiated to inform development of a conceptual model of the thermal system. Stable isotope data show that thermal waters discharging at Gandll K'in Gwaay.yaay originate in deep circulation of meteoric waters, where they are heated by the normal increase in ground temperature with depth. Geothermal gradients in the region are relatively low, and aqueous geothermometry suggests that circulation depths of the system are ∼3.6 km. There is no significant difference in overall water geochemistry from before and after the earthquake, either suggesting that the flow path was clogged, or that changes in water pressure in the recharge zone have reduced the overall system drive. We propose a conceptual model, suggesting that the earthquake induced a drop in the water table of the recharge zone, reducing the driving force of the flow system, leading to flow cessation. As the water table returned back to normal elevations the spring system has begun to return to pre-earthquake discharge patterns. This interpretation is consistent with traditional knowledge of the site, were oral history records previous earthquake induced flow cessations and subsequent returns of spring flow. Highlights • Flow stoppage of thermal springs occurred in response to near-field earthquake. • Gradual 5 year recovery is consistent with previous flow stoppages. • Proposed model suggests seismic reduced pressure drive of the system. [ABSTRACT FROM AUTHOR]

Mercury (Hg) records in marine and terrestrial archives across the Cretaceous/Paleocene (K/Pg) boundary were examined as a proxy for Deccan Large Igneous Province (LIP) eruptions. We examined no less than twenty-six key sections/boreholes that are globally distributed, and show that Hg values have a log-normal distribution. The data have a similar trend to that across other major extinction boundaries in the Phanerozoic record. Questionable Hg/TOC anomalies have been ruled out, indicating excess Hg loading at the K/Pg boundary. Most Hg isotope values across the K/Pg boundary indicate a volcanic Hg source, based on the mass-independent (MIF) Δ199Hg values. However, negative Δ199Hg values suggest continental inputs in the Jhilmili section (India). Near-synchronous Hg and negative carbon-isotope excursion (CIE) patterns are identified in sediments associated with LIPs representing the paired release of Hg and isotopically depleted CO 2 , especially in the Latest Maastrichtian warming event (LMWE) that we attribute to the Deccan LIP. We compared the response of global biotic changes to Deccan volcanism and the Chicxulub impact. It appears that the end-Cretaceous mass extinction was a complex catastrophe caused by volcanism driving major climate fluctuations and ocean acidification, and perhaps exacerbated by the Chicxulub impact. [ABSTRACT FROM AUTHOR]

Summary: Microbial species diversity may peak at certain optimal environmental conditions and decrease toward more extreme conditions. Indeed, bell‐shaped relationships of species diversity against pH and temperature have been demonstrated, but diversity patterns across other environmental conditions are less well reported. In this study, we investigated the impact of salinity on the diversity of microorganisms from all three domains in a large set of natural springs with salinities ranging from freshwater to halite saturated. Habitat salinity was found to be linearly and inversely related to diversity of all three domains. The relationship was strongest in the bacteria, where salinity explained up to 44% of the variation in different diversity metrics (OTUs, Shannon index, and Phylogenetic Diversity). However, the relationship was weaker for Eukarya and Archaea. The known salt‐in strategist Archaea of the Halobacteriaceae even showed the opposite trend, with increasing diversity at higher salinity. We propose that high energetic requirements constrain species diversity at high salinity but that the diversity of taxa with energetically less expensive osmotolerance strategies is less affected. Declining diversity with increasing osmotic stress may be a general rule for microbes as well as plants and animals, but the strength of this relationship varies greatly across microbial taxa. [ABSTRACT FROM AUTHOR]

Many continental large igneous provinces coincide with climate perturbations and mass extinctions. When basaltic plumbing systems traverse carbon-rich sedimentary rocks, large volumes of greenhouse gases may be generated. We document how intrusive sills of the Mesozoic High Arctic Large Igneous Province affected surrounding finegrained, organic-rich siliciclastic rocks of the Sverdrup Basin in the Canadian Arctic Archipelago. Petrographic and X-ray diffraction data from samples located near sills show the presence of high-temperature metamorphic phases (diopside, andalusite, garnet, and cordierite). Raman thermometry on organic matter yields peak temperatures of 385-400 °C near sill contacts, tailing off to far-field temperatures of ≤230 °C. Samples located >20 m from sills show no systematic change in vitrinite reflectance and have a VRo eq% value of ~2.5%, which indicates a temperature of ~210 °C. The finite element thermal modeling tool SUTRAHEAT was applied to the 17-m-thick Hare Sill, emplaced at 3 km depth at 1105 °C. SUTRAHEAT results show that contact-proximal rocks attain temperatures of >700 °C for a brief period (~1 year). By 5 years, the Hare Sill is completely solidified (<730 °C), and the temperature anomaly collapses rapidly thereafter as the thermal pulse propagates outward. By 10 years, all rocks within 10 m of the Hare Sill are between 450 °C and 400 °C, rocks at 20 m from the contact attain 200 °C, yet far-field temperatures (>50 m) have barely changed. When multiple sills are emplaced between 4 km and 6 km depth, all rocks between sills reach ~250 °C after 100 years, showing that it is possible to raise regional-scale background temperatures by ~150 °C for the observed High Arctic Large Igneous Province sill density. Vitrinite reflectance data and pyrolysis results, together with SILLi thermal modeling, indicate that much of the hydrocarbongenerating potential was eliminated by High Arctic Large Igneous Province intrusions. The SILLi model yields ~20 tonnes/m² of organic equivalent CO2 (all carbon gas is reported as CO2) from the Hare Sill alone when emplaced into Murray Harbour Formation rocks with 5.7 wt% organic carbon, and ~226 tonnes/m² by emplacement of multiple sills throughout the 2-km-thick Blaa Mountain Group with 3 wt% organic carbon. On a basin scale, this yields a total of ~2550 Gt CO2 from the Hare Sill, with ~13,000 Gt CO2 being generated by the multiple sill scenario, similar to estimates from other large igneous provinces. Much of the Blaa Mountain Group rocks now have organic carbon contents of <1 wt%, which is consistent with large volumes of carbon-species gas having been generated, likely a mixture of CO2, CH4, and other species. However, organic-rich Murray Harbour Formation rocks show no obvious reduction in organic carbon content toward the Hare Sill intrusive contacts, which suggests that not all of the carbon was lost from the sedimentary package hosting High Arctic Large Igneous Province magmas. We suggest that some of the gas generated by contact metamorphism failed to drain out for lack of high-permeability conduits, and then back-reacted to form calcite cements and pyrobitumen during cooling. [ABSTRACT FROM AUTHOR]

Natural gas is currently being produced from shales of the Montney and Liard basins in western Canada. Production requires hydraulic fracturing due to the low permeability of the shales in the basins. Stratigraphically equivalent shales are present in the northern Canadian Rocky Mountains. Thermal springs with notable hydrocarbon concentrations occur where large-scale faults intersect the same shale units that are the focus of gas development, indicating that under certain circumstances, connection of deep fractured shales to the land surface is possible. To constrain these conditions, simulations were conducted for the spring with the highest hydrocarbon flux (Toad River Spring), results of which indicate that in order to supply sufficient water to a fault to support measurable advection, the effective permeability of the shales in these structurally deformed areas must be one to four orders of magnitude higher than in areas of active gas production to the east. The spatial scale of enhanced permeability is much greater than that which is achieved by hydraulic fracturing and the mechanism of maintaining high pressures at depth is more persistent in time. Examination of groundwater velocities suggests that upward migration of solutes from hydraulic fracturing may take decades to centuries. Results also indicate that any temperature anomaly will be associated with transport along a fault at such velocities. No such temperature anomaly has been documented in regions with unconventional oil and gas development to date. Such an anomaly would be diagnostic of a deep solute source. [ABSTRACT FROM AUTHOR]

Abstract: Analysis of current temperature data in the Canadian Arctic Archipelago results in the recognition of two major thermal regimes. High temperature regions are observed where salt diapirs and salt cored anticlines are present. Low temperature fields are observed along the western and southern basin margins and around Cornwall‐Amund Ringnes islands, where regional Mesozoic aquifers are exposed to surface, connected to basin boundary faults, or regional unconformities. Meteoric and Holocene sub‐glacial water recharge are inferred to be responsible for the low geothermal regime and low formation water salinity. Neither exhumation associated with the Eocene “Eurekan” orogeny nor volcanic intrusion associated with opening of Amerasia Basin in late Jurassic‐early Cretaceous have been interpreted to be a significant influence on the present day temperature field, although thermal indicators show evidence of elevated thermal alteration of organic matter pointing to earlier, but now dissipated, thermal anomalies. [ABSTRACT FROM AUTHOR]

A chloride mass and stable isotope (δ 37 Cl) balance approach was employed to calculate the effect of saline groundwater discharge into the Athabasca and Clearwater rivers in the Athabasca Oil Sands Region (AOSR) in north-eastern Alberta, Canada. Saline groundwater affected by halite, carbonate, and anhydrite dissolution discharges Na-Cl type water with total dissolved solids (TDS) up to 51,700 mg/L from exposed Devonian and Cretaceous units in the river valleys in this area. In this study, nine springs discharging groundwater with a median Cl concentration of 9800 mg/L were sampled and chloride stable isotope ratios were determined, with δ 37 Cl values ranging from 0.2 to 1.0‰. In contrast, river waters had historical monthly median Cl concentrations between 5.9 and 49.5 mg/L and δ 37 Cl values between −2.2 and −1.4‰. The discharge rate of saline groundwater was calculated to be 100 ± 20 L/s into the Clearwater River and 134 ± 68 L/s into the Athabasca River. The chemical composition and discharge rates of saline groundwater were used to estimate its contribution to the mass fluxes of major ions, metals, and PAHs in the Athabasca and Clearwater rivers. Overall, saline groundwater contributed less than 0.2% of river discharge, but 0.04–39% of major ion concentrations in the rivers, with highest contributions under winter low-flow conditions. In the Clearwater River, saline groundwater contributed 23–39% of average monthly Cl flux and 18–32% of average monthly Na flux. For the same major ion fluxes in the Athabasca River, saline groundwater contributed 12–18% and 6–12%, respectively. The influence of saline groundwater discharge on the mass flux of trace elements in the rivers was found to be negligible, contributing less than 1% of river fluxes of Cu, Ni, Pb, and Zn. Similarly, the influence on mass flux of PAHs in the rivers was found to be negligible (<0.03%) but quantifiable. These results provide important insights on the natural contributions of saline groundwater discharge to river chemistry in the AOSR, a necessary factor to consider when monitoring for anthropogenic effects of oil sands development on river water quality. [ABSTRACT FROM AUTHOR]

The temporal link between large igneous province (LIP) eruptions and at least half of the major extinctions of the Phanerozoic implies that large scale volcanism is the main driver of mass extinction. Here we review almost twenty biotic crises between the early Cambrian and end Cretaceous and explore potential causal mechanisms. Most extinctions are associated with global warming and proximal killers such as marine anoxia (including the Early/Middle Cambrian, the Late Ordovician, the intra-Silurian, intra-Devonian, end-Permian, and Early Jurassic crises). Many, but not all of these are accompanied by large negative carbon isotope excursions, supporting a volcanogenic origin. Most post-Silurian biocrises affected both terrestrial and marine biospheres, suggesting that atmospheric processes were crucial in driving global extinctions. Volcanogenic-atmospheric kill mechanisms include ocean acidification, toxic metal poisoning, acid rain, and ozone damage and consequent increased UV-B radiation, volcanic darkness, cooling and photosynthetic shutdown, each of which has been implicated in numerous events. Intriguingly, some of the most voluminous LIPs such as the oceanic plateaus of the Cretaceous were emplaced with minimal faunal losses and so volume of magma is not the only factor governing LIP lethality. The missing link might be continental configuration because the best examples of the LIP/extinction relationship occurred during the time of Pangaea. Many of the proximal kill mechanisms in LIP/extinction scenarios are also potential effects of bolide impact, including cooling, warming, acidification and ozone destruction. However, the absence of convincing temporal links between impacts and extinctions other than the Chicxulub-Cretaceous example, suggests that impacts are not the main driver of extinctions. With numerous competing extinction scenarios, and the realisation that some of the purported environmental stresses may once again be driving mass extinction, we explore how experimental biology might inform our understanding of ancient extinctions as well as future crises. [ABSTRACT FROM AUTHOR]

Dramatic global climate change in the Early Cretaceous suggests that numerous boreal cool events perturbed otherwise warm conditions. Abundant glendonites in Valanginian and Aptian strata are thought to be key markers of cold conditions; however, their use as climate indicators has been questioned. Therefore, a detailed study of glendonites in the context of host-rock geochemistry was conducted on Cretaceous strata exposed on Ellef Ringnes Island, Sverdrup Basin, Canadian High Arctic, to elucidate paleoenvironment controls on periodic glendonite occurrence throughout the Early Cretaceous. Two prominent glendonite zones were identified in Valanginian and Aptian strata. Data for carbon stable isotopes show δ13Ccarb values of -29.5‰ to -10.5‰, consistent with a carbon source from organic matter within the surrounding shale. Trace metal data suggest deposition occurred under an overall oxidizing water column in a setting with higher than average phosphorus and highly degraded organic matter. There is no variation in the geochemical parameters of the mudstones with or without glendonites. Glendonite-bearing zones are coincident, however, with regional evidence for brief periods of colder climate conditions within the otherwise warm Early Cretaceous. We conclude that while the overall conditions for glendonite formation were prevalent throughout the Cretaceous, it was the brief cold periods that provided the final range of stability for their preservation in discrete zones of Valanginian and Aptian strata. These results support the model of an overall warm Early Cretaceous climate being punctuate by several "cold snaps" of as-yet uncertain origin. [ABSTRACT FROM AUTHOR]

During field mapping of Ellef Ringnes Island, Canadian Arctic Archipelago, 139 isolated Early Cretaceous methane seep deposits were found from 75 field sites. Stable isotopes of the carbonates have values of d13C = -47‰ to -35‰ and δ18O = -4.0‰ to +0.7‰. Isoprenoids in organics from one of the seeps are significantly depleted in 13C, with the most negative δ13C value of -118‰ and -113‰ for 2,6,10,15,19-pentamethylicosane (PMI) and phytane/crocetane, respectively. These values indicate an origin through methane oxidation, consistent with biomarkers that are characteristic for anaerobic methanotrophic archaea within the seep deposits, accompanied by terminally branched fatty acids showing similar 13C values (-92‰) sourced from sulfate-reducing bacteria. The seep deposits contain a moderate-diversity macrofaunal assemblage comprising ammonites, bivalves, gastropods, scaphopods, "vestimentiferan" worm tubes, and brachiopods. The assemblage is dominated numerically by species that probably had chemosymbionts. The seep deposits formed in the subsurface within strong redox zones, in an otherwise normal marine setting, characterized by oxic waters at high paleolatitudes. While geographically widespread over an area of ~10,000 km², seep deposits on Ellef Ringnes Island occur in a narrow stratigraphic horizon, suggesting a large release of biogenic methane occurred over a brief period of time. This gas release was coincident with a transition from a cold to warm climate during the latest early Albian, and we hypothesize that this may have been related to gas hydrate release. [ABSTRACT FROM AUTHOR]

A major bio-crisis in the Guadalupian−Lopingian transition (Capitanian−Wuchiapingian, middle−late Permian), possibly driven by the volatile eruption of the Emeishan large igneous province (LIP), was marked by the first-order collapse of global metazoan reefs and decline of fusulinid foraminifera, but with only minor impacts on other marine invertebrates (brachiopod, crustacea, other foraminifera). To assess the exact cause of this event, we conducted geochemical analyses of the shallow marine strata at the global stratotype section and point of the Guadalupian−Lopingian (G−L) boundary (GLB) in Laibin, South China, which corresponds to the last step of the Capitanian bio-crises during Emeishan volcanism. Here, we detect evidence for high temperature combustion of organic matter in air spanning the GLB (indicated by enriched coronene) that was terminated by a soil erosion event accompanied with terrestrial vegetation collapse at the mass extinction level (evidenced by enriched dibenzofuran) and a carbon isotope perturbation (a 2.5–3.5‰ negative shift of δ13C carb). Molybdenum data indicates oxic seawater during the combustion event, likely reflecting regression. These findings imply that large volatile volcanic eruptions of the Emeishan LIP may have caused these environmental extreme events and mass extinctions, and that relatively lower magnitude of volcanism related to Emeishan LIP may have led to impacts on terrestrial−nearshore ecosystems. [Display omitted] • Hg–coronene anomalies in end-Guadalupian strata indicate volcanism. • Coronene indicating high volcanic temperature suggests Emeishan plume volcanism. • A soil erosion event with vegetation collapse was associated with the mass extinction. • Oxic seawater condition was associated with the combustion−soil erosion event. [ABSTRACT FROM AUTHOR]

A geochemical record from a continuous Arctic marine succession of the upper Aptian to upper Albian Christopher Formation exposed at Glacier Fiord on Axel Heiberg Island, Canada, reveals the characteristic carbon isotopic excursions associated with the early Albian cluster of sub-events that comprise Oceanic Anoxic Event 1b (OAE 1b). Concentrations of redox-sensitive elements in the Christopher Formation indicate that conditions ranged from oxic to anoxic, with anoxic conditions during deposition of the Kilian sub-level, and suboxic conditions during deposition of the Jacob and Paquier sub-levels of OAE 1b. Mercury is elevated above siliciclastic background at several horizons in the succession, including prior to, and following, the Jacob, Kilian, and Paquier sub-levels. Sulphides, rather than organic matter, appear to be the most important host phase for Hg in the Christopher Formation, particularly in the mid to upper Albian part of the succession following OAE 1b. A lack of enrichment of most redox sensitive trace elements, and their relationship to detrital indicators Al, Ti, and Li, combined with other indicators of overall ventilated conditions during deposition of the Christopher Formation, suggests a terrigenous source of Hg rather than fixation of Hg by S in an anoxic or euxinic setting. Although volcanic activity associated with the HALIP could have released gaseous Hg to the atmosphere and the surrounding landscape, another potential source of Hg, S, and other metal(loid)s to the basin is mineralization associated with salt diapirism that may have been exhumed by the Albian. A change in clay mineral content (K/Al ratios) in strata overlying the Paquier sub-level indicates a change in continental weathering that may be associated with a widespread increase in humidity and warmer climate conditions at this time, that would have increased the input of detrital metal(loid)s (As, Cu, Hg, Ni, Pb, S) into the Sverdrup Basin. We suggest that Hg input into restricted marine basins can be predominantly detrital, and that there are no unequivocal atmospheric-sourced Hg anomalies associated with the Jacob, Kilian, or Paquier sub-levels of OAE 1b at Glacier Fiord. • Trace element and mercury record across oceanic anoxic event 1b • Predominantly suboxic conditions during deposition of Christopher Formation • Predominantly detrital input of Hg in the restricted Sverdrup Basin at this time [ABSTRACT FROM AUTHOR]

Sedimentary records from the northwest margin of Pangea and the Tethys show anomalously high Hg levels at the latest Permian extinction boundary. Background δ202Hg values are consistent with normal marine conditions but exhibit negative shifts coincident with increased Hg concentrations. Hg isotope mass-independent fractionation (▵ 199Hg) trends are consistent with volcanic input in deep-water marine environments. In contrast, nearshore environments have ▵ 199Hg signatures consistent with enhanced soil and/or biomass input. We hypothesize that the deep-water signature represents an overall global increase in volcanic Hg input and that this isotope signature is overwhelmed in nearshore locations due to Hg from terrestrial sources. High-productivity nearshore regions may have experienced stressed marine ecosystems due to enhanced Hg loading. [ABSTRACT FROM AUTHOR]

The recovery of life after the latest Permian extinction was protracted over Early Triassic time. Detailed geochemistry of marine sections along northwest Pangea indicates that upwelling ceased at the extinction event. Nitrogen stable isotope data suggest that this was associated with progressive increase in nutrient stress throughout the Early Triassic, coincident with a significant decrease in organic carbon content despite pervasive anoxic to euxinic conditions. We argue that the Early Triassic hothouse both reduced marine productivity and deepened the nutricline, reducing the overall rate of nutrient delivery to the photic zone, creating an Early Triassic nutrient gap. When oceans finally cooled by Middle Triassic time, renewed nutrient upwelling and onset of organic-rich shale deposition occurred across northwest Pangea, marking the final return of global marine productivity. [ABSTRACT FROM AUTHOR]

• Ground surface temperature (GST) monitoring network tested as a geothermal resource exploration tool. • Daily GST variation in the snow free season shows clear environmental and topographic footprints, and a snow curtain period of near zero GST in winter with thick snow. • Two GST anomalies associated likely with subsurface heat flow identified during snow curtain period when solar irradiation and surface weather effects were greatly suppressed. • Non-supervised machine learning partitions observation stations into mutually exclusive clusters statistically, useful in data analysis and interpretation. The southern Mount Meager area has been studied for its geothermal resource potential for a half century. Although attempts to commercialize the resource were unsuccessful in the past, a large volume of surface and subsurface geoscience data have been collected and made publicly available, making the Mount Meager area a unique natural laboratory for testing new ideas or tools for geothermal exploration. This study investigates the potential of using a ground surface temperature (GST) monitoring network as a tool in geothermal resource exploration. Twenty-two temperature data loggers were deployed in, and surrounding, the core area of the geothermal prospect for nearly one year. The collected temperature time series were analyzed statistically, and machine learning methods such as hierarchical clustering and k-means classification, were applied to data interpretation. The temporal variation of measured temperature can be divided into four segments: 1) snow free, 2) snow affected, 3) snow curtain, and 4) snow melt seasons. The intensity of daily ground temperature variation in the snow free season shows clear environmental and topographic footprints and is complicated by soil properties. The sites with a short period of near zero GST during the snow curtain period is spatially coincident with high heat flow areas. The measured mean GST shows a close affinity with subsurface heat flow and shallow ground water circulation, suggesting that GST time series contain information indicative of subsurface geothermal anomalies and that a GST monitoring network could be an effective tool for geothermal resource exploration in high latitude and/or elevation areas with seasonal snow cover. [ABSTRACT FROM AUTHOR]

Strata of Permian - Early Triassic age that include a record of three major extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) were examined at the Festningen section, Spitsbergen. Over the c. 12 Ma record examined, mercury in the sediments shows relatively constant background values of 0.005-0.010 µg g-1. However, there are notable spikes in Hg concentration over an order of magnitude above background associated with the three extinctions. The Hg/total organic carbon (TOC) ratio shows similar large spikes, indicating that they represent a true increase in Hg loading to the environment. We argue that these represent Hg loading events associated with enhanced Hg emissions from large igneous province (LIP) events that are synchronous with the extinctions. The Hg anomalies are consistent across the NW margin of Pangea, indicating that widespread mercury loading occurred. While this provides utility as a chemostratigraphic marker the Hg spikes may also indicate loading of toxic metals to the environment, a contributing cause to the mass extinction events. [ABSTRACT FROM AUTHOR]

Stratigraphic records from northwestern Pangea provide unique insight into global processes that occurred during the latest Permian extinction (LPE). We examined a detailed geochemical record of the Fest-ningen section, Spitsbergen. A stepwise extinction is noted as: starting with (1) loss of carbonate shelly macrofauna, followed by (2) loss of siliceous sponges in conjunction with an abrupt change in ichnofabrics as well as dramatic change in the terrestrial environment, and (3) final loss of all trace fossils. We interpret loss of carbonate producers as related to shoaling of the lysocline in higher latitudes, in relationship to building atmospheric CO2. The loss of siliceous sponges is coincident with the global LPE event and is related to onset of high loading rates of toxic metals (Hg, As, Co) that we suggest are derived from Siberian Trap eruptions. The final extinction stage is coincident with redox-sensitive trace metal and other proxy data that suggest onset of anoxia after the other extinction events. These results show a remarkable record of progressive environmental deterioration in northwestern Pangea during the extinction crises. [ABSTRACT FROM AUTHOR]

Natural gas reservoirs in organic-rich shales in the Appalachian and Michigan basins in the United States are currently being produced via hydraulic fracturing. Stratigraphically-equivalent shales occur in the Canadian portion of the basins in southwestern Ontario with anecdotal evidence of gas shows, yet there has been no commercial shale gas production to date. To provide baseline data in the case of future environmental issues related to hydraulic fracturing and shale gas production, such as leakage of natural gas, saline water, and/or hydraulic fracturing fluids, and to evaluate hydrogeochemical controls on natural gas accumulations in shallow groundwater in general, this study investigates the origin and distribution of natural gas and brine in shallow aquifers across southwestern Ontario. An extensive geochemical database of major ion and trace metal chemistry and methane concentrations of 1010 groundwater samples from shallow, domestic wells in bedrock and overburden aquifers throughout southwestern Ontario was utilized. In addition, select wells ( n = 36) were resampled for detailed dissolved gas composition, δ 13 C of CH 4 , C 2 , C 3 , and CO 2 , and δD of CH 4 . Dissolved gases in groundwater from bedrock and overburden wells were composed primarily of CH 4 (29.7–98.6 mol% of total gas volume), N 2 (0.8–66.2 mol%), Ar + O 2 (0.2–3.4 mol%), and CO 2 (0–1.2 mol%). Ethane was detected, but only in low concentrations (<0.041 mol%), and no other higher chain hydrocarbons were present, except for one well in overburden overlying the Dundee Formation, which contained 0.81 mol% ethane and 0.21 mol% propane. The highest methane concentrations (30 to >100 in situ % saturation) were found in bedrock wells completed in the Upper Devonian Kettle Point Formation, Middle Devonian Hamilton Group and Dundee Formation, and in surficial aquifers overlying these organic-rich shale-bearing formations, indicating that bedrock geology is the primary control on methane occurrences. A few ( n = 40) samples showed Na–Cl–Br evidence of brine mixing with dilute groundwater, however only one of these samples contained high (>60 in situ % saturation) CH 4 . The relatively low δ 13 C values of CH 4 (−89.9‰ to −57.3‰), covariance of δD values of CH 4 and H 2 O, positive correlation between δ 13 C values of CH 4 and CO 2 , and lack of higher chain hydrocarbons (C 3+ ) in all but one dissolved gas sample indicates that the methane in groundwater throughout the study area is primarily microbial in origin. The presence or absence of alternative electron acceptors (e.g. dissolved oxygen, Fe, NO 3 , SO 4 ), in addition to organic substrates, controls the occurrence of microbial CH 4 in shallow aquifers. Microbial methane has likely been accumulating in the study area, since at least the Late Pleistocene to the present, as indicated by the co-variance and range of δD values of CH 4 (−314‰ to −263‰) and associated groundwater (−19‰ to −6‰ δD-H 2 O). [ABSTRACT FROM AUTHOR]

We report here the discovery of the northernmost known perennial spring, located in the polar desert of the Canadian High Arctic (average precipitation 75.5 mm/yr; average annual air temperature -19.7 °C). The high-discharge spring (∼520 L/s) has also anomalously high temperatures (9.0 °C), despite occurring in a region of low geothermal gradient and thick (>400 m) permafrost. Active erosion at the spring outlet forms gullies with alcove-channelapron morphology, remarkably similar to archetypal gullies observed on mid-latitude regions of Mars. Geochemical and isotopic data show a meteoric origin for the waters, demonstrating that deep circulating groundwater systems can form active connections through the cryosphere to the subsurface, even in the absence of thermal anomalies. This discovery challenges current understanding of high-latitude permafrost hydrology. [ABSTRACT FROM AUTHOR]

Highlights: [•] Significant declines of river discharges in Canada were reported. [•] There are challenges to extract accurate trends in basins with short periods of record. [•] A correlation model between river flow and climate variables was established to reconstruct natural modes of river discharge. [•] The proposed model is applied to Athabasca River discharge trend analysis. [Copyright &y& Elsevier]

The latest Permian extinction (LPE), ca. 252 Ma, represents the most severe extinction event in Earth's history. The cause is still debated, but widespread marine anoxic to euxinic (H2S rich) conditions, from deep to shallow water environments, are commonly suggested. As a proxy for marine oxygen levels, we analyzed δ98/95Mo of two LPE sections that represent a gradient in water depth on the northwest margin of Pangea. Results from deep-water slope environments show a large shift in δ98/95Mo values from -2.02‰ to +2.23‰ at the extinction horizon, consistent with onset of euxinic conditions. In contrast, sub-storm wave base shelf environments show little change in the molybdenum isotopic composition (-1.34‰ to +0.05‰), indicating ongoing oxic conditions across the LPE. These results indicate that areas of the continental shelf of northwest Pangea underwent mass extinction under oxic conditions throughout the LPE event, and that shallow-water anoxia was therefore not a global phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: A 6.7million year record of marine sedimentation through the Permo Triassic Biotic Crisis shows notable shifts in mercury concentrations that varied over an order of magnitude (0.002 to 0.116μg/g). Mercury concentrations correlate strongly with total organic carbon, showing both parallel increasing and decreasing trends over geologic time scales. Results suggest that changes in bioproductivity strongly influence mercury sequestration into marine sediment. This may provide insight to potential marine response to modern anthropogenic Hg loading, and supports models that suggest enhanced bioproductivity that due to recent climate has increased Hg sequestration over time. [Copyright &y& Elsevier]

Abstract: Two informally named basins (Mirabilite Basins 1 and 2) along a submergent coastline on Banks Island, Canadian Arctic Archipelago, host up to 1m-thick accumulations of mirabilite (Na2SO4·10H2O) underlying stratified water bodies with basal anoxic brines. Unlike isostatically uplifting coastlines that trap seawater in coastal basins, these basins formed from freshwater lakes that were transgressed by seawater. The depth of the sill that separates the basins from the sea is shallow (1.15m), such that seasonal sea ice formation down to 1.6m isolates the basins from open water exchange through the winter. Freezing of seawater excludes salts, generating dense brines that sink to the basin bottom. Progressive freezing increases salinity of residual brines to the point of mirabilite saturation, and as a result sedimentary deposits of mirabilite accumulate on the basin floors. Brine formation also leads to density stratification and bottom water anoxia. We propose a model whereby summer melt of the ice cover forms a temporary freshwater lens, and rather than mixing with the underlying brines, it is exchanged with seawater once the ice plug that separates the basins from the open sea melts. This permits progressive brine development and density stratification within the basins. [Copyright &y& Elsevier]

Late Permian--Early Triassic bulk sedimentary nitrogen isotope (δ15N) and biomarker data have been generated from the northwest margin of Pangea. Sediments from the Buchanan Lake section, Arctic Canada, deposited prior to the latest Permian extinction (LPE) event are characterized by positive δ15N values of ~9‰ associated with the presence of lycopane, implying upwelling of denitrified waters from an expanded oxygen minimum zone. The data show that anoxic bottom-water conditions were not developed in northeastern Panthalassa during the Late Permian. Promoted by dispersing coal ash from Siberian Traps volcanics, as marked by an abrupt rise in C/N ratios (>20) prior to the LPE event, euxinic conditions first developed at the LPE. Pronounced differences in the nitrogen inventory across the LPE event, however, suggest that while unfavorable conditions prevailed for aerobiosis in the paleo-Tethys, persistent upwelling of deoxygenated (denitrified) waters occurred in the Sverdrup Basin across the LPE, excluding the prevalence of photic zone euxinia along the northwest margin of Pangea. [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: The Upper Carboniferous to Upper Permian deposits of the Sverdrup Basin (Arctic Canada) record a transition from carbonate to silica dominated shallow shelf ecosystems. Chert expansion started during the latest Carboniferous in distal deep-water slope environments when prolific warm-water, photozoan carbonate factories developed on the adjacent shallow shelves. A shift to heterozoan factories during the Sakmarian–Artinskian was caused by the introduction of cooler water in response to paleoceanographic changes along NW Pangea. By Kungurian time, heterozoan carbonate factories narrowed substantially while hyalosponge factories had expanded well into the mid shelves. A brief return to widespread heterozoan carbonate sedimentation occurred during the Wordian, followed by further encroachment of shallow shelves by biosiliceous factories during the Capitanian and Wuchiapingian. A major drop in relative rates of carbonate sediment accumulation with time suggests both carbonate and biosiliceous factories were under considerable stress prior to the Late Permian Extinction event. It is proposed that Sverdrup Basin waters became progressively more acidic in response to build up of atmospheric CO2 throughout the Permian which led to a gradual shoaling of the lysocline and the calcite compensation depth, which was amplified by upwelling along the northwestern margin of Pangea. Ocean acidification initiated in response to amalgamation of the Pangea supercontinent. This inhibited the silicate weathering-response through development of thick protective soil blankets. A temperature shock associated with the extinction event led to a major fall of the lysocline allowing carbonates to resume accumulation in spite of low pH conditions. The subsequent die off of terrestrial vegetation, stripping of soil cover, widespread continental erosion and repeated exposures of fresh rock surfaces associated with a major base level shift allowed silicate weathering to restart and drive oceans back to carbonate saturation. [Copyright &y& Elsevier]

Abstract: The Sverdrup Basin holds significant reserves of discovered and undiscovered petroleum that have not been produced to date given its remote arctic setting. Loss of perennial sea ice increases the prospects for producing reserves from this region. Potential renewed drilling and production requires knowledge of formation water geochemistry to aid both exploration as well as regulatory development. Historic data shows formation waters typically have a seawater origin, although there is high variability in formation water geochemistry. Salt diapirs lead to localized brine generation with salinities over an order of magnitude higher than average for the basin. Evidence also shows fresh water influx occurred along the basin margins that initiated biogenic gas generation. [Copyright &y& Elsevier]

Gypsum filled 'pipe' features were discovered in the proglacial area of the Borup Fiord Pass supraglacial sulfur spring. Stable isotope data suggest that gypsum is formed through oxidation of sulfides and are consistent with models of sulfuric acid speleogenesis. These results suggest that gypsum pipes are paleo-spring discharge channels analogous to those that feed the modern sulfur spring at Borup Fiord. A conceptual model is proposed whereby retreat of the glacial front and associated growth of permafrost in ground exposed now to low arctic temperatures leads to 'freezing-in' of the spring system and abandonment of old channels in favor of more open flow systems in the subglacial region. Results provide a model for glacially driven groundwater systems that may form in association with Mars' polar icecaps and potential geological signatures for paleo-groundwater discharge. Key Words: Analogue-Biosignatures. Astrobiology 12, 19-28. [ABSTRACT FROM AUTHOR]

A sedimentary record from the Buchanan Lake section, Canadian High Arctic, shows anomalous high levels of mercury (Hg) during the latest Permian extinction (LPE) on northwest Pangea. Significant influx of Hg progressively overwhelmed the marine system. Major disruption of the organic matter-mediated Hg drawdown process resulted in accumulation of dissolved Hg to maximum levels at the LPE boundary, affecting an already stressed global ecosystem. A switch to euxinic marine conditions at the LPE boundary led to chemical drawdown of Hg sulfides, as marked by progressive Hg mitigation. This allowed self-recovery from toxic Hg conditions, and ultimately led to reestablishment of the internal Hg-organic matter drawdown process. We hypothesize that anomalous Hg levels may be attributed to the significant natural atmospheric emissions caused by catastrophic Siberian Traps volcanic eruptions. [ABSTRACT FROM AUTHOR]

Abstract: A regional groundwater geochemistry study was conducted in the Paskapoo Formation of southern Alberta, Canada. Our study area focused on a region where two continental ice sheets, the Cordilleran and Laurentide met. The glacial deposits transported by these ice sheets have different bulk characteristics reflective of the bedrock of the source region of the ice. Recharge through these two different glacial deposits generates distinctly different water geochemistry within the underlying Paskapoo Formation, such that bedrock aquifer acquires a geochemical signature of the immediately overlying glacial deposits through which recharge occurs. Oxidation of pyrite in Laurentide till generates high-sulphate groundwater, and associated acid generation leads to enhanced mineral weathering. This generates high TDS high Na–SO4 groundwater in underlying bedrock aquifers. This process appears transitory, where thin Laurentide drift deposits are completely oxidized and have reduced capacity to generate high-sulphate water. The same bedrock underlying carbonate dominated Cordilleran drift deposits have low TDS Ca–HCO3 groundwater. [Copyright &y& Elsevier]

Abstract: Spectroscopic analysis of carbonate-bearing samples from a variety of terrestrial environments provides important insights into spectroscopy-based investigations of Mars designed to detect the presence of carbonate minerals. In order to better address the spectral detectability of carbonates on Mars, we examined the spectral reflectance properties of carbonates and carbonate-bearing lithologies from a variety of terrestrial environments, including impact structures (Haughton, St. Martin, Eagle Butte), landslides (Frank), quarrying operations (Hecla), carbonates affected by weathering (Haughton, East German Creek), and sulfide–sulfate–carbonate assemblages (Central Manitoba). The goal is to identify processes and environments that can affect spectroscopy-based carbonate detection, for more detailed follow-on studies. Common carbonates appear to be stable, from a spectroscopic perspective, to various tectonic processes. Iron oxides/hydroxides do not appear to significantly affect spectral detectability of carbonates, as the spectrum-altering effects of these phases are largely restricted to the region below ∼1μm, while useful carbonate absorption bands occur longward of ∼1.8μm. Carbonate detection and characterization in the 0.35–2.5-μm region is largely restricted to a single absorption feature in the 2.3-μm region, which can be problematic for robust carbonate identification. While tectonic processes and iron oxide/hydroxide staining do not appear to significantly impair carbonate detection based on the 2.3-μm region absorption band, a number of other factors can affect carbonate detection. These include the fact that this absorption band is weak compared to many other minerals, a number of other minerals also exhibit absorption bands in this wavelength region (leading to possible misidentifications), and that even small abundances of minerals that absorb strongly in this region will reduce the strength of the carbonate absorption band. Identifying the nature of accessory minerals associated with carbonates can be used to constrain possible formation environments. Ongoing research at carbonate-bearing terrestrial analogue sites will continue to provide new insights into the occurrence and detection of carbonates on Mars. [Copyright &y& Elsevier]

Late Sturtian deglaciation, resulting in development of oxic conditions and deposition of banded iron formations (BIFs), was a pivotal period in evolution of global ocean chemistry. The driving forces behind these Neoproterozoic BIFs and climatic/oceanic changes remain controversial, however. Here we use mercury (Hg) to elucidate the cause(s) of these dramatic changes to earth biogeochemical cycles. In the Guandong section, South China, we observe anomalously low Hg concentrations and Hg to total organic carbon (Hg/TOC) ratios in the Late Sturtian BIFs, suggesting a period of limited continental volcanism during the Late Sturtian deglaciation. We hypothesize that instead of a major LIP event, long-lasting and subdued submarine volcanism slowly increased atmospheric CO 2 to trigger the greenhouse climate that caused deglaciation. Negative shifts of Δ199Hg in the studied section suggest that deglaciation was accompanied by atmospheric mercury depletion events (AMDEs). Extremely low TOC levels in the studied section may suggest low oceanic productivity, and this may support a non-biological cause of oceanic oxygenation during the Late Sturtian glaciation, through the release of photochemically produced H 2 O 2 in melting glaciers. • Anomalously low Hg concentrations in banded iron formations suggest limited volcanism in the Late Sturtian deglaciation. • Negative shifts of Δ199Hg suggest that deglaciation was accompanied by atmospheric mercury depletion events. • Oceanic oxygenation in the Late Sturtian deglaciation was via the release of H 2 O 2 in melting glaciers. [ABSTRACT FROM AUTHOR]

Abstract: A combined sequence stratigraphic and geochemical study of the Latest Permian Extinction event in NW Pangea provides new insight into the onset and extension of basin anoxia onto the adjacent shallow shelf. The Latest Permian transgression in the Sverdrup Basin of Arctic Canada initiated prior to onset of deep-water anoxia and continued past the Latest Permian Extinction event. Deep-water anoxia initiated after the shelf was flooded in mid to Late Changhsingian time, requiring a much more rapid, and much greater vertical, rise in the chemocline than that associated with relative sea level, supporting the chemocline upward excursion model. Our work also extends evidence of global euxinc conditions to NW Pangea. Euxinic conditions developed just prior to the main extinction event, and we suggest that this was associated with a significant pyrite rain-out event which stripped bio-essential nutrients from anoxic seawater prior to the main disruption of the global carbon cycle, as recorded by shifts in the carbon isotope record. [Copyright &y& Elsevier]

Abstract: Formation waters of the 14km thick late Cretaceous–Cenozoic Beaufort–Mackenzie basin were examined as part of a larger project to better understand the petroleum potential of the region, where early exploration defined petroleum reserves of 744×109 bbls recoverable crude oil and 11.74tcf gas. Historical water analyses (2583 samples from 250 wells drilled up to 5km depth) were compiled and culled to remove incomplete and poor quality samples. The resultant database shows a broad range of salinity and water chemistry that has no systematic relationship with depth. Three main water types are defined, paleo seawater, and freshwaters related to a Miocene age gravity-driven flow system, and low TDS–high alkalinity waters. High alkalinity waters are isolated in overpressured fault blocks that were rapidly buried by post-Miocene Iperk shale deposition. The high alkalinities (up to 9000mg/L) are interpreted to be related to in situ CO2 generation through anaerobic methanogenesis in response to freshwater invasion. The dominant control on biogenic gas generation appears to be maximum burial temperature rather than the modern temperature distribution. This is consistent with the paleopasteurization model that suggests once critical burial temperatures are reached, sterilized rocks are inhibited from further biodegradation, even when temperatures subsequently drop back into the habitable zone. [Copyright &y& Elsevier]

Summary: Studies of hydro-meteorological time series have identified decadal and inter-decadal oscillations with quasi-cyclic components as part of long-term natural variations in the data. Concerns over impacts of global warming and climate change have led to many studies of sustainable development and adaptation strategies, involving historic trend estimations in order to forecast future trends. This paper demonstrates the impacts of natural oscillations of quasi-cyclic components on the Mann–Kendal and Thiel–Sen tests, the most common methods used for analyzing data trends. Tests on synthetic and real instrumental hydroclimate records suggest that the Mann–Kendall and Thiel–Sen tests are sensitive to oscillations of quasi-cyclic components. Data record length relative to the periodicity of cycles, magnitude, and phase of the longest quasi-cyclic component are the three most important factors affecting these tests. If the length of the record is greater than three cycle lengths, the impact on the M–K and T–S tests should be minimal. Given the predominance of 45–60 year climate cycles observed in instrumental records, trend analyses of time series records <60 years should be done with caution. These results provide insight for appropriate temporal trend analyses of hydroclimate and associate time series. [Copyright &y& Elsevier]

Abstract: Geochemical data from 151 spring locations within the 37,000km2 South Nahanni River Basin of the Mackenzie Mountains, Northwest Territories, were analysed as part of a reconnaissance assessment of mineral potential in this large and remote region. Statistical data analyses, graphical methods and strategic grouping of springs according to geochemistry, pH and temperature, were used to identify regions with higher mineralization potential quickly and efficiently. Testing of internal consistency indicates that known world class deposits within the basin are readily detected, but by different methods. As different deposit types have different geochemical signatures a new 3-component approach was developed to analyze trace element data for signatures of mineralisation. Estimation of circulation depth, and therefore maximum potential ore depth, further refines the assessment of economic potential. The depth of circulation of the spring waters ranged from 4.7km to less than 200m for the entire dataset. In total, 62 spring locations were identified as having anomalous trace metal content by one or more method (approximately 40% of the dataset). Specifically, 11 spring locations were classified as anomalous by all three methods, and 17 by at least two methods, and 34 by only one method. [Copyright &y& Elsevier]

The Paskapoo Formation of southern Alberta supports more groundwater wells than any other aquifer system in the Canadian Prairies. Located in a region of rapid population growth and straddling watersheds where no new surface water licenses are available, this aquifer system is under increasing pressure to provide water supply. The Paskapoo Formation represents a foreland deposit of a siltstone- and mudstone-dominated fluvial system. The system is highly heterogeneous with broad ranges in physical properties that impact groundwater production. High-porosity coarse-grained channel sandstone can provide productive wells, whereas thin and fractured sands and siltstones are low producers. The basal Haynes Member and western portion of the Paskpaoo Formation have higher sandstone volumes than other portions of the system. Fracture density shows a strong inverse relationship to bed thickness, such that fracture flow becomes more important for thinner sandstone beds. There is no regional-scale flow system associated with the Paskapoo Formation; rather it is dominated by local-scale recharge processes. The geochemistry of Paskapoo Formation groundwater is largely controlled by the variable composition of immediately overlying glacial deposits. La Formation de Paskapoo du sud de l’Alberta supporte plus de puits d’eau souterraine que tout autre système aquifère des Prairies canadiennes. Situé dans une région à forte croissance démographique et chevauchant des bassins versants pour lesquels aucun nouveau permis d’eau de surface n’est disponible, ce système aquifère est de plus en plus sollicité pour des approvisionnements en eau. La Formation de Paskapoo représente un dépôt d’avant-pays d’un système fluvial composé surtout de siltstones et de mudstones. Le système est hautement hétérogène et ses propriétés physiques couvrent une vaste plage de propriétés physiques qui ont un impact sur la production d’eau souterraine. Le grès de chenal, à porosité élevée et à grain grossier, peut alimenter des puits productifs alors que les siltstones et les sables fracturés minces produisent peu. Le membre Haynes à la base et la partie ouest de la Formation de Paskapoo ont des volumes de grès supérieurs aux autres parties du système. La densité des fractures présente une relation inverse à l’épaisseur des lits, telle que pour les lits de grès minces, l’écoulement dans les fractures devient plus important. Il n’y a aucun système à l’échelle régionale associé à la Formation de Paskapoo, il est plutôt dominé par des processus de recharge à l’échelle régionale. La géochimie de l’eau souterraine de la Formation de Paskapoo est principalement contrôlée par la composition variable des dépôts glaciaires qui reposent sur la formation. [ABSTRACT FROM AUTHOR]

Abstract: A major late Paleozoic depocentre, the Sverdrup Basin, Canadian High Arctic, has been largely left out of the latest Permian extinction debate, as early workers presumed Middle to Late Permian strata were absent. Basin-scale sequence-stratigraphic and chemostratigraphic correlations indicate Late Permian strata are only missing on the basin margins, where they were removed by sub-Triassic erosion, whereas continuous deposition is recorded in the basin centre. The varying degree of sub-Triassic erosion has significant impact on the carbon-isotope record across the Latest Permian Extinction event, where both the apparent rate and magnitude of carbon-isotope shift vary as a function of basin position. The intrabasin variability in apparent δ 13Corg shift across the event is equivalent to that observed globally. In contrast to the abrupt isotope shifts recorded on the basin margin, similar to many records reported globally, the basin centre section shows a systematic shift associated with the Latest Permian Extinction. The Earth likely underwent a prolonged period of increasing environmental stress leading up to the event. [Copyright &y& Elsevier]

Abstract: Siliceous ‘solution chimneys’are described from a region unaffected by volcanism or high temperature fluid flow. The features are interpreted as low temperature dissolution/replacement structures formed in Paleozoic carbonates. The features are thought to be paleo-brine spring discharge sites similar to modern springs found within the same area which host a mid-continent marine ecosystem. Geochemical modeling shows mixing of spring waters with shallow groundwater could generate conditions of undersaturation with respect to calcite and silica oversaturation. [Copyright &y& Elsevier]