Petrochemical and stratigraphic aspects of North Mountain basalt from the north shore of the Bay of Fundy, Nova Scotia, Canada

1989 ◽  
Vol 26 (12) ◽  
pp. 2710-2717 ◽  
Author(s):  
John D. Greenough ◽  
Lois M. Jones ◽  
David J. Mossman

Early Jurassic quartz-normative tholeiitic basalts occur in a series of fault blocks at four localities (Cap d'Or, Parrsboro, Five Islands, and Bass River) along the north shore of the Bay of Fundy. Major-element and trace-element data show that they represent outliers of the North Mountain basalt (NMB), which from the south shore of the Bay of Fundy are well-known. Diagnostic 87Sr/86Sr ratios (≈0.70609) indicate that a thick (>90 m) flow at Five Islands and Cap d'Or represents the lower unit of NMB, thus extending this single flow's lateral extent to 230 km. Thin flows overlying the thick flow at Cap d'Or suggest that the middle unit of NMB also occurs on the north shore. A thick flow at McKay Head (Parrsboro area) shows a variable Sr isotopic composition that is probably a result of metasomatism (with Rb addition) along the Cobequid fault. The average composition (0.70656) is similar to that of the upper unit of NMB. If the flow does represent the upper unit, then four thinner flows above it form an "overlying unit" not recognized along North Mountain. Although the nature of contacts between the middle and upper units was not observed, a lack of sedimentary rocks between all other flow units indicates that little or no sedimentation occurred between basalt eruptions. North shore basalts appear less mafic (more evolved) than south shore basalts, providing support for the hypothesis of differentiation during northeasterly magma migration through dykes that fed 230 km long fissure eruptions.

1969 ◽  
Vol 6 (4) ◽  
pp. 771-774 ◽  
Author(s):  
Douglas S. Rankin ◽  
Ravi Ravindra ◽  
David Zwicker

Previous work in the Gulf of St. Lawrence has yielded an unusually high upper-mantle compressional velocity. In the Gaspé area a more recent determination has yielded a value of 8.75 ± 0.20 km/s for an unreversed profile. The arrival time at a station on the north shore of the St. Lawrence River suggests that there is no major difference in velocity and depth relative to the south shore.


1839 ◽  
Vol 129 ◽  
pp. 151-161 ◽  

In former communications to the Society, the laws of high water at Plymouth and other places have been the subject of my researches. These being obtained, the laws of low water are a subject of importance and interest on many accounts. The first ground of my pursuing this subject was the desire to ascertain how far the mean water , that is, the height midway between high and low water, is permanent during the changes which high and low water undergo. That it is approximately so at Ply­mouth, had been ascertained both by Mr. Walker and myself, by means of a com­parison of a short series of observations. But it was desirable to know with more exactness what was the real amount of this permanency, when, by using a long series of observations of high and low water, the irregularities arising from accident, and from taking imperfect cycles of inequalities, were eliminated. There was another reason which made this inquiry important at the present time. An operation has been recently carried on by the direction and at the expense of the British Association, with a view of ascertaining what surface ought to be taken as the permanent level of the sea. A Level Line has been carried with great care and accuracy from the north shore of Somerset to the south shore of Devon ; and the po­sition of this line has been fixed, so as to be recognised at any future time, by means of marks at Axmouth, at East Quantockshead, at Stolford, and at Portishead. This line has also been referred to the sea at its extremities ; and the observations show that the height of mean water coincides, at least very nearly, at different places, as well as at the same place at different times. While the difference of levels of low water at Axmouth on the English Channel, and Wick Rocks on the Bristol Channel, is not less than twelve feet; the mean water at those two places coincides in level within a few inches. In order to determine further what accuracy may be attained in this result, we are led to inquire what is the degree of permanency at one place. I may further add, that it cannot but be instructive to know how far the corrections of the height and time of low water, for lunar parallax and declination, agree in form and amount with the same corrections already obtained for high water.


2010 ◽  
Vol 10 (11) ◽  
pp. 2359-2369 ◽  
Author(s):  
T. Torsvik ◽  
R. Paris ◽  
I. Didenkulova ◽  
E. Pelinovsky ◽  
A. Belousov ◽  
...  

Abstract. Karymskoye caldera lake is a nearly circular body of water with a diameter of approximately 4 km and a depth of up to 60 m. The sublacustrine, Surtseyan-type eruption in the lake on 2–3 January 1996 included a series of underwater explosions. A field survey conducted the following summer showed signs of tsunami wave runup around the entire coastline of the lake, with a maximum of 29 m runup at the north shore near the source of the eruption, and 2–5 m runup at locations on the east and south shore far away from the source. The tsunami has been simulated using the numerical long wave model COULWAVE, with input from reconstructed realistic pre-eruption bathymetry. The tsunami source was chosen as suggested by Le Mehaute (1971) and Mirchina and Pelinovsky (1988). The initial wave was prescribed by a parabolic shape depression with a radius of R=200 m, and a height of 23 m at the rim of the parabola. Simulations were conducted to show principle directions for wave propagation, wave speed and arrival time for the leading wave group at the shore, and the distribution of wave height throughout the lake. Estimated result for wave runup are of the same order of magnitude as field measurements, except near the source of the eruption and at a few locations where analysis show significant wave breaking.


2010 ◽  
Vol 31 (1-2) ◽  
pp. 61-80 ◽  
Author(s):  
Jean-Claude Dionne

The Goldthwait Sea is defined as the late- and post-Glacial marine invasion in the St. Lawrence Estuary and Gulf east of Québec City. In Québec, this sea has submerged an area of about 25 000 km2. The largest areas submerged are the north shore of the St. Lawrence between Les Escoumins and Blanc-Sablon, the south shore between Levis and Tourelles, and the Anticosti Island. The upper limit of the Goldthwait Sea varies from place to place. The Goldthwait Sea began 14 000 years ago and land emergence is still in progress, since the pre-Wisconsin marine level has not been recovered yet. For a better chronology, this long interval needs to be subdivided. Three main periods have been recognized: Goldthwaitian I, II and III. However, a geographical subdivision is also needed. Numerous shorelines were observed at various elevations throughout the area formely submerged by the Goldthwait Sea. However, only a few shorelines are well developed and extensive, and correlations between former shorelines are difficult to establish. Only three levels are widespead and common to the Estuary and parts of the Gulf. The isostatic recovery has been rapid during the first three thousand years after déglaciation of the area: about 75%.


1954 ◽  
Vol 11 (3) ◽  
pp. 198-260 ◽  
Author(s):  
A. G. Huntsman ◽  
W. B. Bailey ◽  
H. B. Hachey

Hydrographic data for late August, 1923, show for the Strait (a) progressive inward movement on the north side of Arctic or sub-Arctic water, (b) progressive outward movement on the south side of Gulf water and (c) a dominant outward flow with evidence of a previous dominant inward flow. Time differences suggest tidal causes for the marked temperature and salinity changes. Current measurements for a double tidal period indicate residual trends of nine and eight miles per day in opposite directions on the north and south sides of the Strait. Inside, the Esquiman Channel shows two contra-clockwise eddies north and south of the Mekattina Bank. In addition, hydrographic data show a strong northeasterly movement along the Newfoundland shore and a weaker southwesterly one along the opposite Quebec shore.Planktonic animals indicate the water movements, Mertensia, Acartia spiniremis, Themisto, Pseudalibrotus and Oikopleura vanhöffeni surviving to various degrees in the water from the Labrador Current that reaches the centre of the Gulf along the north shore of the Strait and Channel. Other forms characterize the warm shallow water along the Newfoundland shore inside the Strait and show its movement outward to the east coast of Newfoundland. The Greenland seal fishery of winter reflects the inward movement from the Labrador Current. Cod and herring fisheries invade this cool water of the north shore only locally in summer with access of warmer water from the south shore. Lobsters and cunners are very abundant in, but particularly confined to, the warm shallow water mentioned above.


2014 ◽  
Vol 38 ◽  
pp. 21-30 ◽  
Author(s):  
B. F. Atwater ◽  
Z. Fuentes ◽  
R. B. Halley ◽  
U. S. Ten Brink ◽  
M. P. Tuttle

Abstract. A post-hurricane survey of a Caribbean island affords comparisons with geologic evidence for greater overwash at the same place. This comparison, though of limited application to other places, helps calibrate coastal geology for assessment of earthquake and tsunami potential along the Antilles Subduction Zone. The surveyed island, Anegada, is 120 km south of the Puerto Rico Trench and is near the paths of hurricanes Donna (1960) and Earl (2010), which were at or near category 4 when at closest approach. The survey focused on Earl's geologic effects, related them to the surge from Hurricane Donna, and compared them further with erosional and depositional signs of southward overwash from the Atlantic Ocean that dates to 1200–1450 AD and to 1650–1800 AD. The main finding is that the geologic effects of these earlier events dwarf those of the recent hurricanes. Hurricane Earl's geologic effects at Anegada, observed mainly in 2011, were limited to wrack deposition along many of the island's shores and salt ponds, accretion of small washover (spillover) fans on the south shore, and the suspension and deposition of microbial material from interior salt ponds. Earl's most widespread deposit at Anegada, the microbial detritus, was abundantly juxtaposed with evidence for catastrophic overwash in prior centuries. The microbial detritus formed an extensive coating up to 2 cm thick that extended into breaches in beach-ridge plains of the island's north shore, onto playas that are underlain by a sand-and-shell sheet that extends as much as 1.5 km southward from the north shore, and among southward-strewn limestone boulders pendant to outcrops as much as 1 km inland. Earl's spillover fans also contrast with a sand-and-shell sheet, which was dated previously to 1650–1800, by being limited to the island's south shore and by extending inland a few tens of meters at most. These findings complement those reported in this issue by Michaela Spiske and Robert Halley (Spiske and Halley, 2014), who studied a coral-rubble ridge that lines part of Anegada's north shore. Spiske and Halley attribute the ridge to storms that were larger than Earl. But they contrast the ridge with coral boulders that were scattered hundreds of meters inland by overwash in 1200–1450.


Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3487
Author(s):  
Ali Arkamose Assani ◽  
Ayoub Zeroual ◽  
Alexandre Roy ◽  
Christophe Kinnard

Several statistical methods were used to analyze the spatio-temporal variability of daily minimum extreme flows (DMEF) in 17 watersheds—divided into three homogenous hydroclimatic regions of southern Quebec—during the transitional seasons (spring and fall), during the 1930–2019 period. Regarding spatial variability, there was a clear difference between the south and north shores of the St. Lawrence River, south of 47° N. DMEF were lower in the more agricultural watersheds on the south shore during transitional seasons compared to those on the north shore. A correlation analysis showed that this difference in flows was mainly due to more agricultural areas ((larger area (>20%) on the south than on the north shore (<5%)). An analysis of the long-term trend of these flows showed that the DMEF of south-shore rivers have increased significantly since the 1960s, during the fall (October to December), due to an increase in rainfall and a reduction in cultivated land, which increased the infiltration in the region. Although there was little difference between the two shores in the spring (April to June), we observed a decrease in minimum extreme flows in half (50%) of the south-shore rivers located north of 47° N.


1974 ◽  
Vol 9 (1) ◽  
pp. 107-114
Author(s):  
Ronald E. Simard ◽  
John A. Zee

Abstract During the summer of 1973, a survey was made in order to establish the level of enteric bacteria in the sediments and water of the St-Lawrence River. In the sediments, the number of total bacteria, yeast and mold fluctuates from station to station and with the tide. Higher counts of total and fecal coliform were encountered on the north shore than on the south shore resulting from Quebec City sewerage. The number of fecal bacteria decreased when approaching the Gulf and their number was higher at rising tide. The main species encountered were Klebsiella pneumonia, Salmonella enteridis and Escherichia spp.


1988 ◽  
Vol 25 (12) ◽  
pp. 1972-1989 ◽  
Author(s):  
J. P. Hodych ◽  
A. Hayatsu

K–Ar isochron dates of 193 ± 2, 189 ± 3, and 191 ± 2 Ma are reported for the Shelburne dike of Nova Scotia, the Avalon dike of Newfoundland, and the Caraquet dike of New Brunswick, respectively. These major tholeiitic dikes agree in radiometric date with the North Mountain Basalt of Nova Scotia and with other tholeiitic flows of the Newark Supergroup that have been paleontologically assigned to the Hettangian. However, further work is needed to resolve the discrepancy between the Triassic–Jurassic boundary date of 193 ± 6 Ma suggested by the Newark Supergroup flows and the boundary dates of 204–213 Ma adopted in recent time scales.The North Mountain Basalt flows at nine sites on the north shore of the Bay of Fundy are shown to have likely magnetized during initial cooling, yielding an Hettangian virtual paleopole at 66°N, 72°E (dp = 9°, dm = 14°). New paleomagnetic results are also reported for the Caraquet and Avalon dikes.The virtual paleopoles from Hettangian flows and dikes of Atlantic Canada lie on average ~11 °north of the virtual paleopoles from Hettangian flows of the northeastern United States. This discrepancy is likely due to insufficient averaging out of paleosecular variation and demonstrates that caution is needed in paleomagnetically correlating among the Early Jurassic flows and intrusions of eastern North America.


2010 ◽  
Vol 41 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Ali A. Assani ◽  
David Landais ◽  
Mhamed Mesfioui ◽  
Martin Matteau

This paper, based on an analysis of the mean annual flow (MAF) of 16 natural rivers over the period 1934–2000, has the following goals: (1) to determine the different temporal variability modes of the MAF in the St. Lawrence watershed, (2) to describe the temporal variability of the streamflow in each mode and (3) to analyze the influence of the AMO (Atlantic Multidecadal Oscillation) on the interannual and interdecadal variability of mean annual flows in this Quebec watershed. This paper shows that the interannual variability of mean annual flow was not synchronous on both sides of the river. During the period analyzed, MAF variability was characterized by a tendency to decrease on the south shore (right bank) but to increase on the north shore (left bank). A correlation analysis reveals that the influence of the AMO was limited exclusively to the north shore of the river, which is characterized by a continental climate. This correlation is negative. On the south shore, streamflow is correlated negatively to the AO (Arctic Oscillation).


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