Paleomagnetism of red cherts: A case study in the Inuyama Area, central Japan

Shibuya, H.; Sasajima, Sadao

doi:10.1029/jb091ib14p14105

Cited by 60 publications

(43 citation statements)

References 32 publications

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“…6). These data are similar to those obtained for Mesozoic radiolarian cherts in Italy (11°± 5°N; Aiello and Hagstrum, 2001), the Mino Terrane of central Japan (1°± 3°N or S; Shibuya and Sasajima, 1986), and along the western margin of North America in California (Hagstrum and Murchey, 1993;Hagstrum et al, 1996) and western Mexico (0°-2°N or S; Hagstrum and Sedlock, 1992). Peri-equatorial paleolatitudes for Jurassic radiolarian cherts of the Peloponnesus further support the hypothesis that they were deposited within zones of equatorial upwelling, high biologic productivity, and preservation of radiolarian tests on the seafloor (Aiello and Hagstrum, 2001;Muttoni et al, 2005).…”

Section: Paleolatitudes Of Mesozoic Radiolarian Cherts In Peloponnesussupporting

confidence: 77%

“…6), and agree with those for other Mesozoic rocks of Argolis and the Pelagonian Zone of Greece (e.g., Turnell, 1988;Morris, 1995). Low paleolatitudes have also been determined for coeval radiolarian cherts of the Italian Alps and Apennines (Aiello and Hagstrum, 2001;Muttoni et al, 2005) and for Mesozoic cherts in central Japan (1°± 3°N or S; Shibuya and Sasajima, 1986), and along the western margin of North America (0°-2°N or S; e.g. Hagstrum et al, 1996).…”

Section: Discussionsupporting

confidence: 66%

“…Paleomagnetic studies of Mesozoic radiolarian cherts in the Italian Alps and Northern Apennines (Aiello and Hagstrum, 2001;Muttoni et al, 2005), along the western margin of North America (Hagstrum and Murchey, 1993;Hagstrum et al, 1996), and in Japan (Shibuya and Sasajima, 1986) have shown that these cherts are well suited for paleomagnetic investigations. Because of their unique lithologic characteristics they alone often preserve primary magnetizations in overprinted terrains that can be successfully isolated using detailed thermal demagnetization procedures.…”

Section: Introductionmentioning

confidence: 99%

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Peri-equatorial paleolatitudes for Jurassic radiolarian cherts of Greece

2008

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Radiolarian-rich sediments dominated pelagic deposition over large portions of the Tethys Ocean during middle to late Jurassic time as shown by extensive bedded chert sequences found in both continental margin and ophiolite units of the Mediterranean region. Which paleoceanographic mechanisms and paleotectonic setting favored radiolarian deposition during the Jurassic, and the nature of a Tethys-wide change from biosiliceous to biocalcareous (mainly nannofossil) deposition at the beginning of Cretaceous time, have remained open questions. Previous paleomagnetic analyses of Jurassic red radiolarian cherts in the Italian Apennines indicate that radiolarian deposition occurred at low peri-equatorial latitudes, similar to modern day deposition of radiolarian-rich sediments within equatorial zones of high biologic productivity. To test this result for other sectors of the Mediterranean region, we undertook paleomagnetic study of Mesozoic (mostly middle to upper Jurassic) red radiolarian cherts within the Aegean region on the Peloponnesus and in continental Greece. Sampled units are from the Sub-Pelagonian Zone on the Argolis Peninsula, the Pindos-Olonos Zone on the Koroni Peninsula, near Karpenissi in central Greece, and the Ionian Zone in the Varathi area of northwestern Greece. Thermal demagnetization of samples from all sections removed low-temperature viscous and moderate-temperature overprint magnetizations that fail the available fold tests. At Argolis and Koroni, however, the cherts carry a third high-temperature magnetization that generally exhibits a polarity stratigraphy and passes the available fold tests. We interpret the high-temperature component to be the primary magnetization acquired during chert deposition and early diagenesis. At Kandhia and Koliaky (Argolis), the primary declinations and previous results indicate clockwise vertical-axis rotations of ∼ 40°relative to "stable" Europe. Due to ambiguities in hemispheric origin (N or S) and thus paleomagnetic polarity, the observed declinations could indicate either clockwise (CW) or counterclockwise (CCW) vertical-axis rotations. Thus at Adriani (Koroni), the primary declinations indicate either CW or CCW rotations of ∼ 95°or ∼84°, depending on paleomagnetic polarity and age. The primary inclinations for all Peloponnesus sites indicate peri-equatorial paleolatitudes similar to those found for coeval radiolarian cherts exposed in other Mediterranean orogenic belts. Our new paleomagnetic data support the interpretation that Mesozoic radiolarites within the Tethys Ocean were originally deposited along peri-equatorial belts of divergence and high biologic productivity.

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Section: Paleolatitudes Of Mesozoic Radiolarian Cherts In Peloponnesussupporting

confidence: 77%

Section: Discussionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

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Peri-equatorial paleolatitudes for Jurassic radiolarian cherts of Greece

2008

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“…Other values as in footnote a. c Apparent average sedimentation rates for radiolarites is the mean of published estimates, a bulk density of 2.6 g/cm (Jenkyns and Winterer, 1982) is assumed unless given otherwise. Inuyama bedded chert-bulk chemistry from Matsumoto and Iijima (1983) assuming their analyzed shale partings comprise 10% of the section; age and bulk average accumulation rate from Matsuda and Isozaki (1991); paleolatitude is from Shibuya and Sasajima (1986). Cedros Island bedded chert-bulk chemistry from Rangin et al (1981) adjusted to yield average outcrop lithology of 20% mudstone (Sedlock and Isozaki, 1990); age and average accumulation rate from Sedlock and Isozaki (1990); paleolatitude of accretion (mid-Cretaceous event) is from Hagstrom and Sedlock ( , 1991.…”

Section: Oxfordian Through Tithonian Radiolarites At Site 801mentioning

confidence: 99%

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Ogg¹,

Stattegger²,

Behl³

1992

Proceedings of the Ocean Drilling Program

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Sedimentation in the central Pacific during the Jurassic and Early Cretaceous was dominated by abundant biogenic silica. A synthesis of the stratigraphy, lithology, petrology, and geochemistry of the radiolarites in Sites 801 and 800 documents the sedimentation processes and trends in the equatorial central Pacific from the Middle Jurassic through the Early Cretaceous. Paleolatitude and paleodepth reconstructions enable comparisons with previous DSDP sites and identification of the general patterns of sedimentation over a wide region of the Pacific.Clayey radiolarites dominated sedimentation on Pacific oceanic crust within tropical paleolatitudes from at least the latest Bathonian through Tithonian. Radiolarian productivity rose to a peak within 5° of the paleoequator, where accumulation rates of biogenic silica exceeded 1000 g/cm 2 /m.y. Wavy-bedded radiolarian cherts developed in the upper Tithonian at Site 801 coinciding with the proximity of this site to the paleoequator. Ribbon-bedding of some radiolarian cherts exposed on Pacific margins may have formed from silicification of radiolarite deposited near the equatorial high-productivity zone where radiolarian/clay ratios were high. Silicification processes in sediments extensively mixed by bioturbation or enriched in clay or carbonate generally resulted in discontinuous bands or nodules of porcellanite or chert, e.g., a "knobby" radiolarite. Ribbon-bedded cherts require primary alternations of radiolarian-rich and clay-rich layers as an initial structural template, coupled with abundant biogenic silica in both layers. During diagenesis, migration of silica from clay-rich layers leaves radiolarian "ghosts" or voids, and the precipitation in adjacent radiolarite layers results in silicification of the inter-radiolarian matrix and infilling of radiolarian tests. Alternations of claystone and clay-rich radiolarian grainstone were deposited during the Callovian at Site 801 and during the Berriasian-Valanginian at Site 800, but did not silicify to form bedded chert.Carbonate was not preserved on the Pacific oceanic floor or spreading ridges during the Jurassic, perhaps due to an elevated level of dissolved carbon dioxide. During the Berriasian through Hauterivian, the carbonate compensation depth (CCD) descended to approximately 3500 m, permitting the accumulation of siliceous limestones at near-ridge sites. Carbonate accumulation rates exceeded 1500 g/cm 2 /m.y. at sites above the CCD, yet there is no evidence of an equatorial carbonate bulge during the Early Cretaceous. In the Barremian and Aptian, the CCD rose, coincident with the onset of mid-plate volcanic activity.Abundance of Fe and Mn and the associated formation of authigenic Fe-smectite clays was a function of proximity to the spreading ridges, with secondary enrichments occurring during episodes of spreading-center reorganizations. Callovian radiolarite at Site 801 is anomalously depleted in Mn, which resulted either from inhibited precipitation of Mn-oxides by lower pH of interstitial waters in...

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“…It has been suspected that the zonal distribution of the geological structure was caused by collision and accretion processes of terranes and seamounts as the result of plate subduction OZAWA et al, 1985). Several authors proposed that such accreted terranes had been originally formed at a much lower latitude than their present positions, on the basis of paleomagnetic investigations of sedimentary and volcanic rocks distributed in the terranes (HATTORI and HIR00KA, 1979;TAIRA, 1981;HATTORI, 1982;HIROOKA et al, 1983;SHIBUYA et al, 1983;SHIBUYA and SASAJIMA, 1986).…”

Section: Introductionmentioning

confidence: 99%