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":"2011 1","pages":""},"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}
Sandra M. Barr, Chris E. White, Teodoro Palacios, Sören Jensen, Deanne van Rooyen, James L. Crowley
{"title":"Reply to the Discussion by Landing and Geyer on “The Terreneuvian MacCodrum Brook section, Mira terrane, Cape Breton Island, Nova Scotia, Canada: age constraints from ash layers, organic-walled microfossils, and trace fossils”","authors":"Sandra M. Barr, Chris E. White, Teodoro Palacios, Sören Jensen, Deanne van Rooyen, James L. Crowley","doi":"10.1139/cjes-2023-0056","DOIUrl":"https://doi.org/10.1139/cjes-2023-0056","url":null,"abstract":"","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136116693","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}
T. Hamilton, R. Enkin, Zhen Li, J. Bednarski, D. C. Stacey, M. McGann, B. Jensen
Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia’s central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and glacial facies. The lavas are within-plate, differentiated (low MgO<7%) Ocean Island Basalts, hawaiites, and mugearites which formed from ~1% decompression melting of asthenosphere with residual garnet. Kitasu Hill, on glaciated bedrock, formed between 18-15 cal ka BP. Dipping, poorly stratified, admixed hyaloclastite and glacial diamicton with large plutonic clasts and pillow breccia comprise its basal tuya platform (0-43 masl). Subaerial nested cinder cones, with smaller capping lava flows, sit atop the tuya. New marine samples show McGregor Cone formed subaerially but now sits submerged at 43-200 mbsl on an eroded moraine at the mouth of Finlayson Channel. Seismic data and cores reveal glaciomarine sediments draping the cone’s lower slopes and show beach terraces. Cores contain glaciomarine diamictons, ice rafted debris, delicate glassy air fall tephra, and shallow, sublittoral, and deeper benthic foraminifera. Dates of 14.1–11.2 cal ka BP show volcanism spanned ~2000 years during floating ice shelf conditions. The MSV have similar proximal positions to the retreating ice sheet, display mixed volcano-glacial facies, and experienced similar unloading stresses during deglaciation. The MSV may represent deglacially triggered volcanism. The dates, geomorphic and geological evidence, constrain a local relative sea level curve for Milbanke Sound and show how ice gave way to fire.
随着威斯康辛冰盖从海岸山脉撤退，北苏山和麦格雷戈火山沿着不列颠哥伦比亚省中部海岸的普林西比拉雷多断层形成。这些小体积的米尔班克海峡火山(MSV)为火山相与冰川相之间的密切关系提供了重要证据。岩浆为板块内分异(低MgO<7%)洋岛玄武岩、夏威夷岩和杂色岩，由软流圈减压融化~1%形成，残留石榴石。北须山位于冰川基岩上，形成于18-15 cal ka BP之间。其基底图雅台地(0-43岩体)为倾斜、层状差、混合透明碎屑岩和冰川碎屑岩与大深成碎屑岩和枕角砾岩组成。地面上嵌套的火山渣锥，覆盖着较小的熔岩流，坐落在火山口之上。新的海洋样本显示，麦格雷戈火山是在水下形成的，但现在位于芬利森海峡口被侵蚀的冰碛上，水深43-200米。地震数据和岩心显示，冰川期海洋沉积物覆盖着圆锥体的较低斜坡，并显示出海滩梯田。岩心中含有冰川期海洋碎屑、浮冰碎屑、精致的玻璃状空气坠层，以及浅层、海底和更深的底栖有孔虫。14.1 ~ 11.2 cal ka BP表明，在浮冰架条件下，火山活动持续了~2000年。MSV与退缩冰盖的近端位置相似，表现为火山-冰川混合相，在消冰过程中经历了相似的卸载应力。MSV可能代表冰川消融引发的火山活动。这些日期、地貌和地质证据限制了米尔班克海峡当地的相对海平面曲线，并展示了冰是如何让位于火的。
{"title":"Where Ice Gave Way to Fire: Deglacial Volcanic Activity at the Edge of the Coast Mountains in Milbanke Sound, B.C.","authors":"T. Hamilton, R. Enkin, Zhen Li, J. Bednarski, D. C. Stacey, M. McGann, B. Jensen","doi":"10.1139/cjes-2023-0080","DOIUrl":"https://doi.org/10.1139/cjes-2023-0080","url":null,"abstract":"Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia’s central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and glacial facies. The lavas are within-plate, differentiated (low MgO<7%) Ocean Island Basalts, hawaiites, and mugearites which formed from ~1% decompression melting of asthenosphere with residual garnet. Kitasu Hill, on glaciated bedrock, formed between 18-15 cal ka BP. Dipping, poorly stratified, admixed hyaloclastite and glacial diamicton with large plutonic clasts and pillow breccia comprise its basal tuya platform (0-43 masl). Subaerial nested cinder cones, with smaller capping lava flows, sit atop the tuya. New marine samples show McGregor Cone formed subaerially but now sits submerged at 43-200 mbsl on an eroded moraine at the mouth of Finlayson Channel. Seismic data and cores reveal glaciomarine sediments draping the cone’s lower slopes and show beach terraces. Cores contain glaciomarine diamictons, ice rafted debris, delicate glassy air fall tephra, and shallow, sublittoral, and deeper benthic foraminifera. Dates of 14.1–11.2 cal ka BP show volcanism spanned ~2000 years during floating ice shelf conditions. The MSV have similar proximal positions to the retreating ice sheet, display mixed volcano-glacial facies, and experienced similar unloading stresses during deglaciation. The MSV may represent deglacially triggered volcanism. The dates, geomorphic and geological evidence, constrain a local relative sea level curve for Milbanke Sound and show how ice gave way to fire.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"24 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87794465","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}
G. Hartman, S. Pawley, D. Utting, N. Atkinson, J. Liggett
Basal gravel and sand mantling the bedrock floors of buried valleys throughout the Canadian Interior Plains, and conformably overlying proglacial lacustrine sediment, comprise the Empress Group. While previously conceptualized as stratigraphically equivalent deposits of preglacial rivers prior to the first and most extensive continental and montane glaciations, subsequent stratigraphic studies indicated that buried valley basal gravel must have been deposited between, or during, progressively more extensive continental glaciations and could not be stratigraphically equivalent throughout the buried valley network. However, in the general absence of formation-rank stratigraphic description of basal gravel units that might better inform the geologic history of the deposits, most workers simply consider Empress Group sediments time-transgressive. In this paper we examine basal gravel at provincial and regional scales to understand its genesis and geologic history. At the provincial scale we map basal gravel in three dimensions using a novel machine learning approach. At the regional scale we formally define basal gravel formations at either end of the largest buried valley system in Alberta, which informs its glacial history and physiographic development, and shows the importance of formation-rank stratigraphic description. Our results indicate that the buried valley network across Alberta is palimpsest in genesis and basal gravel units within it are chronostratigraphically intercalated between tills. We advocate that the Empress Group definition be extended across Alberta with modifications to improve its clarity and utility, and formally define the Old Fort, Unchaga, Ipiatik, and Winefred formations as part of the Empress Group.
{"title":"The Empress Group in Alberta, Canada","authors":"G. Hartman, S. Pawley, D. Utting, N. Atkinson, J. Liggett","doi":"10.1139/cjes-2022-0143","DOIUrl":"https://doi.org/10.1139/cjes-2022-0143","url":null,"abstract":"Basal gravel and sand mantling the bedrock floors of buried valleys throughout the Canadian Interior Plains, and conformably overlying proglacial lacustrine sediment, comprise the Empress Group. While previously conceptualized as stratigraphically equivalent deposits of preglacial rivers prior to the first and most extensive continental and montane glaciations, subsequent stratigraphic studies indicated that buried valley basal gravel must have been deposited between, or during, progressively more extensive continental glaciations and could not be stratigraphically equivalent throughout the buried valley network. However, in the general absence of formation-rank stratigraphic description of basal gravel units that might better inform the geologic history of the deposits, most workers simply consider Empress Group sediments time-transgressive. In this paper we examine basal gravel at provincial and regional scales to understand its genesis and geologic history. At the provincial scale we map basal gravel in three dimensions using a novel machine learning approach. At the regional scale we formally define basal gravel formations at either end of the largest buried valley system in Alberta, which informs its glacial history and physiographic development, and shows the importance of formation-rank stratigraphic description. Our results indicate that the buried valley network across Alberta is palimpsest in genesis and basal gravel units within it are chronostratigraphically intercalated between tills. We advocate that the Empress Group definition be extended across Alberta with modifications to improve its clarity and utility, and formally define the Old Fort, Unchaga, Ipiatik, and Winefred formations as part of the Empress Group.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83552575","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}
D. Milidragovic, L. Ootes, A. Zagorevski, N. Cleven, C. Wall, Yan Luo, R. Friedman
Detrital zircon from three coarse-grained marine siliciclastic rocks was analyzed for U-Pb, Lu-Hf, and trace element compositions to constrain the timing of deposition and sediment provenance of the Cunningham Lake formation (formerly siliciclastic unit of the Sitlika assemblage) in north-central British Columbia. This strategy tests previously proposed sedimentary linkages between the Cache Creek terrane and the westerly rocks of the Stikine terrane. All three samples indicate maximum depositional ages at ca. 205-202 Ma (Rhaetian). The samples contain a predominant ca. 225-215 Ma detrital population, sourced from proximal contemporaneous volcanic arcs, and minor Permian to Middle Triassic and Carboniferous arc-derived detrital populations. The absence of Precambrian grains is consistent with the strongly suprachondritic zircon compositions (Hf(t) =+7 to +20), and indicates exclusively juvenile sources for the Cunningham Lake formation. Late Triassic sources of zircon are not known in the Cache Creek terrane and, except within western Stikine terrane, are uncommon among the Intermontane terranes that amalgamated with the Cache Creek terrane during Late Triassic-Early Jurassic. The Stikine suite (ca. 230-214 Ma) and coeval volcanic rocks in western Stikinia are the most probable sources of Late Triassic detritus for the Cunningham Lake formation. Stikinia’s Paleozoic basement is the probable source of Carboniferous detrital zircon. Volcanic arc-backarc complexes in the Cache Creek terrane are the most likely sources of Permian to Middle-Triassic detritus in the Intermontane terranes. Accordingly, the siliciclastic rocks of the Cunningham Lake formation represent an overlap sedimentary succession that links Stikinia to the Cache Creek terrane by the latest Triassic.
{"title":"Detrital geochronology of the Cunningham Lake formation: an overlap succession linking Cache Creek terrane to Stikinia at ~205 Ma","authors":"D. Milidragovic, L. Ootes, A. Zagorevski, N. Cleven, C. Wall, Yan Luo, R. Friedman","doi":"10.1139/cjes-2023-0018","DOIUrl":"https://doi.org/10.1139/cjes-2023-0018","url":null,"abstract":"Detrital zircon from three coarse-grained marine siliciclastic rocks was analyzed for U-Pb, Lu-Hf, and trace element compositions to constrain the timing of deposition and sediment provenance of the Cunningham Lake formation (formerly siliciclastic unit of the Sitlika assemblage) in north-central British Columbia. This strategy tests previously proposed sedimentary linkages between the Cache Creek terrane and the westerly rocks of the Stikine terrane. All three samples indicate maximum depositional ages at ca. 205-202 Ma (Rhaetian). The samples contain a predominant ca. 225-215 Ma detrital population, sourced from proximal contemporaneous volcanic arcs, and minor Permian to Middle Triassic and Carboniferous arc-derived detrital populations. The absence of Precambrian grains is consistent with the strongly suprachondritic zircon compositions (Hf(t) =+7 to +20), and indicates exclusively juvenile sources for the Cunningham Lake formation. Late Triassic sources of zircon are not known in the Cache Creek terrane and, except within western Stikine terrane, are uncommon among the Intermontane terranes that amalgamated with the Cache Creek terrane during Late Triassic-Early Jurassic. The Stikine suite (ca. 230-214 Ma) and coeval volcanic rocks in western Stikinia are the most probable sources of Late Triassic detritus for the Cunningham Lake formation. Stikinia’s Paleozoic basement is the probable source of Carboniferous detrital zircon. Volcanic arc-backarc complexes in the Cache Creek terrane are the most likely sources of Permian to Middle-Triassic detritus in the Intermontane terranes. Accordingly, the siliciclastic rocks of the Cunningham Lake formation represent an overlap sedimentary succession that links Stikinia to the Cache Creek terrane by the latest Triassic.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"47 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77573941","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}
The upper Silurian(?) to Lower Devonian (Lochkovian) Clam Bank Formation is the most northerly exposed middle Paleozoic foreland-basin succession in the Appalachian orogen. Understanding of its sedimentary history is poor, and there are contradictory interpretations of placement of its lower structural boundary. Our study redefines the lithostratigraphy and subdivides the ∼600 m thick formation into three paleoenvironmental successions: a lower coastal plain setting with fluvial channels giving way upsection to coastal flats with carbonate, colluvium with reworked paleosol material, and aeolian (silt) deposits; a middle coastal zone succession following marine transgression and deposition of shoreface sandstone; and an upper alluvial succession host to pedogenic and groundwater calcretes. A basal disconformity, though not exposed, is inferred from lithic and geochemical evidence for sediment mixing with underlying Upper Ordovician sources in the lowermost part of the formation. This supports previous interpretations of Silurian uplift along the Laurentian margin in response to the Salinian orogeny. Sedimentary provenance indicates quartzo-feldspathic sources throughout the formation, and sediment-transport indicators identify a northeast–southwest-oriented basin with northwest-directed fluvial input. U–Pb detrital zircon distributions associated with the paleocolluvium and younger transgressive sandstone document upsection loss of prominent age peaks of late Grenville (∼0.98 Ga) and pre-Grenville (1.5, 1.65, and 1.75 Ga) sources. The coastal plain succession and related detrital-zircon signature imply a mixture of distal and proximal sediment sources, the latter related to erosion of a weathered upland and exhumed Precambrian inliers in western Newfoundland. A more regional provenance signature with marine transgression suggests sediment transport in response to Acadian orogenesis.
{"title":"Initial development and sedimentary provenance of a middle Paleozoic foreland basin: Clam Bank Formation, western Newfoundland","authors":"G. Dix, G. Pignotta, S. White","doi":"10.1139/cjes-2022-0092","DOIUrl":"https://doi.org/10.1139/cjes-2022-0092","url":null,"abstract":"The upper Silurian(?) to Lower Devonian (Lochkovian) Clam Bank Formation is the most northerly exposed middle Paleozoic foreland-basin succession in the Appalachian orogen. Understanding of its sedimentary history is poor, and there are contradictory interpretations of placement of its lower structural boundary. Our study redefines the lithostratigraphy and subdivides the ∼600 m thick formation into three paleoenvironmental successions: a lower coastal plain setting with fluvial channels giving way upsection to coastal flats with carbonate, colluvium with reworked paleosol material, and aeolian (silt) deposits; a middle coastal zone succession following marine transgression and deposition of shoreface sandstone; and an upper alluvial succession host to pedogenic and groundwater calcretes. A basal disconformity, though not exposed, is inferred from lithic and geochemical evidence for sediment mixing with underlying Upper Ordovician sources in the lowermost part of the formation. This supports previous interpretations of Silurian uplift along the Laurentian margin in response to the Salinian orogeny. Sedimentary provenance indicates quartzo-feldspathic sources throughout the formation, and sediment-transport indicators identify a northeast–southwest-oriented basin with northwest-directed fluvial input. U–Pb detrital zircon distributions associated with the paleocolluvium and younger transgressive sandstone document upsection loss of prominent age peaks of late Grenville (∼0.98 Ga) and pre-Grenville (1.5, 1.65, and 1.75 Ga) sources. The coastal plain succession and related detrital-zircon signature imply a mixture of distal and proximal sediment sources, the latter related to erosion of a weathered upland and exhumed Precambrian inliers in western Newfoundland. A more regional provenance signature with marine transgression suggests sediment transport in response to Acadian orogenesis.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"61 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74818203","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}
The Dunnage Zone of the Newfoundland Appalachians hosts diverse Cambrian–Ordovician volcanogenic massive sulfide (VMS) deposits. The peri-Laurentian Notre Dame Subzone contains Cu–Zn–Au mafic and bimodal mafic deposits in ∼501–485 Ma ophiolitic rocks and Zn–Pb–Cu–(Au–Ag) deposits in ∼471–465 Ma bimodal rifted continental arc sequences (e.g., Buchans). The peri-Gondwanan rocks of the Exploits Subzone host Zn–Pb–Cu–(Au–Ag) bimodal felsic, felsic siliciclastic, and Zn–Ag–Au hybrid bimodal felsic deposits in the ∼513–486 Ma Victoria Lake supergroup; Cu–Zn bimodal felsic to bimodal mafic deposits of the ∼486 Ma Wild Bight Group; and Cu–(Au) mafic siliciclastic deposits of the ∼466 Ma Great Burnt Lake/South Pond belt. Regardless of age or stratigraphic hosts, all VMS deposits are associated with specific magmatic assemblages and extensional tectonism (i.e., rifting). Gold-enriched deposits of the Rambler-Ming district are associated with felsic rocks that formed via slab melting and subsequent melt-mantle wedge interaction, which likely enhanced precious metal enrichment in these deposits. Whereas many deposits exhaled on the seafloor, some deposits formed via subseafloor replacement of host units or as re-sedimented sulfides generated in sediment-gravity flows. Metals in the deposits were derived from leaching of underlying footwall rocks; however, Au–Ag- and epithermal suite element-enriched deposits show evidence for metal contributions from magmatic hydrothermal fluids. Sulfur in deposits was derived predominantly from leaching of H 2 S from underlying footwall rocks and from thermochemical sulfate reduction of seawater sulfate, with lesser input from bacteria-derived H 2 S and magmatic-hydrothermal-derived H 2 S. Despite recent research advances and historic mining, numerous questions remain unresolved and provide opportunities for future study.
纽芬兰-阿巴拉契亚的垫层带拥有多种寒武纪-奥陶系火山块状硫化物矿床。约laurentian Notre Dame亚带包含~ 501-485 Ma蛇绿岩中的Cu-Zn-Au基性和双峰基性矿床，以及~ 471-465 Ma双峰裂陷大陆弧序列(如Buchans)中的Zn-Pb-Cu - (Au-Ag)矿床。在~ 513-486 Ma维多利亚湖超群中，发育Zn-Pb-Cu - (Au-Ag)双峰长英质、长英质硅塑性和Zn-Ag-Au混合双峰长英质矿床;~ 486 Ma Wild Bight群Cu-Zn双峰长晶-双峰镁铁质矿床~ 466 Ma Great burn Lake/South Pond带的Cu - (Au)基性硅质碎屑矿床。无论年龄或地层寄主如何，所有VMS矿床都与特定的岩浆组合和伸展构造(即裂陷)有关。Rambler-Ming地区的富金矿床与长英质岩有关，长英质岩是通过板块熔融和随后的熔融-地幔楔体相互作用形成的，可能增强了这些金矿床的贵金属富集。虽然许多沉积物在海底呼出，但有些沉积物是通过海底替换宿主单元或作为沉积物重力流产生的再沉积硫化物而形成的。矿床中的金属来源于下伏下盘岩石的浸出;而富含Au-Ag和浅成热液组元素的矿床显示岩浆热液对金属的贡献。矿床中的硫主要来自下伏下盘岩石的h2s浸出和海水硫酸盐的热化学硫酸盐还原，细菌衍生的h2s和岩浆热液衍生的h2s的输入较少。尽管最近的研究进展和历史采矿，许多问题仍未解决，并为未来的研究提供了机会。
{"title":"Volcanogenic massive sulfide (VMS) deposits of the Dunnage Zone of the Newfoundland Appalachians: setting, styles, key advances, and future research","authors":"Stephen J. Piercey, John Hinchey, Greg W. Sparkes","doi":"10.1139/cjes-2022-0148","DOIUrl":"https://doi.org/10.1139/cjes-2022-0148","url":null,"abstract":"The Dunnage Zone of the Newfoundland Appalachians hosts diverse Cambrian–Ordovician volcanogenic massive sulfide (VMS) deposits. The peri-Laurentian Notre Dame Subzone contains Cu–Zn–Au mafic and bimodal mafic deposits in ∼501–485 Ma ophiolitic rocks and Zn–Pb–Cu–(Au–Ag) deposits in ∼471–465 Ma bimodal rifted continental arc sequences (e.g., Buchans). The peri-Gondwanan rocks of the Exploits Subzone host Zn–Pb–Cu–(Au–Ag) bimodal felsic, felsic siliciclastic, and Zn–Ag–Au hybrid bimodal felsic deposits in the ∼513–486 Ma Victoria Lake supergroup; Cu–Zn bimodal felsic to bimodal mafic deposits of the ∼486 Ma Wild Bight Group; and Cu–(Au) mafic siliciclastic deposits of the ∼466 Ma Great Burnt Lake/South Pond belt. Regardless of age or stratigraphic hosts, all VMS deposits are associated with specific magmatic assemblages and extensional tectonism (i.e., rifting). Gold-enriched deposits of the Rambler-Ming district are associated with felsic rocks that formed via slab melting and subsequent melt-mantle wedge interaction, which likely enhanced precious metal enrichment in these deposits. Whereas many deposits exhaled on the seafloor, some deposits formed via subseafloor replacement of host units or as re-sedimented sulfides generated in sediment-gravity flows. Metals in the deposits were derived from leaching of underlying footwall rocks; however, Au–Ag- and epithermal suite element-enriched deposits show evidence for metal contributions from magmatic hydrothermal fluids. Sulfur in deposits was derived predominantly from leaching of H 2 S from underlying footwall rocks and from thermochemical sulfate reduction of seawater sulfate, with lesser input from bacteria-derived H 2 S and magmatic-hydrothermal-derived H 2 S. Despite recent research advances and historic mining, numerous questions remain unresolved and provide opportunities for future study.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135717464","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}
Three shelf-derived boulders in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation of western Newfoundland yielded the first record of an Upper Cambrian shelf-margin trilobite fauna from the Elvinia Zone (Steptoean; Jiangshanian) in eastern North America. The fauna is dominated by the “catillicephalid” Buttsia Wilson, 1951, and resembles trilobite biofacies from microbial buildups in the Gatesburg Formation of Pennsylvania. It is correlative with the Cliffia latagenae Subzone, which is the youngest Steptoean biostratigraphic unit in the Gatesburg. New taxa are Triorygma burkhalteri gen. et sp. nov. and Buttsia trema sp. nov.
纽芬兰西部浅湾组Downes Point段碎屑流砾岩中的三个陆架衍生的巨砾，首次记录了Elvinia带(Steptoean;北美东部的江山期)。动物群以“catillicephalid”(Buttsia Wilson, 1951)为主，类似于宾夕法尼亚州盖茨堡组微生物聚集的三叶虫生物相。这与盖茨堡最年轻的阶梯阶生物地层单元——latagenae Cliffia亚带有关。新分类群为Triorygma burkhalteri gen. et sp. 11和Buttsia trema sp. 11。
{"title":"A Jiangshanian (Cambrian; Furongian) trilobite fauna from the Cow Head Group, western Newfoundland","authors":"S. Westrop, Jennifer D. Eoff","doi":"10.1139/cjes-2023-0036","DOIUrl":"https://doi.org/10.1139/cjes-2023-0036","url":null,"abstract":"Three shelf-derived boulders in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation of western Newfoundland yielded the first record of an Upper Cambrian shelf-margin trilobite fauna from the Elvinia Zone (Steptoean; Jiangshanian) in eastern North America. The fauna is dominated by the “catillicephalid” Buttsia Wilson, 1951, and resembles trilobite biofacies from microbial buildups in the Gatesburg Formation of Pennsylvania. It is correlative with the Cliffia latagenae Subzone, which is the youngest Steptoean biostratigraphic unit in the Gatesburg. New taxa are Triorygma burkhalteri gen. et sp. nov. and Buttsia trema sp. nov.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"47 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76213684","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}
J. Russell, B. Edwards, G. Williams-Jones, C. Hickson
The Canadian Cordillera hosts numerous Pleistocene and Holocene volcanoes and volcanic deposits, including a number that have erupted within the last several hundred years. The nature and composition of volcanic edifices and deposits are diverse and dictated by the complex configuration of tectonic plates along the western margin of British Columbia and the thermal structure of the underlying mantle. Our modern knowledge of these is built upon more than a century of field- and increasingly, laboratory-based studies. We recognize five distinct volcanic domains within the Cordillera that are distributed across British Columbia, the Yukon Territory, and easternmost Alaska. These include: the Wrangell Volcanic Belt (WVB), the Northern Cordilleran Volcanic Province (NCVP), the Anahim Volcanic Belt (AVB), the Wells Grey - Clearwater Volcanic Field (WGCVF) and the Garibaldi Volcanic Belt (GVB) representing the northern extension of the Cascade Volcanic Arc. Volcanism in the Canadian Cordillera spans the full range of explosive to effusive behaviours, encompasses the suite of common volcanic chemical compositions (alkaline to calc-alkaline, nephelinite to peralkaline rhyolite), and is expressed by long-lived stratovolcanoes, shield volcanoes, and calderas, as well as shorter-lived tephra cones and associated lava flows. The range in tectonic settings (subduction to extension), eruption environments (subaerial-subaqueous-cryospheric), and topographic variability make volcanism within the Canadian Cordillera as diverse as anywhere on Earth, yet it is also the least studied. Here, we summarize the current state-of-knowledge concerning volcanism within the Canadian Cordillera and conclude with thoughts on research areas that merit further effort, namely glaciovolcanism and volcanic hazards.
{"title":"Pleistocene to Holocene Volcanism in the Canadian Cordillera","authors":"J. Russell, B. Edwards, G. Williams-Jones, C. Hickson","doi":"10.1139/cjes-2023-0065","DOIUrl":"https://doi.org/10.1139/cjes-2023-0065","url":null,"abstract":"The Canadian Cordillera hosts numerous Pleistocene and Holocene volcanoes and volcanic deposits, including a number that have erupted within the last several hundred years. The nature and composition of volcanic edifices and deposits are diverse and dictated by the complex configuration of tectonic plates along the western margin of British Columbia and the thermal structure of the underlying mantle. Our modern knowledge of these is built upon more than a century of field- and increasingly, laboratory-based studies. We recognize five distinct volcanic domains within the Cordillera that are distributed across British Columbia, the Yukon Territory, and easternmost Alaska. These include: the Wrangell Volcanic Belt (WVB), the Northern Cordilleran Volcanic Province (NCVP), the Anahim Volcanic Belt (AVB), the Wells Grey - Clearwater Volcanic Field (WGCVF) and the Garibaldi Volcanic Belt (GVB) representing the northern extension of the Cascade Volcanic Arc. Volcanism in the Canadian Cordillera spans the full range of explosive to effusive behaviours, encompasses the suite of common volcanic chemical compositions (alkaline to calc-alkaline, nephelinite to peralkaline rhyolite), and is expressed by long-lived stratovolcanoes, shield volcanoes, and calderas, as well as shorter-lived tephra cones and associated lava flows. The range in tectonic settings (subduction to extension), eruption environments (subaerial-subaqueous-cryospheric), and topographic variability make volcanism within the Canadian Cordillera as diverse as anywhere on Earth, yet it is also the least studied. Here, we summarize the current state-of-knowledge concerning volcanism within the Canadian Cordillera and conclude with thoughts on research areas that merit further effort, namely glaciovolcanism and volcanic hazards.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"17 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89367943","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}
Sheree Armistead, Bruce Eglington, Sally J. Pehrsson
The package PbIso is a free and open R toolbox for commonly used calculations and plots of Pb-Pb isotope data and for generating Pb evolution models. In this paper, we review Pb isotope systematics and the calculations that are commonly used, such as model age, model source (238U/204Pb), time-integrated (232Th/238U), and initial Pb isotope ratios. These equations are implemented into R functions in the package PbIso. In addition, functions are provided for generating Pb evolution models, paleoisochrons, and isochrons. This allows users to apply calculations to their data in a straightforward way, while providing transparency and flexibility of the calculations used. We have implemented some basic features of the PbIso package into an online shiny R application (see https://shereearmistead.github.io/software/pbiso), which makes it easy for users without any R experience to use these calculations with their own data and to generate plots. We have provided a case study from the Superior Province in Canada, showing how different Pb evolution models can be generated in PbIso and compared to Pb isotope data.
{"title":"PbIso: an R package and web app for calculating and plotting Pb isotope data","authors":"Sheree Armistead, Bruce Eglington, Sally J. Pehrsson","doi":"10.1139/cjes-2023-0029","DOIUrl":"https://doi.org/10.1139/cjes-2023-0029","url":null,"abstract":"The package PbIso is a free and open R toolbox for commonly used calculations and plots of Pb-Pb isotope data and for generating Pb evolution models. In this paper, we review Pb isotope systematics and the calculations that are commonly used, such as model age, model source (238U/204Pb), time-integrated (232Th/238U), and initial Pb isotope ratios. These equations are implemented into R functions in the package PbIso. In addition, functions are provided for generating Pb evolution models, paleoisochrons, and isochrons. This allows users to apply calculations to their data in a straightforward way, while providing transparency and flexibility of the calculations used. We have implemented some basic features of the PbIso package into an online shiny R application (see https://shereearmistead.github.io/software/pbiso), which makes it easy for users without any R experience to use these calculations with their own data and to generate plots. We have provided a case study from the Superior Province in Canada, showing how different Pb evolution models can be generated in PbIso and compared to Pb isotope data.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135656580","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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