Yan Li, Zhao-Bin Yan, Cai Jianfang, Fengjun Nie, Li Wenqing, Dongxu Wang, Yao Zhang, Xiaohui Liu
The Songliao Basin is rich in uranium ores, and the Yaojia Formation, which is dominated by gray fine-grained sandstones, contains the main ore-bearing stratum. Rocks in the formation contain high SiO2, Al2O3, and total alkali, with enrichment in Rb, Th, U, K, and light rare earth elements (LREE), but are depleted in high field strength elements (HFSE), similar to upper crustal rocks. U-Pb dating of zircon grains from sandstones in the formation yielded four groups of ages including 99–182, 202–245, 284–365, and 1800–1900 Ma. These ages combined with the Hf isotope composition, geochemical characteristics, and regional history suggest that the Yaojia Formation rocks are associated with passive and active continental margin settings. These clastic rocks originate principally from felsic rocks in the Zhangguangcailing–Xiao Xing’anling area and these were deposited in oxic freshwater environments.
{"title":"Tectonic setting and provenance analysis of the Yaojia Formation in the northeastern Songliao Basin, NE China: constraints from sandstone geochemistry, Hf isotopes, and zircon U-Pb chronology","authors":"Yan Li, Zhao-Bin Yan, Cai Jianfang, Fengjun Nie, Li Wenqing, Dongxu Wang, Yao Zhang, Xiaohui Liu","doi":"10.1139/cjes-2022-0072","DOIUrl":"https://doi.org/10.1139/cjes-2022-0072","url":null,"abstract":"The Songliao Basin is rich in uranium ores, and the Yaojia Formation, which is dominated by gray fine-grained sandstones, contains the main ore-bearing stratum. Rocks in the formation contain high SiO2, Al2O3, and total alkali, with enrichment in Rb, Th, U, K, and light rare earth elements (LREE), but are depleted in high field strength elements (HFSE), similar to upper crustal rocks. U-Pb dating of zircon grains from sandstones in the formation yielded four groups of ages including 99–182, 202–245, 284–365, and 1800–1900 Ma. These ages combined with the Hf isotope composition, geochemical characteristics, and regional history suggest that the Yaojia Formation rocks are associated with passive and active continental margin settings. These clastic rocks originate principally from felsic rocks in the Zhangguangcailing–Xiao Xing’anling area and these were deposited in oxic freshwater environments.
","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136234258","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}
Martín Valencia-Moreno, Carlos M. González-León, Luigi Solari, Mario Arturo Rascón-Heimpel, Elizard González-Becuar, Rufino Lozano-Santacruz, Ofelia Pérez-Arvizu
Igneous rocks of the Jurassic continental arc of southwest North American Cordillera crop out in the region between Cananea and Nacozari, in northeastern Sonora, Mexico. Contemporaneous igneous rocks occur farther south in the Nazas rift province; however, their tectonic affinity is debated between the southern extension of the Cordilleran arc and an origin associated with decompressive mantle melting during the Pangea breakup. We consider that the studied rocks represent the southernmost expression of the Jurassic continental arc. Four magmatic units are distinguished based on geology, U–Pb zircon geochronology, and geochemical composition. They comprise the Buenos Aires granite dated at 183.8 ± 1.1 Ma, the Mababi granite with ages of 175.5 ± 1.8, 173.5 ± 1.8, and 171.7 ± 1.0 Ma, the Elenita Formation volcanic rocks dated at 169.7 ± 1.7 Ma, and the Cerro Blanco granite dated at 162.3 ± 2.4 Ma. The studied samples correspond to highly differentiated rocks with high-silica contents (69–76 wt.%), low Mg# values (mostly <45), and alkali–calcic and peraluminous compositions suggesting crustal contamination. LREE-enriched normalized slopes with negative Eu anomalies and multielement plots characterized by well-developed negative anomalies of Nb–Ta, P, and Ti provide an unequivocal signal of the continental arc nature. In contrast to the Nazas province, where the Jurassic magmatism consists of discreet volcaniclastic sequences deposited in extensional basins with no evidence of plutonic rocks, the Jurassic continental arc of Arizona and northern Sonora forms a regionally coherent geological feature characterized by large exposures of volcanic and plutonic rocks.
{"title":"U–Pb zircon geochronology and geochemistry of the Jurassic magmatic rocks from the region of Cananea and Nacozari, northeastern Sonora, Mexico: timing and composition of the southernmost edge of the Jurassic continental arc","authors":"Martín Valencia-Moreno, Carlos M. González-León, Luigi Solari, Mario Arturo Rascón-Heimpel, Elizard González-Becuar, Rufino Lozano-Santacruz, Ofelia Pérez-Arvizu","doi":"10.1139/cjes-2023-0059","DOIUrl":"https://doi.org/10.1139/cjes-2023-0059","url":null,"abstract":"Igneous rocks of the Jurassic continental arc of southwest North American Cordillera crop out in the region between Cananea and Nacozari, in northeastern Sonora, Mexico. Contemporaneous igneous rocks occur farther south in the Nazas rift province; however, their tectonic affinity is debated between the southern extension of the Cordilleran arc and an origin associated with decompressive mantle melting during the Pangea breakup. We consider that the studied rocks represent the southernmost expression of the Jurassic continental arc. Four magmatic units are distinguished based on geology, U–Pb zircon geochronology, and geochemical composition. They comprise the Buenos Aires granite dated at 183.8 ± 1.1 Ma, the Mababi granite with ages of 175.5 ± 1.8, 173.5 ± 1.8, and 171.7 ± 1.0 Ma, the Elenita Formation volcanic rocks dated at 169.7 ± 1.7 Ma, and the Cerro Blanco granite dated at 162.3 ± 2.4 Ma. The studied samples correspond to highly differentiated rocks with high-silica contents (69–76 wt.%), low Mg# values (mostly <45), and alkali–calcic and peraluminous compositions suggesting crustal contamination. LREE-enriched normalized slopes with negative Eu anomalies and multielement plots characterized by well-developed negative anomalies of Nb–Ta, P, and Ti provide an unequivocal signal of the continental arc nature. In contrast to the Nazas province, where the Jurassic magmatism consists of discreet volcaniclastic sequences deposited in extensional basins with no evidence of plutonic rocks, the Jurassic continental arc of Arizona and northern Sonora forms a regionally coherent geological feature characterized by large exposures of volcanic and plutonic rocks.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136318338","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}
Matthew James Gill, Kristin M. Poduska, Penny Morrill
This study measured the CO2 gas flux into various aqueous media (i.e., simulated ultra-basic and basic groundwater, and deionized water) containing ultramafic rock. Basic and ultra-basic waters simulated the aqueous chemistry and ion concentrations of distinct groundwaters found within terrestrial ultramafic bodies. Experiments were performed in a closed chamber in line with a CO2 analyzer, which measured the gaseous CO2 concentration in the chamber every second. Total inorganic carbon, as well as aqueous species Ca, Mg, and Si were monitored in the reaction fluids. All three fluid types sequestered CO2. The addition of crushed peridotite to deionized water reduced the CO2 concentration in the headspace by 70 ppm (± 9 ppm, 1σ, n=3) and had a calculated CO2 flux of -2.5 x 104 mol/m2min (± 9 x 105 mol/m2min, 1σ, n=3), while the greatest CO2 flux was observed in ultra-basic Ca-rich waters of -1.40 x 103 mol/m2min (± 3 x 105 mol/m2min, 1σ, n=3) which reduced the headspace CO2 concentration by 323 ppm (± 4 ppm, 1σ, n=3). The presence of calcite was detected using FTIR in ultra-basic waters in the presence and absence of ultramafic rock. A carbon mass balance model, indicated that solid carbonates were precipitated in the ultra-basic water experiments, converting up to 59% of the CO2 removed from the chamber headspace in four hours. Extrapolating the data collected in these experiments, it was estimated that at surface conditions, with an adequate residence time, the mass of ultramafic rock in the Bay of Islands Complex in Newfoundland could sequester up to 4 million tonnes of atmospheric CO2.
{"title":"Evaluation of Carbon Dioxide Sequestration via Interaction with Peridotite and Peridotite Hosted Groundwaters. An Experimental Case Study with Bay of Islands Ophiolite Rocks, Western Newfoundland, Canada.","authors":"Matthew James Gill, Kristin M. Poduska, Penny Morrill","doi":"10.1139/cjes-2022-0116","DOIUrl":"https://doi.org/10.1139/cjes-2022-0116","url":null,"abstract":"This study measured the CO2 gas flux into various aqueous media (i.e., simulated ultra-basic and basic groundwater, and deionized water) containing ultramafic rock. Basic and ultra-basic waters simulated the aqueous chemistry and ion concentrations of distinct groundwaters found within terrestrial ultramafic bodies. Experiments were performed in a closed chamber in line with a CO2 analyzer, which measured the gaseous CO2 concentration in the chamber every second. Total inorganic carbon, as well as aqueous species Ca, Mg, and Si were monitored in the reaction fluids. All three fluid types sequestered CO2. The addition of crushed peridotite to deionized water reduced the CO2 concentration in the headspace by 70 ppm (± 9 ppm, 1σ, n=3) and had a calculated CO2 flux of -2.5 x 104 mol/m2min (± 9 x 105 mol/m2min, 1σ, n=3), while the greatest CO2 flux was observed in ultra-basic Ca-rich waters of -1.40 x 103 mol/m2min (± 3 x 105 mol/m2min, 1σ, n=3) which reduced the headspace CO2 concentration by 323 ppm (± 4 ppm, 1σ, n=3). The presence of calcite was detected using FTIR in ultra-basic waters in the presence and absence of ultramafic rock. A carbon mass balance model, indicated that solid carbonates were precipitated in the ultra-basic water experiments, converting up to 59% of the CO2 removed from the chamber headspace in four hours. Extrapolating the data collected in these experiments, it was estimated that at surface conditions, with an adequate residence time, the mass of ultramafic rock in the Bay of Islands Complex in Newfoundland could sequester up to 4 million tonnes of atmospheric CO2.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135266266","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}
Canada’s recently active volcanic zones (e.g., eruptions during the past 10,000 years) are all located along the tectonic plate boundary region of western Canada, extending for more than 2000 km from southern British Columbia to the Yukon/Alaska border. In this article, we describe the history of seismic monitoring in and near these volcanic zones and the past and current seismicity detection thresholds. The most recently active volcanoes in Canada are Tseax Cone (~1700) and Lava Forks (1800’s), both in northwestern British Columbia. However, no eruptions have occurred in Canada since the deployment of the earliest seismographs in 1898 (Victoria, BC) and 1904 (Sitka, Alaska). Seismic detection levels have decreased from M~7 in 1900 to M~0-1 (in many regions) today, with more than 120 seismic stations currently operating in British Columbia and the Yukon, including ~20 seismic stations within the volcanic zones. The most recent significant seismic activity attributed to volcanic zones in Canada is the 2007 Nazko Cone earthquake swarm when nearly 1000 tiny (M<3) earthquakes occurred here over the span of about two months. These were all deep earthquakes (~30 km) near the base of the crust and showed the patterns expected from an injection of magma deep into the crust. Prior to that, at the western end of the Anahim Volcanic Belt, more than 40 felt earthquakes occurred from 1940-1943. We provide a summary of these two swarms and other seismicity as well as some recent and ongoing studies into seismicity at some of Canada’s volcanic zones and new developments in seismic monitoring of volcanoes (including using distributed acoustic sensing).
{"title":"Seismicity and Seismic Monitoring of Canada's Volcanic Zones","authors":"John F. Cassidy, Taimi L. Mulder","doi":"10.1139/cjes-2023-0078","DOIUrl":"https://doi.org/10.1139/cjes-2023-0078","url":null,"abstract":"Canada’s recently active volcanic zones (e.g., eruptions during the past 10,000 years) are all located along the tectonic plate boundary region of western Canada, extending for more than 2000 km from southern British Columbia to the Yukon/Alaska border. In this article, we describe the history of seismic monitoring in and near these volcanic zones and the past and current seismicity detection thresholds. The most recently active volcanoes in Canada are Tseax Cone (~1700) and Lava Forks (1800’s), both in northwestern British Columbia. However, no eruptions have occurred in Canada since the deployment of the earliest seismographs in 1898 (Victoria, BC) and 1904 (Sitka, Alaska). Seismic detection levels have decreased from M~7 in 1900 to M~0-1 (in many regions) today, with more than 120 seismic stations currently operating in British Columbia and the Yukon, including ~20 seismic stations within the volcanic zones. The most recent significant seismic activity attributed to volcanic zones in Canada is the 2007 Nazko Cone earthquake swarm when nearly 1000 tiny (M<3) earthquakes occurred here over the span of about two months. These were all deep earthquakes (~30 km) near the base of the crust and showed the patterns expected from an injection of magma deep into the crust. Prior to that, at the western end of the Anahim Volcanic Belt, more than 40 felt earthquakes occurred from 1940-1943. We provide a summary of these two swarms and other seismicity as well as some recent and ongoing studies into seismicity at some of Canada’s volcanic zones and new developments in seismic monitoring of volcanoes (including using distributed acoustic sensing).","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135618549","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}
Dawn Anne-Marie Kellett, Isabelle Coutand, Alex Zagorevski, Djordje D. Grujic, Keith Dewing, Luke P. Beranek
The Whitehorse Trough formed during early Mesozoic accretion of the Intermontane terranes to northwestern North America. Here we investigate its thermal history using detrital mineral thermochronology, including 171 single-crystal (U-Th)/He zircon (ZHe) ages from 35 samples, 158 single-crystal (U-Th)/He apatite (AHe) ages from 33 samples, and apatite fission track (AFT) ages from 12 samples. ZHe single crystal ages range from 222-42 Ma and define Triassic-Early Jurassic, Late Jurassic, and Cretaceous-Paleogene age groups. AFT central ages range from 95-30 Ma with a dominant age peak at ~50 Ma, and AHe single crystal ages range from 228-13 Ma with a dominant age peak between 50-40 Ma. Forward and inverse models of thermochronological data are compatible with two regional burial/heating stages that variably reset He in zircon. Maximum temperatures of the Whitehorse Trough strata locally exceeded 150 °C during Early Jurassic burial and shortening into a fold and thrust belt. Following Middle to Late Jurassic exhumation-related cooling and development of a prominent unconformity, Whitehorse Trough strata were buried again. Temperatures locally exceeded 150 °C during the Cretaceous, suggesting maximum burial of between ~4 and 7.5 km. Heating and cooling rates during the Early-Middle Jurassic were ~10 °C/myr, coinciding with deposition, fold and thrust belt development and regional crustal thickening during the final stages of Intermontane terrane accretion. Maximum heating rates during the Cretaceous were ~4-7 °C/myr and likely correspond to regional crustal thickening of the northern Cordillera hinterland and establishment of an outboard, Andean-type continental arc system.
{"title":"Whitehorse Trough records Late Triassic-Cretaceous accretionary orogenesis in the Northern Canadian Cordillera via detrital mineral thermochronometry","authors":"Dawn Anne-Marie Kellett, Isabelle Coutand, Alex Zagorevski, Djordje D. Grujic, Keith Dewing, Luke P. Beranek","doi":"10.1139/cjes-2023-0082","DOIUrl":"https://doi.org/10.1139/cjes-2023-0082","url":null,"abstract":"The Whitehorse Trough formed during early Mesozoic accretion of the Intermontane terranes to northwestern North America. Here we investigate its thermal history using detrital mineral thermochronology, including 171 single-crystal (U-Th)/He zircon (ZHe) ages from 35 samples, 158 single-crystal (U-Th)/He apatite (AHe) ages from 33 samples, and apatite fission track (AFT) ages from 12 samples. ZHe single crystal ages range from 222-42 Ma and define Triassic-Early Jurassic, Late Jurassic, and Cretaceous-Paleogene age groups. AFT central ages range from 95-30 Ma with a dominant age peak at ~50 Ma, and AHe single crystal ages range from 228-13 Ma with a dominant age peak between 50-40 Ma. Forward and inverse models of thermochronological data are compatible with two regional burial/heating stages that variably reset He in zircon. Maximum temperatures of the Whitehorse Trough strata locally exceeded 150 °C during Early Jurassic burial and shortening into a fold and thrust belt. Following Middle to Late Jurassic exhumation-related cooling and development of a prominent unconformity, Whitehorse Trough strata were buried again. Temperatures locally exceeded 150 °C during the Cretaceous, suggesting maximum burial of between ~4 and 7.5 km. Heating and cooling rates during the Early-Middle Jurassic were ~10 °C/myr, coinciding with deposition, fold and thrust belt development and regional crustal thickening during the final stages of Intermontane terrane accretion. Maximum heating rates during the Cretaceous were ~4-7 °C/myr and likely correspond to regional crustal thickening of the northern Cordillera hinterland and establishment of an outboard, Andean-type continental arc system.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728664","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}
John Evangelatos, Karl E. Butler, Jennifer Margita Adam, William A. Morris
The Passamaquoddy Bay region of southwest New Brunswick and northeast Maine is known for its moderate seismicity, yet the structures responsible for these earthquakes are not well understood. To gain insight on the tectonic history of this region, marine magnetic surveys were conducted at speculated intersections of faults and the Early Jurassic Ministers Island dyke. Analysis of the vertical gradient of the magnetic field strongly suggests that the 189 ± 8 Ma Ministers Island dyke is dextrally offset 370 m by the Oak Bay Fault below the St. Croix River. This sense of motion points to a reversal of fault movement compared to that recorded in much older (Silurian) rocks nearby. The interpretation is supported by magnetic modelling, constrained by direct measurements of the magnetic susceptibility and natural remanent magnetization of the dyke. In Passamaquoddy Bay, however, farther to the east, there is no evidence that slight deviations in the trend of the dyke anomaly or its termination result from post-emplacement faulting. Furthermore, the data suggest that a sub-parallel mafic dyke on the northern shore of Passamaquoddy Bay is either a distinct dyke system or a left stepover emplacement of the Ministers Island dyke, as opposed to a faulted offset as previously speculated. This study illustrates how focused high resolution magnetic surveys can strengthen interpretations of faulting in areas of geological ambiguity.
{"title":"New insights on faulting in SW New Brunswick and NE Maine based on marine magnetic mapping of the Ministers Island dyke","authors":"John Evangelatos, Karl E. Butler, Jennifer Margita Adam, William A. Morris","doi":"10.1139/cjes-2023-0083","DOIUrl":"https://doi.org/10.1139/cjes-2023-0083","url":null,"abstract":"The Passamaquoddy Bay region of southwest New Brunswick and northeast Maine is known for its moderate seismicity, yet the structures responsible for these earthquakes are not well understood. To gain insight on the tectonic history of this region, marine magnetic surveys were conducted at speculated intersections of faults and the Early Jurassic Ministers Island dyke. Analysis of the vertical gradient of the magnetic field strongly suggests that the 189 ± 8 Ma Ministers Island dyke is dextrally offset 370 m by the Oak Bay Fault below the St. Croix River. This sense of motion points to a reversal of fault movement compared to that recorded in much older (Silurian) rocks nearby. The interpretation is supported by magnetic modelling, constrained by direct measurements of the magnetic susceptibility and natural remanent magnetization of the dyke. In Passamaquoddy Bay, however, farther to the east, there is no evidence that slight deviations in the trend of the dyke anomaly or its termination result from post-emplacement faulting. Furthermore, the data suggest that a sub-parallel mafic dyke on the northern shore of Passamaquoddy Bay is either a distinct dyke system or a left stepover emplacement of the Ministers Island dyke, as opposed to a faulted offset as previously speculated. This study illustrates how focused high resolution magnetic surveys can strengthen interpretations of faulting in areas of geological ambiguity.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947661","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}
Mahmud Muhammad, Glyn Williams-Jones, René W. Barendregt
The Mount Meager Volcanic Complex (Qwe̓lqwe̓lústen or Mt. Meager) coincides tectonically with the intra-arc to back-arc transition zone and exhibits the loci of strain partitioning in response to a rapid change in orientation of the Pemberton and Garibaldi Arc segments which are coeval with a shift in Pacific plate motion after 5 Ma. This strain partition is manifested through development of a transpressional deformation from 5 Ma to 1.9 Ma at the latitude of Mt. Meager. Mt. Meager is an active volcanic system with at least two explosive eruptions in the last 25,000 years, the most recent occurring around 2360 BP. Additionally, it is the site of the largest landslide in Canadian history, which occurred during the summer of 2010, originating from the southeastern side the massif. During early exploration at Mt. Meager, geothermal boreholes drilled to 3 km reached 270°C but did not find sufficient permeability to sustain self-flowing conditions. To understand the geological challenges in Mt. Meager's geothermal exploration, we analyzed outcrop-scale faults and folds, incorporating structural mapping, volcanic rock paleomagnetism, and radiometric dating to establish kinematic history and kinematic compatibility of structural geology features including faults and folds. Our findings suggest that stress partitioning during the last 5 Ma resulted in formation of a transpressional structure exhibited as an elongate and rhomboidal structure at Mt. Meager with anomalously high topographic elevations which led to ENE-WSW crustal shortening and exhumation of crystalline basement. This new structural geology model improves our understanding of the geothermal reservoir and potentially significant geohazards.
{"title":"Structural Geology of the Mount Meager Volcanic Complex, BC, Canada: Implications for geothermal energy and geohazards","authors":"Mahmud Muhammad, Glyn Williams-Jones, René W. Barendregt","doi":"10.1139/cjes-2023-0077","DOIUrl":"https://doi.org/10.1139/cjes-2023-0077","url":null,"abstract":"The Mount Meager Volcanic Complex (Qwe̓lqwe̓lústen or Mt. Meager) coincides tectonically with the intra-arc to back-arc transition zone and exhibits the loci of strain partitioning in response to a rapid change in orientation of the Pemberton and Garibaldi Arc segments which are coeval with a shift in Pacific plate motion after 5 Ma. This strain partition is manifested through development of a transpressional deformation from 5 Ma to 1.9 Ma at the latitude of Mt. Meager. Mt. Meager is an active volcanic system with at least two explosive eruptions in the last 25,000 years, the most recent occurring around 2360 BP. Additionally, it is the site of the largest landslide in Canadian history, which occurred during the summer of 2010, originating from the southeastern side the massif. During early exploration at Mt. Meager, geothermal boreholes drilled to 3 km reached 270°C but did not find sufficient permeability to sustain self-flowing conditions. To understand the geological challenges in Mt. Meager's geothermal exploration, we analyzed outcrop-scale faults and folds, incorporating structural mapping, volcanic rock paleomagnetism, and radiometric dating to establish kinematic history and kinematic compatibility of structural geology features including faults and folds. Our findings suggest that stress partitioning during the last 5 Ma resulted in formation of a transpressional structure exhibited as an elongate and rhomboidal structure at Mt. Meager with anomalously high topographic elevations which led to ENE-WSW crustal shortening and exhumation of crystalline basement. This new structural geology model improves our understanding of the geothermal reservoir and potentially significant geohazards.
","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135482156","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}
Karol Faehnrich, William C. McClelland, Laura Webb, Karolina Kośmińska, Justin V. Strauss
Neoproterozoic to early Paleozoic strata exposed along the northeastern margin of North America (Franklinian Basin) record a prolonged history of rifting and passive margin development. An episode of Ediacaran–Cambrian extension is potentially recorded in volcanic and sedimentary rocks of the Yelverton Formation, exposed on northern Ellesmere Island, Nunavut, Canada. Here, we present new whole-rock trace element and isotope geochemistry and hornblende 40 Ar/ 39 Ar geochronology from intrusive and extrusive rocks of the Yelverton Formation, along with isotope geochemistry from carbonate rocks underlying the volcanics and detrital zircon U–Pb and Lu–Hf isotopic data from the Yelverton Formation and overlying Grant Land Formation. The carbonate strata yielded an average 87 Sr/ 86 Sr value of 0.7076 ( n = 6), constraining the overlying volcanics to the late Ediacaran–early Cambrian (ca. 570–530 Ma). Flows and dikes/sills show three distinct compositions: (1) a depleted, low La/Yb PM and Th/Nb group, (2) an enriched, higher La/Yb PM and low Th/Nb group, and (3) a low to moderate La/Yb PM and high Th/Nb group. One of the high Th/Nb intrusions produced saddle-shaped 40 Ar/ 39 Ar hornblende spectra with ca. 482 ± 7 Ma age minima and Silurian–Devonian inverse isochron ages, highlighting a hitherto unknown suite of younger intrusions and volcanic rocks. The trace element geochemistry and 143 Nd/ 144 Nd (t) ratios of enriched and depleted volcanic rocks of the indisputable Yelverton Formation are consistent with decompression melting during rifting along a continental margin. We suggest that late Ediacaran–early Cambrian rifting recorded in the Yelverton Formation resulted in the separation of peri-Laurentian terranes, such as the North Slope subterrane and eventual development of the passive margin of northern Laurentia.
{"title":"Late Ediacaran–early Cambrian rifting along the northern margin of Laurentia: constraints from the Yelverton Formation of Ellesmere Island, Canada","authors":"Karol Faehnrich, William C. McClelland, Laura Webb, Karolina Kośmińska, Justin V. Strauss","doi":"10.1139/cjes-2023-0020","DOIUrl":"https://doi.org/10.1139/cjes-2023-0020","url":null,"abstract":"Neoproterozoic to early Paleozoic strata exposed along the northeastern margin of North America (Franklinian Basin) record a prolonged history of rifting and passive margin development. An episode of Ediacaran–Cambrian extension is potentially recorded in volcanic and sedimentary rocks of the Yelverton Formation, exposed on northern Ellesmere Island, Nunavut, Canada. Here, we present new whole-rock trace element and isotope geochemistry and hornblende 40 Ar/ 39 Ar geochronology from intrusive and extrusive rocks of the Yelverton Formation, along with isotope geochemistry from carbonate rocks underlying the volcanics and detrital zircon U–Pb and Lu–Hf isotopic data from the Yelverton Formation and overlying Grant Land Formation. The carbonate strata yielded an average 87 Sr/ 86 Sr value of 0.7076 ( n = 6), constraining the overlying volcanics to the late Ediacaran–early Cambrian (ca. 570–530 Ma). Flows and dikes/sills show three distinct compositions: (1) a depleted, low La/Yb PM and Th/Nb group, (2) an enriched, higher La/Yb PM and low Th/Nb group, and (3) a low to moderate La/Yb PM and high Th/Nb group. One of the high Th/Nb intrusions produced saddle-shaped 40 Ar/ 39 Ar hornblende spectra with ca. 482 ± 7 Ma age minima and Silurian–Devonian inverse isochron ages, highlighting a hitherto unknown suite of younger intrusions and volcanic rocks. The trace element geochemistry and 143 Nd/ 144 Nd (t) ratios of enriched and depleted volcanic rocks of the indisputable Yelverton Formation are consistent with decompression melting during rifting along a continental margin. We suggest that late Ediacaran–early Cambrian rifting recorded in the Yelverton Formation resulted in the separation of peri-Laurentian terranes, such as the North Slope subterrane and eventual development of the passive margin of northern Laurentia.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","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":"135696076","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}
Analysis of biostratigraphically dated boulders demonstrates that the Steptoean Positive Carbon Isotope Excursion (SPICE) is recorded in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation in western Newfoundland. Fifteen boulders composed of bioclastic carbonates were assigned to five faunas based on assemblages of agnostids and trilobites. The Glyptagnostus reticulatus and “ Innitagnostus” inexpectans faunas correlate into strata that record the rising limb of the SPICE in its type area of Nevada and Utah, whereas equivalents of the Acmarhachis kindlei Fauna lie in the interval that records peak δ 13 C values. The Crepicephalus and Triorygma burkhalteri faunas correlate into pre- and post-SPICE strata, respectively. δ 13 C values for boulders from the three faunas correlative with the SPICE are significantly higher than “background” levels of the pre- and post-SPICE boulders, but the maximum value in the A. kindlei Fauna (1.5‰) is less than half of the peak values recorded in Nevada and Utah. The values are, however, in line with those reported from the Port au Port Peninsula of Newfoundland, which reach 2.2‰. The differences in magnitude between Newfoundland and Nevada–Utah hint at differences in the expression of the SPICE in different geographic regions of the Laurentian continent that might reflect oceanographic conditions.
{"title":"A record of the Steptoean Positive Carbon Isotope Excursion (SPICE; Cambrian, Paibian) from the Cow Head Group, western Newfoundland","authors":"Stephen R. Westrop, Michael Engel","doi":"10.1139/cjes-2023-0097","DOIUrl":"https://doi.org/10.1139/cjes-2023-0097","url":null,"abstract":"Analysis of biostratigraphically dated boulders demonstrates that the Steptoean Positive Carbon Isotope Excursion (SPICE) is recorded in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation in western Newfoundland. Fifteen boulders composed of bioclastic carbonates were assigned to five faunas based on assemblages of agnostids and trilobites. The Glyptagnostus reticulatus and “ Innitagnostus” inexpectans faunas correlate into strata that record the rising limb of the SPICE in its type area of Nevada and Utah, whereas equivalents of the Acmarhachis kindlei Fauna lie in the interval that records peak δ 13 C values. The Crepicephalus and Triorygma burkhalteri faunas correlate into pre- and post-SPICE strata, respectively. δ 13 C values for boulders from the three faunas correlative with the SPICE are significantly higher than “background” levels of the pre- and post-SPICE boulders, but the maximum value in the A. kindlei Fauna (1.5‰) is less than half of the peak values recorded in Nevada and Utah. The values are, however, in line with those reported from the Port au Port Peninsula of Newfoundland, which reach 2.2‰. The differences in magnitude between Newfoundland and Nevada–Utah hint at differences in the expression of the SPICE in different geographic regions of the Laurentian continent that might reflect oceanographic conditions.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136016359","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}
Alexander L Peace, H. Sandeman, J. Welford, G. Dunning, Alfredo Camacho
The small volume, Mesozoic alkali gabbro intrusions of the Budgell Harbour and Dildo Pond stocks and associated alkaline lamprophyre dykes in Notre Dame Bay in Newfoundland are an example of onshore magmatism which may be associated with North Atlantic Ocean opening. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb dating of zircon from Budgell Harbour Stock drill core samples yielded a weighted average 206Pb/238U age of 147.9 ± 0.5 Ma (95% CI, MSWD = 0.10). Five 40Ar/39Ar laser step-heating, single phlogopite grain analyses from the Budgell Harbour and Dildo Pond stocks, plus a lamprophyre dyke, yielded ages ranging from 146.3 ± 0.2 to 149.5 ± 0.5 Ma. The data demonstrate a ca. 148 Ma (Jurassic, Tithonian) alkaline magmatic event in Newfoundland, contemporaneous with rifting and offshore basin formation. These new age data and published determinations from magmatic rocks on conjugate margins and adjacent regions reveal long-lived episodic magmatism in the embryonic North Atlantic rift environment. We propose a new model whereby magmatism occurred in Notre Dame Bay at the convergence of older crustal-scale faults and localized Moho depth variations which may have triggered lithospheric mantle melting through isothermal, distal, edge-driven upwelling related to regional extension.
{"title":"Tithonian mafic intrusions in north-central Newfoundland: link to Atlantic rifting?","authors":"Alexander L Peace, H. Sandeman, J. Welford, G. Dunning, Alfredo Camacho","doi":"10.1139/cjes-2023-0022","DOIUrl":"https://doi.org/10.1139/cjes-2023-0022","url":null,"abstract":"The small volume, Mesozoic alkali gabbro intrusions of the Budgell Harbour and Dildo Pond stocks and associated alkaline lamprophyre dykes in Notre Dame Bay in Newfoundland are an example of onshore magmatism which may be associated with North Atlantic Ocean opening. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb dating of zircon from Budgell Harbour Stock drill core samples yielded a weighted average 206Pb/238U age of 147.9 ± 0.5 Ma (95% CI, MSWD = 0.10). Five 40Ar/39Ar laser step-heating, single phlogopite grain analyses from the Budgell Harbour and Dildo Pond stocks, plus a lamprophyre dyke, yielded ages ranging from 146.3 ± 0.2 to 149.5 ± 0.5 Ma. The data demonstrate a ca. 148 Ma (Jurassic, Tithonian) alkaline magmatic event in Newfoundland, contemporaneous with rifting and offshore basin formation. These new age data and published determinations from magmatic rocks on conjugate margins and adjacent regions reveal long-lived episodic magmatism in the embryonic North Atlantic rift environment. We propose a new model whereby magmatism occurred in Notre Dame Bay at the convergence of older crustal-scale faults and localized Moho depth variations which may have triggered lithospheric mantle melting through isothermal, distal, edge-driven upwelling related to regional extension.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86335809","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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