Canadian Journal of Earth Sciences最新文献_第4页

Fluid evolution and ore genesis of Huaduoshan Cu-Mo prospect, Duobaoshan ore field, Northeastern China: Evidence from fluid inclusions, H-O-S-Pb isotopes, geochronology and geochemistry 多宝山矿田花多山铜钼远景区流体演化与矿床成因:流体包裹体、H-O-S-Pb同位素、年代学和地球化学证据

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-26 DOI: 10.1139/cjes-2022-0130

Hao–ming Li, Keyou Wang, Jianghua Geng, Wen–hao Tang, Qing-fei Sun, Xue Wang

{"title":"Fluid evolution and ore genesis of Huaduoshan Cu-Mo prospect, Duobaoshan ore field, Northeastern China: Evidence from fluid inclusions, H-O-S-Pb isotopes, geochronology and geochemistry","authors":"Hao–ming Li, Keyou Wang, Jianghua Geng, Wen–hao Tang, Qing-fei Sun, Xue Wang","doi":"10.1139/cjes-2022-0130","DOIUrl":"https://doi.org/10.1139/cjes-2022-0130","url":null,"abstract":"The Huaduoshan Cu-Mo prospect is located in the Duobaoshan orefield, Northeast China. The Cu-Mo mineralization occurs in the granodiorites as veinlet-disseminated. The ore-forming process can be divided into four mineralization stages: (I) quartz-pyrite-magnetite; (II) quartz-pyrite-chalcopyrite±molybdenite; (III) quartz-pyrite-molybdenite-chalcopyrite-sphalerite and (IV) quartz-calcite-minor pyrite. Liquid-rich two-phase aqueous (L-type), vapor-rich aqueous (V-type) and daughter-minerals three-phase (S-type) fluid inclusions (FIs) were identified at Huaduoshan. The last two types of FIs are absent in stage III-IV. The homogenization temperatures of FIs from stages I-IV are 375-438, 335-378, 283-335, and 223-267 摄氏, with corresponding salinities of 2.4-50.4, 2.1-44.9, 2.7-10.1, and 1.7-7.3 wt. % NaCl eqv., respectively. The H-O isotope data of quartz in stages I (δ18OH2O = 6.1‰ to 8.0‰, δDH2O = -102.4‰ to -94.6‰) show a magmatic origin of ore-forming fluid, the decreasing δ18OH2O (-6.8 to 3.2‰) and δDH2O (-117.1 to -98.5‰) values of quartz in stage II-IV show the fluid mixing with meteoric water. The S-Pb isotopic values (δ34S = -2.7 to 0.8‰; 206Pb/204Pb = 18.236-18.599, 207Pb/204Pb = 15.504-15.557, 208Pb/204Pb = 37.816-38.629) of pyrites indicate that the ore-forming materials are magmatic origin. Fluid boiling and mixing may be the major mechanisms of ore precipitation. Zircon U-Pb age (172.1 ± 0.5 Ma) and geochemical data indicate that the ore-related granodiorites are I-type rocks formed in subduction setting of the Paleo-Pacific Ocean Plate in Early-Middle Jurassic. In conclusion, we propose that Huaduoshan Cu-Mo prospect is a porphyry deposit and has potential for further exploration of porphyry Cu-Mo prospecting.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"45 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83722655","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}

引用次数: 0

Seismicity at the Intersection of the Coast Shear Zone and Anahim Volcanic Belt near Bella Coola, British Columbia, Canada 加拿大不列颠哥伦比亚省贝拉库拉附近海岸剪切带和阿纳希姆火山带交汇处的地震活动性

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-10 DOI: 10.1139/cjes-2023-0057

G. Littel, M. Bostock

{"title":"Seismicity at the Intersection of the Coast Shear Zone and Anahim Volcanic Belt near Bella Coola, British Columbia, Canada","authors":"G. Littel, M. Bostock","doi":"10.1139/cjes-2023-0057","DOIUrl":"https://doi.org/10.1139/cjes-2023-0057","url":null,"abstract":"In the Coast Mountains of western British Columbia, an anomalous seismicity concentration exists near the intersection of the Coast Shear Zone, a major NW-SE trending Eocene-age shear zone that accommodated deformation between the Pacific and North America plates, with the Anahim Volcanic Belt, an ENE-WSW trending zone of volcanic features that decrease in age to the east. To better characterize seismicity in the Coast Mountains, we augment the existing Natural Resources Canada seismicity catalog by applying an automatic detection and location algorithm to both permanent Canadian National Seismic Network stations and temporary stations from the 2005-2006 BATHOLITHS deployment, resulting in 837 relocated events with at least 3 paired P and S phase picks. Double-difference relocation reveals several small-scale linear strands subparallel to the Coast Shear Zone and within the Anahim Volcanic Belt, and three clusters of events striking at a high angle to the Coast Shear Zone that occurred as swarms in 2015 and 2017. First-motion focal mechanisms exhibit extensional and strike-slip faulting. Our observations indicate that most of these events are not associated with surficial processes such as landslides, but rather, we hypothesize that interaction of the Anahim Volcanic Belt and Coast Shear Zone has weakened the lithosphere in this region leading to current-day strain localization and high heat flow that manifest seismicity including swarm-like activity.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"17 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84585808","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}

引用次数: 0

Geochronology, petrogenesis, and mineralization potential of the syenogranites in the Yama fluorite deposit, Tataleng granitic batholith, Qilian Orogen, NW China 祁连造山带他塔棱花岗岩基阎罗萤石矿床正长花岗岩年代学、成因及成矿潜力

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-10 DOI: 10.1139/cjes-2023-0044

He Jiao, Haifeng Lu, Guo-Biao Huang, Qiang-Qiang Cui, Q. Ding, Xuan Zhou, Ruiing Wu

{"title":"Geochronology, petrogenesis, and mineralization potential of the syenogranites in the Yama fluorite deposit, Tataleng granitic batholith, Qilian Orogen, NW China","authors":"He Jiao, Haifeng Lu, Guo-Biao Huang, Qiang-Qiang Cui, Q. Ding, Xuan Zhou, Ruiing Wu","doi":"10.1139/cjes-2023-0044","DOIUrl":"https://doi.org/10.1139/cjes-2023-0044","url":null,"abstract":"The Yama fluorite deposit in the Qilian Orogen in NW China is characterized by predominant granitic magmatism and fluorite mineralization. The wall rocks hosting the fluorite–quartz veins in the Yama area consist of the Yama porphyritic syenogranite and the Wulandawu syenogranite. In this study, the major and trace element compositions, zircon U–Pb ages, and zircon Hf isotopes and trace element compositions were investigated. Two samples for the Yama porphyritic syenogranite yielded weighted mean 206Pb/238U zircon ages of 440.7±4.8 Ma and 447.9±6.0 Ma, and one sample for the Wulandawu syenogranite yielded a weighted mean 206Pb/238U zircon age of 441.2±5.0 Ma, all of which indicate a Late Ordovician to Early Silurian crystallization age. Geochemically, both syenogranites are peraluminous, with high alkali contents, low Zr+Nb+Ce+Y contents, relatively low (K2O+Na2O)/CaO ratios, and high Rb/Sr and Rb/Ba ratios, suggesting that they are fractionated S-type granites. They have zircon εHf(t) values of –14.9 to –4.4 and −12.2 to −4.5, respectively, suggesting that they were derived from the partial melting of pelitic-rich sources within the relatively shallow Paleoproterozoic reworked crust. The detailed geochronological and geochemical data suggest that the studied syenogranites were emplaced in a post-collisional setting related to the closure of the South Qilian Ocean. Finally, they have relatively low quantitative oxygen fugacity (fO2) values, indicating relatively reduced redox states, but their very low zircon Ce4+/Ce3+ ratios, low whole-rock K/Rb ratios, relatively high Nb/Ta ratios, and low Zr/Hf ratios suggest that they are not likely to form important W-Sn deposits and related fluorite deposits.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"17 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81297691","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}

引用次数: 0

Coseismic Coulomb Stress Changes on Intraplate Faults in the Western Quebec Seismic Zone Following Three Major Earthquakes in the Past Century 上个世纪三次大地震后西魁北克地震带板内断层同震库仑应力变化

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-10 DOI: 10.1139/cjes-2023-0025

J. Rimando, A. Peace, K. Goda, Navid Sirous, P. Rosset, L. Chouinard

{"title":"Coseismic Coulomb Stress Changes on Intraplate Faults in the Western Quebec Seismic Zone Following Three Major Earthquakes in the Past Century","authors":"J. Rimando, A. Peace, K. Goda, Navid Sirous, P. Rosset, L. Chouinard","doi":"10.1139/cjes-2023-0025","DOIUrl":"https://doi.org/10.1139/cjes-2023-0025","url":null,"abstract":"There is currently no active fault map for the intraplate western Quebec seismic zone (WQSZ) in eastern Canada, and consequently, no detailed finite-fault source models which are critical for seismic hazard assessments in this region with a rapidly growing population. While previous numerical stress modelling studies have shown that mostly NNW-SSE to NW-SE-striking faults exhibit the highest potential for reactivation under the present-day tectonic stress field, such modelling is unable to take into account the interaction of faults and earthquakes. This study attempts to identify possible future rupture zones using Coulomb stress analysis. We explore the static stress transfer caused by the 1935 M_W 6.1 Témiscaming, 1944 M_W 5.8 Cornwall-Massena, and the 2013 M_W 4.7 Ladysmith earthquakes, which are proximal to faults in the WQSZ that exhibit a relatively high reactivation potential, to determine if they have an increased potential for failure. The significance of Coulomb stress changes (ΔCFS) observed on the nearby ‘receiver’ faults varied widely. Among the events analyzed in this study, only the 1935 M_W 6.1 Témiscaming earthquake caused extensively positive ΔCFS (≥ 0.1 Bar) on its receiver fault. The areal extent of the receiver fault that has been promoted to failure suggests that earthquakes with a comparable magnitude to the 1935 event can be triggered. This work is the first attempt to provide a physical basis for seismic hazard assessment input parameters in the WQSZ based on the results of numerical stress modelling.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"11 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78751154","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}

引用次数: 0

Origin of gases and waters from a hypersaline, carbonate spring on Anticosti Island, Québec, Canada 加拿大魁姆海省安提科斯蒂岛一个高盐碳酸盐温泉的气体和水的来源

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-05 DOI: 10.1139/cjes-2023-0019

P. Daoust, I. Clark, A. Desrochers

{"title":"Origin of gases and waters from a hypersaline, carbonate spring on Anticosti Island, Québec, Canada","authors":"P. Daoust, I. Clark, A. Desrochers","doi":"10.1139/cjes-2023-0019","DOIUrl":"https://doi.org/10.1139/cjes-2023-0019","url":null,"abstract":"Hypersaline spring water (TDS ∼ 85 g/L) and gas are escaping from the top of a calcite travertine mound on Anticosti Island. This mound is located in the Chaloupe River area above the Jupiter Fault which cuts through the Ordovician formations in the subsurface, including the oil and gas-rich Macasty Shale Formation. The Cl content is approximately 3 times that of seawater, but the geochemical profile indicates it to be a Paleozoic basin brine (geogenic He = 2E–7 cc/cc) evaporatively enriched beyond halite saturation (Br:Cl molar ratio = 0.0022 ± 0.00013) that has been diluted by some 73 ± 6% with meteoric waters. Measurable tritium (3.4 TU) indicates this to be a mixture of modern and Holocene recharge. The radioiodine (129I < 10 million atoms/L) is a three-component mixture of geogenic and post-nuclear contributions with low levels in pre-nuclear Holocene recharge. Degassing at the vent (1% to 2% CO2, PCO2 = 0.02 atm, >90% CH4) provokes calcite precipitation and travertine mound formation. Methane comprises a thermo-catalytic component and a biogenic component produced at depth in the organic-rich Macasty Formation by reduction of surface-derived dissolved inorganic carbon (DIC; a14C = 3.5 pMC), producing enriched δ13CDIC values recorded in the travertine. The occurrence of basin-derived brine and gas discharging in association with the surface expression of the Jupiter fault implies that this fault provides a pathway for deep circulation of meteoric waters, likely driven by the relief on the island.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"27 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84066636","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}

引用次数: 0

Calibrating geologic strata, dinosaurs, and other fossils at Dinosaur Provincial Park (Alberta, Canada) using a new CA-ID-TIMS U–Pb geochronology 使用新的CA-ID-TIMS U-Pb地质年代学校准加拿大亚伯达省恐龙省立公园的地质地层、恐龙和其他化石

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-05 DOI: 10.1139/cjes-2023-0037

D. Eberth, David C Evans, J. Ramezani, S. Kamo, Caleb M. Brown, P. Currie, D. R. Braman

{"title":"Calibrating geologic strata, dinosaurs, and other fossils at Dinosaur Provincial Park (Alberta, Canada) using a new CA-ID-TIMS U–Pb geochronology","authors":"D. Eberth, David C Evans, J. Ramezani, S. Kamo, Caleb M. Brown, P. Currie, D. R. Braman","doi":"10.1139/cjes-2023-0037","DOIUrl":"https://doi.org/10.1139/cjes-2023-0037","url":null,"abstract":"The 100 m thick stratigraphic section exposed at Dinosaur Provincial Park (DPP, southern Alberta) contains bentonites that have been used for more than 30 years to date DPP's rocks and fossils using the K-Ar decay scheme. Limited reproducibility among different vintages of K-Ar and 40Ar/39Ar ages inhibited the development of a high resolution chronostratigraphy. Here we employ and further test a recently completed CA-ID-TIMS U–Pb geochronology and associated age-stratigraphy model to update temporal constraints on the Park’s bentonites, formational contacts, and other markers. In turn, we document rock accumulation rates, and calibrate ages and durations of informal megaherbivore dinosaur assemblage zones and other biozones. Weighted mean 206Pb/238U ages from five bentonites range from 76.718 ± 0.020 Ma to 74.289 ± 0.014 Ma (2σ internal uncertainties) through an interval of 88.75 m, indicating a duration of ~2.43 Myr and an overall rock accumulation rate of 3.65 ± 0.04 cm/ka. An increase in rate above the Oldman-Dinosaur Park formational contact conforms to a regionally expressed pattern of increased accommodation at ~76.3 Ma across Alberta and Montana. Palynological biozone data suggest a condensed section/hiatus in the uppermost portion of the Oldman Formation. Dinosaur assemblage zones exhibit durations of ~600–700 kyr and are significantly shorter than those in the overlying Horseshoe Canyon Formation. A decreased rate in dinosaur-assemblage turnovers in the last eight million years of the Mesozoic in western Canada may be explained by withdrawal of the Western Interior Seaway and the expansion of ecologically homogenous lowlands in its wake.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"54 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72562048","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}

引用次数: 0

Paradoxical mid-crustal displacements and stratigraphic continuity: structural evolution of the northeastern Paleoproterozoic Amer belt, Nunavut, Canada 矛盾的中地壳位移与地层连续性:加拿大努纳武特东北古元古代阿米尔带的构造演化

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-01 DOI: 10.1139/cjes-2022-0083

J. White, Lydia Calhoun, C. Jefferson

{"title":"Paradoxical mid-crustal displacements and stratigraphic continuity: structural evolution of the northeastern Paleoproterozoic Amer belt, Nunavut, Canada","authors":"J. White, Lydia Calhoun, C. Jefferson","doi":"10.1139/cjes-2022-0083","DOIUrl":"https://doi.org/10.1139/cjes-2022-0083","url":null,"abstract":"The structural geology of the northeastern Paleoproterozoic Amer belt, central Nunavut, has been evaluated in light of new field mapping combined with legacy data and independently acquired subsurface geophysics data. Proterozoic sequences Ps1–Ps4 of the Amer supergroup unconformably overlie Archean basement. Of these sequences, Ps1–Ps3 have been intensely deformed (D1) in association with the Snowbird Orogeny (2.05–1.865 Ga). Ps4 was deposited unconformably on the first three sequences and exhibits none of the D1 effects. Deformation within Ps4 is slight compared to the underlying sequences and is restricted to D2 folding that occurred in the 1.84–1.81 Ga Hudsonian Orogeny. Deformation of sequences Ps1–Ps3 forms the core of this study. D1 comprises imbricate thrusting, intersequence detachment, and three generations of isoclinal folding and transposition. The stratigraphic order is maintained in many areas by decoupling of sequence packages along incompetent units so as not to “mix” lithologies; there is a fundamental mechanical stratigraphy. Within sequences, transposition can be otherwise intense. The resultant architecture is a shallowly southwest-dipping sequence of tectonically rotated and transposed layering (primary and tectonic) similar in many ways in orientation regardless of whether preserved with original bedding features or completely transposed. D1 folding is characterized by recumbent folds, noncylindrical folds that are sometimes rooted in detachments, verging to the northeast. D2 folding is controlled by the pre-existing large-scale D1 fabric, resulting in the overturned synforms that parallel the belt. Post-D2 fault modification of northern side of the belt along northwest-trending faults is interpreted to relate to extension and exhumation.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"22 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87652044","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}

引用次数: 1

Understanding the Precambrian: a collection of papers in celebration of the life and work of Grant McAdam Young (1937–2020) 理解前寒武纪:纪念格兰特·麦克亚当·杨(1937-2020)的生活和工作的论文集

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-07-01 DOI: 10.1139/cjes-2022-0111

D. Long, C. Jefferson, R. Rainbird, Patricia Corcoran

引用次数: 0

Cheakamus Basalt Lavas, British Columbia: A Pleistocene record of rapid, continuous eruption within a mountainous drainage system 契卡穆斯玄武岩熔岩，不列颠哥伦比亚省:在山区排水系统中快速持续喷发的更新世记录

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-06-27 DOI: 10.1139/cjes-2023-0004

A. Borch, J. Russell, R. Barendregt

{"title":"Cheakamus Basalt Lavas, British Columbia: A Pleistocene record of rapid, continuous eruption within a mountainous drainage system","authors":"A. Borch, J. Russell, R. Barendregt","doi":"10.1139/cjes-2023-0004","DOIUrl":"https://doi.org/10.1139/cjes-2023-0004","url":null,"abstract":"The Cheakamus basalts are voluminous (1.65 km3) Late Pleistocene, valley-filling lavas erupted from a vent situated near Conflict Lake, in the alpine Callaghan Valley near Whistler, British Columbia. Geochemical and petrographic properties suggest these olivine-plagioclase porphyritic basalts derive from a single magma batch affected by minor sorting of phenocrysts and xenocrystic plagioclase. Thirty-four sites sampled for paleomagnetic direction measurement record a mean pole direction of 345.2 ̊ / 73.0 ̊ (α95 = 1.3°), showing no statistical variation nor drift with stratigraphic position. These data suggest the lavas were emplaced in a single paleomagnetic moment – a period of time significantly less than 2,000 years. 40Ar/39Ar geochronometry on three samples return a weighted mean age estimate of 15.95 ± 7.9 ka (2s) and field evidence, including till-covered, well-glaciated lava flow surfaces, indicate the eruption coincided with the early stages of the Fraser glaciation (~18-20 ka). The lavas preserve features indicative of a landscape hosting diverse and dynamic paleoenvironments. Subaerial eruption of basalt filled an ice-free Callaghan Creek drainage before inundating and damming the paleo-Cheakamus River, creating an upstream rising body of water. Periodic lava-dam overtopping resulted in syn-eruptive intermittent flooding of lava surfaces, expressed by discontinuous interflow sediment lenses. Rare instances of enigmatic cooling columns may also indicate localized ice-contact with glaciers that partially filled the Cheakamus Valley. The displacement of the modern Cheakamus River and the formation of Callaghan and Conflict Lakes via long-term lava-damming remain direct indicators of the impact basaltic eruptions have on the geomorphology of valley systems.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"7 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87569185","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}

引用次数: 1

Geodynamic studies of southwestern Canada: Subduction zone processes and backarc mantle dynamics 加拿大西南部地球动力学研究:俯冲带过程和弧后地幔动力学

IF 1.4 4区地球科学

Canadian Journal of Earth Sciences Pub Date : 2023-06-27 DOI: 10.1139/cjes-2022-0140

C. Currie, Tai‐Chieh Yu

{"title":"Geodynamic studies of southwestern Canada: Subduction zone processes and backarc mantle dynamics","authors":"C. Currie, Tai‐Chieh Yu","doi":"10.1139/cjes-2022-0140","DOIUrl":"https://doi.org/10.1139/cjes-2022-0140","url":null,"abstract":"Geodynamic models allow insights into the processes that control lithosphere structure and evolution. Here, we highlight geodynamic studies along a profile through southwestern Canada, from the Cascadia subduction zone into the Laurentian craton. Geophysical and geological observations show distinct changes in thermal structure along this profile. One major change is between the cool forearc and hot volcanic arc. This marks the transition from (1) a stagnant forearc mantle that is cooled by the subducting Juan de Fuca Plate to (2) an advection-dominated arc region, where high temperatures arise from mantle flow driven by the subducting plate (corner flow). High temperatures occur for 400-500 km east of the arc to the Rocky Mountain Trench (RMT), where lithosphere thickness increases from 60-70 km below the Cordillera to >200 km below the craton. The timing of Cordillera lithosphere thinning is debated. A long-lived (>100 Ma) thin lithosphere inherited from earlier tectonics requires vigorous convection of a weak, hydrated mantle. Conversely, thinning may have occurred through gravitational removal of the lower lithosphere in the Eocene. Models show that a removal event only allows for a short-lived thin lithosphere (~25 Myr), owing to conductive cooling. Even if there was Eocene delamination, the present-day thin lithosphere requires small-scale convection in the Cordillera mantle. The thermal contrast across the RMT is enhanced by edge-driven convection at the Cordillera-craton lithosphere step. The step itself is an enigmatic feature, and its long-term preservation requires that the craton mantle lithosphere is strong (dry) with moderate chemical depletion.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"116 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80753857","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}

引用次数: 0