Paleomagnetism of the Borden dykes of Baffin Island and its bearing on the Grenville Loop

1983 ◽  
Vol 20 (2) ◽  
pp. 275-289 ◽  
Author(s):  
K. W. Christie ◽  
W. F. Fahrig
Keyword(s):  
Pole Position ◽  
Fault Zones ◽  
Baffin Island ◽  
The West ◽  
Similar Position ◽  
Paleomagnetic Pole ◽  
Igneous Activity ◽  
Southern Extremity

Northern Baffin Island is intersected by spectacular swarms of predominantly northwesterly trending diabase dykes. Cross-cutting relationships, K–Ar ages, and paleomagnetic contact tests indicate that these dykes represent at least two major episodes of Hadrynian igneous activity. The Borden dykes were emplaced during the earlier of these episodes. They are about 950 Ma old and have a paleomagnetic pole position of 153.3°E, 26.7°S, δm = 8.6e, δp = 6.1°. The later episode saw the emplacement of the previously defined Franklin dykes, which are about 750 Ma old. The newly defined Borden pole lies at the southern extremity of the Grenville Loop and has an age consistent with poles of similar position that were derived from rocks of the Grenville Province.All of the dykes probably reflect tension acting in an east-northeast–west-southwest direction. The directions of thick northwest trending dykes, which form a considerable angle to that expected from east-northeast tension, are thought to have been controlled by earlier (circa 1200 Ma) fractures of the Borden fault zones. The two main surges of magma may coincide with two -periods of Hadrynian uplift in the Boothia Peninsula area to the west.

Paleomagnetism of the ~860 Ma Manso dyke swarm, West Africa: implications for the assembly of Rodinia

2021 ◽  
Author(s):  
Paul Yves Jean Antonio ◽  
Lenka Baratoux ◽  
Ricardo Ivan Ferreira Trindade ◽  
Sonia Rousse ◽  
Anani Ayite ◽  
...  
Keyword(s):  
West Africa ◽  
West African ◽  
Dyke Swarm ◽  
Jigsaw Puzzle ◽  
The West ◽  
West African Craton ◽  
Contact Test ◽  
Fine Grained ◽  
Paleomagnetic Pole ◽  
Coarse To Fine

<p>The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000–750 Ma). In the Rodinian models, the position of West Africa is mainly constrained by the assumption that it had been a partner of Amazonia since the Paleoproterozoic. Unfortunately, no paleomagnetic data are available for these cratons when the Rodina supercontinent is considered tectonically stable (~1000-750 Ma). Thus, every new reliable paleomagnetic pole for the West African Craton during the Neoproterozoic times is of paramount importance to constrain its position and testing the Rodinia models. In this study we present a combined paleomagnetic and geochronological investigation for the Manso dyke swarm in the Leo-Man Shield, southern West Africa (Ghana). The ~860 Ma emplacement age for the NNW-trending Manso dykes is thus well-constrained by two new U-Pb apatite ages of 857.2 ± 8.5 Ma and 855 ± 16 Ma, in agreement with baddeleyite data. Remanence of these coarse-to-fine grained dolerite dykes is carried by stable single to pseudo-single domain (SD-PSD) magnetite. A positive baked-contact test, associated to a positive reversal test (Class-C), support the primary remanence obtained for these dykes (13 sites). Moreover, our new paleomagnetic dataset satisfy all the seven R-criteria (R=7). The ~860 Ma Manso pole can thus be considered as the first key Tonian paleomagnetic pole for West Africa. We propose that the West Africa-Baltica-Amazonia-Congo-São Francisco were associated in a long-lived WABAMGO juxtaposition (~1100–800 Ma).</p><p><strong>Keywords:</strong> West Africa, Neoproterozoic, Tonian, Rodinia, paleomagnetism.</p><p> </p>

scholarly journals Marmara Island earthquakes, of 1265 and 1935; Turkey

2006 ◽  
Vol 6 (6) ◽  
pp. 999-1006 ◽  
Author(s):  
Y. Altınok ◽  
B. Alpar
Keyword(s):  
Fault Zones ◽  
Marmara Sea ◽  
Sea Waves ◽  
Rock Falls ◽  
The West ◽  
Moderate Size ◽  
Northwestern Turkey ◽  
Earthquake Ruptures ◽  
Fundamental Understanding

Abstract. The long-term seismicity of the Marmara Sea region in northwestern Turkey is relatively well-recorded. Some large and some of the smaller events are clearly associated with fault zones known to be seismically active, which have distinct morphological expressions and have generated damaging earthquakes before and later. Some less common and moderate size earthquakes have occurred in the vicinity of the Marmara Islands in the west Marmara Sea. This paper presents an extended summary of the most important earthquakes that have occurred in 1265 and 1935 and have since been known as the Marmara Island earthquakes. The informative data and the approaches used have therefore the potential of documenting earthquake ruptures of fault segments and may extend the records kept on earthquakes far before known history, rock falls and abnormal sea waves observed during these events, thus improving hazard evaluations and the fundamental understanding of the process of an earthquake.

Paleomagnetism of the Great Slave Supergroup, Northwest Territories, Canada: the Stark Formation

1976 ◽  
Vol 13 (4) ◽  
pp. 563-578 ◽  
Author(s):  
D. K. Bingham ◽  
M. E. Evans
Keyword(s):  
Northwest Territories ◽  
North American ◽  
Geomagnetic Field ◽  
Pole Position ◽  
The West ◽  
Stratigraphic Sequence ◽  
Polar Wander ◽  
Early Proterozoic ◽  
The North ◽  
Polarity Reversals

Paleomagnetic results from 55 sampling sites throughout the Stark Formation are reported. The known stratigraphic sequence of these sites enables the behaviour of the geomagnetic field in these remote times (1750 m.y.) to be elucidated. Two polarity reversals are identified and these represent potentially useful correlative features in strata devoid of index fossils. One of these is investigated in detail and indicates that behaviour of the geomagnetic field during polarity reversals was essentially the same in the early Proterozoic as it has been over the last few million years. The pole position (145°W, 15°S, dp = 3.5, dm = 6.9) lies far to the west of that anticipated from earlier results, implying further complexity of the North American polar wander curve. Possible alternatives to this added complexity are discussed.

CALCULATION OF THE MAGNETIZATION OF UPLIFTS FROM COMBINING TOPOGRAPHIC AND MAGNETIC SURVEYS

Geophysics ◽  
1967 ◽  
Vol 32 (4) ◽  
pp. 678-707 ◽  
Author(s):  
M. L. Richards ◽  
V. Vacquier ◽  
G. D. Van Voorhis
Keyword(s):  
Pacific Ocean ◽  
Horizontal Plane ◽  
Large Scale ◽  
Geomagnetic Latitude ◽  
Pole Position ◽  
Present Position ◽  
Paleomagnetic Pole ◽  
The Pacific ◽  
Geomagnetic Pole ◽  
The Pacific Ocean

The direction and magnitude of the magnetization of a uniformly magnetized structure can be computed by combining topographic and magnetic surveys. The previously reported method has been extended to include more than one structure, each possessing its particular magnetization. Also, the bottom of the structure need not be a horizontal plane but can be an arbitrary surface. The method was applied to 21 seamounts, one laccolith and two Aleutian volcanoes. Four of the seamounts were found to be reversely magnetized. The virtual paleomagnetic pole positions for 16 Pacific Ocean seamounts, representing three widely separated locations, are significantly different from the present geomagnetic pole position but near Mesozoic virtual pole positions from Australia. For two locations, radiometric age determinations give an average date for their formation in the Cretaceous. The apparent 30 degree shift in geomagnetic latitude of the seamounts is interpreted as the result of large scale movements of the Pacific Ocean floor or, alternatively, as the result of the paleomagnetic equator being north of its present position in the Pacific during the growth of the seamounts.

Glacial dispersal train of Paleozoic erratics, central Baffin Island, N.W.T., Canada

1985 ◽  
Vol 22 (12) ◽  
pp. 1818-1826 ◽  
Author(s):  
Clinton R. Tippett
Keyword(s):  
Baffin Island ◽  
The West ◽  
Quaternary Sediment ◽  
Foxe Basin

A glacial dispersal train of erratics derived from Paleozoic bedrock has been delineated stretching east-northeast–west-southwest across central Baffin Island. The lithologies of these erratics suggest a derivation from strata of member B of the Ordovician Ship Point Formation to the west, which are presently either submerged or covered by Quaternary sediment in the eastern part of Foxe Basin. These Paleozoic erratics were carried from Foxe Basin onto the Baffin Upland and the western edge of the Davis Highlands. They can be inferred to have reached at least Ekalugad Fiord and the eastern part of Home Bay.

scholarly journals A chronological and geochemical study of the Tadamigawa older-stage granites: Igneous activity in the west of the Tanakura Tectonic Line (TTL) of northeastern Japan

2020 ◽  
Vol 54 (4) ◽  
pp. 203-220
Author(s):  
Yuki Wakasugi ◽  
Shigeyuki Wakaki ◽  
Yudai Tanioka ◽  
Koki Ichino ◽  
Motohiro Tsuboi ◽  
...  
Keyword(s):  
The West ◽  
Northeastern Japan ◽  
Geochemical Study ◽  
Igneous Activity ◽  
Tectonic Line

scholarly journals IV. Extract from Inspection Report of the Island of Trinidad, made in the year 1816, by the Inspector of Hospitals, in conjunction with the Quarter-Master General and Chief Engineer for the Windward and Leeward Colonies of the West Indies

1823 ◽  
Vol 9 (1) ◽  
pp. 93-96
Author(s):  
William Ferguson
Keyword(s):  
West Indies ◽  
Mud Volcanoes ◽  
The West ◽  
Chief Engineer ◽  
Southern Extremity ◽  
Made In

Having heard at Port-of-Spain of an appearance that went by the name of the Mud Volcanoes, we took the opportunity when surveying the southern quarter of Trinidad, to examine them. They are situated near Point Icaque, the southern extremity of the island, on an alluvial tongue of land, that has been appended to the primitive rocks, where no doubt the land originally terminated. This appendage is several miles in length, and points directly into one of the mouths of the Oronoko, on the mainland, about twelve or fifteen miles off.We landed nearly opposite to where we were told we should find the mud volcanoes, and after making our way about five miles through the woods, across the sandy isthmus, we came upon two plantations very pleasantly situated, amidst a group of remarkable round little hills, each from eighty to a hundred feet in height.

Mapping of the West Yakut barrier reef in the junction zone of the Vilyui syneclise and Aldan anteclise using electro-facies analysis

2021 ◽  
pp. 40-48
Author(s):  
A. A. Kravchenko
Keyword(s):  
Facies Analysis ◽  
Fault Zones ◽  
Junction Zone ◽  
Barrier Reef ◽  
The West ◽  
Geoelectric Section ◽  
Drilling Data ◽  
Operational Information ◽  
Speed Up

The aim of the study was to test the method of electro-facies analysis for mapping reef structures in the conditions of the junction of the Vilyui syneclise and Aldan anteclise. The article presents the results of a study of geoelectric characteristics using the method of electro-facies analysis. The confinement of buried bioherms to fault zones has been established. Facies zones corresponding to paleographic representations of the development of the region were identified. A map of the distribution of electrofacies for the Cambrian section interval was constructed, with boundaries of the distribution of reef deposits in the aisles of the study area. A typical geoelectric section showing the geoelectric properties of a section of the West Yakut barrier reef is given. Separation of facies based on electrical exploration data is able to provide operational information on the boundaries of the studied area. With insufficient drilling data, electro-facies analysis can speed up the interpretation of electrical exploration data.

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