Crustal Structure of Baffin Bay from the Earthquake-generated Lg Phase

1974 ◽  
Vol 11 (1) ◽  
pp. 123-130 ◽  
Author(s):  
R. J. Wetmiller
Keyword(s):  
Oceanic Crust ◽  
Crustal Structure ◽  
Propagation Path ◽  
Baffin Island ◽  
Intermediate Type ◽  
Baffin Bay ◽  
Nares Strait ◽  
Earthquake Record ◽  
Cape York ◽  
Sufficient Proof

The Lg phase generated by earthquakes is used to infer the gross crustal structure of Baffin Bay. The principle of interpretation is that the presence of the Lg phase on an earthquake record is sufficient proof of the existence of continental crustal structure along the entire propagation path, while the absence of the Lg phase is a consequence but not sufficient proof of the existence of a section of oceanic crust somewhere along the propagation path. Examples are given of earthquake records involving propagation paths through three distinct types of gross crustal structure, namely shield-type continental, intermediate-type continental, and oceanic. These examples are used to interpret the records at four seismic observatories located around Baffin Bay for eleven earthquakes, which occurred in and around the Bay in the years 1965 to 1967. The records reveal two areas of Baffin Bay that appear to have oceanic crust, one in the northern part of the Bay at the entrance to Nares Strait, and one in the deep central part of the Bay separated by a bridge of continental crust from Cape York on Greenland to Cape Macculloch on Baffin Island.

Geophysical Studies in Baffin Bay and some Tectonic Implications

1972 ◽  
Vol 9 (3) ◽  
pp. 239-256 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett ◽  
K. S. Manchester ◽  
D. I. Ross
Keyword(s):  
Oceanic Crust ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
The Arctic ◽  
Spreading Center ◽  
Labrador Sea ◽  
Baffin Bay ◽  
Definitive Evidence ◽  
Nares Strait ◽  
The North

A recent seismic refraction experiment in the deep central region of Baffin Bay showed that it is underlain by oceanic crust. This paper describes the results of gravity, magnetic, and seismic reflection profiling measurements in the bay. There is no definitive evidence for a buried ridge or for magnetic lineations in the center of the area. The magnetic and gravity anomaly fields have been used to define the boundary between the oceanic and continental crust around the bay and therefore the extent of oceanic crust presumed to have been formed by sea-floor spreading. Some of the characteristics of the seismic reflection lines across the continental margins, perhaps typical of this area, are also discussed. The results have been used to reconstruct the history of opening of Baffin Bay in conjuction with geophysical measurements in the Labrador Sea to the south and over the Alpha Ridge in the Arctic Ocean to the north. An attempt has been made to reconcile the geometry of opening with continental geology. Two phases of spreading are suggested. The first involves openings, in both the Labrador Sea and in Baffin Bay, about a pole in the Canadian Arctic Islands. The second, most recent stage of opening, requires that the Nares Strait was once a transform fault, perhaps connecting a Baffin Bay spreading center to the Alpha Ridge to the north.

Insights into the crustal structure of the transition between Nares Strait and Baffin Bay

2016 ◽  
Vol 691 ◽  
pp. 31-47 ◽  
Author(s):  
Tabea Altenbernd ◽  
Wilfried Jokat ◽  
Ingo Heyde ◽  
Volkmar Damm
Keyword(s):  
Crustal Structure ◽  
Baffin Bay ◽  
Nares Strait

An Early Tertiary Outcrop in North-Central Baffin Island, Northwest Territories, Canada: Environment and Significance

1972 ◽  
Vol 9 (3) ◽  
pp. 233-238 ◽  
Author(s):  
J. T. Andrews ◽  
J. D. Ives ◽  
G. K. Guennel ◽  
J. L. Wray
Keyword(s):  
Laminated Sediments ◽  
Coarse Grained ◽  
Baffin Island ◽  
Vertical Movements ◽  
North Central ◽  
Baffin Bay ◽  
Ice Cap ◽  
Early Tertiary ◽  
Warm Temperate

A thin, impure limestone was found in situ on Precambrian bedrock at latitude 70°36.6′ N and longitude 75°20′ W some 26 km northwest of the Barnes Ice Cap. The unit consists of undulating laminations composed of alternating fine- and coarse-grained sediment, which are interpreted as a series of algal mats or algal-laminated sediments. An analysis of enclosed palynomorphs indicates the presence of Ulmus, Taxodiutm, Liriodendron, Carpinus, and Engelhardtia plus other genera. On the basis of the microflora a Paleogene age is assigned to the unit. The climate at that time was warm-temperate and the environment suggested is a freshwater marsh or swamp. The outcrop is restricted to a single hill summit and its location suggests considerable Neogene geomorphological activity, primarily river-cutting associated with vertical movements along the western margin of the Davis Strait/Baffin Bay Tift.

Crustal structure of the southeast flank of Kilauea Volcano, Hawaii, from seismic refraction measurements

1980 ◽  
Vol 70 (4) ◽  
pp. 1149-1159
Author(s):  
John J. Zucca ◽  
David P. Hill
Keyword(s):  
Oceanic Crust ◽  
Crustal Structure ◽  
Seismic Refraction ◽  
Kilauea Volcano ◽  
Geological Survey ◽  
Pn Velocity ◽  
Kīlauea Volcano ◽  
Volcanic Pile ◽  
Rift Zones ◽  
The U.S

abstract In November 1976, the U.S. Geological Survey, in conjunction with the Hawaii Institute of Geophysics, established a 100-km-long seismic refraction line normal to the southeast coast of Hawaii across the submarine flank of Kilauea Volcano. Interpretation of the data suggests that the oceanic crust dips about 2° toward the island underneath the volcanic pile. The unreversed Pn velocity is 7.9 km/ sec with crustal velocities varying strongly along the profile. Profiles across the rift zones of Kilauea suggest that the velocity in the rifts is higher than the velocity in the surrounding extrusive rocks and that the velocity in the southwest rift (∼6.5 km/sec) is lower than the velocity in the east rift (∼7.0 km/sec). The rift boundaries seem to dip away from the rift such that a large part of the volcanic pile is composed of the higher velocity core of riftzone rock.

Shallow Crustal Structure in the DehDasht Region (SW Iran) from Ambient Seismic Noise Tomography

2021 ◽  
Author(s):  
Nastaran Shakeri ◽  
Taghi Shirzad ◽  
Shobeir Ashkpour Motlagh ◽  
Siavash Norouzi
Keyword(s):  
Crustal Structure ◽  
High Velocity ◽  
Seismic Noise ◽  
Seismic Exploration ◽  
Propagation Path ◽  
Ambient Seismic Noise ◽  
Fast Marching Method ◽  
Fast Marching ◽  
Main Challenge ◽  
Sw Iran

<p>Zagros continental collision zone (S-SW Iran) is tectonically active and extends over 1800 km contained most part of hydrocarbon reservoirs worldwide. The DehDasht region is located in the southeast of the Dezful embayment in the Zagros fold-and-thrust belt. The existence of an evaporation layer with high velocity features is the main challenge to apply classical seismic exploration in this region. However, ambient seismic noise carries valuable information about the propagation path; hence it could be a useful tool for studying crustal structure in the DehDasht region. For this purpose, we used up to 9 months of continuous data recorded by 107 stations in the area with ~16 × ~24 km<sup>2</sup>. All stations are equipped with broadband (120s) sensors recording at 100 sps. The standard ambient seismic noise processing was done as outlined by Bensen et al. (2007), and optimize empirical Green’s function (EGF) was retrieved based on the WRMS stacking method. Afterward, Rayleigh wave dispersion measurements were calculated using the FTAN approach in the period range of 0.1-5.0 s, then the inversion procedure was performed by the Fast-Marching Method with an inversion cell size of 2×2 km. Our group velocity tomographic maps show a high velocity anomaly in the Khaviz Mountain belt (west part of the study area) is generally linked to the older, consolidated bodies while two low velocity anomalies are related to the presence of fluids and or younger structures.</p>

Radiogenic Isotope Signatures of Holocene Sediments from Kane Basin: Linkage with the Re-opening and Evolution of Nares Strait

2021 ◽  
Author(s):  
Lina Madaj ◽  
Friedrich Lucassen ◽  
Claude Hillaire-Marcel ◽  
Simone A. Kasemann
Keyword(s):  
Ellesmere Island ◽  
The Arctic ◽  
Baffin Bay ◽  
Low Salinity ◽  
The Core ◽  
The Past ◽  
Nares Strait ◽  
The North ◽  
Sediment Input ◽  
Detrital Sediment

<p>The re-opening of the Arctic Ocean-Baffin Bay gateway through Nares Strait, following the Last Glacial Maximum, has been partly documented, discussed and revised in the past decades. The Nares Strait opening has led to the inception of the modern fast circulation pattern carrying low-salinity Arctic water towards Baffin Bay and further towards the Labrador Sea. This low-salinity water impacts thermohaline conditions in the North Atlantic, thus the Atlantic Meridional Overturning Circulation. Available land-based and marine records set the complete opening between 9 and 7.5 ka BP [1-2], although the precise timing and intensification of the southward flowing currents is still open to debate. A recent study of a marine deglacial sedimentary record from Kane Basin, central Nares Strait, adds information about subsequent paleoceanographic conditions in this widened sector of the strait and proposed the complete opening at ~8.3 ka BP [3].</p><p>We present complementary radiogenic strontium, neodymium and lead isotope data of the siliciclastic detrital sediment fraction of this very record [3] further documenting the timing and pattern of Nares Strait opening from a sediment provenance approach. The data permit to distinguish detrital material from northern Greenland and Ellesmere Island, transported to the core location from both sides of Nares Strait. Throughout the Holocene, the evolution of contributions of these two sources hint to the timing of the ice break-up in Kennedy Channel, north of Kane Basin, which led to the complete opening of Nares Strait [3]. The newly established gateway of material transported to the core location from the north via Kennedy Channel is recorded by increased contribution of northern Ellesmere Island detrital sediment input. This shift from a Greenland (Inglefield Land) dominated sediment input to a northern Ellesmere Island dominated sediment input supports the hypothesis of the newly proposed timing of the complete opening of Nares Strait at 8.3 ka BP [3] and highlights a progressive trend towards modern-like conditions, reached at about 4 ka BP.</p><p>References:</p><p>[1] England (1999) Quaternary Science Reviews, 18(3), 421–456. [2] Jennings et al. (2011) Oceanography, 24(3), 26-41. [3] Georgiadis et al. (2018) Climate of the Past, 14 (12), 1991-2010.</p>

Baffin Bay/Nares Strait surface (seafloor) sediment mineralogy: further investigations and methods to elucidate spatial variations in provenance

2019 ◽  
Vol 56 (8) ◽  
pp. 814-828 ◽  
Author(s):  
John T. Andrews
Keyword(s):  
Strong Association ◽  
Optimum Number ◽  
Baffin Island ◽  
Number Of Clusters ◽  
Data Transformations ◽  
West Greenland ◽  
Weight Percentage ◽  
Nares Strait ◽  
Significant Difference ◽  
Sediment Mineralogy

The goal of the paper is to ascertain whether there are significant regional variations in sediment mineral composition that might be used to elucidate ice sheet histories. The weight percentages of nonclay and clay minerals were determined by quantitative X-ray diffraction. Cluster analysis, an unsupervised learning approach, is used to group sediment mineralogy of 263 seafloor/core top samples between ∼80°N and 62°N. The optimum number of clusters, based on 30 indexes, was three for the weight percentage data but varied with data transformations. Maps of the distribution of the three mineral clusters or facies indicate a significant difference in weight percentages between samples from the West Greenland and Baffin Island shelves. However, several indexes support a larger number of clusters and similar analyses of the spatial distribution and defining minerals of nine mineral facies indicated a strong association with the original three clusters and with broad geographic designations (i.e., West Greenland shelf, Baffin Island fiords, etc). Classification Decision Tree analysis indicates that this difference is primarily controlled by the percentages of plagioclase feldspars versus alkali feldspars.

Sea ice melt and meteoric water distributions in Nares Strait, Baffin Bay, and the Canadian Arctic Archipelago

2010 ◽  
Vol 68 (6) ◽  
pp. 767-798 ◽  
Author(s):  
Matthew B. Alkire ◽  
Kelly K. Falkner ◽  
Timothy Boyd ◽  
Robie W. Macdonald
Keyword(s):  
Sea Ice ◽  
Meteoric Water ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Baffin Bay ◽  
Ice Melt ◽  
Nares Strait

Hydrographic Changes in Nares Strait (Canadian Arctic Archipelago) in Recent Decades Based on δ18O Profiles of Bivalve Shells

ARCTIC ◽  
2011 ◽  
Vol 64 (1) ◽  
pp. 45 ◽  
Author(s):  
Marta E. Torres ◽  
Daniela Zima ◽  
Kelly K. Falkner ◽  
Robie W. Macdonald ◽  
Mary O'Brien ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Past Century ◽  
Depth Range ◽  
Baffin Bay ◽  
Nares Strait ◽  
The North ◽  
The Arctic Ocean ◽  
Oxygen Isotopic ◽  
Bivalve Shells

<span style="font-family: 'Times New Roman';">Nares Strait is one of three main passages of the Canadian Archipelago that channel relatively fresh seawater from the Arctic Ocean through Baffin Bay to the Labrador Sea. Oxygen isotopic profiles along the growth axis of bivalve shells, collected live over the 5 – 30 m depth range from the Greenland and Ellesmere Island sides of the strait, were used to reconstruct changes in the hydrography of the region over the past century. The variability in oxygen isotope ratios is mainly attributed to variations in salinity and suggests that the northern end of Nares Strait has been experiencing an increase in freshwater runoff since the mid 1980s. The recent changes are most pronounced at the northern end of the strait and diminish toward the south, a pattern consistent with proximity to the apparently freshening Arctic Ocean source in the north and mixing with Baffin Bay waters as the water progresses southward. This increasing freshwater signal may reflect changes in circulation and ice formation that favor an increased flow of relatively fresh waters from the Arctic Ocean into Nares Strait. </span>

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