The Origin of Shallow Water Carbonates in Lake Hövsgöl, Northern Mongolia, Central Asia: Potential Implications for Paleoclimatology
Shallow lacustrine carbonates were discovered in the southern part of Lake Hövsgöl in northern Mongolia, Central Asia. Lake Hövsgöl is a fresh water lake with water temperatures as low as 4- 6°C in summer. Based on previous core studies, it was suggested that carbonates are only abundant in the pre-LGM sediments, whereas Holocene sediments are enriched in siliceous constituents such as diatoms. The carbonates are present in the form of encrusting microbialites on the pebbles in shallow water (< 1 m water depth). Thus, this study documents the first occurrence of shallow lacustrine carbonates in Lake Hövsgöl that resemble modern stromatolites. It is commonly reported that most marine and nonmarine stromatolites tend to occur more in warm water environments under microbial influence. Here, the microstructure of 4-6 mm thick semi-lithified stromatolite encrustations includes layers of botryoidal fibrous LMC (1-2 mm thick) alternating with microcrystalline calcite layers (60-80 μ m thick), and botryoidal fibrous LMC appears to be inorganic in origin. These two major components constitute the stromatolite laminae and may represent different growth phases during their growth. The presence of inorganic LMC strongly suggests that lake water was highly supersaturated with respect to LMC, probably due to long residence time (up to 600 years) and evaporation, despite the cold water temperature. Oxygen and carbon isotope compositions of ten stromatolite samples range from -8.0 to -7.0‰ (PDB) and 2.9 to 5.1‰ (PDB), respectively, and are probably close to isotopic equilibrium. The origin and growth conditions of these carbonates may help, not only to understand the growth of modern stromatolites in cold lake water but also to understand paleoclimatic history during the Holocene from adjacent carbonate-rich sediments in the future.
New Occurrences of Sub-till Organic Deposits in Southwestern Ontario: Are They Really all That Rare?
Until the early 1900s, sub-till organic deposits in southern Ontario were considered to be rare, usually discovered by 1:50 000 surface mapping. Refined groundwater resources management has motivated provincial and municipal government agencies to undertake large-scale 3-D mapping programs, supported by extensive drilling. An interlobate corridor between Ingersoll and Kitchener-Waterloo has been a focus of recent attention. More than 150 continuously-cored borings, many to bedrock, have been completed within this area. Natural and man-made surface exposures have been reexamined as well. Surprisingly, a large number of these new borings intersected fossiliferous sub-till units. To date, over 30 cored borings have confirmed organic remains at depth and numerous non-cored holes suggest additional occurrences. The fossiliferous units mostly occur either beneath or within Nissouri Phase Catfish Creek Drift and comprise thin (<2-3 m) units of waterlain sediment with detrital plant and animal fossils (insects, molluscs, ostracodes, bones/teeth, seeds, leaves, etc.) and well preserved pollen. Reddish glacigenic deposits, derived from the Erie/Ontario lake basins, likely correlatable to Canning Drift, underlie most of the organic sequences. In a few instances, associated deposits display pedogenic features suggesting a possible weathering interval. AMS radiocarbon dates on wood samples range from 42.7 to 50.5 ka BP (7 dates on 3 sites). Thirteen additional dates from 9 sites are pending. Fossil remains have also been recovered from sandy glaciolacustrine deposits between both Port Stanley and Catfish Creek tills (Erie Phase) and Wentworth and Port Stanley/Catfish Creek tills (Mackinaw Phase). AMS radiocarbon ages of 30.8 and 38.3 ka BP have been obtained on wood from two localities with dates from a couple of other sites pending. These dates are considered significantly older than the sediments containing them. Most fossils are probably not in-situ and are thought to represent material either transported long-distances via wind, water and ice, reworked from other environments or originating from deposits of different ages. The fossils suggest the existence of a mix of treeless, open parkland, and more forested landscapes, along with localized aquatic habitats (stream, riverine and wetlands of several kinds), which further indicates the possibility that the fossils were brought together by chance at the depositional sites. Together, the fossil assemblages imply a typical cool interstadial climate.
The Anatomy of an Archean Fault Zone, Abitibi, Quebec
What is the structural anatomy of an Archean fault zone ? The study area, the Kinojévis area, is located in the
Abitibi greenstone belt, Quebec (Canada), 50 km to the north of the city of Val-d'Or. The Kinojévis fault zone is
similar to other main breaks such as the Cadillac-Larder Lake fault zone, Abitibi, Quebec, the Lefroy fault zone,
Yilgarn craton, Australia, and the San Andrea fault zone, California, USA.
The objective is to determine if a core and a damage zone would be define in such a fault zone, and what are the degree and mechanisms of structural focalization. New data comprising a detailed magnetic field map, recent boreholes from Cartier Resources inc, and mapping from the Ministère des Ressources Naturelles du Québec allow to define the geological environment. Key outcrops in the Mc Cormack gold showing area have permitted to establish succession of deformation phases. First phase of deformation (D1) is characterized by E-W trending schistosity (S1) and shear zones. Second phase of deformation (D2) corresponds to a second schistosity (S2) trending NE-SW, open folds (P2) affecting the first schistosity, and shear zones parallel to S2. Third and last deformation stage (D3) corresponds to late brittle faulting. The most penetrative deformation in the Kinojévis area is D1, it is associated with differential alteration forming listwaenite and iron-carbonate rich facies. Four stages of veining were distinguished and classification has been done using their mineralogical associations and spatial relations; tension veins are restricted to more competent horizons and are characterized by their regular spacing.
The construction of the anatomy of the Kinojévis fault zone includes therefore an intense shearing, followed by differential alteration and formation of listwaenite which creates mechanical anisotropies that separate the fault zone in units with different mechanical and hydraulic characteristics. Shear reactivation and folding of these units modify the permeability and restore hydraulic connection in the fault zone.
Quality Assessment, Reserve Estimation and Economic Analysis of Roofing Slate in the West Central Lesser Himalaya-Nepal
The Tertiary and Quaternary: Their Status, Duration, and Progress as Official Chronostratigraphic Units
The Tertiary and Quaternary are relics of a four-fold chronostratigraphic classification proposed by Arduino in 1759. Whereas Primary and Secondary have long since fallen out of service, the terms Tertiary and Quaternary are useful and have persisted to the present day. The official 'keepers' of geological time have nonetheless attempted to suppress both terms, and the Tertiary remains omitted from the current (2000) time scale of the International Union of Geological Sciences (IUGS). Problems for the Quaternary began with its removal from the 2004 geological time scale published by the International Commission on Stratigraphy (ICS), its place being taken by an extended Neogene. This was the culmination of objections that the Quaternary had never been a properly-defined chronostratigraphic unit, and that Hoernes (1851, 1853) intended his Neogene to extend to the present day. Both of these propositions have since been refuted, and the IUGS reasserted in 2007 that the Quaternary has period/system status, directly overlies the Neogene, and begins together with the Pleistocene at 1.8 Ma. Vigorous debate nonetheless ensued, resulting in a consensus that the Quaternary should begin at 2.6 Ma. To maintain hierarchy within the time scale, the base of the Pleistocene must then be lowered from its current position to that of the Quaternary. Discussions to affirm this lowering are in progress at the ICS as of March 2008. The Tertiary disappeared from the current IUGS time scale in 2000, with the Paleogene and Neogene periods/systems simply replacing it by default. The Tertiary nonetheless continues to appear, usually at period/system rank, in popular and official time scales including that of the US Geological Survey. Once the duration of the Quaternary has been resolved, the ICS will be presented with an official proposal to reinstate the Tertiary as a period/system below the Quaternary.
Turning on, then off, of Local Subsidence and Differential Middle to Late Ordovician Foreland-Basin Fill in the Ottawa Embayment, inboard of the Taconic Orogen
The Ottawa Embayment is a regional structural remnant of Lower Paleozoic strata cutting across underlying Grenville orogenic fabric, and contains the Ottawa-Bonnechere Graben. Middle to Upper Ordovician shallow- water sediments, succeeded by deep- to shallow-water shale fill, define development and fill of the foreland basin west of the Taconic orogen's limit. Previous work dentified accumulation of strata coincident with net onlap driven by regional subsidence, development of the graben usually viewed to be a post-Paleozoic reactivation of late Precambrian structure. Despite the interpreted regionality of deposition, correlation of the foreland stratigraphy beyond the embayment's boundaries was made with difficulty. Integration of core and outcrop data now reveal that this difficulty stems from local differential erosion, subsidence, and carbonate basin fill during specific stages of the Middle to Late Ordovician foreland basin history, despite the area extending (150 km) well inboard of the western limit of the Taconic orogen. These stages include: 1) step-like westward onlap of late Middle Ordovician dolostones (Carillon Formation) marking onset of foreland basin development; 2) deeper water shale and sandstone forming the base of the foreland carbonate platform succession, yet are anomalous compared to equivalent peritidal deposits beyond the embayment's boundaries; 3) differential thickening of peritidal carbonates (Pamelia Formation) toward the centre of the embayment; 4) faulting, differential erosion, and dramatic thickening (14-40 m) of uppermost Black River- lowermost Trenton strata toward the centre of the embayment; and 5) anomalously thick coarse-grained limestones (Hull Formation = Kings Falls Formation) along the northern limit of the embayment. Differential sediment accumulation was turned on, then off, several times, and preferential thickening of units toward the embayment's centre is directed towards, and partly overlies, the Precambrian Morin-Adirondack Highland lithotectonic boundary, which is oriented parallel to synsedimentary faults within the orogen, and was likely subject to preferential weakening by westerly directed Taconic orogenesis. Preferential erosion and local thickening of units marginal to the trace of present-day faults help identify the role of synsedimentary faulting within the embayment. As with intraorogen fault development, the Ottawa Embayment's basin-fill history records basement reactivation driven by Taconic orogenesis.
Shirley's Box - The Highgate Mastodon Story
Shirley Fenton discovered a biscuit box containing teeth and a tusk while clearing out her parents' attic in Highgate Ontario. They were subsequently donated to the Earth Sciences Museum, University of Waterloo in 2005. The fossils pointed in the direction to the Highgate mastodon, found by William Reycraft, a relative of Shirley's. This is the most complete Ontario mastodon ever found, yet it is now on display at the North Dakota Heritage Centre in Bismark. Why did the mastodon end up so far from home? Colin Hunter of The Record newspaper became interested in the story and followed Paul and Peter as they searched for evidence. Were the teeth and tusk part of this original find or another beast? Colin's articles in the newspaper sparked interest and the story travelled across North America. Peter and Paul received many requests to speak on the subject and the lectures lead to finding other mastodon and mammoth sites in Ontario and the donation of a mammoth tibia from Wartburg Ontario. Colin Hunter received the GAC Yves O. Fortier Earth Science Journalism Award in 2007 for his articles on the Highgate Mastodon story. Ripples continue to move out from this story.
New Glacial Lake Episodes During the Deglaciation of the Southern Part of the Canadian Shield : the Taureau Glacial Lake of the Saint-Michel-des Saints Area (Quebec).
Recents mapping of surficial deposits in the Saint-Michel-des-Saints region (Quebec) have permitted to identify glaciolacustrine sediments in several valleys of this sector of the southern part of the Canadian shield, a vast territory where the deglaciation pattern of the Laurentide Ice Sheet is poorly known. The glaciolacustrine deposits found in the Saint-Michel-des-Saints area (laminated deep water sediments, deltaic sands, and sandy beach ridges) are associated with the lowering levels of successive glacial lakes in the Saint-Maurice river watershed. These glacial lakes were trapped between the ice margin, which was retreating northward, and the highlands to the south, which form the limit with three others watersheds (Rouge river, l'Assomption river and Maskinongé river watersheds). According to Dyke et al. (2003), the deglaciation of those highlands started about 10 250 years 14C BP. Three lacustrine phases have been identified in the studied area. The first phase, which was the highest (500 m) but the less extensive, occupied the Saint-Zénon area. This glacial lake was drained southward via the Noire river, from an outlet in the highlands south of Saint- Zénon. The second phase (460 m) has occupied the Sauvage and Pin Rouge rivers valleys, north of Saint- Zénon. The drainage of this glacial lake was eastward, through a pass leading to the Mastigouche river. At the same time, farther west, the Matawin river depression was flooded by another body of water in contact with the Laurentide Ice Sheet, initiating the third glacial lake phase which has been the longest and most extensive in the studied area. We suggest to name that glacial lake episode "glacial lake Taureau". As the ice margin retreated, the glacial lake Taureau gradually expended northward. At its maximum extent, a distance of 20 km was separating the glacial lake's outlet (Anodin river; 400 m) to the south and the ice margin to the north. Deltas and beaches associated with the glacial Lake Taureau (phase 3) have been correlated by their altitude and two isobases are proposed at 410 m and 420 m. The distance between these isobases revealed an isostatic warping of 0.9 m/km toward the NNW (345º). A 1.3 m section of laminated glaciolacustrine sediments in the Kaiagamac lake area, identified as varves by their pollen content (85 couplets), combine with drill holes data in the vicinity, allowed an estimate of 140 years for the duration of glacial lake Taureau. From this estimate, we have evaluated that the ice margin was retreating northward at a rate of around 142 m/year. By 10 100 years 14C BP, the retreat of the Laurentide Ice Sheet north of the Matawin river (outlet at 350 m) and the isostatic rebound have put an end to glacial lake Taureau.
Diagenesis of Middle Ordovician Carbonates From the Lake Simcoe Area, South-Central Ontario
Strata in the Lake Simcoe area consist of Ordovician limestones and dolomites unconformably overlying Precambrian basement. Correlative carbonates elsewhere in Ontario are significant hydrocarbon reservoirs, for example in eastern Essex County and southern Kent County. These reservoirs are typically dolomitized and are associated with fracturing in the Black River and Trenton limestones. Stable carbon and oxygen isotope values were determined from early diagenetic calcite (in and near hardgrounds) and microcrystalline replacive dolomite from core samples and on late-stage calcite, microcrystalline dolomite and saddle dolomite from fractures in outcrop. Early calcite cement has d13C values ranging from -1.7‰ to +2.9‰ (PDB) and d18O values ranging from -10.3‰ to -4.2‰ (PDB). Early replacive dolomite has d13C values ranging from -2.3‰ to +0.3‰ and d18O values ranging from -11.1‰ to -1.6‰. Late-stage calcite cement has d13C values ranging from -8.4‰ to +2.9‰ and d18O values ranging from -11.4‰ to -6.0‰. Late-stage dolomite has d13C values ranging from -3.9‰ to +1.9‰ and d18O values ranging from -13.8‰ to -7.6‰. Cathodoluminescence (CL) of fracture-related calcite displays zoning and dull to moderately bright orange luminescence. Microcrystalline dolomite is generally dull to weak red luminescent with dark to bright red rims whereas saddle dolomite is zoned and has dark red luminescence. Besides the fracture-related calcite and dolomite, other late-stage minerals include pyrite, glauconite, megaquartz and barite. The hardground calcite and the replacive dolomite have more depleted d13C values and more enriched d18O values whereas late-stage fracture-related calcite and dolomite have more enriched d13C and more depleted d18O values. The hardgrounds also have the same isotopic signature as adjacent limestones lacking evidence of early sea floor lithification. The d13C and d18O values for early calcite and dolomite are interpreted to reflect early diagenesis during shallow burial. The similarity of the stable isotopic compositions of hardgrounds and surrounding limestones indicates their lithification involved fluids compositionally similar to coeval seawater. The d13C and d18O values of the late-stage calcite and dolomite are interpreted to reflect precipitation during deeper burial. Previous studies on correlative carbonates in the Manitoulin Island area describe similar trends in d13C and d18O values, and came to similar conclusions. Future work will include fluid inclusion analysis to provide insight into fluid salinities and precipitation temperatures of fracture-related carbonates. Of particular interest are anomalously high temperatures which have been reported in correlative carbonates associated with hydrocarbon reservoirs elsewhere in southwestern Ontario. These reported temperatures are widespread yet poorly understood as they are higher than can be explained simply by deep burial. Therefore a clearer understanding of the diagenetic evolution of these carbonates in the Lake Simcoe area could shed additional light on their reservoir equivalents in southwestern Ontario.
Provenance and Tectonic Setting of the Neoproterozoic Um Hassa Greywacke Member at the Central Eastern Desert, Egypt
The Um Hassa Greywacke Member occurs as the top member of the Neoproterozoic Hammamat Group in the Eastern Desert of Egypt. Petrographic point counting modal analysis reveals that the Um Hassa greywackes consist mainly of 34% quartz, 19% rock fragments, 11% feldspar, 12% miscellaneous minerals (epidote, chlorite, opaque minerals, mica, and calcite), and 20% matrix. The matrix is composed mostly of silt- and clay- sized quartz, feldspar, clay minerals and chlorite. Quartz is mainly monocrystalline and shows strong undulosity. Rock fragments are composed mainly of intermediate to felsic volcanic rocks. Plagioclase is much more abundant than K-feldspar (P/F > 0.9). The Um Hassa greywackes are both chemically and texturally immature. They are characterized by low chemical index of alteration (48-65) and SiO2/Al2O3 (4.6-6.1), indicating limited chemical weathering of the source rocks and deposition close to the source area. Diagenetic changes are characterized by mechanical compaction and minor K-metasomatism on the A-CN-K ternary diagram. Major element data suggest that Um Hassa greywackes have a composition ranging between the Andean-type margin (Dokhan Volcanics Unit and Older Granitoids of Egypt) and arc-ophiolitic assemblage rocks. On the chrondrite-normalized diagram, the greywackes display LREE-enriched patterns (La/Ybcn= 4.5-8.1), but they are not as enriched as the Upper Continental Crust (UCC). Niobium contents are lower than that of the UCC. These features can be attributed to the sediment contributions from oceanic arc and crust. The greywackes are enriched in transition metals, particularly in Cr (234-434 ppm) and Ni (49-84 ppm), consistent with an ophiolitic source rock (e.g., Fawakhir ophiolite). On the Qt-F-L ternary diagram, the modal analyses data plot in the recycled orogen field with an extension to the arc terrane provenance filed. On the Lv-Qp-Ls ternary diagram, the greywackes spread between arc orogen field and subduction complex field. Collectively, these petrographic characteristic suggest that the Um Hassa Greywacke Member may be formed in a foreland basin to the east of accreted Fawakhir ophiolite upon which the continental volcanic arc edifice was built during the period of 650-580 Ma ago.
Middle Devonian Sea Level Rise: A Case Study of the MacKenzie Basin, Northwest Territories, Canada
The MacKenzie Basin, located in the southern part of the Northwest Territories, was bordered by the Canadian Shield on the east, the Tathlina high to the south, and the open ocean to the north. Paleozoic strata representing sediments that accumulated in the MacKenzie Basin out crop on the west side of Great Slave Lake. These strata are divided into the Cambrian La Matre Falls Formation, which rests on the Precambrian shield, the Ordovician Chedabucto Lake Formation, and a thick succession of Devonian strata that include the Chinchaga Formation, Lonely Bay Formation, Horn Plateau Formation, and the Horn River Formation. The rocks from the MacKenzie Basin provide an ideal opportunity to resolve past discrepancies in published sea level curves due to its direct connectivity to the open ocean throughout its existence. Devonian strata exposed on the west side of Great Slave Lake record a transgressive succession that began in the Eiflian (australis conodont Zone) and continued into the middle to late Givetian (disparilis conodont Zone). Deposition was on the shallow portion of a ramp that gently dipped to the west, southwest. Rapid deepening periodically interrupted the gradual increase in water depth associated with this transgression. The facies successions evident in the Middle Devonian strata of this region reflect these changes in water depth. The Chinchaga Formation is formed of evaporites, collapse breccias, hard resistant dolomite, and limestone breccias. The collapse breccias were a consequence of evaporite dissolution. Limestones in the overlying Lonely Bay Formation are composed largely of micrite with scattered corals and brachiopods. Fossil lags indicate that the water depth was above storm wave base. A significant sea level rise in the early Givetian triggered reef growth. These reefs, belonging to the Horn Plateau Formation, range in thickness from 60-120 m. The Horn Plateau Formation, which outcrops only in the Fawn Lake area and is also found in numerous wells to the southwest, is formed of isolated coral and/or stromatoporoid reefs. The Horn Plateau reefs are aligned along a NE-SW trend on the MacKenzie Basin carbonate ramp. These reefs are encased by calcareous shales of the Horn River Formation that formed in response to ever deepening seas at the end of the Middle Devonian.
Sediment hosted Cu mineralization of the Mesoproterozoic Belt-Purcell Basin, Southeast British Columbia
Proterozoic sedimentary basins contain significant copper resources. Sediment-hosted stratabound Cu deposits are the second most important global sources of Cu, only surpassed by porphyry Cu deposits. Major stratabound Cu deposits lie within the Kupferschiefer belt of Europe and the Zambian Copperbelt of Africa. The Mesoproterozoic Belt-Purcell Basin has sediment thickness of at least 19 km within the central part of the basin in BC and up to 18 km in the U.S. This large thickness of sediment was deposited in a relatively rapid period leading to the formation of numerous sediment-hosted stratabound Cu-Ag occurrences and deposits in the quartzite dominated Revett Formation. These deposits, including the Troy, Rock Creek and Montanore, are all located in western Montana. The sandstone-dominated middle Creston Formation, exposed in SE BC., appears to correlate lithostratigraphically with the Revett Formation in Montana. Tracing of prospective middle Creston strata helped to identify several new Cu-Ag occurrences. A pilot biogeochemical survey indicates that Lodgepole Pine bark may be an effective means of exploration in areas of the Purcell Basin that have little or no bedrock exposure. Above the Creston Formation, shallow water, fine grained clastics dominate the Purcell Basin and there is no evidence of stratabound-Cu mineralization. A series of copper occurrences are located, however, at the unconformity between alkali flood basalts of the Nicol Creek Formation and overlying coarse clastic carbonate rocks and stromatolites of the Sheppard Formation. These Cu occurrences, near Roosville B.C., also contain elevated levels of Co, Ni, As, and Au. This polymetalic mineralization is found in combination with a significant alteration halo and localized quartz and barite veining. These factors favor a model for mineralization that involves Nicol Creek volcanic and hydrothermal activity. Detrital zircon was separated from an interflow sediment collected from the Nicol Creek Formation. The youngest grain from this sample had a 207Pb/206Pb age of 1439 Ma, consistent with a 1443 ±7 Ma age for the Purcell Lavas in Montana.
Geospatial Presence and Abundance of Benthic Invertebrates and Physical Characteristics of the Lake Floor Substrates Along a Submerged Section of the Niagara Escarpment, Lake Huron, Canada.
One fifth of the world's surface freshwater supply is held in the Great Lakes. Thirty seven million people live in the surrounding area; 10% of Americans and 31% of Canadians. Twenty six million of them draw their drinking water directly from the lakes and the other 11 million rely on Great Lakes groundwater. In the late 19th century fish harvests were 67 million kilograms (147 million pounds), initially harvests declined due to overfishing but present day harvests (29 million kilograms (63 million pounds)) are challenged by habitat destruction and invasive species (more than 160 since the late 1800s). In fact, 75% of the regions shorelines and 2/3 of its wetlands have been altered or destroyed yet are vital fish spawning grounds. A prominent data gap is that of relating the biotic components of the ecosystem to the abiotic factors such as substrate type, temperature, dissolved oxygen content, light penetration, water depth, fetch, and bottom heterogeneity. The work reported here involves reconnaissance geophysical investigations aimed at rapid assessment of lake floor habitat along a submerged portion of the Niagara Escarpment in Lake Huron adjacent to Fathom Five National Marine Park where water depths approach 100m. A GIS based geospatial and statistical analysis will determine which abiotic factors have the most effect on benthic invertebrate and macrophyte distribution and abundance. The backbone of the analysis is two multibeam sonar data sets. The first is a detailed bathymetry layer; the other consists of acoustic backscatter returned from the lake floor reflecting grain size, substrate type, macrophyte and invertebrate presence and abundance and bottom hardness. Physical samples include approximately 100 sets of GPS tagged sediment and bottom water samples and underwater video.
An Integrated Approach to Paleo Ice Stream Determination
Ice stream research has gained momentum in the last decade due to the increased need to understand ice sheet dynamics and instability, and by extension the role it has in climate change and glacial landscape evolution. Although there has been a lot of work done recently with respect to ice sheet dynamics, much remains to be done for understanding the role of terrestrial paleo ice streams. We have recently proposed a model that shows at least two large systems of ice streams and tributaries with contrasting characteristics in southern Saskatchewan (Canada). The focus of this current research is to further test the sediment-landform assemblages that are central to the proposed model. This is done through spatial analysis of sediment and landform characteristics (e.g. compositional data, till fabric, types of landforms). Provenance is determined by using radiometric data, Ar/Ar dating of hornblende grains and geochemical (carbonate) dispersals. Preliminary results show spatially consistent patterns that fit within the structure of the proposed ice stream model. More data is currently being added to the analysis including additional Ar ages, till fabric data, and striations on lodged boulders. All of the data is geo-referenced in GIS to examine the potential sediment-landform relationships. Further characterization of the paleo-ice stream systems in the Prairies is critical to improve our understanding of how large past ice sheets, like the Laurentide Ice Sheet, evolved and eventually collapsed. This work also has implications to mineral exploration over glaciated terrains.
Hydrothermal Alteration-Mineralization At Chahfiroozeh Porphyry Copper Deposit, Kerman Province, Southern Iran
The Chahfiroozeh copper prospect is located 32 km north of Shahr-Babak in Kerman province, southern Iran. The prospect lies in the Kerman porphyry belt in southern section of the Urumieh-Dokhtar magmatic arc (UDMA). The UDMA developed in Cenozoic in response to subduction and collision processes associated with the closure of Neotethys in western Asia. The copper mineralization is associated with a porphyritic quartz-diorite to quartz-monzodiorite pluton of Miocene age intruded into Eocene andesitic volcanic and pyroclastic rocks. The porphyritic pluton occurs as an elongated body with steep walls, 1500 m long and 400 m wide in plan view. The pluton was intruded by a post- ore, dioritic intrusion and associated dykes. Potassic, phyllic and propylitic alteration assemblages are well developed. The potassic alteration is characterized by abundant biotite, magnetite, but minor K-feldspar. Phyllic alteration is widespread and occurs as irregular patches within, as well as a distinct shell, around the potassic zone. The alteration is distinguished by abundant sericite, pyrite, quartz, and chlorite. The propylitic alteration, developed mostly in the older volcanic rocks, is distinguished by the occurrence of carbonates, epidote and chlorite. The post-ore diorite is weakly to moderately chloritized and carbonatized. Post-mineral erosion has stripped much of the overlying rocks; the porphyritic body is well exposed, and potassic alteration can be distinguished at surface exposures. The copper mineralization occurs as stockworks as well as disseminated in the porphyritic body, and in the immediate host rocks. The hypogene ore is distinguished by chalcopyrite and minor bornite; molybdenite is rare. The hypogene ore has been traced by diamond drill holes for over 500 meters from surface. The Chahfiroozeh deposit bears features typical of porphyry copper deposits. Representative samples from the intrusive body and the post-ore diorite were analyzed for a wide range of elements by fused-disc ICP-MS in ACME Labs, Vancouver, Canada. Primitive mantle-normalized plots indicate distinct enrichments in LREE relative to HREE, and slightly positive Eu anomalies; The La/YbN varies between 12-27. The rocks further display features typical of adakitic rocks (e.g. high Al, Sr, low Mg, Y, Yb). An adakitic affinity has been reported from many Neogene porphyritic intrusions associated with copper deposits and occurrences in the Urumieh-Dokhtar magmatic arc. It appears that a genetic link exist between adakitic magmas and porphyry copper deposits.
Lidar Data Applied to Quaternary Geology Regional Mapping in the Reservoir Gouin Area (Québec): An Important Tool for the Identification of Glacial and Postglacial Landforms.
In the reservoir Gouin area, like other regions of the Grenville province, the lack of interest from mining industry and a poor road access led to a fragmentary knowledge of the quaternary paleogeography. Moreover, the dense forest cover complicates the accurate geomorphological interpretation with conventional aerial photography. When available, the use of digital elevation model (DEM) built by airborne lidar (light detection and ranging) data give a precise examination of the territory under those conditions. In the studied area, located 200 km northwest of La Tuque, we have been able to use a 1400 km² of continued lidar coverage, which seems to be an uncommon case and allows the mapping of the quaternary deposits at a regional scale (1:50 000). Therefore, the interpretation by a high-resolution lidar DEM (1m/pixel) gives the opportunity to identify (directly from the computer screen) with great level of details, the landforms associated with the Laurentide Ice Sheet and his retreat. The use of the lidar reveal a performing tool to interpret ice flows by the identification of meter scale flow indicators, like fluting, and larger scale as drumlins and crag-and-tails. In the studied region, these landforms indicate a gradual shift in the ice flow direction, from the N-S in the eastern area to NNE-SSW in the western area. The quality of the DEM has also showed a high efficiency to identify small ice-contact features as metric moraines (more than a thousand as been identified), eskers and several meter wide meltwater channels, from which it is possible to reconstruct the deglaciation pattern. Finally, the sharpness of this tool provided as well the possibility to locate and calculate with precision (less than 25 cm) the altitude of beach ridges, terraces, deltas and wave-washed limit in till, that allows to evaluate the extent and evolution of an identified glacial lake in the area. Furthermore, we were able to calculate and simulate the isostatic warping of this glacial lake to approximately 1m/km toward the NNW.
Geological Investigations in the Southern Indian Lake Area, Northern Manitoba
Preliminary geochemical results from the Southern Indian Lake area in northern Manitoba confirm the presence of two chemically distinct packages of volcanic rocks in the Pukatawakan Bay greenstone belt, which provide evidence for gold and base metal potential. The work being conducted by the Manitoba Geological Survey in collaboration with the Geological Survey of Canada is designed to re-examine the geology of Southern Indian Lake in detail, with particular emphasis on documenting the nature, age, affinity and mineral potential of the Pukatawakan Bay (2008) and Partridge Breast Lake (2009) belts. The Pukatawakan Bay belt is composed largely of massive to pillowed, variably altered and recrystallized tholeiitic basaltic flows with minor amounts of interlayered sedimentary rocks ("Pukatawakan Bay" assemblage) adjacent to a mixed suite of orthogneiss and paragneiss. The trace and rare earth element geochemistry of the flows indicate an affinity to modern NMORB and is nearly identical to basalt dykes that crosscut a preexisting fabric in adjacent gneisses, suggesting an unconformable relationship between the two sequences. The presence of ∼ 2.5 Ga inherited and detrital zircon elsewhere around Southern Indian Lake indicates that these gneisses may represent Archean basement onto which the volcanics were extruded. Where exposed, the contact is strongly tectonized. Tholeiitic to calc-alkaline volcanic and volcaniclastic rocks with interbedded garnet-cordierite bearing turbiditic rocks ("Whyme Bay" assemblage) occur in the southeastern part of the belt and are exposed as km-scale screens within a relatively young monzogranitic batholith. The trace and rare earth element contents of the volcanic rocks indicate an affinity to modern arc magmas. The "Whyme Bay" assemblage is unconformably overlain by fluvial-alluvial sedimentary rocks, dominated by polymictic conglomerate and well- bedded to massive arenite. Given that the tectonostratigraphic position of volcanic rocks at Southern Indian Lake (within the regional framework of the Trans Hudson Orogen) is similar to those in the Lynn Lake and Rusty Lake belts, it is possible that they represent eastward extensions, albeit tectonically and magmatically dismembered, of related or equivalent supracrustal sequences and may therefore share similar endowments in VMS, orogenic lode gold and/or magmatic sulphide mineralization. The tectonized contact between tholeiitic basalt and the adjacent gneiss is strongly altered (silica, chlorite, and carbonate alteration) and locally contains disseminated to stringer sulphide. This contact is considered a favourable environment for orogenic gold occurrences. Assay values up to 2.2% Cu from narrow, malachite-rich fracture veins in the arc-like basalt indicate the possible presence of a base metal mineralizing system. Emerging geochemical, isotopic, and geochronological data will provide the basis for more accurate comparisons between supracrustal rocks in the Southern Indian Lake area with similar sequences along strike to the west. These data will also be integrated with and used to update existing models for the evolution of the Trans Hudson Orogen in Manitoba.
Ni-Fe-Co Alloys and Sulphides in Serpentinized Harzburgites of the Asbestos and Thetford Mines Ophiolites.
Harzburgite tectonites from the Asbestos (100 % serpentinized) and Thetford Mines (partially serpentinized) ophiolites were subjected to a complex serpentinization history leading to the formation of mineral assemblages comprising Ni- and Co-rich alloys and sulphides. Ni-Fe(-Co) alloys are widespread and their grain size increases with the degree of recrystallization and veining of the serpentinites from < 5 microns in pseudomorphically replaced olivine to > 150 microns in the more strongly reworked serpentinites where it is often associated with abundant brucite (locally > 50%). The sulphides, which generally occur as larger grains, comprise heazlewoodite and, more rarely, cobaltian or cobalt-rich pentlandite. They replace Ni-Fe(-Co) alloys in the serpentinites which show advanced recrystallization and veining. At the sheared or calc-silicate- altered contacts with felsic intrusive bodies, Ni-Fe(-Co) alloys and heazlewoodite coexist with Ni-rich arsenide instead of cobalt-rich pentlandite. All the pentlandite grains analyzed (18) contain > 33.8 wt. % Co (up to 58 wt. % Co). In serpentinized harzburgites from other localities in the world where they form an assemblage with Ni-Fe alloys and heazlewoodite, pentlandites rarely contain > 10 wt. % Co. One possible explanation for the widespread occurrence of cobalt-rich pentlandite in this study is that serpentinization took place by reaction of high salinity aqueous fluids with cobalt-bearing Ni-Fe alloys containing on average 2.35 ± 0.6 (1 std; n=501) wt. % Co. Cobalt minerals are generally more soluble than nickel minerals in aqueous solutions. Cobalt presumably tends to associate more readily with chloride and form complexes with higher numbers of chloride ligands. Increased aCl- would favour an increase in the aCo2+/aNi2+ ratio of the fluid phase and contribute further to solution of Co into the pentlandite. Fluid inclusions containing halite in granite and those in rodingites (with up to 25 wt.% NaCl equivalent) from Asbestos indicate that such high salinity fluids could have formed these Co-rich sulphides during replacement of Ni-Fe(-Co) alloys. The composition of the cobalt-rich pentlandite is compatible with formation at temperatures that correspond to the trapping temperatures of fluid inclusions in rodingites from Asbestos. Fluid inclusion data also suggest that the mineral assemblages discussed here have formed under conditions (reducing) that were amenable to saturation of a carbonic fluid with methane and other volatile components. Reaction of the separated carbon-rich volatile phase with metallic minerals would facilitate catalytic conversion to hydrocarbons at elevated hydrogen fugacity conditions. Under these reducing conditions, the solubility of cobalt- and nickel-rich metallic minerals in aqueous solutions is very low. Reaction at more elevated oxygen fugacity, however, would be an efficient mechanism to selectively extract Co from the more Ni-rich protolith. This study shows that Ni-Fe alloys persist in these completely serpentinized harzburgites. Furthermore it demonstrates that cobalt-rich pentlandite in serpentinized harzburgites is an indication of a chloride-rich fluids environment. Environments favourable for metal transport and deposition by chloride-rich fluids in ophiolites may be indicated by the presence of cobalt pentlandite in serpentinized harzburgites.
Midwisconsinan sedimentology, 3d stratigraphic mapping and paleogeography in the Appalachians of southeastern Quebec
Complex sequences of ice marginal and frontal deposits have been mapped and documented in the Saint- François and Chaudiere river valleys, north of the international border. In most cases, these sediments and landforms as well as other geomorphological features, are valuable indicators of the extent of former ice- dammed lakes, as their elevation is strongly constrained by well-documented outlets. However the complex stratigraphic architecture of the subsurface is poorly documented. The Quaternary geology of Eastern Quebec is unique in several aspects, the Pleistocene stratigraphy is characterized by a three till sequence, each till being underlain and overlain by glaciolacustrine sediments deposited in ice-dammed lakes during the advance or retreat phases of each glaciation. The Gayhurst Formation includes all glacial lake sediments deposited in the Chaudiere and St-Francois valley during the time interval between the Chaudiere and Lennoxville glacial phases (MIS 3 ?). A methodology for three-dimensional numeric geomodelization of surficial deposits is proposed in this study. This kind of model is based on the integration of surficial sediments map and boreholes logs with the use of GIS and 3D geomodeling system. The objectives of this geomodeling study 1) are to define the physical lateral extension of the Gayhurst Formation; 2) to devise paleogeographic reconstructions testing possible glacial water routing in New-Brunswick, Maine and Vermont and 3) to determine the age of this glacial lacustrine sequence using IRSL. New field and stratigraphic data are being acquired in the Chaudiere and Saint-François, in the course of a groundwater/Quaternary geology mapping project that was initiated in 2007, some of which will be presented at the meeting.
GA71A-20 [Moved to CG11A]
Canadian Arctic And Prairie Ground Heat Flux During The Recent Warm Period As Derived From Single And Repeated Well Temperature Logs
Temperature-depth profiles in the Canadian Prairie and Canadian Arctic regions infer very strong 1-4ºC warming during the Recent Warm Period (RWP), spanning the past 100-200 years. Temperature-logs in boreholes made initially two decades ago, and repeated a single decade ago, were recently repeated in 2006 and 2007. Repeated logs in the Canadian North do not follow air surface temperature forcing for the time interval between logs. However, there is agreement for those in the Canadian Prairies. Temperature changes at 20m level were 0.2ºC, and 0.4ºC, for time spans of one and two decades, respectively. This has caused the Earth to store large amount of heat. The average heat flux into the ground corresponding to the transient component of the subsurface temperature is calculated. In the Canadian Arctic, average heat flux over the RWP is 43-64 mW/m2 for the last 120-80 years respectively, while in the Canadian Prairies it is 30-40mW/m2 for the past 120-80 years respectively. Uncertainty in heat flux estimates from single logs arrives from the uncertainty in determining the timing of the onset of the RWP. This is bypassed by determining the heat flux for the time interval between repeated logs in the Prairies. We determine heat flow where observed temperature change can be replicated by the synthetic transient based on surface air temperature (SAT) forcing. It is some 30-50 mW/m2 (20-40 mW/m2 for one decade and 40-50 mW/m2 for two decades). Heat flux superposes with the steady state terrestrial heat flux of the opposite direction, which comes from the Earth's interior. It is 30-90 mW/m2 in Canada ( Arctic Canada, 55 mW/m2, SD=13 mW/m2; Prairies, 60 mW/m2 , SD=11 mW/m2 ). Composite TOA solar irradiance recorded by satellite since 1978 was scaled to provide a forcing signal to model subsurface temperatures as we did with the SAT data. The results indicate that the modeled energy flux at the surface due to solar irradiance is much less than half of the observed energy flux.
GA71A-21 [Moved to CG11A]
Shallow Geothermal Energy Content Across Canada - Heat Gain And Heat Sink
Maps of shallow depth (from the ground surface down to 250m) temperature distribution across Canada based on well temperature logs show large variability, related mainly to surface climatic forcing. The cross- correlation of Canadian SAT normals and subsurface temperatures from logs shows close link (Corr. Coeff.0.9). These maps and analysis of temperature vs. depth shows that heat gain by the subsurface related to recent global warming is a cause of very small changes of temperature with depth in the upper 250 m and a large amount of heat gain towards the surface (upper 50 to 100 m). The heat flux of 30-70 mW/m2 into the upper 250m due to circa 100 year surface temperature change due to climatic warming is derived from temperature-depth profiles. This is comparable with mean deep heat flow value from 3085 heat flow determinations for Canada (64 mW/m2 +/- 16 mW/m2). Temperature data compiled from precise temperature logs in equilibrium wells, and temperature time series from a network of meteorological stations, allows calculation of the available heat energy for heating in the cold period and for cooling in peak warm months. Utilisation of this energy resource has potential for significant CO2 reduction in Canada. The amount of potential heat available is vast. In the area of Canada south of permafrost border integrated value of potentially available heat during heating season is 1.1.E21 Joules (1100 quads) down to -50m.
Late Ordovician Marginal Marine Environments and Biotas at the William Lake Site, Central Manitoba, Canada
The Williams Member of the Stony Mountain Formation near William Lake, central Manitoba, contains a remarkable biotic assemblage of Late Ordovician (Richmondian) age. Fossils are preserved in thin-bedded dolomudstones representing deposition in shallow-water marginal marine conditions, probably in lagoon to tidal flat environments. The assemblage constitutes both mineralized and unmineralized tissues of a variety of organisms, very different from those seen elsewhere in the Ordovician of the Williston Basin. Marginal marine biotas of this age are poorly known, and most typically comprise non-biomineralizing taxa. Given the global paucity of Ordovician Konservat Lagerstätten, the William Lake assemblage is significant for both its age and paleoenvironmental setting. Intensive collecting over the past several years has allowed us to thoroughly sample the lower 1.4 metres of a potentially 3 metre-thick fossiliferous interval. Fossils tend to be rare at most horizons, but are locally more concentrated. Individual bed surfaces appear broadly rippled or hummocky, and in section may show trough cross-lamination or channel-like features. Distinct horizons contain common shelly fragments, simple horizontal burrows, and minor iron oxide staining; partings between beds often occur in conjunction with these. Between such horizons, beds show less distinct internal structure; lenses or layers of monotonous mud occur at some levels. Higher in the sampled interval, increasing abundance of salt crystal moulds and probable microbial mats suggests more restricted conditions. A few fossils are found throughout the sampled interval, including linguloid brachiopods, eurypterids, gastropods, and the recently described early xiphosurid Lunataspis aurora. Other groups are narrowly concentrated in particular horizons. Cnidarian medusae, probably including hydrozoans and scyphozoans, are common in some beds in the lower to middle part of the interval, but are absent from upper beds. Large tubes of undetermined affinity occur only in the lower part of the interval. Probable algal fronds are common only in a single upper bed, and this thinly laminated unit is also unusual for the occurrence of ostracodes and tiny juvenile specimens of Lunataspis. Very rare taxa are represented by one to a handful of individuals. A single pycnogonid specimen is the geologically earliest known adult sea spider and the first report of the group from the fossil record of North America. Probable polychaete worms similar to Palaeoscolex are present in a cluster on a single slab surface. Other uncommon elements represent normal marine shelly forms such as nautiloid cephalopods and rhynchonelliform brachiopods; these are probably examples of postmortem transportation by waves and currents. Cnidarian medusae and articulated arthropods tend to occur in largely homogeneous mud layers or lenses. The character of both fossils and lithology suggests that such mud bodies were deposited relatively rapidly. Medusae are preserved as sparry dolomite that is slightly enriched in iron and silica, and blebs of degraded pyrite occur around some medusan structures. Linguloids, gastropods, and disarticulated arthropods are most common in horizons that also exhibit horizontal burrows and minor degraded pyrite. These layers may have accumulated during times of reduced sedimentation.
MOVE: a new Earth Sciences Museum at Vesuvius Observatory(Naples, Italy)
The Vesuvius Observatory is the oldest volcanological observatory in the world. It was founded in 1841 by the King of the Two Sicilies, Ferdinand II of Bourbons, in order to study the volcanic activity of Vesuvius, for the early warning of the population. The historical site of the observatory is an elegant neo-classical building, strategically located on a hill, at an elevation of 608 m a.s.l. It hosts a permanent exhibition in which the visitors are introduced to volcanism and related hazards, the monitoring systems of active volcanoes, and the history of Mt. Vesuvius and its Observatory. The exhibition is visited by a public of about 10.000 people per year, mainly composed of students from both Italy and other countries. The MOVE project (Museo dell'Osservatorio VEsuviano) has been thought up with the aim of greatly improve the potential to communicate Earth Science, by implementing and expanding the old exhibition with new spaces, new exhibits and new multimedia and interactive technologies. The third millennium is the age of images: a true bombing of images, coupled with winning sounds, in fact is at the base of the modern advertising strategies, which are aimed at reaching as much people as possible. The same concept lies at the origin of MOVE, whose primary objective is to widely disseminate the knowledge on volcanic and seismic phenomena, their related hazards, and the geological background that links these phenomena to the evolution of the Earth. An exhaustive, rigorous and up to date information has the chance of reaching a wide range of people if it is transmitted in a snappy and fascinating way. In doing so, the most recent computer technologies can greatly improve the quality, flexibility and effectiveness of the Museum communication power, through the realization of an extraordinary exhibition idea that allows technologic, scenographic, and innovation primacy. The MOVE project provides the integration between conventional and innovative exhibitions, by implementing the wonderful collections of rocks and minerals, old books, historical instruments and paintings, with computer graphics reconstructions, HD and 3D documentaries on Earth Sciences topics, scenographic decors reproducing in virtual and increased reality volcanic eruptions, earthquakes, and their effects on the environment, interactive dioramas showing the evolution of the Neapolitan volcanoes, multimedia systems of communication to guide the visitors throughout the exhibition, digitalizing of old books and documents for the creation of a virtual library, aimed at sharing the huge cultural heritage of the Vesuvius Observatory. Mt. Vesuvius is by far the most famous volcano in the world, and its impact on the surrounding areas and human civilization has been very strong throughout the centuries. It is visited by thousands of people every year and is still active and looming over a wide and densely inhabited area. As the MOVE project configure itself as a very innovative and powerful teaching tool, it has to be regarded as an irreplaceable instrument of civil protection. Infact the MOVE project acts to improve the knowledge about the workings of Neapolitan volcanoes, their state of activity and the monitoring system of the Vesuvius Observatory - INGV, contributing to the mitigation of volcanic risk by increasing the population awarness about the threat posed by these volcanoes. Training the new generations to a culture of the risk, ultimately, generates the conditions for a correct land-planning and management, and a sustainable development of the territory. MOVE has been submitted for financial support to the local Government of the Campania Region.