Atlantic Geology最新文献_第7页

The Litchfield Pluton in South-Central Maine: Carboniferous Alkalic Magmatism in northern New England, USA 缅因州中南部的利奇菲尔德岩体:美国新英格兰北部石炭系碱性岩浆作用

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-06-30 DOI: 10.4138/ATLGEOL.2016.008

D. P. West, D. Bradley, R. Coish

{"title":"The Litchfield Pluton in South-Central Maine: Carboniferous Alkalic Magmatism in northern New England, USA","authors":"D. P. West, D. Bradley, R. Coish","doi":"10.4138/ATLGEOL.2016.008","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2016.008","url":null,"abstract":"The Litchfield pluton is a poorly exposed 7 km 2 composite alkalic intrusive complex that cuts previously deformed and metamorphosed Silurian turbidites in south-central Maine. The pluton includes a variety of alkaline syenites, including the type locality of “litchfieldite”, a coarse-grained cancrinite, sodalite, and lepidomelane bearing nepheline syenite first recognized over 150 years ago and common in many petrologic collections. A new U-Pb zircon age of 321 ± 2 Ma from the nepheline syenite is interpreted to represent the crystallization age of the plutonic complex. A new biotite 40 Ar/ 39 Ar age of 239 ± 1 Ma from the syenite is similar to previously published mica ages from the surrounding country rocks and dates the time of regional cooling in the area below ~ 300°C. Whole rock geochemical analyses from rocks of the Litchfield pluton are compatible with strongly alkaline A-type granitoid rocks that formed in a within plate or continental rift tectonic setting. The age and geochemical characteristics of the alkalic igneous rocks near Litchfield are consistent with a model that invokes the generation of a small volume of alkalic magma beneath south-central Maine during a period of Carboniferous transcurrent tectonism in the northern Appalachian orogen.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"52 1","pages":"169-187"},"PeriodicalIF":1.6,"publicationDate":"2016-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70755064","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: 2

Geochronology and lithogeochemistry of granitoid rocks from the central part of the Central plutonic belt, New Brunswick, Canada: implications for Sn-W-Mo exploration 加拿大新不伦瑞克省中央深部带中部花岗质岩石年代学和岩石地球化学:对Sn-W-Mo勘探的意义

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-04-29 DOI: 10.4138/ATLGEOL.2016.007

Reginald A. Wilson, S. Kamo

{"title":"Geochronology and lithogeochemistry of granitoid rocks from the central part of the Central plutonic belt, New Brunswick, Canada: implications for Sn-W-Mo exploration","authors":"Reginald A. Wilson, S. Kamo","doi":"10.4138/ATLGEOL.2016.007","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2016.007","url":null,"abstract":"The central part of the Central plutonic belt in New Brunswick is underlain by numerous plutons of calc-alkaline, foliated and unfoliated granite that intrude Cambrian to Early Ordovician metasedimentary rocks. U-Pb (zircon) dating demonstrates that granites range in age from Middle Ordovician to Late Devonian, although most are late Silurian to Early Devonian. An age of 467 ± 7 Ma has been obtained on the foliated McKiel Lake Granite, whereas unfoliated intrusions yield ages of 423.2 ± 3.2 Ma (Bogan Brook Granodiorite), 420.7 +1.8/-2.0 Ma (Nashwaak Granite), 419.0 ± 0.5 Ma (Redstone Mountain Granite), 416.1 ± 0.5 Ma (Beadle Mountain Granite), 415.8 ± 0.3 Ma (Juniper Barren Granite), 409.7 ± 0.5 Ma (Lost Lake Granite), and 380.6 ± 0.3 Ma (Burnthill Granite). All plutons exhibit mixed arc-like and within-plate geochemical signatures, although the Redstone Mountain and Burnthill granites are dominantly of within-plate type. Trace element data reveal a close overall geochemical similarity between Ordovician and Silurian – Devonian plutons, indicating that all were generated by partial melting of the same crustal source. Late Silurian to Early Devonian plutons mainly comprise biotite and/or muscovite-bearing, peraluminous granite and are considered prospective for granophile-element mineralization. All plutons contain Sn well in excess of the granite global average abundance, and several contain average tin values comparable to productive stanniferous granites elsewhere. The Burnthill, Lost Lake, Beadle Mountain, and Nashwaak granites are geochemically most evolved and enriched in Sn and W. The Burnthill Granite in particular has experienced late-stage hydrothermal processes that have resulted in local enrichments of these elements.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"52 1","pages":"125-167"},"PeriodicalIF":1.6,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70754891","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: 17

Megapezia longipes Willard and Cleaves 1930 from the Pennsylvanian Rhode Island Formation of Massachusetts: ichnotaxonomic status 威拉德和克利夫斯1930年发现于马萨诸塞州的宾夕法尼亚罗德岛地层:技术分类地位

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-04-10 DOI: 10.4138/ATLGEOL.2016.006

P. Getty

引用次数: 0

GAC - Newfoundland and Labrador Section Abstracts: 2016 Spring Technical Meeting GAC -纽芬兰和拉布拉多部分摘要:2016年春季技术会议

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-03-23 DOI: 10.4138/ATLGEOL.2016.005

C. White

引用次数: 0

Atlantic Geoscience Society Abstracts: 42nd Annual Colloquium & General Meeting 2016 大西洋地球科学学会文摘:2016年第42届学术年会暨大会

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-03-14 DOI: 10.4138/ATLGEOL.2016.004

C. White

引用次数: 1

Field relations, age, and tectonic setting of metamorphic and plutonic rocks in the Creignish Hills – North Mountain area, southwestern Cape Breton Island, Nova Scotia, Canada 加拿大新斯科舍省布雷顿角岛西南部Creignish Hills - North Mountain地区变质岩和深成岩的场关系、年龄和构造背景

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-02-04 DOI: 10.4138/ATLGEOL.2016.003

C. White, S. Barr, D. Davis, David S. Swanton, J. Ketchum, P. Reynolds

{"title":"Field relations, age, and tectonic setting of metamorphic and plutonic rocks in the Creignish Hills – North Mountain area, southwestern Cape Breton Island, Nova Scotia, Canada","authors":"C. White, S. Barr, D. Davis, David S. Swanton, J. Ketchum, P. Reynolds","doi":"10.4138/ATLGEOL.2016.003","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2016.003","url":null,"abstract":"The Creignish Hills and North Mountain areas of southwestern Cape Breton Island consist mostly of Neoproterozoic rocks typical of the Ganderian Bras d’Or terrane. U-Pb ages presented here for detrital zircon in the Blues Brook Formation of the Creignish Hills confirm a depositional age no greater than about 600 Ma. Although it is possible that some components of the formation are much older, similarities in rock types and field relations suggest that this is not the case. It is likely that the equivalent Malagawatch Formation of the North Mountain area, as well as high-grade metasedimentary rocks of the Melford Formation and Chuggin Road complex in the Creignish Hills and Lime Hill gneiss complex in the North Mountain area, represent the same or stratigraphically equivalent units as the Blues Brook Formation. The minimum ages of all of these units are constrained by cross-cutting syn- and post-tectonic plutons with ages mostly between 565 and 550 Ma, indicating that sediments were deposited, regionally metamorphosed, deformed, and intruded by plutons in less than 40–50 million years. The assemblage of pelitic, psammitic, and carbonate rocks indicates that a passive margin in a tropical climate was quickly changed to an active Andean-type continental margin in which voluminous calcalkaline dioritic to granitic plutons were emplaced. This sedimentary and tectonic history is characteristic of the Bras d’Or terrane and is shared by its likely correlative, the Brookville terrane in southern New Brunswick.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"52 1","pages":"037-059"},"PeriodicalIF":1.6,"publicationDate":"2016-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70754913","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: 9

Reassessment of vertebrate ichnotaxa from the Upper Carboniferous ‘Fern Ledges’, Lancaster Formation, Saint John, New Brunswick, Canada 加拿大新不伦瑞克省圣约翰兰开斯特组上石炭世“蕨类岩壁”脊椎动物区系的重新评估

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-01-18 DOI: 10.4138/ATLGEOL.2016.002

M. Stimson, Randall F. Miller, S. Lucas

引用次数: 4

Redescription of tetrapod trackways from the Mississippian Mabou Group, Lepreau Falls, New Brunswick, Canada 加拿大新不伦瑞克省Lepreau Falls，密西西比Mabou群四足动物足迹的重新描述

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2016-01-14 DOI: 10.4138/ATLGEOL.2016.001

M. Stimson, Randall F. Miller, S. Lucas, A. Park, S. Hinds

引用次数: 5

Assessing patterns of dissolved methane in shallow aquifers related to Carboniferous and Triassic sedimentary basins, Nova Scotia, Canada 加拿大新斯科舍省石炭纪和三叠纪沉积盆地浅层溶解甲烷模式评估

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2015-12-09 DOI: 10.4138/ATLGEOL.2015.009

G. Kennedy, J. Drage

{"title":"Assessing patterns of dissolved methane in shallow aquifers related to Carboniferous and Triassic sedimentary basins, Nova Scotia, Canada","authors":"G. Kennedy, J. Drage","doi":"10.4138/ATLGEOL.2015.009","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2015.009","url":null,"abstract":"The study examines patterns of groundwater methane in shallow aquifers located in Carboniferous and Triassic sedimentary basins in Nova Scotia to improve our understanding of the factors influencing the observed distribution. A combined total of over 800 dissolved methane samples were collected from water wells during surveys conducted in 1975 and 2013. Statistical analyses of the methane data did not detect a significant difference between groupings of methane concentrations for aquifer type, bedrock group, and distance to wetlands. A significant difference, however, was observed between sedimentary basins and bedrock formations, which was largely attributed to localized higher methane concentrations found in the Stellarton Formation/basin compared to other on-shore sedimentary basins of the province. A significant difference was also found between groupings of methane data based on the distance to major stream systems, which was used to indicate topographic position (i.e., valley vs. upslope). The low sample density and percentage of detectable methane concentrations, and the multiple sources of dissolved methane in shallow groundwater in sedimentary basins made it difficult to detect and interpret statistical and spatial trends. Geochemical classification indicates that elevated dissolved methane in well water is associated with sodium dominated groundwater.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"51 1","pages":"233-241"},"PeriodicalIF":1.6,"publicationDate":"2015-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70754325","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: 5

Establishing geochemical baselines in forest soils for environmental risk assessment in the Montague and Goldenville gold districts, Nova Scotia, Canada 加拿大新斯科舍省Montague和Goldenville金矿区森林土壤地球化学基线的建立及其环境风险评价

IF 1.6 4区地球科学

Atlantic Geology Pub Date : 2015-12-09 DOI: 10.4138/ATLGEOL.2015.017

M. Parsons, M. Little

{"title":"Establishing geochemical baselines in forest soils for environmental risk assessment in the Montague and Goldenville gold districts, Nova Scotia, Canada","authors":"M. Parsons, M. Little","doi":"10.4138/ATLGEOL.2015.017","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2015.017","url":null,"abstract":"Mine tailings at historical gold districts in Nova Scotia, Canada, contain high concentrations of arsenic (As) and mercury (Hg), which may represent a risk to ecosystems and human health. Two sites, Montague and Goldenville, are of particular concern as tailings are located close to residences and are occasionally used for racing off-road vehicles. Risk-assessment calculations require knowledge of the naturally occurring concentrations of As and Hg in soils overlying mineralized bedrock within these gold districts. In this study, we collected samples of the top 0–5 cm of surface soil (the Public Health layer) from 46 sites near Montague, and 39 sites near Goldenville. Samples of individual soil horizons (H, Ae, B, and C) were also taken from selected sites to evaluate the vertical distribution of elements in the soil profile. Results show that the concentrations of As and Hg in all soil horizons are generally higher down-ice, southeasterly, of the ore zones in both districts, reflecting glacial erosion and transport of mineralized bedrock. Analysis of the top 0–5 cm of soils shows the following ranges in As and Hg concentrations (<2 mm size fraction): Montague: As, 4–273 mg/kg (median 42 mg/kg); Hg, 72–490 µg/kg (median 164 µg/kg); Goldenville: As, 2–140 mg/kg (median 13 mg/kg); Hg, 39–312 µg/kg (median 114 µg/kg). In general, the concentrations of As are highest in the B and C horizons, whereas Hg concentrations are highest in humus (H). Results from this study have been used to assess the distribution of tailings at these sites, and to help guide risk-management decisions.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"23 1","pages":"364-386"},"PeriodicalIF":1.6,"publicationDate":"2015-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70754416","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: 2