Pub Date : 2017-10-02DOI: 10.4138/ATLGEOL.2017.012
R. Hooke, P. Hanson
Between ~20 and 15 ka the Laurentide Ice Sheet retreated from the edge of the continental shelf, ἀrst to the Maine coast and then across Maine to the northern reaches of the Penobscot Lowland. The Lowland, being isostatically depressed, was inundated by the sea. As ice then retreated into Maine’s western mountains, valleys through the mountains became estuaries. In the estuary now occupied by the Penobscot River’s East Branch, ten ice-marginal deltas were built during pauses in this part of the retreat. By 14 ka the ice had retreated far enough to expose land in the valley bottom between the ice front and the sea, and the Penobscot River was (re)born. This occurred near the present conᴀuence of the Seboeis River and the East Branch. The river gradually extended itself northward as the ice retreated and southward as relative sea level fell. Braidplains were formed and incised, leaving terraces. High initial discharges eroded the eastern ᴀanks of the esker and deltas, redepositing silt, sand, and gravel all the way to the present head of Penobscot Bay. By ~10 ka the discharge had decreased, the river was adjusting to on-going differential isostatic rebound, and finer sediment was accumulating, forming the present floodplain.
{"title":"Late- and Post-glacial history of the East Branch of the Penobscot River, Maine, USA","authors":"R. Hooke, P. Hanson","doi":"10.4138/ATLGEOL.2017.012","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2017.012","url":null,"abstract":"Between ~20 and 15 ka the Laurentide Ice Sheet retreated from the edge of the continental shelf, ἀrst to the Maine coast and then across Maine to the northern reaches of the Penobscot Lowland. The Lowland, being isostatically depressed, was inundated by the sea. As ice then retreated into Maine’s western mountains, valleys through the mountains became estuaries. In the estuary now occupied by the Penobscot River’s East Branch, ten ice-marginal deltas were built during pauses in this part of the retreat. By 14 ka the ice had retreated far enough to expose land in the valley bottom between the ice front and the sea, and the Penobscot River was (re)born. This occurred near the present conᴀuence of the Seboeis River and the East Branch. The river gradually extended itself northward as the ice retreated and southward as relative sea level fell. Braidplains were formed and incised, leaving terraces. High initial discharges eroded the eastern ᴀanks of the esker and deltas, redepositing silt, sand, and gravel all the way to the present head of Penobscot Bay. By ~10 ka the discharge had decreased, the river was adjusting to on-going differential isostatic rebound, and finer sediment was accumulating, forming the present floodplain.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"285-300"},"PeriodicalIF":1.6,"publicationDate":"2017-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43982802","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 : 2017-08-27DOI: 10.4138/atlgeol.2017.011
Martin A Becker, Rebecca B. Chamberlain, Harry M. Maisch, A. Bartholomew, J. Chamberlain
Glacial erratics belonging to the Rickard Hill facies (RHF) of the Saugerties Member of the Schoharie Formation (upper Emsian: Lower Devonian) occur scattered throughout the Piedmont of northern New Jersey and Lower Hudson Valley of New York. These RHF glacial erratics contain an assemblage of trilobites belonging to: Anchiopella anchiops , Burtonops cristatus , Calymene platys , Terataspis grandis , cf. Trypaulites sp. and cf. Coniproetus sp. This RHF glacial erratic trilobite assemblage consists predominately of disarticulated cephala and pygidia that were originally preserved as part of a localized, third-order eustatic sea level lag deposit in the Helderberg Mountains region of central New York State and subsequently transported in glacially plucked blocks by the Hudson-Champlain Lobe of the Laurentide Ice Sheet southward into New Jersey. Physical and chemical weathering during glacial erosion, transportation and deposition of the RHF glacial erratics has revealed some anatomical features of these trilobites in high detail along with other invertebrates. This unique sequence of weathering reveals additional characteristics that bear upon issues of bathymetric controls on upper Schoharie Formation lithology, trilobite faunal abundance and taphonomy during the upper Emsian (Lower Devonian) of eastern New York State.
{"title":"Trilobites from the Rickard Hill facies of the Saugerties Member of the Schoharie Formation, eastern New York (upper Emsian and Lower Devonian): a case study in taphonomy and sequence stratigraphy from glacial erratics","authors":"Martin A Becker, Rebecca B. Chamberlain, Harry M. Maisch, A. Bartholomew, J. Chamberlain","doi":"10.4138/atlgeol.2017.011","DOIUrl":"https://doi.org/10.4138/atlgeol.2017.011","url":null,"abstract":"Glacial erratics belonging to the Rickard Hill facies (RHF) of the Saugerties Member of the Schoharie Formation (upper Emsian: Lower Devonian) occur scattered throughout the Piedmont of northern New Jersey and Lower Hudson Valley of New York. These RHF glacial erratics contain an assemblage of trilobites belonging to: Anchiopella anchiops , Burtonops cristatus , Calymene platys , Terataspis grandis , cf. Trypaulites sp. and cf. Coniproetus sp. This RHF glacial erratic trilobite assemblage consists predominately of disarticulated cephala and pygidia that were originally preserved as part of a localized, third-order eustatic sea level lag deposit in the Helderberg Mountains region of central New York State and subsequently transported in glacially plucked blocks by the Hudson-Champlain Lobe of the Laurentide Ice Sheet southward into New Jersey. Physical and chemical weathering during glacial erosion, transportation and deposition of the RHF glacial erratics has revealed some anatomical features of these trilobites in high detail along with other invertebrates. This unique sequence of weathering reveals additional characteristics that bear upon issues of bathymetric controls on upper Schoharie Formation lithology, trilobite faunal abundance and taphonomy during the upper Emsian (Lower Devonian) of eastern New York State.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"269-284"},"PeriodicalIF":1.6,"publicationDate":"2017-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46667010","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 : 2017-06-28DOI: 10.4138/ATLGEOL.2017.010
Larbi Rddad
The Byram and Walls Island members in the lower and upper sections, respectively, of the Lockatong Formation in the Newark basin near the border between Pennsylvania and New Jersey were chosen to assess (i) the role of euxinic/anoxic conditions in sequestering arsenic (As) and other trace elements and (ii) the redistribution of these elements during catagenetic transformations. ἀese members are rich in organic matter and host pyrite which occurs as disseminations, small patches, and subparallel veins. ἀe sulfur isotope values of pyrite samples range between -7.5 and 0.5 ‰CDT (average = -3.5‰CDT). ἀe negative δ34S values are indicative of Bacterial Sulfate Reduction (BSR) under low temperature and euxinic/anoxic conditions. ἀe total organic carbon (TOC) values in this member ᴀuctuate between 0.5 and 2.1%. ἀese euxinic/anoxic conditions enhanced the incorporation of As and other trace elements in both organic matter and pyrite. ἀe As concentrations range from 13 to 800 mg/kg and from 1.4 to 34 mg/kg in pyrite and black shale samples, respectively. Rock Eval analyses reveal that organic matter is over-mature which altered the correlation between TOC and As. ἀe thermal cracking of organic matter resulted in the removal of these elements from organic matter and their subsequent incorporation in pyrite and bitumen. Organic matter- and pyrite-rich anoxic black shale layers and bitumen veins are potential sources of arsenic in groundwater in the Newark basin, with arsenic values that reach up to 215 μg/L.
{"title":"Fixation and redistribution of arsenic during early and late diagenesis in the organic matter-rich members of the Lockatong Formation, Newark basin, USA: implication for the quality of groundwater","authors":"Larbi Rddad","doi":"10.4138/ATLGEOL.2017.010","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2017.010","url":null,"abstract":"The Byram and Walls Island members in the lower and upper sections, respectively, of the Lockatong Formation in the Newark basin near the border between Pennsylvania and New Jersey were chosen to assess (i) the role of euxinic/anoxic conditions in sequestering arsenic (As) and other trace elements and (ii) the redistribution of these elements during catagenetic transformations. ἀese members are rich in organic matter and host pyrite which occurs as disseminations, small patches, and subparallel veins. ἀe sulfur isotope values of pyrite samples range between -7.5 and 0.5 ‰CDT (average = -3.5‰CDT). ἀe negative δ34S values are indicative of Bacterial Sulfate Reduction (BSR) under low temperature and euxinic/anoxic conditions. ἀe total organic carbon (TOC) values in this member ᴀuctuate between 0.5 and 2.1%. ἀese euxinic/anoxic conditions enhanced the incorporation of As and other trace elements in both organic matter and pyrite. ἀe As concentrations range from 13 to 800 mg/kg and from 1.4 to 34 mg/kg in pyrite and black shale samples, respectively. Rock Eval analyses reveal that organic matter is over-mature which altered the correlation between TOC and As. ἀe thermal cracking of organic matter resulted in the removal of these elements from organic matter and their subsequent incorporation in pyrite and bitumen. Organic matter- and pyrite-rich anoxic black shale layers and bitumen veins are potential sources of arsenic in groundwater in the Newark basin, with arsenic values that reach up to 215 μg/L.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"253-268"},"PeriodicalIF":1.6,"publicationDate":"2017-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41955821","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 : 2017-05-06DOI: 10.4138/ATLGEOL.2017.008
N. Mohammadi, L. Fyffe, C. McFarlane, K. Thorne, D. Lentz, Brittany E. Charnley, L. Branscombe, S. Butler
The Late Silurian to Late Devonian Saint George Batholith in southwestern New Brunswick is a large composite intrusion (2000 km 2 ) emplaced into the continental margin of the peri-Gondwanan microcontinent of Ganderia. The batholith includes: (1) Bocabec Gabbro; (2) equigranular Utopia and Wellington Lake biotite granites; (3) Welsford, Jake Lee Mountain, and Parks Brook peralkaline granites; (4) two-mica John Lee Brook Granite; (6) Jimmy Hill and Magaguadavic megacrystic granites; and (6) rapakivi Mount Douglas Granite. New LA ICP-MS in situ analyses of six samples from the Saint George Batholith are as follows: (1) U-Pb monazite crystallization age of 425.5 ± 2.1 Ma for the Utopia Granite in the western part of the batholith (2) U-Pb zircon crystallization ages of 420.4 ± 2.4 Ma and 420.0 ± 3.5 Ma for two samples of the Utopia Granite from the central part of the batholith; (3) U-Pb zircon crystallization age of 418.0 ± 2.3 Ma for the Jake Lee Mountain Granite; (4) U-Pb zircon crystallization age of 415.5 ± 2.1 Ma for the Wellington Lake Granite; and (5) U-Pb monazite crystallization age of 413.3 ± 2.1 Ma for the John Lee Brook Granite. The new geochronological together with new and existing geochemical data suggest that the protracted magmatic evolution of the Late Silurian to Early Devonian plutonic rocks is related to the transition of the Silurian Kingston arc-Mascarene backarc system from an extensional to compressional tectonic environment during collision of the Avalonian microcontinent with Laurentia followed by slab break-off.
新不伦瑞克省西南部的晚志留世至晚泥盆世圣乔治岩基是一个大型复合侵入体(2000平方公里)，位于冈瓦南周边甘德拉微大陆的大陆边缘。岩基包括:(1)Bocabec辉长岩;(2)等粒状乌托邦和惠灵顿湖黑云母花岗岩;(3)威尔斯福德、杰克李山和帕克斯布鲁克过碱性花岗岩;(4)二云母约翰李布鲁克花岗岩;(6) Jimmy Hill和Magaguadavic巨晶花岗岩;(6)拉帕基维道格拉斯山花岗岩。新的LA ICP-MS原位分析结果如下:(1)基岩西部乌托邦花岗岩的U-Pb单氮石结晶年龄为425.5±2.1 Ma;(2)基岩中部乌托邦花岗岩的2个样品的U-Pb锆石结晶年龄分别为420.4±2.4 Ma和420.0±3.5 Ma;(3)杰克李山花岗岩U-Pb锆石结晶年龄为418.0±2.3 Ma;(4)惠灵顿湖花岗岩U-Pb锆石结晶年龄为415.5±2.1 Ma;(5)李溪花岗岩U-Pb独居石结晶年龄为413.3±2.1 Ma。新的年代学和现有的地球化学资料表明，晚志留世至早泥盆世深成岩的岩浆演化与志留纪金斯顿弧-马斯喀林弧后体系在阿瓦洛尼亚微大陆与劳伦提亚碰撞过程中由伸展构造环境过渡到挤压构造环境有关。
{"title":"Geological relationships and laser ablation ICP-MS U-Pb geochronology of the Saint George Batholith, southwestern New Brunswick, Canada: implications for its tectonomagmatic evolution","authors":"N. Mohammadi, L. Fyffe, C. McFarlane, K. Thorne, D. Lentz, Brittany E. Charnley, L. Branscombe, S. Butler","doi":"10.4138/ATLGEOL.2017.008","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2017.008","url":null,"abstract":"The Late Silurian to Late Devonian Saint George Batholith in southwestern New Brunswick is a large composite intrusion (2000 km 2 ) emplaced into the continental margin of the peri-Gondwanan microcontinent of Ganderia. The batholith includes: (1) Bocabec Gabbro; (2) equigranular Utopia and Wellington Lake biotite granites; (3) Welsford, Jake Lee Mountain, and Parks Brook peralkaline granites; (4) two-mica John Lee Brook Granite; (6) Jimmy Hill and Magaguadavic megacrystic granites; and (6) rapakivi Mount Douglas Granite. New LA ICP-MS in situ analyses of six samples from the Saint George Batholith are as follows: (1) U-Pb monazite crystallization age of 425.5 ± 2.1 Ma for the Utopia Granite in the western part of the batholith (2) U-Pb zircon crystallization ages of 420.4 ± 2.4 Ma and 420.0 ± 3.5 Ma for two samples of the Utopia Granite from the central part of the batholith; (3) U-Pb zircon crystallization age of 418.0 ± 2.3 Ma for the Jake Lee Mountain Granite; (4) U-Pb zircon crystallization age of 415.5 ± 2.1 Ma for the Wellington Lake Granite; and (5) U-Pb monazite crystallization age of 413.3 ± 2.1 Ma for the John Lee Brook Granite. The new geochronological together with new and existing geochemical data suggest that the protracted magmatic evolution of the Late Silurian to Early Devonian plutonic rocks is related to the transition of the Silurian Kingston arc-Mascarene backarc system from an extensional to compressional tectonic environment during collision of the Avalonian microcontinent with Laurentia followed by slab break-off.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"207-240"},"PeriodicalIF":1.6,"publicationDate":"2017-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47440500","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 : 2017-04-27DOI: 10.4138/ATLGEOL.2017.007
P. Getty, Robert G. Sproule, M. Stimson, P. Lyons
A large open-pit quarry in Plainville, Massachusetts, has yielded fourteen invertebrate ichnotaxa from the Pennsylvanian Rhode Island Formation of the Narragansett Basin. These traces include Cochlichnus anguineus , Diplichnites cuithensis, Diplichnites gouldi, Diplopodichnus biformis, Gordia carickensis, Helminthoidichites tenuis, Lockeia isp., Mitchellichnus cf. ferrydenensis, Planolites montanus, Siskemia elegans, Stiallia pilosa, Stiaria intermedia, Tonganoxichnus buildexensis and Narragansettichnus fortunatus new ichnogenus and ichnospecies. Specimens were collected from talus and the depositional environment has been inferred from sedimentary structures. The sediment - ology of the slabs on which the traces were preserved indicates that the rocks represent lake-margin and shallowlacustrine sedimentary facies. Distinct ichnofacies occur in the different sedimentary environments. The lake-margin traces belong to the Scoyenia ichnofacies and include traces of apterygote insects, arthropleurid myriapods, bivalved arthropods and vermiform animals in association with tracks of temnospondyl amphibians and diapsid reptiles. The lacustrine traces include arthropod trackways, fish trails and a newly named body imprint possibly produced by an aquatic mayfly larva. These shallow lacustrine traces are attributed to the Mermia ichnofacies.
{"title":"Invertebrate trace fossils from the Pennsylvanian Rhode Island Formation of Massachusetts, USA","authors":"P. Getty, Robert G. Sproule, M. Stimson, P. Lyons","doi":"10.4138/ATLGEOL.2017.007","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2017.007","url":null,"abstract":"A large open-pit quarry in Plainville, Massachusetts, has yielded fourteen invertebrate ichnotaxa from the Pennsylvanian Rhode Island Formation of the Narragansett Basin. These traces include Cochlichnus anguineus , Diplichnites cuithensis, Diplichnites gouldi, Diplopodichnus biformis, Gordia carickensis, Helminthoidichites tenuis, Lockeia isp., Mitchellichnus cf. ferrydenensis, Planolites montanus, Siskemia elegans, Stiallia pilosa, Stiaria intermedia, Tonganoxichnus buildexensis and Narragansettichnus fortunatus new ichnogenus and ichnospecies. Specimens were collected from talus and the depositional environment has been inferred from sedimentary structures. The sediment - ology of the slabs on which the traces were preserved indicates that the rocks represent lake-margin and shallowlacustrine sedimentary facies. Distinct ichnofacies occur in the different sedimentary environments. The lake-margin traces belong to the Scoyenia ichnofacies and include traces of apterygote insects, arthropleurid myriapods, bivalved arthropods and vermiform animals in association with tracks of temnospondyl amphibians and diapsid reptiles. The lacustrine traces include arthropod trackways, fish trails and a newly named body imprint possibly produced by an aquatic mayfly larva. These shallow lacustrine traces are attributed to the Mermia ichnofacies.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"185-206"},"PeriodicalIF":1.6,"publicationDate":"2017-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49310238","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 : 2017-03-29DOI: 10.4138/ATLGEOL.2017.004
D. B. Clarke, C. McFarlane, D. Hamilton, D. Stevens
In Halifax, Nova Scotia, 149 victims of the 1912 sinking of the Titanic lie beneath petrologically identical "black granite" headstones. Those headstones, supplied by the White Star Line, arrived in Halifax in late 1912, but no known historical document reveals their source. They consist of medium- to coarse-grained olivine-bearing gabbro, with cumulus phases consisting of randomly oriented euhedral plagioclase laths, corroded olivine, and titaniferous magnetite, and intercumulus material consisting of augite with reaction rims of hornblende, both of which are variably altered to actinolite and biotite. Three types of forensic evidence [quantitative – radiometric age of 422.1 ± 1.3 Ma (n = 17), mean olivine FeO/(FeO + MgO) values ranging from 0.43 to 0.46, augite rim trace- element compositions (35 elements), and whole-rock chemical compositions (48 elements), including statistical analysis of all these data showing no significant differences between the headstones and their putative source quarry; qualitative – mineral assemblages, modal proportions, textural parameters, style and degree of alteration; and circumstantial – regional reputation, quarrying history, local logistics, regional transportation, McGrattan marker] connect the Titanic headstones to the Saint George Batholith in southwestern New Brunswick. Precise matching of any dimension stone to its source quarry is problematic, because that material connects only to a void in the quarry. Ideally, all physical-chemical-temporal properties of the dimension stone and source quarry should match, both quantitatively and qualitatively, but in reality only the ages must almost certainly match. Thus it is remotely possible for the right quarry to mismatch most of the properties of the dimension stone, and for a wrong quarry to match most of the properties of the dimension stone. However, in the case of the Titanic headstones, the cumulative weight of all the quantitative, qualitative, and circumstantial evidence, combined with a process of elimination and application of Ockham’s razor, indicate that the Charles Hanson quarry near Bocabec, southwestern New Brunswick, is the likely source for the gabbroic Titanic headstones in Halifax, Nova Scotia.
在新斯科舍省的哈利法克斯，1912年泰坦尼克号沉没的149名遇难者躺在岩石学上完全相同的“黑色花岗岩”墓碑下。这些墓碑是由白星航运公司提供的，于1912年底抵达哈利法克斯，但没有已知的历史文献显示它们的来源。它们由中~粗粒含橄榄岩辉长岩组成，积云相由随机取向的自面斜长石板条、腐蚀橄榄石和含钛磁铁矿组成，积云间物质由带有角闪石反应边缘的辉长岩组成，两者都不同程度地蚀变为放线石和黑云母。三种类型的法医证据[定量-辐射年龄为422.1±1.3 Ma (n = 17)，平均橄榄石FeO/(FeO + MgO)值在0.43 ~ 0.46之间，奥辉石边缘微量元素组成(35个元素)和全岩化学成分(48个元素)]，包括统计分析在内，所有这些数据在墓碑与推测的来源采石场之间没有显著差异;质性-矿物组合、模态比例、结构参数、样式和蚀变程度;而环境因素——地区声誉、采石历史、当地物流、地区运输、麦格拉坦标志——则将泰坦尼克号的墓碑与新不伦瑞克省西南部的圣乔治巴托利特联系起来。任何尺寸的石头与其源采石场的精确匹配都是有问题的，因为这种材料只连接到采石场的一个空隙。理想情况下，尺寸石和源采石场的所有物理-化学-时间特性都应该在数量和质量上相匹配，但实际上只有年龄必须几乎肯定相匹配。因此，正确的采石场不匹配尺寸石的大部分属性，而错误的采石场不匹配尺寸石的大部分属性是不可能的。然而，在泰坦尼克号墓碑的案例中，所有定量、定性和间接证据的累积重量，结合奥卡姆剃刀的排除和应用过程，表明新不伦瑞克西南部博卡贝克附近的查尔斯·汉森采石场可能是新斯科舍省哈利法克斯辉长岩泰坦尼克号墓碑的来源。
{"title":"Forensic igneous petrology: locating the source quarry for the “black granite\" Titanic headstones in Halifax, Nova Scotia, Canada","authors":"D. B. Clarke, C. McFarlane, D. Hamilton, D. Stevens","doi":"10.4138/ATLGEOL.2017.004","DOIUrl":"https://doi.org/10.4138/ATLGEOL.2017.004","url":null,"abstract":"In Halifax, Nova Scotia, 149 victims of the 1912 sinking of the Titanic lie beneath petrologically identical \"black granite\" headstones. Those headstones, supplied by the White Star Line, arrived in Halifax in late 1912, but no known historical document reveals their source. They consist of medium- to coarse-grained olivine-bearing gabbro, with cumulus phases consisting of randomly oriented euhedral plagioclase laths, corroded olivine, and titaniferous magnetite, and intercumulus material consisting of augite with reaction rims of hornblende, both of which are variably altered to actinolite and biotite. Three types of forensic evidence [quantitative – radiometric age of 422.1 ± 1.3 Ma (n = 17), mean olivine FeO/(FeO + MgO) values ranging from 0.43 to 0.46, augite rim trace- element compositions (35 elements), and whole-rock chemical compositions (48 elements), including statistical analysis of all these data showing no significant differences between the headstones and their putative source quarry; qualitative – mineral assemblages, modal proportions, textural parameters, style and degree of alteration; and circumstantial – regional reputation, quarrying history, local logistics, regional transportation, McGrattan marker] connect the Titanic headstones to the Saint George Batholith in southwestern New Brunswick. Precise matching of any dimension stone to its source quarry is problematic, because that material connects only to a void in the quarry. Ideally, all physical-chemical-temporal properties of the dimension stone and source quarry should match, both quantitatively and qualitatively, but in reality only the ages must almost certainly match. Thus it is remotely possible for the right quarry to mismatch most of the properties of the dimension stone, and for a wrong quarry to match most of the properties of the dimension stone. However, in the case of the Titanic headstones, the cumulative weight of all the quantitative, qualitative, and circumstantial evidence, combined with a process of elimination and application of Ockham’s razor, indicate that the Charles Hanson quarry near Bocabec, southwestern New Brunswick, is the likely source for the gabbroic Titanic headstones in Halifax, Nova Scotia.","PeriodicalId":49235,"journal":{"name":"Atlantic Geology","volume":"53 1","pages":"087-114"},"PeriodicalIF":1.6,"publicationDate":"2017-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47690795","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 : 2017-03-29DOI: 10.4138/ATLGEOL.2017.005
A. Berger
At various coastal and inland sites in and around Gros Morne National Park in western Newfoundland, photographs taken periodically over many decades illustrate the physical stability of landforms. ἀese images provide a convenient, qualitative way to track the development of stone rings and patterned ground, the movement of rocks along intertidal platforms, changes to marine estuaries and to alluvial rivers and fans, temporal trends in late-lying snow beds along mountain tops, and slope failure by landslides and rock falls. ἀis study has established a spatial and temporal photographic record of slope failures along the steep cliḀs of Western Brook Pond, showing that nearly all of the sites identiᴀed in earlier studies as high risk of failure have remained stable. In contrast, thin-skinned landslides along Winter House Brook have remained active for at least 100 years. Little evidence of physical changes in patterned ground features in Trout River Gulch was found, other than frost-heaving in soils disturbed by road construction. Fluctuations from year to year in the level of gravel beaches along parts of the coast are common, and blow-outs continue to modify coastal sand dunes. Apart from certain engineered sites where change was obviously driven by direct human activities, the immediate cause or “driver” of change was natural (non-human), the result of gravitational instability, heavy precipitation, wave and storm action, frost heaving, and other background processes of the sort that long pre-date the coming of people to the region. Continuation of this kind of inexpensive, non-invasive monitoring can assist in assessing ecological integrity, managing public safety, and interpreting landscape processes for Park visitors.
在纽芬兰西部格罗斯莫恩国家公园及其周围的各个沿海和内陆地区，几十年来定期拍摄的照片说明了地貌的物理稳定性。ἀ这些图像提供了一种方便、定性的方法来跟踪石环和花纹地面的发展、岩石沿潮间带平台的运动、海洋河口和冲积河流和扇的变化、山顶晚伏雪床的时间趋势以及山体滑坡和落石造成的斜坡破坏。ἀ这项研究建立了沿陡峭海岸线边坡破坏的时空照片记录Ḁs，显示几乎所有的遗址ᴀ在早期的研究中，ed作为高失败风险一直保持稳定。相比之下，Winter House Brook沿线的薄皮滑坡已经活跃了至少100年。除了道路施工扰动的土壤冻胀外，几乎没有发现特劳特河峡谷地形地貌发生物理变化的证据。海岸部分地区的砾石海滩水平每年都会出现波动，井喷继续改变海岸沙丘。除了某些明显由人类直接活动驱动变化的工程场地外，变化的直接原因或“驱动因素”是自然的（非人类），是引力不稳定、强降水、波浪和风暴作用、冻胀以及其他早在人类来到该地区之前的背景过程的结果。继续进行这种廉价、无创的监测可以帮助评估生态完整性、管理公共安全，并为公园游客解释景观过程。
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Pub Date : 2017-03-16DOI: 10.4138/ATLGEOL.2017.003
A. Ludman, J. Hopeck, Henry N Berry Iv
Recent mapping in eastern and east-central Maine addresses long-standing regional correlation issues and permits reconstruction of post-Middle Ordovician, pre-Devonian paleogeography of sedimentary basins on the Ganderian composite terrane. Two major Late Ordovician-Silurian depocenters are recognized in eastern Maine and western New Brunswick separated by an emergent Miramichi terrane: the Fredericton trough to the southeast and a single basin comprising the Central Maine and Aroostook-Matapedia sequences to the northwest. This Central Maine/Aroostook-Matapedia (CMAM) basin received sediment from both the Miramichi highland to the east and highlands and islands to the west, including the pre-Late Ordovician Boundary Mountains, Munsungun-Pennington, and Weeksboro-Lunksoos terranes. Lithofacies in the Fredericton trough are truncated and telescoped by faulting along its flanks but suggest a similar basin that received sediment from highlands to the west (Miramichi) and east (St. Croix). Deposition ended in the Fredericton trough following burial and deformation in the Late Silurian, but continued in the CMAM basin until Early Devonian Acadian folding. A westward-migrating Acadian orogenic wedge provided a single eastern source of sediment for the composite CMAM basin after the Salinic/Early Acadian event, replacing the earlier, more local sources. The CMAM, Fredericton, and Connecticut Valley-Gaspe depocenters were active immediately following the Taconian orogeny and probably formed during extension related to post-Taconian plate adjustments. These basins thus predate Acadian foreland sedimentation. Structural analysis and seismic reflection profiles indicate a greater degree of post-depositional crustal shortening than previously interpreted. Late Acadian and post-Acadian strike-slip faulting on the Norumbega and Central Maine Boundary fault systems distorted basin geometries but did not disturb paleogeographic components drastically.
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