Pub Date : 2023-12-18DOI: 10.12789/geocanj.2023.50.202
John Greenough, Mikkel Tetland
For 100 years, placer gold has been important to the settlement, economic development, and, recently, recreational geology of the Kelowna, British Columbia, area. It is best-known to occur in modern-day, Mission Creek and Lambly Creek sedimentary rocks, as well as a paleoplacer occurrence in Miocene sediments of the historical Winfield mine. The Mission Creek and Winfield localities are east of the west-dipping, low-angle, normal Okanagan Fault, which has been active since the Eocene. Lambly Creek is west of the fault. Late Paleozoic to Eocene igneous and metasedimentary rocks occur in the Lambly Creek catchment but Eocene gneiss units, unroofed by the fault, occur on the Okanagan Valley’s east side. This study tests the hypothesis that native placer gold compositions vary across the Okanagan Fault reflecting different sources and histories for the gold. A modest number of Au and Ag analyses (23 analyses) in usefully representative placer gold samples were determined on a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS). Spots analyzed for Au and Ag were also analyzed for 19 trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Mercury was semi-quantitatively determined in ‘unknown’ gold grains by first estimating its concentration (~3.69 ppm) in the AuRM2 external standard. Proportions of Au:Ag:Cu in grain cores indicate all the gold came from mesothermal/hypogene or possibly Au porphyry bedrock deposits though primary signatures may have been obscured by metamorphism or weathering. Winfield and Mission Creek grains tend to have higher siderophile Fe, Ni, Pd and Pt and chalcophile elements As, Se, Te, Hg, Pb and Bi but lower Cu and Sb concentrations than Lambly Creek gold. Mercury is distinctly higher in Winfield and Mission Creek gold than in Lambly Creek gold from the west side of the valley; the element appears particularly useful for ‘fingerprinting’ gold. Lambly Creek gold compositions indicate derivation from two orogenic/hypogene sources from greenstone and plutonic/hydrothermal rocks present in the catchment area. Modern day Mission Creek and Miocene paleoplacer Winfield grains have a similar hypogene trace element signature but there are no known local bedrock gold sources. The Mission Creek and Winfield gold grain cores are surrounded by < 10 µm, Au-rich, Ag- and trace element-poor, rims. Lambly Creek grains lack such rims. The Au-rich rims on modern day Mission Creek and Miocene Winfield gold may reflect prolonged near-surface exposure with surficial electrochemical dissolution of hypogene trace elements or the biological precipitation of gold. Low Ag and red colouration on the surface of grains support the biological precipitation hypothesis. The shared trace element signature, together with the Au-rich rims indicate that modern day placer gold in Mission Creek was multiply reworked from Miocene paleoplacers similar to the Winfield occurrence as a result of uplift a
100 年来，块金对不列颠哥伦比亚省基洛纳地区的定居、经济发展以及最近的娱乐地质学都非常重要。最著名的是在现代的 Mission Creek 和 Lambly Creek 沉积岩中，以及历史上温菲尔德矿区的中新世沉积物中发现的古块状金矿。Mission Creek 和 Winfield 矿区位于西倾、低角度、正常的 Okanagan 断层以东，该断层自始新世以来一直处于活跃状态。兰布利溪位于该断层以西。晚古生代至始新世火成岩和变质岩出现在兰姆利溪流域，但始新世片麻岩单元则出现在奥肯那根谷东侧，未被断层覆盖。这项研究检验了一个假设，即奥肯那根断层上的原生块金成分各不相同，反映了金的不同来源和历史。在一台带有能量色散光谱仪（SEM-EDS）的扫描电子显微镜上，对具有实用代表性的块状金样本进行了少量的金和银分析（23 项分析）。此外，还利用激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）对金和银分析点进行了 19 种痕量元素的分析。通过首先估算 AuRM2 外部标准中的汞浓度（约 3.69 ppm），对 "未知 "金粒中的汞进行了半定量测定。晶核中金：银：铜的比例表明，所有的金都来自中温/恒温或可能是金斑岩的基岩矿床，但原生特征可能已被变质或风化所掩盖。与兰姆利溪金矿相比，温菲尔德和使命溪金矿的金粒往往含有较高的亲硒元素铁、镍、钯和铂，以及亲铬元素砷、硒、碲、汞、铅和铋，但铜和锑的含量较低。温菲尔德溪和使命溪金矿中的汞含量明显高于山谷西侧的兰布利溪金矿；汞元素似乎对金矿的 "指纹识别 "特别有用。兰布利溪金的成分表明，它来自集水区的绿岩和深成岩/热液岩中的两个造山运动/热成岩源。现代的 Mission Creek 和中新世古矿床 Winfield 金矿具有类似的次新世微量元素特征，但当地没有已知的基岩金矿来源。Mission Creek 和 Winfield 金晶粒核心周围有小于 10 µm 的富金、贫析出银和微量元素的边缘。Lambly Creek 金粒则没有这种边缘。现代 Mission Creek 和中新世 Winfield 金矿上的富 Au 边缘可能反映了长时间的近地表暴露，以及下统微量元素的表层电化学溶解或金的生物沉淀。金粒表面的低银和红色支持生物沉淀假说。共同的微量元素特征以及富含金的边缘表明，由于奥肯那根断层东侧岩石的隆起和侵蚀，任务溪的现代块状金矿是由与温菲尔德矿点类似的中新世古块状金矿多次再加工而成的。
{"title":"Trace Element Composition of Placer Gold Across the Okanagan Fault, Kelowna, British Columbia, Canada","authors":"John Greenough, Mikkel Tetland","doi":"10.12789/geocanj.2023.50.202","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.202","url":null,"abstract":"For 100 years, placer gold has been important to the settlement, economic development, and, recently, recreational geology of the Kelowna, British Columbia, area. It is best-known to occur in modern-day, Mission Creek and Lambly Creek sedimentary rocks, as well as a paleoplacer occurrence in Miocene sediments of the historical Winfield mine. The Mission Creek and Winfield localities are east of the west-dipping, low-angle, normal Okanagan Fault, which has been active since the Eocene. Lambly Creek is west of the fault. Late Paleozoic to Eocene igneous and metasedimentary rocks occur in the Lambly Creek catchment but Eocene gneiss units, unroofed by the fault, occur on the Okanagan Valley’s east side. This study tests the hypothesis that native placer gold compositions vary across the Okanagan Fault reflecting different sources and histories for the gold. A modest number of Au and Ag analyses (23 analyses) in usefully representative placer gold samples were determined on a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS). Spots analyzed for Au and Ag were also analyzed for 19 trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Mercury was semi-quantitatively determined in ‘unknown’ gold grains by first estimating its concentration (~3.69 ppm) in the AuRM2 external standard. Proportions of Au:Ag:Cu in grain cores indicate all the gold came from mesothermal/hypogene or possibly Au porphyry bedrock deposits though primary signatures may have been obscured by metamorphism or weathering. Winfield and Mission Creek grains tend to have higher siderophile Fe, Ni, Pd and Pt and chalcophile elements As, Se, Te, Hg, Pb and Bi but lower Cu and Sb concentrations than Lambly Creek gold. Mercury is distinctly higher in Winfield and Mission Creek gold than in Lambly Creek gold from the west side of the valley; the element appears particularly useful for ‘fingerprinting’ gold. Lambly Creek gold compositions indicate derivation from two orogenic/hypogene sources from greenstone and plutonic/hydrothermal rocks present in the catchment area. Modern day Mission Creek and Miocene paleoplacer Winfield grains have a similar hypogene trace element signature but there are no known local bedrock gold sources. The Mission Creek and Winfield gold grain cores are surrounded by < 10 µm, Au-rich, Ag- and trace element-poor, rims. Lambly Creek grains lack such rims. The Au-rich rims on modern day Mission Creek and Miocene Winfield gold may reflect prolonged near-surface exposure with surficial electrochemical dissolution of hypogene trace elements or the biological precipitation of gold. Low Ag and red colouration on the surface of grains support the biological precipitation hypothesis. The shared trace element signature, together with the Au-rich rims indicate that modern day placer gold in Mission Creek was multiply reworked from Miocene paleoplacers similar to the Winfield occurrence as a result of uplift a","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138963516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-03DOI: 10.12789/geocanj.2023.50.198
Katie M. Maloney, Alexander L. Peace, Joe Hansen, Keira L. Hum, Julia P. Nielsen, Kate F. Pearson, Shania Ramharrack-Maharaj, Deana M. Schwarz, Elli Papangelakis, Carolyn H. Eyles
As geoscientists, we must prioritize improving our ability to communicate science to the public. Effective geoscience communication enables communities to understand how geological processes have shaped our planet and make informed decisions about Earth’s future. However, geoscience research outputs have traditionally been published in peer-reviewed journals and presented at academic conferences. Consequently, essential information about local geology is rarely available in accessible, open access, and engaging formats. Here, we propose virtual field trips, or ‘GeoTrails’, as a possible solution to address the disconnect between geoscience research and public knowledge by improving our communication to the public. This initiative is largely driven by undergraduate students, who identify points of geological interest along selected hiking trails, write concise descriptions derived from scientific sources (e.g. longer peer-reviewed articles and government reports), and collect field data (e.g. 3-D LiDAR models, drone photography) to illustrate the characteristics of these geological features. The goal of the project is to communicate the importance of local geology on our environment and to raise awareness of how changing climates could affect us in the future; this information can empower communities to make better, more informed planning decisions. The creation of GeoTrails along the Niagara Escarpment offers a promising strategy to highlight the role of geoscientists and to engage the public in our ongoing research that aims to showcase Canada’s geoheritage.
{"title":"Earth Science Education #7. GeoTrails: Accessible Online Tools for Outreach and Education","authors":"Katie M. Maloney, Alexander L. Peace, Joe Hansen, Keira L. Hum, Julia P. Nielsen, Kate F. Pearson, Shania Ramharrack-Maharaj, Deana M. Schwarz, Elli Papangelakis, Carolyn H. Eyles","doi":"10.12789/geocanj.2023.50.198","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.198","url":null,"abstract":"As geoscientists, we must prioritize improving our ability to communicate science to the public. Effective geoscience communication enables communities to understand how geological processes have shaped our planet and make informed decisions about Earth’s future. However, geoscience research outputs have traditionally been published in peer-reviewed journals and presented at academic conferences. Consequently, essential information about local geology is rarely available in accessible, open access, and engaging formats. Here, we propose virtual field trips, or ‘GeoTrails’, as a possible solution to address the disconnect between geoscience research and public knowledge by improving our communication to the public. This initiative is largely driven by undergraduate students, who identify points of geological interest along selected hiking trails, write concise descriptions derived from scientific sources (e.g. longer peer-reviewed articles and government reports), and collect field data (e.g. 3-D LiDAR models, drone photography) to illustrate the characteristics of these geological features. The goal of the project is to communicate the importance of local geology on our environment and to raise awareness of how changing climates could affect us in the future; this information can empower communities to make better, more informed planning decisions. The creation of GeoTrails along the Niagara Escarpment offers a promising strategy to highlight the role of geoscientists and to engage the public in our ongoing research that aims to showcase Canada’s geoheritage.","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135743927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-03DOI: 10.12789/geocanj.2023.50.199
Andrew Kerr
Increased use of renewable energy, coupled with electrification of the economy, is considered important in efforts to limit future climate change. This energy transition is predicted to increase demands for some commodities, many of which are now labelled as critical mineral. The quest for such commodities is now a persistent theme for the resource industry and emerging government policies. This review for non-specialists explains several key concepts but also explores some challenges and apparent contradictions in the context of Canada. Canada now has a list of 31 critical minerals, but this includes some major commodities for which domestic production is significant and supply risk is low. The differences between our list and those of other jurisdictions reflect our more specific definitions. Most other commodities on Canada’s list are also identified by other countries and some are specifically linked to the energy transition. These include cobalt, lithium, manganese, nickel, graphite and vanadium (used in electric vehicle batteries and static energy storage), rare earth elements (REE; used for magnets in EV motors and wind turbines) and some rarer elements (e.g. germanium, gallium, indium and tellurium) used in photovoltaic (solar) energy systems. Some of these are potential primary products (e.g. lithium, graphite and REE) but many others (e.g. cobalt, platinum group elements and the photovoltaic elements) are byproducts from the production of major commodities, notably nickel, copper and zinc. The REE represent coproducts that are closely associated in nature and very hard to separate from each other; they are produced as a group. There are some specific challenges in exploring for and developing critical mineral resources. The end-use technology driving demand evolves on a timescale of years, but mineral exploration and development now typically take multiple decades. Material substitutions and unpredictable developments in technology complicate the exact prediction of future demands. The forecasts of overall relative demand growth are impressive, but for some key commodities global production will remain small in absolute terms, which may limit the potential for new discoveries. Simple measures of grade and tonnage are not always guarantees of viability, because deposits of some commodities (e.g. the REE) are mineralogically complex. Byproduct commodities cannot be produced in isolation, and many of these are only extracted in smelting and refining. Domestic production of these commodities is effectively lost if concentrates are exported for processing. The emissions and environmental impacts associated with production of critical mineral resources will also become important if such activity is to be linked to wider climate goals. This may present challenges in northern Canada, where renewable or low-carbon energy options are limited. Most draft Land Use Plans in the north presently emphasize large-scale land conservation, which could lim
{"title":"Critical Minerals in the Context of Canada: Concepts, Challenges and Contradictions","authors":"Andrew Kerr","doi":"10.12789/geocanj.2023.50.199","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.199","url":null,"abstract":"Increased use of renewable energy, coupled with electrification of the economy, is considered important in efforts to limit future climate change. This energy transition is predicted to increase demands for some commodities, many of which are now labelled as critical mineral. The quest for such commodities is now a persistent theme for the resource industry and emerging government policies. This review for non-specialists explains several key concepts but also explores some challenges and apparent contradictions in the context of Canada. Canada now has a list of 31 critical minerals, but this includes some major commodities for which domestic production is significant and supply risk is low. The differences between our list and those of other jurisdictions reflect our more specific definitions. Most other commodities on Canada’s list are also identified by other countries and some are specifically linked to the energy transition. These include cobalt, lithium, manganese, nickel, graphite and vanadium (used in electric vehicle batteries and static energy storage), rare earth elements (REE; used for magnets in EV motors and wind turbines) and some rarer elements (e.g. germanium, gallium, indium and tellurium) used in photovoltaic (solar) energy systems. Some of these are potential primary products (e.g. lithium, graphite and REE) but many others (e.g. cobalt, platinum group elements and the photovoltaic elements) are byproducts from the production of major commodities, notably nickel, copper and zinc. The REE represent coproducts that are closely associated in nature and very hard to separate from each other; they are produced as a group. There are some specific challenges in exploring for and developing critical mineral resources. The end-use technology driving demand evolves on a timescale of years, but mineral exploration and development now typically take multiple decades. Material substitutions and unpredictable developments in technology complicate the exact prediction of future demands. The forecasts of overall relative demand growth are impressive, but for some key commodities global production will remain small in absolute terms, which may limit the potential for new discoveries. Simple measures of grade and tonnage are not always guarantees of viability, because deposits of some commodities (e.g. the REE) are mineralogically complex. Byproduct commodities cannot be produced in isolation, and many of these are only extracted in smelting and refining. Domestic production of these commodities is effectively lost if concentrates are exported for processing. The emissions and environmental impacts associated with production of critical mineral resources will also become important if such activity is to be linked to wider climate goals. This may present challenges in northern Canada, where renewable or low-carbon energy options are limited. Most draft Land Use Plans in the north presently emphasize large-scale land conservation, which could lim","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135743763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.12789/geocanj.2023.50.197
S. Reidel, M. Ross, J. Kasbohm
Magnetitite deposits like El Laco (Chile) are rare and have controversial origins. An unusual magnetitite lava flow overlying a rhyolite unit occurs in the north-central Alaska Range and originally covered ~ 750 km2 of the Miocene Nenana basin. Dating of the rhyolite and relationships between the magnetitite and sedimentary rocks indicate that both are of Late Miocene age. The magnetitite flow is mainly magnetite with some post-eruptive alteration to hematite. Both the rhyolite flow and the magnetitite flow are vesicular, but the magnetitite flow also has small, millimetre-scale columnar jointing. The vesicular zones in the magnetitite flow grade into massive rock on the scale of a thin section, suggesting a degassing lava origin. Samples of the magnetitite flow contain between 12 and 26 wt.% SiO2 and between 45 and 75 wt.% FeO. Rare earth elements (REE) and trace elements from the magnetitite and rhyolite have similar patterns but with lesser abundance in the magnetitite. Both the rhyolite and the magnetitite have light-REE-enriched REE profiles with negative Eu anomalies. Electron microscopic analysis shows that most of the silica and trace element content of the magnetitite flow comes from very finely disseminated silicate minerals and glass in the magnetite. This suggests that the magnetitite was derived from a magma that had undergone unmixing into a silica-rich phase and an iron-rich phase prior to its eruption. Fractures and vesicles within the magnetitite flow contain minor rhyolitic glass and minerals suggesting that the rhyolite magma invaded columnar joints in the solidified magnetitite flow, and is a subvolcanic sill-like body at the studied locality. The magnetitite flow erupted prior to the emplacement of the rhyolite, which may be extrusive on a regional scale. The features of the Nenana magnetitite, and its geological relationships, are consistent with genetic models that invoke unmixing of magma into immiscible Fe-rich and Si-rich liquids during ascent.
{"title":"Igneous Rock Associations 29. The Nenana Magnetitite Lava Flow, Alaska Range, Alaska","authors":"S. Reidel, M. Ross, J. Kasbohm","doi":"10.12789/geocanj.2023.50.197","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.197","url":null,"abstract":"Magnetitite deposits like El Laco (Chile) are rare and have controversial origins. An unusual magnetitite lava flow overlying a rhyolite unit occurs in the north-central Alaska Range and originally covered ~ 750 km2 of the Miocene Nenana basin. Dating of the rhyolite and relationships between the magnetitite and sedimentary rocks indicate that both are of Late Miocene age. The magnetitite flow is mainly magnetite with some post-eruptive alteration to hematite. Both the rhyolite flow and the magnetitite flow are vesicular, but the magnetitite flow also has small, millimetre-scale columnar jointing. The vesicular zones in the magnetitite flow grade into massive rock on the scale of a thin section, suggesting a degassing lava origin. Samples of the magnetitite flow contain between 12 and 26 wt.% SiO2 and between 45 and 75 wt.% FeO. Rare earth elements (REE) and trace elements from the magnetitite and rhyolite have similar patterns but with lesser abundance in the magnetitite. Both the rhyolite and the magnetitite have light-REE-enriched REE profiles with negative Eu anomalies. Electron microscopic analysis shows that most of the silica and trace element content of the magnetitite flow comes from very finely disseminated silicate minerals and glass in the magnetite. This suggests that the magnetitite was derived from a magma that had undergone unmixing into a silica-rich phase and an iron-rich phase prior to its eruption. Fractures and vesicles within the magnetitite flow contain minor rhyolitic glass and minerals suggesting that the rhyolite magma invaded columnar joints in the solidified magnetitite flow, and is a subvolcanic sill-like body at the studied locality. The magnetitite flow erupted prior to the emplacement of the rhyolite, which may be extrusive on a regional scale. The features of the Nenana magnetitite, and its geological relationships, are consistent with genetic models that invoke unmixing of magma into immiscible Fe-rich and Si-rich liquids during ascent.","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46859735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.12789/geocanj.2023.50.196
B. Pratt, G. Young
Tyndall Stone is a distinctively mottled and strikingly fossiliferous dolomitic limestone that has been widely used for over a century in Canada, especially in the Prairie Provinces. It comprises 6–8 m within the lower part of the 43 m thick Selkirk Member of the Red River Formation, of Late Ordovician (Katian) age. It has been quarried exclusively at Garson, Manitoba, 37 km northeast of Winnipeg, since about 1895, and for the past half-century extraction has been carried out solely by Gillis Quarries Ltd. The upper beds tend to be more buff-coloured than the grey lower beds, as a result of groundwater weathering. Tyndall Stone, mostly with a smooth or sawn finish, has been put to a wide variety of uses, including exterior and interior cladding with coursed and random ashlar, and window casements and doorways. Split face finish and random ashlar using varicoloured blocks split along stylolites have become popular for commercial and residential buildings, respectively. Tyndall Stone lends itself to carving as well, being used in columns, coats of arms and sculptures. Many prominent buildings have been constructed using Tyndall Stone, including the provincial legislative buildings of Saskatchewan and Manitoba, the interior of the Centre Block of the House of Commons in Ottawa, courthouses, land titles buildings, post offices and other public buildings, along with train stations, banks, churches, department stores, museums, office buildings and university buildings. These exhibit a variety of architectural styles, from Beaux Arts to Art Deco, Châteauesque to Brutalist. The Canadian Museum of History and the Canadian Museum for Human Rights are two notable Expressionist buildings. The lower Selkirk Member is massive and consists of bioturbated, bioclastic wackestone to packstone, rich in crinoid ossicles. It was deposited in a low-energy marine environment within the photic zone, on the present-day eastern side of the shallow Williston Basin, which was part of the vast equatorial epicontinental sea that covered much of Laurentia at the time. Scattered thin bioclastic grainstone lenses record episodic, higher energy events. Tyndall Stone is spectacularly fossiliferous, and slabs bearing fossils have become increasingly popular. The most common macrofossils are receptaculitids, followed by corals, stromatoporoid sponges, nautiloid cephalopods, and gastropods. The relative abundance of the macrofossils varies stratigraphically, suggesting that subtle environmental changes took place over time. The distinctive mottles—‘tapestry’ in the trade—have been regarded as dolomitized burrows assigned to Thalassinoides and long thought to have been networks of galleries likely made by arthropods. In detail, however, the bioclastic muddy sediment underwent a protracted history of bioturbation, and the large burrows were mostly horizontal back-filled features that were never empty. They can be assigned to Planolites. The matrix and the sediment filling them wer
{"title":"Heritage Stone 9. Tyndall Stone, Canada’s First Global Heritage Stone Resource: Geology, Paleontology, Ichnology and Architecture","authors":"B. Pratt, G. Young","doi":"10.12789/geocanj.2023.50.196","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.196","url":null,"abstract":"Tyndall Stone is a distinctively mottled and strikingly fossiliferous dolomitic limestone that has been widely used for over a century in Canada, especially in the Prairie Provinces. It comprises 6–8 m within the lower part of the 43 m thick Selkirk Member of the Red River Formation, of Late Ordovician (Katian) age. It has been quarried exclusively at Garson, Manitoba, 37 km northeast of Winnipeg, since about 1895, and for the past half-century extraction has been carried out solely by Gillis Quarries Ltd. The upper beds tend to be more buff-coloured than the grey lower beds, as a result of groundwater weathering. Tyndall Stone, mostly with a smooth or sawn finish, has been put to a wide variety of uses, including exterior and interior cladding with coursed and random ashlar, and window casements and doorways. Split face finish and random ashlar using varicoloured blocks split along stylolites have become popular for commercial and residential buildings, respectively. Tyndall Stone lends itself to carving as well, being used in columns, coats of arms and sculptures. Many prominent buildings have been constructed using Tyndall Stone, including the provincial legislative buildings of Saskatchewan and Manitoba, the interior of the Centre Block of the House of Commons in Ottawa, courthouses, land titles buildings, post offices and other public buildings, along with train stations, banks, churches, department stores, museums, office buildings and university buildings. These exhibit a variety of architectural styles, from Beaux Arts to Art Deco, Châteauesque to Brutalist. The Canadian Museum of History and the Canadian Museum for Human Rights are two notable Expressionist buildings. The lower Selkirk Member is massive and consists of bioturbated, bioclastic wackestone to packstone, rich in crinoid ossicles. It was deposited in a low-energy marine environment within the photic zone, on the present-day eastern side of the shallow Williston Basin, which was part of the vast equatorial epicontinental sea that covered much of Laurentia at the time. Scattered thin bioclastic grainstone lenses record episodic, higher energy events. Tyndall Stone is spectacularly fossiliferous, and slabs bearing fossils have become increasingly popular. The most common macrofossils are receptaculitids, followed by corals, stromatoporoid sponges, nautiloid cephalopods, and gastropods. The relative abundance of the macrofossils varies stratigraphically, suggesting that subtle environmental changes took place over time. The distinctive mottles—‘tapestry’ in the trade—have been regarded as dolomitized burrows assigned to Thalassinoides and long thought to have been networks of galleries likely made by arthropods. In detail, however, the bioclastic muddy sediment underwent a protracted history of bioturbation, and the large burrows were mostly horizontal back-filled features that were never empty. They can be assigned to Planolites. The matrix and the sediment filling them wer","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47473723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-29DOI: 10.12789/geocanj.2023.50.194
A. Hynes
{"title":"Tuzo: The Unlikely Revolutionary of Plate Tectonics","authors":"A. Hynes","doi":"10.12789/geocanj.2023.50.194","DOIUrl":"https://doi.org/10.12789/geocanj.2023.50.194","url":null,"abstract":"","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46334736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Some months ago I received from Dr. J. Cosmo Melvill a small box containing brachiopods from the Persian Gulf. These had been obtained by Mr. F. W. Townsend in the course of his dredgings for Mollusca in that region. The locality on the box containing the specimens is Dabai, which lies within the Persian Gulf on the N.W. coast of Oman. Its exact position is on the west side of the peninsula of Ruus El Jibal, on what is known as the Pirate Coast. Unfortunately, no particulars as to depth etc. accompanied the specimens. With the exception of the Mollusca and some Madreporarian corals very little appears to be known of the fauna of the Persian Gulf. The Mollusca have been ably dealt with in a series of papers by Messrs. Melvill and Standen*, and the corals were described in 1911 in a paper by Miss Ruth Harrison "f, to which Professor S. J. Hickson added some further notes J. The discovery of Brachiopoda in the Persian Gulf is of very great interest, not only from the fact that these specimens are the first of the class to be recorded from this region — i. e., the N.W. corner of the Indian Ocean (including the Persian Gulf, Gulf of Oman, and Arabian Sea), — but more especially from the important bearing of these specimens on the subject of the relation of the fauna of the Persian Gulf to that of the Mediterranean Sea and Atlantic Ocean. Four specimens only were present in the box, one of which is a Terebratulina, the other three belonging to the genus Muhlfeldtia. All are dead empty shells, and a small quantity of greyish marl was present in the interior of one or two. Unfortunately , in the case of the Terebratulina, the brachidium, or loop, is broken, but the shell is otherwise quite perfect, both valves being present. In form and size it is very like a specimen of Terebratulina caput-serpentis figured by Fischer and Oehlert from the ' Talisman ' Expedition in the Lusitanian Subregion §. It has the same general outline and is cut off
几个月前，我从J. Cosmo melville博士那里收到了一个小盒子，里面装着来自波斯湾的腕足类动物。这些是f·w·汤森先生在那个地区为软体动物进行疏浚时获得的。装标本的盒子上的地点是大拜，它位于阿曼西北海岸的波斯湾内。它的确切位置在Ruus El Jibal半岛的西侧，被称为海盗海岸。不幸的是，这些标本没有关于深度等细节。除了软体动物和一些珊瑚外，人们对波斯湾的动物群所知甚少。在梅尔维尔先生和斯坦登先生的一系列论文中，对软体动物进行了巧妙的研究*，1911年露丝·哈里森小姐的一篇论文中对珊瑚进行了描述，s·j·希克森教授在论文中补充了一些进一步的注释。J.在波斯湾发现腕足动物引起了极大的兴趣，不仅因为这些标本是该地区首次记录到的同类标本也就是说，印度洋的西北角(包括波斯湾、阿曼湾和阿拉伯海)，但更重要的是，这些标本对波斯湾动物群与地中海和大西洋动物群的关系这一主题的重要意义。盒子里只有四个标本，其中一个是Terebratulina，另外三个属于Muhlfeldtia属。所有的都是死的空壳，有一两个的内部有少量的灰色泥灰岩。不幸的是，在Terebratulina的情况下，腕足或环被破坏了，但外壳在其他方面非常完美，两个瓣膜都存在。在形状和大小上，它很像一个由Fischer和Oehlert在卢西塔尼亚分区的“护身符”探险队中发现的Terebratulina caput- serentis标本。它有相同的大致轮廓，并被切断
{"title":"in the Persian Gulf","authors":"Mr J W Jackson","doi":"10.2307/j.ctt1r33pxt.4","DOIUrl":"https://doi.org/10.2307/j.ctt1r33pxt.4","url":null,"abstract":"Some months ago I received from Dr. J. Cosmo Melvill a small box containing brachiopods from the Persian Gulf. These had been obtained by Mr. F. W. Townsend in the course of his dredgings for Mollusca in that region. The locality on the box containing the specimens is Dabai, which lies within the Persian Gulf on the N.W. coast of Oman. Its exact position is on the west side of the peninsula of Ruus El Jibal, on what is known as the Pirate Coast. Unfortunately, no particulars as to depth etc. accompanied the specimens. With the exception of the Mollusca and some Madreporarian corals very little appears to be known of the fauna of the Persian Gulf. The Mollusca have been ably dealt with in a series of papers by Messrs. Melvill and Standen*, and the corals were described in 1911 in a paper by Miss Ruth Harrison \"f, to which Professor S. J. Hickson added some further notes J. The discovery of Brachiopoda in the Persian Gulf is of very great interest, not only from the fact that these specimens are the first of the class to be recorded from this region — i. e., the N.W. corner of the Indian Ocean (including the Persian Gulf, Gulf of Oman, and Arabian Sea), — but more especially from the important bearing of these specimens on the subject of the relation of the fauna of the Persian Gulf to that of the Mediterranean Sea and Atlantic Ocean. Four specimens only were present in the box, one of which is a Terebratulina, the other three belonging to the genus Muhlfeldtia. All are dead empty shells, and a small quantity of greyish marl was present in the interior of one or two. Unfortunately , in the case of the Terebratulina, the brachidium, or loop, is broken, but the shell is otherwise quite perfect, both valves being present. In form and size it is very like a specimen of Terebratulina caput-serpentis figured by Fischer and Oehlert from the ' Talisman ' Expedition in the Lusitanian Subregion §. It has the same general outline and is cut off","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68720516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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