Atlantic Geoscience最新文献

{"title":"An overview of Early Paleozoic arc systems in New Brunswick, Canada, and eastern Maine, USA","authors":"L. Fyffe, C. V. van Staal, Reginald A. Wilson, S. C. Johnson","doi":"10.4138/atlgeo.2023.001","DOIUrl":"https://doi.org/10.4138/atlgeo.2023.001","url":null,"abstract":"A plate tectonic model involving northwesterly retreat of an Iapetan subducting slab has been developed over the last three decades to explain the time span of volcanism recorded within the development of Early Paleozoic arc systems preserved in New Brunswick. These arc systems are referred as the Penobscot arc-backarc (514–482 Ma), and Popelogan–Meductic arc (478–460 Ma). Opening of the Tetagouche backarc basin associated with the Popelogan–Meductic arc was diachronous and heterogeneous and involved volcanism associated mainly with the crustal extension and rifting between 472–455 Ma. The complex evolution of the Tetagouche backarc basin is examined in respect to six sub-basins, containing relatively well documented stratigraphic sections in New Brunswick: namely from northeast to southwest the Fournier, California Lake, Bathurst, Sheephouse Brook, Napadogan, and Becaguimec sub-basins. Recently, alternate plate tectonic models have been proposed for the northern Appalachians based on newly acquired geochronological data from northern Maine. We integrate these new data with existing stratigraphic, structural, paleontological, and geochemical evidence to support and refine the previously proposed migrating-arc model for New Brunswick and Maine.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114426677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Devonian palynoevents in the circum-Arctic region","authors":"J. Marshall, Gunn Mangerud, M. Bringué, J. Bujak","doi":"10.4138/atlgeo.2022.015","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.015","url":null,"abstract":"Devonian strata of the present-day Arctic contain abundant and diverse assemblages of terrestrial palynomorphs, particularly from Middle and Upper Devonian sections; few intervals of Lower Devonian and Silurian strata have been palynologically studied, and these demonstrate strong palynofloral similarities across the region. Based on published records, we present a compilation of six last occurrence events (LOs), 44 first occurrence events (FOs) and one acme event that have proven of value in correlation in the present-day Arctic. Although their chronostratigraphic resolution is relatively low, and a scarcity of independent age control hampers precise age assignments, palynology is the only biostratigraphic discipline available for confident chronostratigraphic correlation of most Arctic Devonian strata.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116964702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to the Discussion of “The ‘lost’ islands of Cardigan Bay, Wales, UK: insights into the post-glacial evolution of some Celtic coasts of northwest Europe” by Catherine Delano-Smith, Phil Bradford, and William Shannon","authors":"S. Haslett, David G. Willis","doi":"10.4138/atlgeo.2022.014","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.014","url":null,"abstract":"range of conclusions. Whilst prefacing their introduction to sources with a general note of caution, Haslett and Willis (2022) present examples, not in support of any conclusions of their own but as a prerequisite for embarking on the study in providing at the outset a level of reassurance that suggests the islands depicted on the Gough Map merit further consideration. However, Delano-Smith et al. (2022) provide a welcome clarification to the mistake that the Gough Map is not the earliest known map of Great Britain (Haslett and Willis 2022; National Library of Scotland 2022) but rather is more correctly described, for example, as the “earliest known surviving map of Britain drawn on a separate sheet” (DelanoSmith et al. 2017, p. 3) and the “the earliest map to show Britain in recognizable form” (Nurse 2022, p. 50). The possibility that islands once existed in Cardigan Bay, as depicted on the Gough Map, prompted Haslett and Willis (2022) to reconsider Ptolemy’s coordinates as corrected by North (1957). The coordinate for the mouth of the River Teifi (Afon Teifi) at the southern end of Cardigan Bay is near its present-day location. A geomorphological explanation for an unchanged position is possible in that a radiocarbon date of 9539-10 154 cal. BP suggests that the Trawling Grounds bathymetric feature offshore of the river mouth may have been open to marine conditions and possibly a seaway for several thousand years, which may conceivably have been accessible to early seafarers (see fig. 4 of Haslett and Willis 2022). Northward along the coast, however, the next coordinate, for the mouth of the River Ystwyth (Afon Ystwyth), lies some 8 miles (ca. 13 km) west of the present-day location of the river mouth. While fully appreciating the comments of Delano-Smith et al. (2022), the depiction of offshore islands on the Gough Map appears consistent with REPLY","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"23 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126699948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atlantic Universities Geoscience Conference Abstracts: 72nd Annual Conference, October 27–29, 2022","authors":"C. White","doi":"10.4138/atlgeo.2022.013","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.013","url":null,"abstract":"","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125576175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overview of age constraints for gold mineralization in central and western Newfoundland and new 40Ar/39Ar ages for muscovite from selected auriferous zones","authors":"H. Sandeman, I. Honsberger, A. Camacho","doi":"10.4138/atlgeo.2022.012","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.012","url":null,"abstract":"This contribution presents new 40Ar/39Ar laser step-heating data for muscovite associated with four significant orogenic gold-mineralized zones in central and western Newfoundland to build upon existing geochronological constraints for orogenic gold mineralization across much of the Newfoundland Appalachians. Additionally, we provide the first 40Ar/39Ar laser step-heating data for detrital muscovite from gold-mineralized sandstone of the Wigwam Formation (Botwood Group) at the Moosehead gold prospect. Most known gold zones on the isIand occur in proximity to reactivated crustal-scale faults and related structures, and are commonly localized within competent, rigid lithological units (e.g., granitoid rocks); although, some vein systems cut less competent, clastic sedimentary rock sequences. Host rocks range in age from Neoproterozoic to Devonian and may extend into the Carboniferous. Robust Pragian to Emsian (ca. 410–375 Ma) rutile, muscovite and zircon ages constrain the timing of gold mineralization in parts of the Exploits Subzone, whereas less precise age estimates for gold mineralization in the Notre Dame Subzone and Laurentian margin range from Wenlock to Emsian (ca. 433–375 Ma). Collectively, the geochronological data suggest that fluid-pressure cycling associated with gold mineralization in central and western Newfoundland occurred during progressive Siluro-Devonian tectonics associated with the waning stages of the Salinic orogenic cycle and spanning the Acadian and Neoacadian orogenic cycles. Multiple, polyphase, overlapping orogenic events allowed for repeated, gold mineralizing fluid flow events, particularly in proximity to long-lived, reactivated crustal-scale fault zones.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130777284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discussion of “The ‘lost’ islands of Cardigan Bay, Wales, UK: insights into the post-glacial evolution of some Celtic coasts of northwest Europe” by Simon K. Haslett and David Willis","authors":"C. Delano-smith, P. Bradford, W. Shannon","doi":"10.4138/atlgeo.2022.011","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.011","url":null,"abstract":"can be relied upon to identify and date the lost lowlands of Cardigan Bay might be a matter for speculation. Such legends are far from unique. There are plenty of myths of lost lands and sunken cities around the British Isles, many supported by botanical and archaeological evidence of the large scale loss of real areas (Pennick 1987). One has only to consider Doggerland, the great land-mass between Britain and the continent that was finally submerged around 6500 BCE, or well-documented cases of settlements lost to storms and coastal erosion more recently such as Ravenser Odd at the mouth of the Humber, a prosperous port abandoned and overwhelmed in the midfourteenth century. However, it is abundantly clear that early maps, including the three cited by Haslett and Willis, cannot be used in the way they do to provide details of coastal erosion, still less to date the existence and disappearance of particular islands. Haslett and Willis attempt to use Ptolemy’s Geography (compiled ca. 150 AD) to argue that roughly 1900 years ago, the coast of Wales was some eight miles to the west of its current position. This is to misunderstand the original source completely. Claudius Ptolemy, based in Alexandria, did a brilliant job of pulling together disparate sources to produce a map of the known world. That map has not survived. What does survive are his instructions for making it, and a series of regional maps in the form of lists of coordinates or grid references. It is probable that the latitudes of a small number of Ptolemy’s places were located from astronomical observation. But no secure method existed for estimating longitude, and the position of most places given by Ptolemy from his sources would have been derived from statements of the approximate distance and direction between them (as in itineraries). For Britain, it may be that Ptolemy was using DISCUSSION","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129076149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Batrachichnus salamandroides trackway from the Minto Formation of central New Brunswick, Canada: implications for alternative trackmaker interpretations","authors":"Luke F. Allen, M. Stimson, Olivia A. King, Rowan E. Norrad, S. Lucas, Arjan Mann, S. Hinds, A. Park, J. Calder, Hillary C. Maddin, Martin Montplaisir","doi":"10.4138/atlgeol.2022.010","DOIUrl":"https://doi.org/10.4138/atlgeol.2022.010","url":null,"abstract":"A new specimen of Batrachichnus salamandroides was recovered from a recently discovered fossil-bearingsite situated along the southern shore of Grand Lake, New Brunswick, among a diverse ichnofaunal assemblagefrom the Middle Pennsylvanian (upper Bolsovian; lower Moscovian), upper Minto Formation. The identity ofthe tracemaker of this ichnogenus is reinterpreted as a composite of various late Paleozoic tetrapod taxa, basedon similarities of the postcranial skeletons, notably that of the manus and pes, of both temnospondyls and some“microsaurs”. These results indicate that the tracemaker of the monospecific ichnogenus Batrachnichus is notlimited solely to a temnospondyl tracemaker, as previously interpreted, and that some “microsaurs” should alsobe considered among tracemaker candidates for this ichnotaxon.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133171014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"U–Pb geochronology of Late Silurian (Wenlock to Pridoli) volcanic and sedimentary rocks, central Newfoundland Appalachians: targeting the timing of transient extension as a prelude to Devonian orogenic gold mineralization","authors":"I. Honsberger, W. Bleeker, S. Kamo, C. N. Sutcliffe, H. Sandeman","doi":"10.4138/atlgeo.2022.009","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.009","url":null,"abstract":"Bimodal igneous suites and associated immature clastic sedimentary rocks are characteristic of many orogenic gold-mineralized, crustal-scale fault zones globally. In the central Newfoundland Appalachian orogen, the Rogerson Lake Conglomerate belt and Botwood basin are Late Silurian (Wenlock to Pridoli), fault-controlled sedimentary rock sequences and magmatic suites closely associated with orogenic gold mineralization; however, the spatio-temporal evolution of faulting and associated sedimentation and magmatism are not fully resolved.\u0000U–Pb zircon geochronological results were obtained by using an integrated approach employing LA-ICPMS (laser ablation-inductively coupled plasma mass spectrometry) followed by CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) on the same detrital samples. Using this approach, a maximum depositional age for sedimentary rocks of the Rogerson Lake Conglomerate sequence is 421.9 ± 1.0 Ma (Pridoli), which confirms that they are younger than, and stratigraphically overlie, ca. 422–420 Ma igneous rocks exposed along the central Newfoundland gold belt. Towards the stratigraphic middle of the Botwood basin in north-central Newfoundland, a tuffite layer intercalated with graded siltstone produced a maximum depositional age of 427.9 ± 3.1 Ma (Wenlock; Homerian). The age of emplacement of an autobrecciated, flow-banded rhyolite dome of the Charles Lake volcanic belt along the northwestern Botwood basin is 429.3 ± 0.7 Ma (Wenlock; Homerian). The high-precision CA-ID-TIMS zircon data establish a clear link between Wenlock to Pridoli magmatism and sedimentation throughout central Newfoundland. Furthermore, these geochronological results are consistent with a structural model involving the southeastward (present-day coordinates) advancement of a transient extensional fault system across strike of the Exploits Subzone between ca. 429 and 418 Ma, with propagation along strike to the southwest (Rogerson Lake Conglomerate belt) between ca. 422 and 418 Ma. Extensional faulting may have contributed to basin formation, subsidence, and exhumation of pre-Late Silurian rocks of the Exploits Subzone.\u0000Time-transgressive, extension-related magmatism and clastic sedimentation appear to mark the transition between the Salinic and Acadian orogenic cycles along the central Newfoundland gold belt. Transient Wenlock to Pridoli lithospheric extension may have been important for increasing heat and fluid flow in the crust as a prelude to Devonian crustal thickening, fluid focussing, and orogenic gold mineralization.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121068993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revised stratigraphy in the eastern Meguma terrane, Nova Scotia, Canada, and variations in whole-rock chemical and Sm–Nd isotopic compositions of the Goldenville and Halifax groups","authors":"S. Barr, C. White, C. Pin","doi":"10.4138/atlgeo.2022.008","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.008","url":null,"abstract":"As a result of new geological mapping, the Goldenville and Halifax groups in the eastern Meguma terrane have been divided into formations. They have a total stratigraphic thickness of about 7750 m and correspond to only the upper half of the Goldenville Group and lower half of the Halifax Group in the northwestern and southeastern areas of the terrane. The revised stratigraphy combined with compiled and new whole-rock major and trace element and Sm–Nd isotopic analyses enable more detailed documentation of the chemical changes with stratigraphy that were demonstrated in previous studies. Based on chemical compositions, the protolith compositions of the analysed samples range from lithic arenite to wacke to shale. Major and trace element characteristics are consistent with deposition in an active continental margin, basins associated with island arcs, or most likely at a passive continental margin with volcanic rocks in the source area. Chemical compositions show a scattered but overall increasing abundance of lithophile elements such as La and Th with stratigraphic position. Epsilon Nd(t) values become increasingly negative up-section, and depleted mantle model ages become increasingly older. The data are consistent with increased mixing between sediments  derived from Mesoproterozoic upper crustal sources and sediments derived from a magmatic arc. These data are consistent with published detrital zircon patterns which show increasing amounts of ca. 2 Ga zircon with decreasing age, and with a source area comprising a Pan-African (800–540 Ma) volcanic arc and/or active margin magmatism and mainly Eburnean crust, most likely in the West African craton.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115779131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potential for critical mineral deposits in Maine, USA","authors":"J. Slack, Frederick M. Beck, D. Bradley, M. Felch, R. Marvinney, A. Whittaker","doi":"10.4138/atlgeo.2022.007","DOIUrl":"https://doi.org/10.4138/atlgeo.2022.007","url":null,"abstract":"An analysis of the potential for deposits of critical minerals and elements in Maine presented here includes data and discussions for antimony, beryllium, cesium, chromium, cobalt, graphite, lithium, manganese, niobium, platinum group elements, rhenium, rare earth elements, tin, tantalum, tellurium, titanium, uranium, vanadium, tungsten, and zirconium. Deposits are divided into two groups based on geological settings and common ore-deposit terminology. One group consists of known deposits (sediment-hosted manganese, volcanogenic massive sulphide, porphyry copper-molybdenum, mafic- and ultramafic-hosted nickel-copper [-cobalt-platinum group elements], pegmatitic lithium-cesium-tantalum) that are in most cases relatively large, well-documented, and have been explored extensively in the past. The second, and much larger group of different minerals and elements, comprises small deposits, prospects, and occurrences that are minimally explored or unexplored. The qualitative assessment used in this study relies on three key criteria: (1) the presence of known deposits, prospects, or mineral occurrences; (2) favourable geologic settings for having certain deposit types based on current ore deposit models; and (3) geochemical anomalies in rocks or stream sediments, including panned concentrates. Among 20 different deposit types considered herein, a high resource potential is assigned only to three: (1) sediment-hosted manganese, (2) mafic- and ultramafic-hosted nickel-copper(-cobalt-platinum group elements), and (3) pegmatitic lithium-cesium-tantalum. Moderate potential is assigned to 11 other deposit types, including: (1) porphyry copper-molybdenum (-rhenium, selenium, tellurium, bismuth, platinum group elements); (2) chromium in ophiolites; (3) platinum group elements in ophiolitic ultramafic rocks; (4) granite-hosted uranium-thorium; (5) tin in granitic plutons and veins; (6) niobium, tantalum, and rare earth elements in alkaline intrusions; (7) tungsten and bismuth in polymetallic veins; (8) vanadium in black shales; (9) antimony in orogenic veins and replacements; (10) tellurium in epithermal deposits; and (11) uranium in peat.","PeriodicalId":142525,"journal":{"name":"Atlantic Geoscience","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115116628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}