scholarly journals Paleomagnetism of the Cretaceous rocks from Cape Kronotskiy, East Kamchatka and reconstruction of terrane trajectories in the NE Pacific area

2009 ◽  
Vol 4 ◽  
pp. 313-327 ◽  
Author(s):  
W. Harbert ◽  
N. V. Tsukanov ◽  
D. V. Alexeiev ◽  
C. Gaedicke ◽  
R. Freitag ◽  
...  
Keyword(s):  
Kamchatka Peninsula ◽  
Northeastern Russia ◽  
K Value ◽  
Polar Wander ◽  
True Polar Wander ◽  
The North ◽  
Paleomagnetic Study ◽  
Northwestern Margin ◽  
Accreted Terranes ◽  
Ne Pacific

Abstract. The Kamchatka Peninsula of northeastern Russia is located along the northwestern margin of the Bering Sea and consists of zones of complexly deformed accreted terranes. Paleomagnetic samples were collected for study from a Late Cretaceous aged locality at Cape Kronotskiy (λ=54°44.8´ N, φ=162°1.29´ E). Two components of magnetization were observed. During stepwise thermal demagnetization, the B-magnetic component was observed up to 600°C having a direction and associated uncertainty in stratigraphic coordinates of Ds=300.7°, Is=48.7°, α95=10.9°, k-value=11.8, n=17. The B component paleolatitude calculated from the Fisher mean in stratigraphic coordinates and associated statistics are λobs=30.4° N or S, λ95=8.9°, n=17 (sites), k-value=11. Our overall study paleolatitude result is similar to a previously reported paleomagnetic study completed within this unit. Terrane trajectories calculated using the finite rotation poles of Engebretson et al. (1985), which are corrected for either Pacific-hotspot drift or True Polar Wander hotspot-spin axis relative motion, show that the sampled unit represents a far traveled tectonostratigraphic terrane and support a model in which accretion (docking) events of this composite or superterrane with the North America plate occur at approximately 40 Ma.

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.

Enigma of the Jurassic monster shift of the North China block

2020 ◽  
Author(s):  
Shihong Zhang ◽  
Yangjun Gao ◽  
Qiang Ren
Keyword(s):  
North China ◽  
Rotation Axis ◽  
Eastern Asia ◽  
North China Block ◽  
Polar Wander ◽  
Plate Convergence ◽  
True Polar Wander ◽  
The North ◽  
Geochronological Study ◽  
Oceanic Plates

<p>Accumulation of the global paleomagnetic data, from both continental and oceanic plates, may suggest a true polar wander (TPW) event in Jurassic, with a rotation axis located in the present northwestern Africa, but no consensus has been reached regarding to the initiation, duration and velocity of the TPW. As one of the eastern Asian blocks, the north China block (NCB) is then located far from the rotation axis of the TPW and the plate convergence between Siberia and the Amur-NCB, known as the subduction in the Mesozoic Okhotsk-Baikal ocean, did exist. Paleogeographic changes observed of the eastern Asian blocks in Jurassic thus should contain the TPW component and plate moving component. To better estimate the influence of the TPW in the Eastern Asia blocks, we carried out a new paleomagnetic and precision U-Pb geochronological study on the middle Jurassic lavas in the NCB. Being profoundly different to the recent paleogeographic model (Yi et al., 2019, https://doi .org/10.1130/G46641.1) that suggest that the NCB experienced a large latitudinal displacement (monster-shift) responding to the TPW event between ~174 and ~157 Ma, we suggest that the NCB, as well as other blocks already connected with it, do not record any monster-shift between ~170 and ~160 Ma. The strata, ranging from 160 to 145 Ma, however, yield considerable paleomagnetic variations and need further investigation.</p>

The Neoproterozoic geomagnetic field: new insights from a high-resolution paleomagnetic study in South China

2021 ◽  
Author(s):  
Justin Tonti-Filippini ◽  
Boris Robert ◽  
Élodie Muller ◽  
Michael Wack ◽  
Xixi Zhao ◽  
...  
Keyword(s):  
South China ◽  
Geomagnetic Field ◽  
Alternative Explanation ◽  
Rotation Axis ◽  
Sedimentary Rocks ◽  
Polar Wander ◽  
True Polar Wander ◽  
Paleomagnetic Study ◽  
Stratigraphic Height ◽  
Independent Motion

<p>The paleomagnetic record during the middle Neoproterozoic (~825-780 Ma) displays rapid apparent polar wander variations leading to large discrepancies in paleogeographic reconstructions. Some authors propose that these data may represent true polar wander events, which correspond to independent motion of the mantle and lithosphere with respect to Earth’s rotation axis. An alternative explanation might be a perturbation of the geomagnetic field, such as a deviation from a predominantly dipole field or a hyper-reversing field. To test these hypotheses, we sampled 1200 oriented cores over a stratigraphic height of 100 metres in sedimentary rocks of the 820-810 Ma Laoshanya Formation in South China. We will present preliminary paleomagnetic and rock magnetic analyses together with results of petrologic and geochemical experiments to better understand the origin of the paleomagnetic signal.</p>

Preliminary Proterozoic apparent polar wander paths for the South China Block and their tectonic implications

1998 ◽  
Vol 35 (3) ◽  
pp. 302-320 ◽  
Author(s):  
Huimin Zhang
Keyword(s):  
South China ◽  
North China ◽  
Eastern China ◽  
North China Block ◽  
Polar Wander ◽  
Late Proterozoic ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
Middle Proterozoic

Results of a regional paleomagnetic study of Precambrian rocks in central-east China are summarized and interpreted. The study is a partial outcome of a geoscience transect incorporating three terranes, namely the Yangzi, Jiangnan, and Huaxia blocks. Paleomagnetic poles derived from a range of metamorphic, igneous, and sedimentary rocks define a northeast to southwest swath crossing the present Pacific Ocean and interpreted to embrace Early to Late Proterozoic times. All three terranes define segments of the same swath and correlate with a similar apparent polar wander path previously defined from the North China Block. The results imply that the constituent blocks of eastern China formed a united block during Early to Middle Proterozoic times. Later relatively large fragmentation is confirmed by Late Proterozoic apparent polar wander path records of the North China and South China Blocks.

Broad-scale Proterozoic deformation of the central Superior Province revealed by paleomagnetism of the 2.45 Ga Matachewan dyke swarm

1991 ◽  
Vol 28 (11) ◽  
pp. 1780-1796 ◽  
Author(s):  
M. P. Bates ◽  
H. C. Halls
Keyword(s):  
Large Scale ◽  
Dyke Swarm ◽  
Superior Province ◽  
Polar Wander ◽  
The North ◽  
Paleomagnetic Study ◽  
Secondary Feature ◽  
Dual Polarity ◽  
Host Rocks ◽  
Broad Scale

An extensive paleomagnetic study of the 2.45 Ga Matachewan dyke swarm of the North American Superior Province suggests that the interior of an Archean shield can undergo broad-scale distortion as a result of later (Proterozoic) orogenic activity around the craton margins. Data collected from over 300 sites, of which 137 are reported here for the first time, reveal that the dykes contain a dual-polarity primary remanence that varies across the swarm in both inclination and declination. These regional variations are statistically significant at the 95% confidence level, and cannot be attributed to remagnetization or to magnetic anisotropy. Inclination variation is probably due to real or apparent polar wander during the emplacement of the swarm, and may in part explain the declination variation as well. However, for dykes within and northwest of the Kapuskasing Structural Zone (KSZ) a positive correlation is found between regionally averaged values of declination and dyke trend. Here the dykes appear to have suffered differential rotations about vertical axes of up to 40° since emplacement. The Matachewan swarm radiates northwards from a broad focus situated approximately in northern Lake Huron but the trend of the western half of the swarm follows a broad Z-shaped pattern where it crosses the KSZ. Our data suggest that this changing trend is a secondary feature and that the western dykes, like their eastern counterparts, originally had a more uniform trend. This large-scale distortion of the western Matachewan swarm and Archean host rocks within and north of the KSZ is probably the result of broad-scale deformation during the Trans-Hudson Orogeny at about 1.95 Ga, coeval with uplift along the KSZ.

Accreted Terranes of the North Cascades Range, Washington: Spokane to Seattle, Washington, July 21–29, 1989

10.1029/ft307 ◽  
1989 ◽  
Author(s):  
R. W. Tabor ◽  
R. A. Haugerud ◽  
E. H. Brown ◽  
R. S. Babcock ◽  
R. B. Miller
Keyword(s):  
North Cascades ◽  
The North ◽  
Accreted Terranes

scholarly journals Style of density stratification in the mantle and true polar wander induced by ice loading

2002 ◽  
Vol 107 (B10) ◽  
pp. ETG 16-1-ETG 16-17 ◽  
Author(s):  
R. Sabadini ◽  
A. M. Marotta ◽  
R. De Franco ◽  
L. L. A. Vermeersen
Keyword(s):  
Density Stratification ◽  
Polar Wander ◽  
True Polar Wander

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

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