Paleomagnetism of Late Cretaceous alkaline rocks in the Nemuro Peninsula, Hokkaido, N.E.Japan.

Fujiwara, Yoshiki; Ohtake, Toshinori

doi:10.5636/jgg.26.549

Cited by 12 publications

(5 citation statements)

References 14 publications

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“…These show much shallower inclinations, indicating much lower paleolatitudes than expected if these terranes were part of the Eurasian continent, suggesting an allochthonous, intra-Panthalassa origin. The declinations from the Nemuro belt show that it experienced a ∼15-25°counterclockwise rotation since the Late Cretaceous (Bazhenov & Burtman, 1994;Fujiwara & Ohtake, 1974; Figure S2). The site from the NNE-SSW-trending Tokoro belt shows a ∼130°clockwise rotation (Kanamatsu et al, 1992).…”

Section: 1029/2018tc005164mentioning

confidence: 99%

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

2019

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The Eocene (~50–45 Ma) major absolute plate motion change of the Pacific plate forming the Hawaii‐Emperor bend is thought to result from inception of Pacific plate subduction along one of its modern western trenches. Subduction is suggested to have started either spontaneously, or result from subduction of the Izanagi‐Pacific mid‐ocean ridge, or from subduction polarity reversal after collision of the Olyutorsky arc that was built on the Pacific plate with NE Asia. Here we provide a detailed plate‐kinematic reconstruction of back‐arc basins and accreted terranes in the northwest Pacific region, from Japan to the Bering Sea, since the Late Cretaceous. We present a new tectonic reconstruction of the intraoceanic Olyutorsky and Kronotsky arcs, which formed above two adjacent, oppositely dipping subduction zones at ~85 Ma within the north Pacific region, during another Pacific‐wide plate reorganization. We use our reconstruction to explain the formation of the submarine Shirshov and Bowers Ridges and show that if marine magnetic anomalies reported from the Aleutian Basin represent magnetic polarity reversals, its crust most likely formed in an ~85‐ to 60‐Ma back‐arc basin behind the Olyutorsky arc. The Olyutorsky arc was then separated from the Pacific plate by a spreading ridge, so that the ~55‐ to 50‐Ma subduction polarity reversal that followed upon Olyutorsky‐NE Asia collision initiated subduction of a plate that was not the Pacific. Hence, this polarity reversal may not be a straightforward driver of the Eocene Pacific plate motion change, whose causes remain enigmatic.

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Section: 1029/2018tc005164mentioning

confidence: 99%

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

2019

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“…A series of dolerite outcrops in this region (Geological Survey of Japan, 1992) show an exceedingly high magnetization of about 10 A/m (Fujiwara and Ohtake, 1975). However, they are not enough to explain the whole geomagnetic anomalies because the thickness of the dolerite outcrops is several tens meter or so (Yagi, 1969).…”

Section: Modeling Of the Geomagnetic Anomaliesmentioning

confidence: 99%

Tectonomagnetic study in the eastern part of Hokkaido, NE Japan: Discrepancy between observed and calculated results

et al. 2014

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Continuous and repeated geomagnetic observations have been performed at 8 stations in the eastern part of Hokkaido, NE Japan, to confirm a detailed picture of geomagnetic secular changes. The observation delineated anomalously large secular changes of about 1 nT/year that have lasted at least for about 3 to 30 years (depending on the period of observations) at 3 stations situated in the remarkable geomagnetic anomaly region. Contributions from the earth's core or ionospheric origin are ruled out as source mechanisms because of the local distribution of the anomalous stations. Heat-triggered volcanomagnetic effect cannot be the origin of such secular changes because the stations are quite far from the volcanoes. Instead, we propose the changes originate from stressinduced tectonomagnetic effect (piezomagnetism). We performed piezomagnetic modeling under the condition that observed regional tectonic stress has been applied to the highly magnetized rock bodies inferred from the analysis of the observed geomagnetic anomalies. The modeling explained well the secular changes by assuming the stress sensitivity of the order of 10 −2 MPa −1 , which is one order larger than the ordinarily used value.

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“…(AH) Alkaline complexes, Hokkaido, Ku(Fujiwara and Ohtake 1975); (AI) Akagane intrusives, N. Honshu(Nedachi et al, 1970); (CP) Capo Passero lavas, E. Sicily,(1)); (GL) Gargano limestone, Apulia, Ku (16-79(1)); (HI) Igneous rocks, SW Honshu, Ku (Sasajima and Shimada, 1966); (IK) Inkstone Series, SW Honshu (Domen, 1971); (KA) Kalimantan igneous rocks, Malaya, K1 (Haile et al, 1977); (KL) Korean lavas (8-49(1)); (MC) Mr. Cerviero lava's, Italy, Ku (Manzoni 1975); (PB) Penzhinsk Bay sedimentary rocks, Siberia, Ku (4-24 in U.S.S.R. list 1973); (PD) Primore dykes and contacts, Ku (4-32 in U.S.S.R. list 1975); (SI) Sedimentary rocks, southern Italy, Ku (14-216(;J'); (SK) Sedimentary rocks, Sakhkalin, Ku (4-33 in U.S.S.R. list, 1975); (SR) Scaglia Rossa, Umbria, Ku-Pg (14-170(1)); (WS) Volcanics, west Sicily, Ku (15-54(1)); (1) Geophysical Journal lists. Mean reference palaeopoles for stable Eurasia for-70 to -130 Ma are marked.…”

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confidence: 99%

Fragmentation and assembly of the continents, Mid-carboniferous to present

Irving

1983

Geophysical Surveys

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Eighteen maps showing the motions of the major continents following the break-up of Wegener's Pangaea in the Early to Mid-Jurassic are presented. Palaeolatitudes are determined palaeomagnetically, palaeolongitudes mainly from sea-floor spreading evidence. The break-up commences with the opening of the southern North Atlantic in the mid-Jurassic and its extension north and south in the Cretaceous and Cenozoic. Concurrently the northern continents move northwards away from the southern continents (Gondwana) and a continuous east-west seaway is formed between them in the Cretaceous. Successive fragmentation of continents then created the Arctic, Indian and Antarctic Oceans. Five maps showing the disposition of land in the Permian are also given. These are based on the palaeomagnetic evidence and the idea of minimizing the motions required to bring the continents into their known Early Jurassic configuration. The Permian maps show Gondwana situated further east than in the Pangaea configuration of Wegener. There are severe problems in constructing palaeogeographical maps for the Triassic and none are presented. Palaeomagnetic results from smaller crustal fragments are also reviewed and the evidence for the former dismemberment of Eurasia and the western part of the North American cordillera are set out. The results indicate that most orogenies are to some degree collisional in nature.

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Paleomagnetism of Late Cretaceous alkaline rocks in the Nemuro Peninsula, Hokkaido, N.E.Japan.

Cited by 12 publications

References 14 publications

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

Reconstruction of Subduction and Back‐Arc Spreading in the NW Pacific and Aleutian Basin: Clues to Causes of Cretaceous and Eocene Plate Reorganizations

Tectonomagnetic study in the eastern part of Hokkaido, NE Japan: Discrepancy between observed and calculated results

Fragmentation and assembly of the continents, Mid-carboniferous to present

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