scholarly journals Rotation of the Philippine Sea plate inferred from paleomagnetism of oriented cores taken with an ROV-based coring apparatus

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Toshitsugu Yamazaki ◽  
Shun Chiyonobu ◽  
Osamu Ishizuka ◽  
Fumisato Tajima ◽  
Naoki Uto ◽  
...  
Keyword(s):  
Plate Motion ◽  
Philippine Sea Plate ◽  
Late Oligocene ◽  
Clockwise Rotation ◽  
Polar Wander ◽  
Philippine Sea ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
History Of ◽  
The Mean

AbstractReconstructing the history of Philippine Sea (PHS) plate motion is important for better understanding of the tectonics of the surrounding plates. It is generally considered that the PHS plate migrated northward since Eocene, but its rotation has not been constrained well; some reconstructions incorporated a large clockwise rotation but others did not. This is mainly because the difficulty of collecting oriented rocks from the mostly submerged PHS plate hindered establishing an apparent polar wander path. In this study, we conducted a paleomagnetic study of oriented cores taken using an ROV-based coring apparatus from the Hyuga Seamount on the northern part of the Kyushu-Palau Ridge, a remnant arc in the stable interior of the PHS plate. Stepwise thermal and alternating-field demagnetizations were applied to specimens taken successively from two ~ 30 cm long limestone cores of middle to late Oligocene age, and characteristic remanent magnetization directions could be isolated. Declination and inclination of D = 51.5° and I = 39.8°, respectively, were obtained as the mean of the two cores. The easterly-deflected declination means ~ 50° clockwise rotation of the PHS plate since middle to late Oligocene. In addition, ~ 5° latitudinal change of the site is estimated from the mean inclination. The result implies that the Kyushu-Palau Ridge was located to the southwest of the present position in middle to late Oligocene, and that PHS plate rotation as well as the Shikoku and Parece Vela Basin spreading contributed to the eastward migration of the Izu-Ogasawara (Bonin) Arc to the current position.

Paleomagnetism of the Lawrenceton Formation volcanic rocks, Silurian Botwood Group, Change Islands, Newfoundland

1989 ◽  
Vol 26 (2) ◽  
pp. 296-304 ◽  
Author(s):  
Julie E. Gales ◽  
Ben A. van der Pluijm ◽  
Rob Van der Voo
Keyword(s):  
North American ◽  
Volcanic Rocks ◽  
Mobile Belt ◽  
Structural Mapping ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
North American Craton

Paleomagnetic sampling of the Lawrenceton Formation of the Silurian Botwood Group in northeastern Newfoundland was combined with detailed structural mapping of the area in order to determine the deformation history and make adequate structural corrections to the paleomagnetic data.Structural analysis indicates that the Lawrenceton Formation experienced at least two folding events: (i) a regional northeast–southwest-trending, Siluro-Devonian folding episode that produced a well-developed axial-plane cleavage; and (ii) an episode of local north-trending folding. Bedding – regional cleavage relationships indicate that the latter event is older than the regional folding.Thermal demagnetization of the Lawrenceton Formation yielded univectorial southerly and shallow directions (in situ). A fold test on an early mesoscale fold indicates that the magnetization of the Botwood postdates this folding event. However, our results, combined with an earlier paleomagnetic study of nearby Lawrenceton Formation rocks, demonstrate that the magnetization predates the regional folding. Therefore, we conclude that the magnetization occurred subsequent to the local folding but prior to the period of regional folding.While a tectonic origin for local folding cannot be entirely excluded, the subaerial nature of these volcanics, the isolated occurrence of these folds, and the absence of similar north-trending folds in other areas of eastern Notre Dame Bay suggest a syndepositional origin. Consequently, the magnetization may be nearly primary. Our study yields a characteristic direction of D = 175°, I = +43°, with a paleopole (16°N, 131 °E) that plots near the mid-Silurian track of the North American apparent polar wander path. This result is consistent with an early origin for the magnetization and supports the notion that the Central Mobile Belt of Newfoundland was adjacent to the North American craton, in its present-day position, since the Silurian.

Basin filling related to the Philippine Sea Plate motion in Beppu Bay, southwest Japan

2016 ◽  
Vol 117 ◽  
pp. 13-22 ◽  
Author(s):  
Keitaro Yamada ◽  
Keiji Takemura ◽  
Michinobu Kuwae ◽  
Ken Ikehara ◽  
Masanobu Yamamoto
Keyword(s):  
Plate Motion ◽  
Philippine Sea Plate ◽  
Southwest Japan ◽  
Philippine Sea

scholarly journals Philippine Sea Plate motion since the Eocene estimated from paleomagnetism of seafloor drill cores and gravity cores

2010 ◽  
Vol 62 (6) ◽  
pp. 495-502 ◽  
Author(s):  
Toshitsugu Yamazaki ◽  
Masaki Takahashi ◽  
Yasufumi Iryu ◽  
Tokiyuki Sato ◽  
Motoyoshi Oda ◽  
...  
Keyword(s):  
Plate Motion ◽  
Philippine Sea Plate ◽  
Philippine Sea ◽  
Drill Cores

A paleomagnetic study of the lava flows within the Copper Harbor Conglomerate, Michigan: new results and implications

1994 ◽  
Vol 31 (2) ◽  
pp. 369-380 ◽  
Author(s):  
J. F. Diehl ◽  
T. D. Haig
Keyword(s):  
High Temperature ◽  
Entire Range ◽  
Lava Flows ◽  
Polar Wander ◽  
Lake Shore ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Pole ◽  
Complete Section ◽  
Paleomagnetic Study ◽  
Petrographic Analyses

New paleomagnetic data have been obtained from the interbedded lava flows within the Copper Harbor Conglomerate on Michigan's Keweenaw Peninsula. Previous paleomagnetic studies of these lava flows, known collectively as the Lake Shore Traps, have produced contradictory results. To investigate the cause of these conflicting results, 30 sites encompassing the most complete section of lava flows possible were collected and analyzed.Well-defined characteristic directions of magnetization were isolated using either alternating-field or thermal demagnetization or a combination of both. These directions of magnetization are interpreted as primary magnetizations acquired during the original cooling of the lavas. Hysteresis, thermomagnetic, and petrographic analyses suggest the carrier of magnetization is a pseudo-single-domain, titanium-poor magnetite that has undergone some high-temperature oxidation.Site means determined from the 30 lava flows define three distinct directional clusters. Each cluster of directions corresponds to a different stratigraphic package of lava flows with the Copper Harbor Conglomerate. Between-site dispersion for each stratigraphic package or unit is much less than the expected value for Keweenawan-age rocks. Therefore, we suggest that most of the lava flows in each unit were extruded rapidly and that within an individual stratigraphic unit, paleosecular variation has not been adequately sampled. This explains why previous studies on the Lake Shore Traps have produced such different results; each study did not sample the entire range of directions possible in these lava flows.The paleomagnetic pole calculated from the 30 site-mean virtual geomagnetic poles is located at 22.2°N, 180.8°E (k = 35.0; A95 = 6.5°). The new Copper Harbor pole is now located in the appropriate chronological position with respect to the underlying Portage Lake Volcanics and the overlying Nonesuch Shale on the Keweenawan apparent polar wander path. The similarity of our Copper Harbor pole to that of the Portage Lake Volcanics reinforces the idea that the Copper Harbor Conglomerate is more closely related in time to the Portage Lake Volcanics than to the Nonesuch Shale.

Paleomagntism of Archean rocks from northwestern Ontario: II. Shelley Lake granite, Quetico Subprovince

1984 ◽  
Vol 21 (8) ◽  
pp. 869-878 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Dipole Field ◽  
Polar Wander ◽  
Orthogonal Vector ◽  
Site Type ◽  
Apparent Polar Wander Path ◽  
Northwestern Ontario ◽  
Heating Event ◽  
The Mean

The 2580 ± 20 Ma Shelley Lake granite of the Quetico gneiss belt in northwestern Ontario preserves two distinct natural remanent magnetizations (NRM's) of different ages. Type 1 NRM of either normal (1N) or reverse (1R) polarity was isolated in 43 samples, using three methods: stable end-point directions, orthogonal vector plots, and converging remagnetization circles. The mean direction based on both 1N and 1R results is D = 5.9 °I = +56.4 °(k = 95.4, α95 = 4.4°, N = 12 sites), which is significantly different from both the present Earth's field (PEF) and axial dipole field directions at the site. Type 2 NRM, either normal (2N) or reverse (2R), was successfully separated from 1N/1R in 13 samples. Its mean direction, combining both polarities, is D = 70.3 °I = −27.8 °(k = 20.1, α95 = 9.4°, N = 13 samples).The paleopole SL1 corresponding to 1N/1R falls at 65.8°E, 77.6°N, near track 6 of the Laurentian apparent polar wander path (APWP) around 2600 Ma. This remanence is carried principally by primary multidomain magnetite with blocking temperatures up to 580 °C. If it is a primary thermoremanence, as is argued here, SL1 provides a well dated tie point for the APWP at 2580 ± 20 Ma.Paleopole SL2 corresponding to 2N/2R falls at 157.1°W, 1.3°S, around 1250 Ma on the APWP. The remanence is probably a chemical or thermochemical overprint acquired during a mild heating event (T < 300 °C, t > 1100 Ma) that reset 40Ar/39Ar feldspar ages. An earlier tentative assignment of SL2 to track 6 around 2800 Ma is incorrect.

Geodetic constraints on postseismic deformation following the 1990Ms7.8 Luzon earthquake and implications for Luzon tectonics and Philippine Sea plate motion

2001 ◽  
Vol 2 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
John Beavan ◽  
David Silcock ◽  
Michael Hamburger ◽  
Emmanuel Ramos ◽  
Catherine Thibault ◽  
...  
Keyword(s):  
Plate Motion ◽  
Philippine Sea Plate ◽  
Postseismic Deformation ◽  
Philippine Sea
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