Oceanic heat flow measurements over the continental margins of eastern Canada

1976 ◽  
Vol 13 (8) ◽  
pp. 1031-1038 ◽  
Author(s):  
J. F. Lewis ◽  
R. D. Hyndman
Keyword(s):  
Nova Scotia ◽  
Heat Flow ◽  
Numerical Models ◽  
Continental Margins ◽  
Eastern Canada ◽  
Flow Measurements ◽  
Grand Banks ◽  
The Mean ◽  
Seismic Reflection Profiles ◽  
Heat Flow Variations

Sixteen heat flow measurements have been obtained on the continental rise and slope off Nova Scotia and off the southern Grand Banks of Newfoundland. The mean of the 14 most reliable values is 48 ± 4 mW m−2 (1.15 ± 0.09 μcal cm−2 s−1), which is in agreement with the mean for previous measurements on ocean floor of age greater than 100 m.y. However, the heat flux from the crust indicated by the new values is significantly lower because of the heat produced in the some 5 km of terrigenous sediments underlying the stations. The low values could represent an edge effect between continent and ocean. Two lines of stations across the Nova Scotia rise show large heat flow variations. Numerical models indicate that the variations could arise from thermal refraction by high thermal conductivity salt, which probably constitutes the 'sedimentary ridge complex' outlined by deep seismic reflection profiles. The salt or evaporites formed in the restricted basin that was parallel to this rifted margin during the first phase of opening of the Atlantic Ocean. The heat flow variations measured on a profile perpendicular to the southern edge of the Grand Banks are smaller. This margin was a transform fault between Newfoundland and northwest Africa during the early ocean opening, so that the seafloor in the region of the profile was produced after the restricted basin phase of evaporite formation.

Some new measurements of heat flow in the Superior Province of the Canadian Shield

1987 ◽  
Vol 24 (7) ◽  
pp. 1486-1489 ◽  
Author(s):  
Malcolm Drury ◽  
Alan Taylor
Keyword(s):  
Standard Deviation ◽  
Heat Flow ◽  
Canadian Shield ◽  
Superior Province ◽  
Flow Measurements ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Climatic Variations ◽  
The Mean ◽  
A Site

Borehole heat-flow measurements are reported from six new sites in the Superior Province of the Canadian Shield. Values adjusted for glaciation effects, but not for Holocene climatic variations, range from 42 to 56 mW/m2. When these new values are combined with 21 previously published borehole values the mean is 42 mW/m2 with a standard deviation of 11 mW/m2. The data for a site on the Lac du Bonnet batholith suggest that the batholith has a thin veneer, less than 3 km, of rock of high radiogenic heat production at the surface.

Some ectoparasitic trichodinids from Atlantic cod, Gadus morhua L., with a description of Trichodina cooperi n.sp.

1989 ◽  
Vol 67 (7) ◽  
pp. 1793-1800 ◽  
Author(s):  
S. L. Poynton ◽  
J. Lom
Keyword(s):  
Nova Scotia ◽  
Body Surface ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Geographic Range ◽  
The Body ◽  
Wild Fish ◽  
Eastern Canada ◽  
Mean Diameter ◽  
The Mean

Trichodina murmanica Polyanskiy, 1955 (= Trichodina domerguei subsp. saintjohnsi Lom and Laird, 1969) and Trichodina cooperi n.sp. were commonly encountered on skin and fins of Atlantic cod, Gadus morhua L., near Halifax, Nova Scotia, Canada. A third species of Trichodina, probably new, was recorded from the skin of one fish. This is believed to be the first report of the genus Trichodina from the body surface of gadoid fish from eastern Canada, and the known geographic range of T. murmanica is extended. Trichodina cooperi n.sp. has an adoral ciliary spiral of 370–380° and is relatively large, the mean diameter of the body is 110 μm, of the adhesive disc (with dark center), 95 μm, and of the denticulate ring, 59 μm. The denticulate ring consists of 24–29 denticles (usually 27), with 7–9 radial pins per denticle. Each denticle has a broad blade, a large central part, and a slightly curved thorn of moderate to broad width, with a central rib when mature. The thorn is approximately twice the length of the blade. The horseshoe-shaped macronucleus has a diameter of 80.0 μm and the micronucleus is in the +y position. Trichodina spp. infected 26% of 39 wild fish 20 to < 60 cm long. Most wild fish yielded less than five ciliates per 24 × 50 mm smear.

Three measurements of heat flow in Eastern Canada

1968 ◽  
Vol 5 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Alan M. Jessop
Keyword(s):  
Heat Flow ◽  
Superior Province ◽  
Geochemical Analysis ◽  
Eastern Canada ◽  
Flow Measurements ◽  
Grenville Province ◽  
World Average ◽  
Average Value ◽  
The World

Heat flow measurements, with appropriate corrections for the effects of Wisconsin glaciation, from three widely separated locations in eastern Canada are reported. One value in the Grenville rocks of Ontario agrees with earlier published values, but, when corrected for the effects of glaciation, becomes close to the world average value. The heat flow found in the New Quebec part of the Superior Province is significantly lower than is found in the Grenville Province. This can be explained by a hypothesis based on geochemical analysis of the surface rocks.

Shallow Water Heat Flow Measurements in Bras D'or Lake, Nova Scotia

1971 ◽  
Vol 8 (1) ◽  
pp. 96-101 ◽  
Author(s):  
Douglas S. Rankin ◽  
Roy D. Hyndman
Keyword(s):  
Heat Flux ◽  
Nova Scotia ◽  
Heat Flow ◽  
Surface Temperature ◽  
Shallow Water ◽  
Thermal Gradient ◽  
Light Weight ◽  
Flow Measurements ◽  
Made In ◽  
Conductivity Contrast

A light-weight oceanic thermal gradient probe was used for heat flow studies in Bras d'Or Lake, Nova Scotia. The measurements were made in St. Andrew's Channel, an elongated trough 270 m deep and 540 m wide. The heat flux of 1.50 μcal/cm2 s (63 mW/m2) is corrected for sedimentation, conductivity contrast, topography, and surface temperature differences.

Queen Charlotte fault zone: heat flow measurements

1982 ◽  
Vol 19 (8) ◽  
pp. 1657-1669 ◽  
Author(s):  
R. D. Hyndman ◽  
T. J. Lewis ◽  
J. A. Wright ◽  
Margaret Burgess ◽  
D. S. Chapman ◽  
...  
Keyword(s):  
Heat Flow ◽  
Fault Zone ◽  
Deep Sea ◽  
Frictional Heat ◽  
Flow Transition ◽  
Flow Measurements ◽  
Bottom Water Temperature ◽  
Sea Floor ◽  
Land Site ◽  
The Mean

The heat flow pattern from the deep sea across the Queen Charlotte Terrace to the west coast of the Queen Charlotte Islands has been determined through 20 marine heat flow measurements and by 11 borehole measurements at one land site. There is a continuous transition from very high deep sea heat flow, through intermediate values on the terrace, to low continental heat flow. The deep sea values are scattered, probably reflecting hydrothermal circulation in the crust, but their mean is in agreement with the theoretical value for the 7 Ma deep sea oceanic crust. The mean heat flow at the land site of 47 mW m−2 is similar to the average for the coast Insular Belt to the south and east. The measurements on the 30 km wide 2 km deep terrace are less scattered and much lower than those on the deep sea floor. The main thermal contrast is at the seaward edge of the terrace rather than near the coast where the earthquakes of the main plate boundary are located. Numerical models suggest that no reasonable steady state ocean–continent boundary can explain the observed heat flow transition. The data are consistent with a model of oblique underthrusting of the deep sea floor beneath the terrace. The continental margin heat flow transition will tend to mask any thermal anomaly generated by fault motion, but the results imply that there is no large frictional heat generated by motion on the Queen Charlotte fault.Nine marine heat flow measurements were made at the southwestern end of Queen Charlotte Sound south of the Queen Charlotte fault zone to test the hypothesis that the sound is a zone of recent crustal extension or rifting. The measurements were limited to isolated pockets of soft sediment and to sea floor depths greater than 800 m where bottom water temperature transients are negligible. The heat flow values are fairly uniform with an average of 86 mW m−2, which is about double the mean of other Insular Belt values. The Queen Charlotte Sound values could be affected by a nearby ocean spreading centre or by sediment erosion, but they are consistent with the rift hypothesis.

The thermal structure of the central Nova Scotia Slope (eastern Canada): seafloor heat flow and thermal maturation models

2017 ◽  
Vol 54 (2) ◽  
pp. 146-162 ◽  
Author(s):  
Eric Negulic ◽  
Keith E. Louden
Keyword(s):  
Heat Flow ◽  
Thermal Structure ◽  
Conductive Heat ◽  
Borehole Data ◽  
Eastern Canada ◽  
Flow Measurements ◽  
Seismic Reflection Data ◽  
Radiogenic Heat ◽  
Reflection Data ◽  
Hydrocarbon Maturation

The thermal history and maturation potential of the central Scotian Slope is constrained using a combination of 47 recently acquired seafloor heat flow measurements, two-dimensional (2D) seismic reflection data, available well data, simple lithospheric rift models, and thermal and petroleum systems modelling. Consistent heat flow values of 41–46 mW·m−2 were measured seaward of the salt diapiric province and across the slope away from the influence of salt structures. Significant but highly variable increases in heat flow were measured for stations overlying salt diapiric structures, reaching values upwards of 72 mW·m−2. Simple models of conductive heat transfer with static salt geometries constrained from reflection profiles indicate that two of the four models fit the data, whereas two indicate much higher values suggestive of additional, convective effects. Dynamic 2D thermal models were developed to incorporate the effects of lithospheric rifting, crustal stretching, and radiogenic heat production in the sediment and basement. These models help constrain the hydrocarbon maturation potential of the central Scotian Slope, where deep borehole data are lacking. Our results suggest that a potential Late Jurassic source rock interval rests primarily within the late oil window and that salt structures act primarily to reduce maturation in the adjacent deep sediment layers.

Reading the stripes: offshore discoveries in plate tectonics with examples from eastern Canada

1993 ◽  
Vol 30 (2) ◽  
pp. 261-277 ◽  
Author(s):  
Jacob Verhoef ◽  
Walter R. Roest
Keyword(s):  
Plate Tectonics ◽  
Sedimentary Basins ◽  
Geological Survey ◽  
Continental Margins ◽  
Eastern Canada ◽  
Data Set ◽  
Grand Banks ◽  
The Earth ◽  
Wide Acceptance

The emergence and wide acceptance of plate tectonics has had a profound influence on the way we look at the Earth. Starting as a theory to explain similarities in coast lines across the Atlantic, plate tectonics has become a unifying theory in the earth sciences. In this paper, we describe the role of staff of the Geological Survey of Canada in the developing and refining of this theory. At the same time, we illustrate the effect plate tectonics has had on our understanding of the evolution of offshore eastern Canada. Of critical importance in this development was the unique data set collected by systematic surveying of this region, largely by the Geological Survey of Canada, making the Grand Banks of Newfoundland one of the best-studied offshore areas in the world. Plate tectonic theory not only offers a framework for the evolution of ocean basins, continental margins, and their sedimentary basins, but also for the assemblage of continents.

scholarly journals Evolution of heat flow, hydrothermal circulation and permeability on the young southern flank of the Costa Rica Rift

2019 ◽  
Vol 220 (1) ◽  
pp. 278-295 ◽  
Author(s):  
Kannikha Parameswari Kolandaivelu ◽  
Robert N Harris ◽  
Robert P Lowell ◽  
Adam H Robinson ◽  
Dean J Wilson ◽  
...  
Keyword(s):  
Costa Rica ◽  
Heat Flow ◽  
Heat Loss ◽  
Seismic Velocity ◽  
Conductive Heat ◽  
Hydrothermal Circulation ◽  
Flow Measurements ◽  
Conductive Heat Flow ◽  
The Mean ◽  
Southern Flank

SUMMARY We analyse 67 new conductive heat-flow measurements on the southern flank of the Costa Rica Rift (CRR). Heat-flow measurements cover five sites ranging in oceanic crustal age between approximately 1.6 and 5.7 Ma, and are co-located with a high-resolution multichannel seismic line that extends from slightly north of the first heat-flow site (1.6 Ma) to beyond ODP Hole 504B in 6.9 Ma crust. For the five heat-flow sites, the mean observed conductive heat flow is ≈85 mW m−2. This value is approximately 30 per cent of the mean lithospheric heat flux expected from a half-space conductive cooling model, indicating that hydrothermal processes account for about 70 per cent of the heat loss. The advective heat loss fraction varies from site to site and is explained by a combination of outcrop to outcrop circulation through exposed basement outcrops and discharge through faults. Supercritical convection in Layer 2A extrusives occurs between 1.6 and 3.5 Ma, and flow through a thinly sedimented basement high occurs at 4.6 Ma. Advective heat loss diminishes rapidly between ≈4.5 and ≈5.7 Ma, which contrasts with plate cooling reference models that predict a significant deficit in conductive heat flow up to ages ≈65 ± 10 Ma. At ≈5.7 Ma the CRR topography is buried under sediment with an average thickness of ≈150 m, and hydrothermal circulation in the basement becomes subcritical or perhaps marginally critical. The absence of significant advective heat loss at ≈5.7 Ma at the CRR is thus a function of both burial of basement exposure under the sediment load and a reduction in basement permeability that possibly occurs as a result of mineral precipitation and original permeability at the time of formation. Permeability is a non-monotonic function of age along the southern flank of the CRR, in general agreement with seismic velocity tomography interpretations that reflect variations in the degree of ridge-axis magma supply and tectonic extension. Hydrothermal circulation in the young oceanic crust at the southern flank of CRR is affected by the interplay and complex interconnectedness of variations in permeability, sediment thickness, topographical structure, and tectonic and magmatic activities with age.

Sign in / Sign up

Export Citation Format

Share Document