6 results on '"LAURENTIAN"'
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2. Repurposing of archived CO1 sequence data reveals unusually high genetic structure between North American and European zebra mussels ( Dreissena polymorpha ).
- Author
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David, Andrew A. and Gardner, Kendall
- Subjects
ZEBRA mussel ,DREISSENA ,HAPLOTYPES ,ECOLOGY - Abstract
The invasion of the zebra mussel, Dreissena polymorpha in the Great Lakes of North America is regarded as one of the most catastrophic ecological events in recent history. Previous studies showed a close kinship between European zebra mussels and their invasive cohorts in the Great Lakes. In this study, we repurposed and reanalyzed archived CO1 sequence data from Lake Superior and multiple sites in Europe that were collected between 1991 and 2011 to illustrate an interesting pattern of genetic isolation that was overlooked in previous studies. The results showed extreme genetic isolation of Lake Superior zebra mussels as evident by high ϕ
ST values and strong geographic patterning of Lake Superior haplotypes. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
3. Late Proterozoic reconstructions of North-West Scotland and Central Canada: Magnetic fabrics, paleomagnetism and tectonics
- Author
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Borradaile, Graham J. and Geneviciene, Ieva
- Subjects
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PROTEROZOIC stratigraphic geology , *PALEOMAGNETISM , *STRUCTURAL geology , *ANISOTROPY - Abstract
Abstract: Red-beds dominate the Stoer Group and the unconformably overlying Torridon Group, having accumulated between ∼1400 and ∼1000Ma, in a rift of the Hebridean foreland. The sequences were weakly strained and shortened E–W, and each underwent successive diagenetic changes which altered their magnetic properties and caused their different characteristic post-depositional magnetizations. Anisotropy of magnetic susceptibility (AMS) reveals an N–S vertical tectonic foliation superimposed on the bedding-planar AMS sub-fabric. The tectonic AMS sub-fabric was isolated by comparing normalized and non-normalized mean tensors of multiple specimens. The N–S vertical AMS tectonic foliation postdates warps of bedding; thus the high-susceptibility minerals, including those carrying palaeomagnetic signals re-oriented or recrystallized after deposition and diagenesis. Thus characteristic remanence vectors (ChRM) were acquired long after deposition, first in the Stoer Group, then in the Torridon. ChRMs were isolated for 143 Stoer specimens and 94 Torridon specimens using two cycles of low-temperature demagnetization followed by at least 12 steps of thermal demagnetization. For the Stoer Group, two structurally integral groups of sites yield mean magnetizations of 317.0/+43.1 α 95 =11.3 (n =49) and 309.9/52.1 α 95 =10.6 (n =23). Some Stoer specimens bear a Torridon age overprint 133.3/+525 α 95 =9.6 (n =19). The younger Torridon Group yields 138.4/+52.2 α 95 =7.4 (n =42); 134.9/+45.5 α 95 =16.0 (n =15) and 134.4/+55.1 α 95 =11.3 (n =19) from three structurally integral clusters of sites. These late chemical magnetizations postdate bedding warps, faults and tectonic AMS fabrics; they do not warrant local “rigid-body” tilt corrections. However, we restored the ChRM directions for the regional post-Cambrian eastwards tilt which affected the entire foreland from the Lewisian basement to the overlying Proterozoic strata. Paleopoles calculated from the strata''s restored vectors were rotated into Laurentian coordinates for comparison with Canadian Proterozoic palaeopoles. The Stoer Group was magnetized in a normal polarity geomagnetic field whereas the Torridon Group was magnetized in a reversed polarity epoch. However, both sequences include at least one polarity transition, indicating long duration chemical magnetizations successfully averaging secular variation. At a minimum, red-bed magnetization processes exceeded 0.1Ma and may have encompassed several million years. During Stoer Group magnetization, the Hebridean craton was at paleolatitudes of 26–44°N; when the Torridon Group magnetized it was at 23–27°S. Accepting published ages, this defines a minimum southward latitudinal displacement rate of 27–40km/Ma. Restored Stoer Group paleopoles lie in the present-day north-central Pacific Ocean (∼190E/25N); corresponding to the Laurentian APWP dated at between 1090 and 1109Ma. Torridon Group paleopoles lie in the south-central Pacific (∼210E/25S) near the poorly documented (<900Ma) southernmost part of the Laurentian APWP. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
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4. Comment on Alley et al. (2006): “Outburst flooding and the initiation of ice-stream surges in response to climatic cooling: A hypothesis”, Geomorphology 75, 76–89
- Author
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Erlingsson, U.
- Subjects
- *
AUFEIS , *ICE streams , *CLIMATE change , *PHYSICAL geography - Abstract
Abstract: While the paper by Alley et al. (Alley, R.B., Dupont, T.K., Parizek, B.R., Anandakrishnan, S., Lawson, D.E., Larson, G.J., Evenson, E.B., 2006. Outburst flooding and the initiation of ice-stream surges in response to climatic cooling: A hypothesis. Geomorphology 75, 76–89) is a welcome contribution as it presents some new arguments and expands the discussion, it unfortunately overlooked the literature on the captured ice shelf (CIS) hypothesis. Considering all recent results, the hypothesis has the potential for drastically altering our understanding of sudden climate change during the Quaternary period. Also, the interpretation of macrogeomorphology in land-ice covered continents and seas, including the Hudson Bay and the Baltic Sea, is affected. [Copyright &y& Elsevier]
- Published
- 2007
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5. Buried Dreams: Refitting and Ritual at the Mount Albert Site, Southern Ontario
- Author
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Forsythe, Kyle D
- Subjects
ceremonial practices ,bannerstones ,Middle Archaic ,Laurentian ,Brewerton ,refitting ,experimental archaeology ,lithic analysis ,ritual breakage ,Archaeological Anthropology - Abstract
Few intact Middle Archaic sites have been investigated in Southwestern Ontario and attention has focused on large, multicomponent sites, which are difficult to interpret. This thesis focuses on recent work that has been conducted on an undisturbed, single-component Brewerton site in Mount Albert south of Lake Simcoe, where the lithic assemblage presents an unprecedented view of lifeways in the Middle Archaic (ca. 5000-4500 B.P.). Notable is the presence of high numbers of fragmented formal flaked stone tools - moreso than is consistent with solely tool production activities. The thesis evaluates the possibility that the artifacts were intentionally destroyed as part of previously undocumented ceremonial practices in the region. Refitting of the pieces and experimental breakage of reproduction bifaces each offer insights into strategies for the purposeful breakage of stone artifacts.
- Published
- 2016
6. Hypoxia In The Lower St. Lawrence Estuary: How Physics Controls Spatial Patterns
- Author
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Lefort, S., Gratton, Y., Mucci, A., Dadou, I., Gilbert, D., GEOTOP and Department of Earth and Planetary Sciences, McGill University = Université McGill [Montréal, Canada], Centre Eau Terre Environnement [Québec] (INRS - ETE), Institut National de la Recherche Scientifique [Québec] (INRS), DYNBIO LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Fisheries and Oceans Canada, Maurice Lamontagne Institute, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,ORGANIC-MATTER ,UPWELLING SYSTEM ,GULF ,RESPIRATORY ACTIVITY ,BOTTOM WATERS ,GEOCHEMICAL EVIDENCE ,TROUGH ,LAURENTIAN ,COASTAL OCEAN ,CARBON BUDGET ,OXYGEN - Abstract
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Gratton, Y. Mucci, A. Dadou, I. Gilbert, D. Gilbert, Denis/A-3067-2010 Gilbert, Denis/0000-0002-9554-9594 NSERC Strategic grant; DFO CCSI (Climate Change Science Initiative) grant; Department of Earth and Planetary Sciences/McGill; GEOTOP-UQAM-McGill research center; LEGOS laboratory; University of Toulouse III (Paul Sabatier, France) This research was funded by a NSERC Strategic grant to A.M., D.G. and Y.G, and a DFO CCSI (Climate Change Science Initiative) grant to D.G. Additional financial support to S.L. was provided by the Department of Earth and Planetary Sciences/McGill, the GEOTOP-UQAM-McGill research center, the LEGOS laboratory and the University of Toulouse III (Paul Sabatier, France). We thank the captains and crew of R/V Alcide C. Horth and R/V Coriolis II for their help during the numerous cruises between 2002 and 2011. We acknowledge the two anonymous reviewers for their insightful comments. 1 AMER GEOPHYSICAL UNION WASHINGTON J GEOPHYS RES-OCEANS; A laterally integrated advection-diffusion two-dimensional model was implemented to simulate the spatial distribution of dissolved oxygen and the development of hypoxic conditions in the deep waters of the Laurentian Channel (Estuary and Gulf of St. Lawrence, Eastern Canada). Our simulations reveal that the horizontal distribution of dissolved oxygen in the bottom waters of the Laurentian Channel is determined by a combination of physical and biogeochemical processes, whereas its vertical distribution is governed by the deep water circulation. This result strongly suggests that the physics of the system and the source water properties are mostly responsible for the generation of a mid-water column oxygen minimum and the oxygen distribution pattern in the deep water column.
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- 2012
- Full Text
- View/download PDF
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