Pub Date : 2020-09-28DOI: 10.12789/GEOCANJ.2020.47.163
S. Mccutcheon, J. Walker
In the Bathurst Mining Camp (BMC), 12 of the 45 known massive sulphide deposits were mined between 1957 and 2013; one was mined for iron prior to 1950, whereas three others had development work but no production. Eleven of the deposits were mined for base metals for a total production of approximately 179 Mt, with an average grade of 3.12% Pb, 7.91% Zn, 0.47% Cu, and 93.9 g/t Ag. The other deposit was solely mined for gold, present in gossan above massive sulphide, producing approximately one million tonnes grading 1.79 g/t Au. Three of the 11 mined base-metal deposits also had a gossan cap, from which gold was extracted. In 2012, the value of production from the Bathurst Mining Camp exceeded $670 million and accounted for 58 percent of total mineral production in New Brunswick.Base-metal production started in the BMC in 1957 from deposits at Heath Steele Mines, followed by Wedge in 1962, Brunswick No. 12 in 1964, Brunswick No. 6 in 1965, Caribou in 1970, Murray Brook, Stratmat Boundary and Stratmat N-5 in 1989, Captain North Extension in 1990, and lastly, Half Mile Lake in 2012. The only mine in continuous production for most of this time was Brunswick No. 12. During its 49-year lifetime (1964–2013), it produced 136,643,367 tonnes of ore grading 3.44% Pb, 8.74% Zn, 0.37% Cu, and 102.2 g/t Ag, making it one of the largest underground base-metal mines in the world.The BMC remains important to New Brunswick and Canada because of its contributions to economic development, environmental measures, infrastructure, mining innovations, and society in general. The economic value of metals recovered from Brunswick No. 12 alone, in today’s prices exceeds $46 billion. Adding to this figure is production from the other mines in the BMC, along with money injected into the local economy from annual exploration expenditures (100s of $1000s per year) over 60 years. Several environmental measures were initiated in the BMC, including the requirement to be clean shaven and carry a portable respirator (now applied to all mines in Canada); ways to treat acid mine drainage and the thiosalt problem that comes from the milling process; and pioneering studies to develop and install streamside-incubation boxes for Atlantic Salmon eggs in the Nepisiguit River, which boosted survival rates to over 90%. Regarding infrastructure, provincial highways 180 and 430 would not exist if not for the discovery of the BMC; nor would the lead smelter and deep-water port at Belledune. Mining innovations are too numerous to list in this summary, so the reader is referred to the main text. Regarding social effects, the new opportunities, new wealth, and training provided by the mineral industry dramatically changed the living standards and social fabric of northern New Brunswick. What had been a largely poor, rural society, mostly dependent upon the fishing and forestry industries, became a thriving modern community. Also, untold numbers of engineers, geologists, miners, and prospectors `cu
{"title":"Great Mining Camps of Canada 8. The Bathurst Mining Camp, New Brunswick, Part 2: Mining History and Contributions to Society","authors":"S. Mccutcheon, J. Walker","doi":"10.12789/GEOCANJ.2020.47.163","DOIUrl":"https://doi.org/10.12789/GEOCANJ.2020.47.163","url":null,"abstract":"In the Bathurst Mining Camp (BMC), 12 of the 45 known massive sulphide deposits were mined between 1957 and 2013; one was mined for iron prior to 1950, whereas three others had development work but no production. Eleven of the deposits were mined for base metals for a total production of approximately 179 Mt, with an average grade of 3.12% Pb, 7.91% Zn, 0.47% Cu, and 93.9 g/t Ag. The other deposit was solely mined for gold, present in gossan above massive sulphide, producing approximately one million tonnes grading 1.79 g/t Au. Three of the 11 mined base-metal deposits also had a gossan cap, from which gold was extracted. In 2012, the value of production from the Bathurst Mining Camp exceeded $670 million and accounted for 58 percent of total mineral production in New Brunswick.Base-metal production started in the BMC in 1957 from deposits at Heath Steele Mines, followed by Wedge in 1962, Brunswick No. 12 in 1964, Brunswick No. 6 in 1965, Caribou in 1970, Murray Brook, Stratmat Boundary and Stratmat N-5 in 1989, Captain North Extension in 1990, and lastly, Half Mile Lake in 2012. The only mine in continuous production for most of this time was Brunswick No. 12. During its 49-year lifetime (1964–2013), it produced 136,643,367 tonnes of ore grading 3.44% Pb, 8.74% Zn, 0.37% Cu, and 102.2 g/t Ag, making it one of the largest underground base-metal mines in the world.The BMC remains important to New Brunswick and Canada because of its contributions to economic development, environmental measures, infrastructure, mining innovations, and society in general. The economic value of metals recovered from Brunswick No. 12 alone, in today’s prices exceeds $46 billion. Adding to this figure is production from the other mines in the BMC, along with money injected into the local economy from annual exploration expenditures (100s of $1000s per year) over 60 years. Several environmental measures were initiated in the BMC, including the requirement to be clean shaven and carry a portable respirator (now applied to all mines in Canada); ways to treat acid mine drainage and the thiosalt problem that comes from the milling process; and pioneering studies to develop and install streamside-incubation boxes for Atlantic Salmon eggs in the Nepisiguit River, which boosted survival rates to over 90%. Regarding infrastructure, provincial highways 180 and 430 would not exist if not for the discovery of the BMC; nor would the lead smelter and deep-water port at Belledune. Mining innovations are too numerous to list in this summary, so the reader is referred to the main text. Regarding social effects, the new opportunities, new wealth, and training provided by the mineral industry dramatically changed the living standards and social fabric of northern New Brunswick. What had been a largely poor, rural society, mostly dependent upon the fishing and forestry industries, became a thriving modern community. Also, untold numbers of engineers, geologists, miners, and prospectors `cu","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43965639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-28DOI: 10.12789/GEOCANJ.2020.47.162
R. Mitchell
Lamproite is a rare ultrapotassic alkaline rock of petrological importance as it is considered to be derived from metasomatized lithospheric mantle, and of economic significance, being the host of major diamond deposits. A review of the nomenclature of lamproite results in the recommendation that members of the lamproite petrological clan be named using mineralogical-genetic classifications to distinguish them from other genetically unrelated potassic alkaline rocks, kimberlite, and diverse lamprophyres. The names “Group 2 kimberlite” and “orangeite” must be abandoned as these rock types are varieties of bona fide lamproite restricted to the Kaapvaal Craton. Lamproites exhibit extreme diversity in their mineralogy which ranges from olivine phlogopite lamproite, through phlogopite leucite lamproite and potassic titanian richterite-diopside lamproite, to leucite sanidine lamproite. Diamondiferous olivine lamproites are hybrid rocks extensively contaminated by mantle-derived xenocrystic olivine. Currently, lamproites are divided into cratonic (e.g. Leucite Hills, USA; Baifen, China) and orogenic (Mediterranean) varieties (e.g. Murcia-Almeria, Spain; Afyon, Turkey; Xungba, Tibet). Each cratonic and orogenic lamproite province differs significantly in tectonic setting and Sr–Nd–Pb–Hf isotopic compositions. Isotopic compositions indicate derivation from enriched mantle sources, having long-term low Sm/Nd and high Rb/Sr ratios, relative to bulk earth and depleted asthenospheric mantle. All lamproites are considered, on the basis of their geochemistry, to be derived from ancient mineralogically complex K–Ti–Ba–REE-rich veins, or metasomes, in the lithospheric mantle with, or without, subsequent contributions from recent asthenospheric or subducted components at the time of genesis. Lamproite primary magmas are considered to be relatively silica-rich (~50–60 wt.% SiO2), MgO-poor (3–12 wt.%), and ultrapotassic (~8–12 wt.% K2O) as exemplified by hyalo-phlogopite lamproites from the Leucite Hills (Wyoming) or Smoky Butte (Montana). Brief descriptions are given of the most important phreatomagmatic diamondiferous lamproite vents. The tectonic processes which lead to partial melting of metasomes, and/or initiation of magmatism, are described for examples of cratonic and orogenic lamproites. As each lamproite province differs with respect to its mineralogy, geochemical evolution, and tectonic setting there is no simple or common petrogenetic model for their genesis. Each province must be considered as the unique expression of the times and vagaries of ancient mantle metasomatism, coupled with diverse and complex partial melting processes, together with mixing of younger asthenospheric and lithospheric material, and, in the case of many orogenic lamproites, with Paleogene to Recent subducted material.
煌斑岩是一种稀有的超古生代碱性岩石，在岩石学上具有重要意义，被认为起源于交代岩石圈地幔，并具有重要的经济意义，是主要金刚石矿床的宿主。在对煌斑岩命名法的回顾中，建议使用矿物学-成因分类来命名煌斑岩岩石学家族的成员，以区分它们与其他遗传上不相关的钾碱性岩石、金伯利岩和各种煌斑岩。必须放弃“第二组金伯利岩”和“橙色岩”的名称，因为这些岩石类型是真正的煌斑岩品种，仅限于卡普瓦尔克拉通。煌斑岩的矿物学表现出极大的多样性，从橄榄绿云母煌斑岩，到绿云母白闪辉斑岩和钾钛辉辉透辉辉斑岩，再到白闪辉辉斑岩。菱形橄榄石煌斑岩是一种杂化岩，广泛受到幔源异晶橄榄石的污染。目前，煌斑岩分为克拉通型(如美国的Leucite Hills;白芬，中国)和造山带(地中海)品种(如西班牙的穆尔西亚-阿尔梅里亚;金丝黄、土耳其;Xungba、西藏)。各克拉通造山带煌斑岩省在构造背景和Sr-Nd-Pb-Hf同位素组成上存在显著差异。同位素组成表明，相对于大块地球和衰竭软流圈地幔，地幔源长期具有低Sm/Nd和高Rb/Sr的特征。根据其地球化学特征，所有煌斑岩都被认为来源于岩石圈地幔中具有或不具有近期软流圈或俯冲成分的古老矿物学复杂的富含k - ti - ba - ree的矿脉或交代体。煌斑岩原生岩浆被认为是相对富硅(~ 50-60 wt.% SiO2)、贫镁(~ 3-12 wt.%)和超经典(~ 8-12 wt.% K2O)的煌斑岩，例如来自怀俄明州的Leucite Hills和蒙大拿州的Smoky Butte的透明质-绿云母煌斑岩。简要介绍了最重要的含金刚石煌斑岩喷口。构造过程导致交代岩的部分熔融和/或岩浆活动的开始，以克拉通和造山煌斑岩为例。由于每个煌斑岩省的矿物学、地球化学演化和构造背景不同，它们的成因没有一个简单或共同的成岩模式。每一个省都必须被认为是古地幔交代作用的时代和变幻莫测的独特表现，加上多样化和复杂的部分熔融过程，以及年轻的软流圈和岩石圈物质的混合，在许多造山煌斑岩的情况下，与古近纪到近代的俯冲物质。
{"title":"Igneous Rock Associations 26. Lamproites, Exotic Potassic Alkaline Rocks: A Review of their Nomenclature, Characterization and Origins","authors":"R. Mitchell","doi":"10.12789/GEOCANJ.2020.47.162","DOIUrl":"https://doi.org/10.12789/GEOCANJ.2020.47.162","url":null,"abstract":"Lamproite is a rare ultrapotassic alkaline rock of petrological importance as it is considered to be derived from metasomatized lithospheric mantle, and of economic significance, being the host of major diamond deposits. A review of the nomenclature of lamproite results in the recommendation that members of the lamproite petrological clan be named using mineralogical-genetic classifications to distinguish them from other genetically unrelated potassic alkaline rocks, kimberlite, and diverse lamprophyres. The names “Group 2 kimberlite” and “orangeite” must be abandoned as these rock types are varieties of bona fide lamproite restricted to the Kaapvaal Craton. Lamproites exhibit extreme diversity in their mineralogy which ranges from olivine phlogopite lamproite, through phlogopite leucite lamproite and potassic titanian richterite-diopside lamproite, to leucite sanidine lamproite. Diamondiferous olivine lamproites are hybrid rocks extensively contaminated by mantle-derived xenocrystic olivine. Currently, lamproites are divided into cratonic (e.g. Leucite Hills, USA; Baifen, China) and orogenic (Mediterranean) varieties (e.g. Murcia-Almeria, Spain; Afyon, Turkey; Xungba, Tibet). Each cratonic and orogenic lamproite province differs significantly in tectonic setting and Sr–Nd–Pb–Hf isotopic compositions. Isotopic compositions indicate derivation from enriched mantle sources, having long-term low Sm/Nd and high Rb/Sr ratios, relative to bulk earth and depleted asthenospheric mantle. All lamproites are considered, on the basis of their geochemistry, to be derived from ancient mineralogically complex K–Ti–Ba–REE-rich veins, or metasomes, in the lithospheric mantle with, or without, subsequent contributions from recent asthenospheric or subducted components at the time of genesis. Lamproite primary magmas are considered to be relatively silica-rich (~50–60 wt.% SiO2), MgO-poor (3–12 wt.%), and ultrapotassic (~8–12 wt.% K2O) as exemplified by hyalo-phlogopite lamproites from the Leucite Hills (Wyoming) or Smoky Butte (Montana). Brief descriptions are given of the most important phreatomagmatic diamondiferous lamproite vents. The tectonic processes which lead to partial melting of metasomes, and/or initiation of magmatism, are described for examples of cratonic and orogenic lamproites. As each lamproite province differs with respect to its mineralogy, geochemical evolution, and tectonic setting there is no simple or common petrogenetic model for their genesis. Each province must be considered as the unique expression of the times and vagaries of ancient mantle metasomatism, coupled with diverse and complex partial melting processes, together with mixing of younger asthenospheric and lithospheric material, and, in the case of many orogenic lamproites, with Paleogene to Recent subducted material.","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66818047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-28DOI: 10.12789/GEOCANJ.2020.47.161
C. V. Staal, A. Zagorevski
We argue there is no distinction between accretion and collision as a process, except when accretion is used in the sense of incorporating small bodies of sedimentary and/or volcanic rocks into an accretionary wedge by off-scraping or underplating. There is also a distinction when these terms are used in classifying mountain belts into accretionary and collisional orogens, although such classifications are commonly based on a qualitative assessment of the scale and nature of the accreted terranes and continents involved in formation of mountain belts. Soft collisions occur when contractional deformation and associated metamorphism are principally concentrated in rocks of the leading edge of the partially pulled-down buoyant plate and the upper plate forearc terrane. Several young arc-continent collisions show evidence for partial or wholesale subduction of the forearc such that the arc is structurally juxtaposed directly against lower plate rocks. This process may explain the poor preservation of forearcs in the geological record. Soft collisions generally change into hard collisions over time, except if the collision is rapidly followed by formation of a new subduction zone due to step-back or polarity reversal. Thickening and metamorphism of the arc's suprastructure and retro-arc part of upper plate due to contractional deformation and burial are the characteristics of a hard collision or an advancing Andean-type margin. Strong rheological coupling of the converging plates and lower and upper crust in the down-going continental margin promotes a hard collision. Application of the soft–hard terminology supports a structural juxtaposition of the Taconic soft collision recorded in the Humber margin of western Newfoundland with a hard collision recorded in the adjacent Dashwoods block. It is postulated that Dashwoods was translated dextrally along the Cabot-Baie Verte fault system from a position to the north of Newfoundland where the Notre Dame arc collided ca. 10 m.y. earlier with a wide promontory in a hyperextended segment of the Laurentian margin.
{"title":"Accretion, Soft and Hard Collision: Similarities, Differences and an Application from the Newfoundland Appalachian Orogen","authors":"C. V. Staal, A. Zagorevski","doi":"10.12789/GEOCANJ.2020.47.161","DOIUrl":"https://doi.org/10.12789/GEOCANJ.2020.47.161","url":null,"abstract":"We argue there is no distinction between accretion and collision as a process, except when accretion is used in the sense of incorporating small bodies of sedimentary and/or volcanic rocks into an accretionary wedge by off-scraping or underplating. There is also a distinction when these terms are used in classifying mountain belts into accretionary and collisional orogens, although such classifications are commonly based on a qualitative assessment of the scale and nature of the accreted terranes and continents involved in formation of mountain belts. Soft collisions occur when contractional deformation and associated metamorphism are principally concentrated in rocks of the leading edge of the partially pulled-down buoyant plate and the upper plate forearc terrane. Several young arc-continent collisions show evidence for partial or wholesale subduction of the forearc such that the arc is structurally juxtaposed directly against lower plate rocks. This process may explain the poor preservation of forearcs in the geological record. Soft collisions generally change into hard collisions over time, except if the collision is rapidly followed by formation of a new subduction zone due to step-back or polarity reversal. Thickening and metamorphism of the arc's suprastructure and retro-arc part of upper plate due to contractional deformation and burial are the characteristics of a hard collision or an advancing Andean-type margin. Strong rheological coupling of the converging plates and lower and upper crust in the down-going continental margin promotes a hard collision. Application of the soft–hard terminology supports a structural juxtaposition of the Taconic soft collision recorded in the Humber margin of western Newfoundland with a hard collision recorded in the adjacent Dashwoods block. It is postulated that Dashwoods was translated dextrally along the Cabot-Baie Verte fault system from a position to the north of Newfoundland where the Notre Dame arc collided ca. 10 m.y. earlier with a wide promontory in a hyperextended segment of the Laurentian margin.","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42841917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-10DOI: 10.12789/geocanj.2020.47.155
A. Kerr
{"title":"Geoscience in the Time of Covid","authors":"A. Kerr","doi":"10.12789/geocanj.2020.47.155","DOIUrl":"https://doi.org/10.12789/geocanj.2020.47.155","url":null,"abstract":"","PeriodicalId":55106,"journal":{"name":"Geoscience Canada","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48778731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-10DOI: 10.12789/geocanj.2020.47.157
M. Wit, B. Linol, V. Nengovhela
The Kango (Cango) region flanks the northern margins of the Klein Karoo and the Cape Mountains across the Western Cape Province of South Africa. It preserves a condensed Proterozoic–Paleozoic stratigraphy exposed via a Mesozoic–Cenozoic morphology with a present Alpine-like topography. Its rocks and landscapes have been repeatedly mapped and documented for the past 150 years. Over the last 25 years, we remapped and dated a central-eastern section of this region. The subvertically bedded and cleaved rocks reveal an 8–10 km thick stratigraphy covering more than 700 million years between ca. 1200 and 500 Ma with several unconformities and disconformities. At ca. 252 Ma, during the Cape orogeny, this Kango Complex was deformed along thrusts and sub-isoclinal folds producing steeply dipping phyllites and slates. It was uplifted by 3–5 km during the Kalahari epeirogeny between 140 and 60 Ma while eroding at ca. 100–200 m/m.y. (120–80 Ma). During the Cenozoic, the rate of uplift decreased by an order of magnitude and today is ca. 0.4–0.7 m/m.y. across steep slopes and canyons in contrast to the Himalayas where erosion rates are about hundred times faster. A recent publication about this central-eastern section of the Kango region disputes the existence of regional isoclinal folds and suggests that deposition of the oldest sedimentary successions, including carbonate rocks of the Cango Caves (limestone-marble with enigmatic microfossils) was simple, continuous and restricted to between ca. 700 and 500 Ma, decreasing earlier estimates of the stratigraphic age range by 60–80%. Similarly, recent interpretations of the complex landscapes link the northern contact between the Kango and Table Mountain rock sequences to Quaternary faults. We present a new geological database, mapped between 1:500 and 1:10,000 scales, and twelve stratigraphic sections with younging directions linked to structural and isotopic data that support repetitions along regional isoclinal folds and thrust zones of the Kango sequences during the Permo–Triassic Cape orogeny, and geomorphic data that link the origin of its landscapes to weathering and erosion during the Cretaceous–Cenozoic Kalahari epeirogeny. During its evolution, the Kango Basin directly flanked both Grenvillian and Pan-African Mountain systems. But, at an average sedimentation rate of ca. 1 mm/70 years (0.014 mm/year) and with present low erosion rates (0.005 mm/year), there is likely more time missing than preserved of the tectono-erosion across these different regions of Rodinia and Gondwana before Africa emerged. To further evaluate the geodynamic significance of these time gaps requires more field mapping linked to new transdisciplinary geosciences. RÉSUMÉLa région du Kango (Cango) flanque les marges nord du petit Karoo et des montagnes du Cap dans la province du Western Cape en Afrique du Sud. Elle préserve une stratigraphie condensée protérozoïque–paléozoïque exposée via une morphologie mésozoïque–cénozoïque avec u
康戈(Cango)地区位于克莱因卡鲁和开普山脉的北部边缘，横跨南非西开普省。它保留了一个浓缩的元古代-古生代地层，通过中新生代的形态暴露出来，具有现在的高山状地形。在过去的150年里，它的岩石和景观被反复绘制和记录。在过去的25年里，我们重新绘制了该地区中东部的地图，并确定了年代。亚垂直层状和劈裂岩石显示出8-10公里厚的地层，覆盖约1200 - 500 Ma之间的7亿多年，并有一些不整合和不整合。约252 Ma，在开普造山运动期间，该坎戈杂岩沿逆冲和次等斜褶皱变形，形成了陡倾千层岩和板岩。在140 ~ 60 Ma的喀拉哈里造山运动期间，抬升了3 ~ 5 km，侵蚀速度约为100 ~ 200 m/m.y。(120 - 80 Ma)。在新生代，抬升速率降低了一个数量级，今天的抬升速率约为0.4-0.7 m/m.y.。穿越陡峭的山坡和峡谷，而喜马拉雅山的侵蚀速度要快上百倍。最近一份关于Kango地区中东部地区的出版物对区域等斜褶皱的存在提出了质疑，并认为最古老的沉积序列，包括Cango洞穴(石灰石-大理石和神秘的微化石)的碳酸盐岩的沉积是简单的，连续的，并且限制在大约700到500 Ma之间，将早期对地层年龄范围的估计降低了60-80%。同样，最近对复杂地貌的解释将康戈和桌山岩石层序之间的北部接触与第四纪断裂联系起来。我们提出了一个新的地质数据库，绘制了1:500到1:10 000的比例尺，12个地层剖面的年轻方向与构造和同位素数据相关联，这些数据支持二叠纪-三叠纪Cape造山运动期间Kango序列沿区域等斜褶皱和冲断带的重复，以及将其景观起源与白垩纪-新生代Kalahari造山运动期间的风化和侵蚀联系起来的地貌数据。在其演化过程中，Kango盆地直接位于格伦维利安山脉和泛非山脉的两侧。但是，在平均沉积速率约为1毫米/70年(0.014毫米/年)和目前较低的侵蚀速率(0.005毫米/年)的情况下，在非洲出现之前，罗迪尼亚和冈瓦纳这些不同地区的构造侵蚀可能比保存的时间更少。为了进一步评估这些时间间隙的地球动力学意义，需要更多与新的跨学科地球科学相联系的野外测绘。RÉSUMÉLa康戈共和国(康戈)附属于小卡鲁北部地区和丹斯角山区、西开普省和南非洲。通过一个morphologie Elle保存一个stratigraphie condensee proterozoique-paleozoique exposee mesozoique-cenozoique用一个topographie actuelle de alpin类型。这些数据包括:电子数据、电子数据、电子数据、电子数据、电子数据、电子数据、电子数据、电子数据、电子数据、电子数据和电子数据。Au course des 25 derniires annacei, nous avons re- cartographihi<s:1>和dataest section du centrest de ceetacei。从地层上看，有8 × 10 km和7 × 10 km和7 × 10 km，分别是不符合条件的、不符合条件的和不符合条件的。À 252 Ma, au ' orogenses de Cap, ce de Kango复合物' s est danci.9cha.com, le long de chevauchements and plisisoclinaux prochistes chiistes pendage。1 .在Kalahari中心140至60英里处的3公里处，有1个<s:1> <s:1> 5公里处的<s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> - 200米/小时。(120 - 80 Ma)。Pendant le Cénozoïque, le taux de souldevement和miniuvel 'un order de magnificent等将在每年0,4至0,7 m/m之间进行测试。<s:2>穿越山脉，穿越峡谷，穿越峡谷，穿越喜马拉雅山脉où，穿越高山，穿越高山，穿越环境，穿越高山，穿越急流。一份出版物《<s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1>)》，其中包括<s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1> <s:1>(或)<s:1> <s:1> <s:1>(或)<s:1> <s:1>(或)有限的(或)简单的、连续的、有限的)<s:1>(700至500 Ma)的环境，以及60-80%的<s:1> <s:1>地层)。电子邮箱même，电子邮箱，电子邮箱，电子邮箱，电子邮箱，电子邮箱，电子邮箱，电子邮箱。 我们提出一个新的地质数据库,绘制地图比例尺1:50至1:10,000、十二和地层剖面结构叠加与管理层的相关数据和信息吻合的同位素与沿线区域的褶皱isoclinaux彩排期间Kango的序列重叠区l’orogenèse permo—triassique开普敦以及将其地貌起源与卡拉哈里火山成因至白垩纪至新生代期间的蚀变和侵蚀联系起来的地貌数据。在其发展过程中，坎戈盆地两侧是格伦维尔山脉和泛非山脉。但是,平均沉降率约为1 / 70岁(0.014毫米/年),并与现有的侵蚀率低(0.005 mm / yr),他可能缺乏更大地和侵蚀,这些记录Rodinia不同区域和Gondwana非洲崛起之前,这是目前保存完好。为了评估这些缺失时间间隔的地球动力学意义，需要更多的地面测绘与新的跨学科地球科学相结合。
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Pub Date : 2020-07-10DOI: 10.12789/geocanj.2020.47.159
A. Kerr
The spectacular angular unconformity at Siccar Point is the most famous site associated with James Hutton (1726–1797), but it was not his only place of insight. In 1785, three years before he discovered Siccar Point, Hutton examined outcrops in the still-remote valley of Glen Tilt, in the Scottish Highlands. He documented contact relationships between Precambrian metasedimentary rocks and Paleozoic granite bodies, although he had no knowledge of their true ages. Near to the hunting lodge where he and his colleague John Clerk of Eldin stayed, veins of granite clearly cut through relict bedding in the stratified rocks and disrupt their layering, breaking apart individual strata and leaving fragments (xenoliths) surrounded by granite. Hutton correctly deduced that the granite must originally have been in a ‘state of fusion’ and was forcefully injected into much older ‘schistus’. Such conclusions contravened prevailing ideas that granite bodies formed from aqueous solutions, and also refuted a wider philosophical view that granite and other crystalline rocks were the oldest and first-created parts of the Earth. Hutton’s key outcrops in Glen Tilt are easy to visit, although they do require a long (but easy) roundtrip hike of some 25 km. These are certainly not the most spectacular intrusion breccias that I have ever seen, but they are very instructive, and were very influential, because they sparked a long, and at times acrimonious, debate about the origins of igneous rocks and especially granite. This controversy had many strange twists and turns. These include the disappearance of Hutton’s original manuscript after his death, and its serendipitous rediscovery a century later, and the similar loss and rediscovery of exquisite drawings by John Clerk, almost two centuries after they were first penned. Among the lost drawings is an early example of detailed outcrop-scale mapping, which would become a key field-work technique. Hutton’s vision of granite as the product of hot, liquid material that moved upward in the Earth’s crust (plutonism) eventually prevailed over the idea that crystalline rocks formed from a primordial ocean that once enveloped the Earth (neptunism), but this victory did not come easily or quickly. In another strange twist of history, new evidence from the Cape of Good Hope in South Africa eventually acted to further the plutonist cause. Glen Tilt has changed very little since the time of Hutton, but the observations that were made here, and the long debate that followed, brought fundamental changes in our understanding of the Earth. Although Siccar Point should remain the first entry on the bucket list of any prospective geopilgrim to Scotland, the long and beautiful valley of the River Tilt should also be a priority. RÉSUMÉLa spectaculaire discordance angulaire de Siccar Point est le site le plus célèbre associé à James Hutton (1726–1797), mais ce n'était pas le seul lieu qui l’ait inspiré. En 1785, trois ans avant de découvrir Sic
西卡角壮观的角度不整合是与詹姆斯·赫顿（1726-1797）有关的最著名的地点，但这并不是他唯一的洞察力所在。1785年，在他发现Siccar Point的三年前，Hutton检查了苏格兰高地仍然偏远的Glen Tilt山谷的露头。他记录了前寒武纪变质沉积岩和古生代花岗岩体之间的接触关系，尽管他不知道它们的真实年龄。在他和同事埃尔丁的约翰·克莱克（John Clerk of Eldin）居住的狩猎小屋附近，花岗岩的矿脉清楚地穿过层状岩石中的残余层理，破坏了它们的分层，撕裂了各个地层，留下了被花岗岩包围的碎片（捕虏体）。Hutton正确地推断出，花岗岩最初一定处于“融合状态”，并被有力地注入了更古老的“片岩”中。这些结论违背了花岗岩体由水溶液形成的主流观点，也驳斥了更广泛的哲学观点，即花岗岩和其他结晶岩石是地球上最古老和最早形成的部分。Hutton在Glen Tilt的主要露头很容易参观，尽管它们确实需要大约25公里的长时间（但很容易）往返徒步旅行。这些当然不是我见过的最壮观的侵入角砾岩，但它们非常有指导意义，也非常有影响力，因为它们引发了关于火成岩，尤其是花岗岩起源的长期争论，有时甚至激烈。这场争论有许多奇怪的曲折。其中包括赫顿去世后原稿的消失，以及一个世纪后偶然的重新发现，以及约翰·克莱克在精美画作首次创作近两个世纪后的类似丢失和重新发现。在丢失的图纸中，有一个详细的露头比例测绘的早期例子，这将成为一项关键的野外工作技术。Hutton认为花岗岩是地壳中向上移动的热液体物质的产物（深成主义），最终战胜了晶体岩石是由曾经包围地球的原始海洋形成的观点（海王星主义），但这一胜利来之不易。在另一个奇怪的历史转折中，来自南非好望角的新证据最终推动了政治经济学事业。自Hutton时代以来，Glen Tilt几乎没有变化，但在这里进行的观测以及随后的长期辩论，使我们对地球的理解发生了根本性的变化。尽管Siccar Point应该仍然是苏格兰潜在地质专家名单上的第一个项目，但倾斜河漫长而美丽的山谷也应该是优先事项。Siccar Point的RÉSUMÉLa壮观的不和谐角度是詹姆斯·赫顿（1726-1797）的一个地点，这是一个充满灵感的地方。1785年，在Siccar Point的三驾马车上，Hutton对高地的Glen Tilt的英勇事迹进行了考察。这是一份与柬埔寨人民和Paléozoïque花岗岩军团之间的联系文件，这是一个值得纪念的时刻。Eldin ont séjourné的John Clerker和Chlègue之子的pavillon de chasse oúlui先生，花岗岩脉是分层和扰动叠加的宗教序列的组成部分，是花岗岩内部碎片（xénolithes）的个人策略和来源。Hutton纠正了“融合状态”的起源，并为“分裂”和古代注入了力量。我们得出的结论是，花岗岩军团的主导者是解决方案的一部分，也是未来哲学愿景的一部分。HuttonàGlen Tilt的主要工作人员很容易访问，因为他们需要在25公里外的环境中进行长期的访问。这是一个肯定的事实，因为它是一种入侵，加上我的眼睛，我的眼睛是一种指导，而不是欧盟的影响，汽车是一种长时间的撞击，是一种激烈的争论，是关于岩石的起源，尤其是花岗岩的起源。这是对欧盟重新组建的一次反对。Ceux ci包括Hutton的原始手稿的差异，以及一个偶然的加上延迟的红色，以及John Clerk的再婚设计的相似性和红色。
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Pub Date : 2020-07-10DOI: 10.12789/geocanj.2020.47.160
E. Koster
Increasingly, deliberations to potentially add the Anthropocene to the Geological Time Scale in recognition of humanity’s environmental impacts and stratigraphic record are attracting interest from non-geological disciplines and the news media. The 35 member Anthropocene Working Group, a constituent body of the International Commission on Stratigraphy, recently concluded that the worldwide fallout of radionuclides from atomic bomb testing in the mid-20th century best defines the base of the Anthropocene. With a search for the optimal ‘golden spike’ locality in progress as a key step toward any ratification by the International Union of Geological Sciences, there are widely held views outside of geological circles that the Anthropocene is already designated as an epoch. Regardless of its eventual formal or informal standing, this article opines that the term Anthropocene has become valuable shorthand for recognizing humanity as the dominant species which, in a geological nanosecond, has extensively detached itself from the Earth System, endangering the future of both. Accordingly, this article urges the entire geological profession to engage with the work of the Anthropocene Working Group and, as the originator of the term, to coalesce its activities with those of other disciplines concerned with environmental health and linked human health challenges. RÉSUMÉDe plus en plus, les délibérations visant à éventuellement ajouter l'Anthropocène à l'échelle du temps géologique en reconnaissance des impacts environnementaux de l'humanité et des données stratigraphiques suscitent l'intérêt des disciplines non géologiques et des médias. Les 35 membres du Groupe de travail sur l'Anthropocène, un organe constitutif de la Commission internationale de stratigraphie, ont récemment conclu que les retombées mondiales des radionucléides résultant des essais de bombes atomiques au milieu du XXe siècle définissent le mieux la base de l'Anthropocène. Avec la recherche de la localité de référence optimale du « clou d'or » en cours comme étape clé vers toute ratification par l'Union internationale des sciences géologiques, il existe des opinions largement partagées en dehors des cercles géologiques selon lesquelles l'Anthropocène est déjà désigné comme une époque. Indépendamment de sa position finale formelle ou informelle, cet article estime que le terme Anthropocène est devenu un raccourci précieux pour reconnaître l'humanité comme l'espèce dominante qui, dans une nanoseconde géologique, s'est largement dissocié du système terrestre, mettant en danger l'avenir des deux. Par conséquent, cet article exhorte l'ensemble de la profession géologique à s'engager dans les travaux du Groupe de travail sur l'Anthropocène et, en tant que créateur du terme, à fusionner ses activités avec celles d'autres disciplines concernées par la santé environnementale et les défis liés à la santé humaine.
考虑到人类对环境的影响和地层记录，有可能将人类世添加到地质时间尺度中，这引起了非地质学科和新闻媒体的兴趣。人类世工作组由35名成员组成，是国际地层学委员会的一个组成机构，最近得出结论，20世纪中期原子弹试验产生的放射性核素在世界范围内的沉降物最好地定义了人类世的基础。寻找最佳的“金钉”位置是获得国际地质科学联合会(International Union of Geological Sciences)认可的关键一步，在此过程中，地质圈之外有广泛的观点认为，人类世已经被指定为一个时代。无论其最终的正式或非正式地位如何，这篇文章认为，“人类世”一词已经成为一种有价值的简写，它承认人类是在地质纳秒内广泛脱离地球系统的主导物种，危及两者的未来。因此，本文敦促整个地质专业参与人类世工作组的工作，并作为该术语的发起者，将其活动与与环境健康和相关人类健康挑战有关的其他学科的活动结合起来。RÉSUMÉDe + en + en +，将所有的人都纳入到人类系统的范围内，将所有的人都纳入到人类系统的范围内，将所有的人都纳入到人类系统的范围内，将所有的人都纳入到人类的范围内。人类工作小组的35个成员，国际地层学委员会的组织组成，以及人类工作小组的35个成员，人类工作小组的35个成员，人类工作小组的35个成员，人类工作小组的35个成员，人类工作小组的35个成员，人类工作小组的35个成员。如果在国际科学联盟的批准中，将有许多意见存在，例如，在国际科学联盟的批准中，将有许多意见存在，例如，在国际科学联盟的批准中，将有许多意见存在，例如，在国际科学联盟的批准中，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在，例如，将有许多意见存在。1 . 人道主义系统系统的最大分离，1纳秒人道主义系统系统的最大分离，1纳秒人道主义系统系统的最大分离，1纳秒人道主义系统系统的最大分离，1纳秒人道主义系统系统的最大分离，1纳秒人道主义系统系统的最大分离。与此同时，该条款还敦促所有职业的薪金薪金与人类职业的薪金薪金有关，所有职业的薪金薪金与人类职业的薪金薪金有关，所有职业的薪金薪金与人类职业的薪金薪金有关，所有职业的薪金薪金与人类职业的薪金薪金有关，所有职业的薪金薪金与人类职业的薪金薪金有关。
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Pub Date : 2020-07-10DOI: 10.12789/geocanj.2020.47.158
V. Oliveros, P. Moreno-Yaeger, Laura Flores
Andean-type magmatism and the term ‘andesite’ are often used as the norm for the results of subduction of oceanic lithosphere under a continent, and the typical rock formed. Although the Andes chain occupies the whole western margin of South America, the most comprehensively studied rocks occur in the present-day Chilean territory and are the focus of this paper. Andean magmatism in this region developed from the Rhaetian-Hettangian boundary (ca. 200 Ma) to the present and represents the activity of a long-lived continental magmatic arc. This paper discusses Pre-Pleistocene volcanic, plutonic, and volcano-sedimentary rocks related to the arc that cover most of the continental mass of Chile (between the Pacific coast and the High Andes) between the latitudes of 18° and 50°S. They comprise most of the range of sub-alkaline igneous rocks, from gabbro to monzogranite and from basalt to rhyolite, but are dominated by the tonalite-granodiorite and andesite example members. Variations in the petrographic characteristics, major and trace element composition and isotopic signature of the igneous rocks can be correlated to changes in the physical parameters of the subduction zone, such as dip angle of the subducting slab, convergence rate and angle of convergence. Early Andean magmatic products (Jurassic to Early Cretaceous) are found along the Coastal Cordillera in the westernmost part of the Andes. The rock record of the subsequent stages (Late Cretaceous, Paleocene–Early Eocene, Middle Eocene–Oligocene, Miocene) is progressively shifted to the east, reflecting migration of the magmatic front towards the continent. Tectonic segmentation of the convergent margin, as attested by the magmatic record, may have occurred throughout the Andean life span but it is particularly evident from the Eocene onwards, where the evolution of the northern part of the Chilean Andes (north of 27°S latitude) is very different to that of the southern segment (south of 27°S latitude). RÉSUMÉLe magmatisme de type andin et le terme « andésite » sont souvent les appellations utilisées pour décrire les résultats de la subduction de la lithosphère océanique sous un continent, et la roche typique formée. Bien que la chaîne des Andes occupe toute la marge ouest de l'Amérique du Sud, les roches les plus étudiées se trouvent dans le territoire chilien actuel et sont l'objet de cet article. Le magmatisme andin dans cette région s'est développé depuis la limite rhéto-hettangienne (environ 200 Ma) jusqu'à aujourd'hui et représente l'activité d'un arc magmatique continental persistant. Cet article a pour sujet les roches volcaniques, plutoniques et volcano-sédimentaires du pré-Pléistocène liées à l'arc qui couvrent la majeure partie de la masse continentale du Chili (entre la côte du Pacifique et les Hautes Andes) entre les latitudes de 18° et 50°S. Elles comprennent la majeure partie de la gamme de roches ignées sous-alcalines, du gabbro à la monzogranite et du basalte à la rhyolite, mais
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