High-Resolution, Whole-Core Magnetic Susceptibility Data from Leg 130, Ontong Java Plateau .

Tarduno, J. A.; Mayer, Larry A.; Musgrave, R. J.

doi:10.2973/odp.proc.ir.130.111.1991

Cited by 10 publications

(10 citation statements)

References 21 publications

(23 reference statements)

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“…We did not take continuous measurements on cores below Section 130-803A-4H-4 because the magnetic remanence of these sediments became abruptly very weak, below the noise level of the magnetometer. As previously mentioned, this decay in magnetization is attributed to a postdepositional dissolution of magnetite by reduction diagenesis (Tarduno et al, 1991a;Karlin andLevi, 1983, 1985;Canfield and Berner, 1987).…”

Section: Hole 803amentioning

confidence: 53%

“…For the three records, no direct correlation was observed between the susceptibility and the magnetic intensity of the samples. The magnetic susceptibility records show fluctuations that Tarduno et al (1991a) suggested are related to terrestrial influx and probably also to carbonate dilution. As observed with the continuous measurements on U-channels, the directional changes are closely related to a decrease in magnetic intensity.…”

Section: Measurements On U-channels and Discrete Samplesmentioning

confidence: 80%

“…However, the intensity of magnetization abruptly dropped below the noise level of the shipboard magnetometer at a common sub-bottom depth in all holes drilled at a given site. The "critical depth" varied with water depth and latitude (e.g., distance from the zone of equatorial upwelling) and was postulated to mark postdepositional dissolution of magnetite (Tarduno et al, 1991a; see also Karlin andLevi, 1983, 1985;Canfield and Berner, 1987). From sub-bottom depths less than the "critical depth," the paleomagnetic records appear unaffected.…”

Section: Introductionmentioning

confidence: 99%

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Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Gallet¹,

Gee²,

Tauxe³

et al. 1993

Proceedings of the Ocean Drilling Program

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We document three short normal intervals in the natural remanent magnetization of sediments within the Matuyama Chron. These three anomalous zones of magnetization between the Jaramillo and Olduvai subchrons were identified from continuous measurements of archive halves from Hole 803 A using the pass-through 2G cryogenic magnetometer at Scripps. The U-channel samples were taken from the three intervals, analyzed using the pass-through system, and then cut into discrete 1 -cm-thick samples. Measurements on discrete samples confirmed the presence of the upper normal polarity zone. Based on sedimentation rate calculations, this zone is confidently correlated with the Cobb Mountain Subchron. For the two other anomalous zones, complete thermal demagnetization revealed a high-stability component (250°-575°C) of reversed polarity. The intensity of the low-stability normal polarity component, normalized by susceptibility, remains roughly constant throughout the entire interval sampled, whereas the intensity of the high-stability reversed component is much lower within the normal zone than outside. We interpret these two normal zones, then, as periods of low (reversed polarity) geomagnetic field intensity resulting in low magnetization of the sediments; the periods of these low magnetization reversed polarity zones are completely masked by the component acquired viscously in a normal polarity field.

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Section: Hole 803amentioning

confidence: 53%

Section: Measurements On U-channels and Discrete Samplesmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Gallet¹,

Gee²,

Tauxe³

et al. 1993

Proceedings of the Ocean Drilling Program

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“…The period of this variation is too long (50 m represents roughly 0.2 m.y. over this stratigraphic interval) to result from Milankovitch forcing, which has been shown to control susceptibility variation in other studies (e.g., Tarduno et al, 1991). Glacial-interglacial variations in sediment grain size or provenance during the Pliocene are the likely cause.…”

Section: Remanence and Susceptibility (Continuous Sections)mentioning

confidence: 56%

Site 859

1992

Proceedings of the Ocean Drilling Program, 141 Initial Reports

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“…In the report for Site 865, we suggested that rust contamination (Sager, 1986(Sager, , 1988Tarduno et al, 1991) could be a possible cause of the abnormally high intensities observed in the upper sections of the cores. At this site, we observed large (>l mm) rust flakes between the sediment and the core liner in the top sections of highly magnetic cores.…”

Section: Paleomagnetism Apc Coresmentioning

confidence: 89%

Site 869

1993

Proceedings of the Ocean Drilling Program

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, et al., 1993. Proc. ODP, Init. Repts., 143: College Station, TX (Ocean Drilling Program)." Shipboard Scientific Party is as given in list of participants preceding the contents.Principal results: Site 869 (proposed Site Syl-3) is situated 45 nmi (83 km) southwest of the atoll-guyot pair, Pikinni Atoll (formerly Bikini) and Wodejebato Guyot (formerly Sylvania). Drilling at this location was planned to provide a basinal reference section for comparison to Leg 144 drill holes on the summit of Wodejebato and prior drilling on Pikinni. Site-survey data suggested that a thick, layered succession of sediments exists at the site that consists mainly of turbidites. Volcanic basement is not obvious in the site-survey seismic lines, so drilling was not expected to encounter basement basalt. Approximately 850 m of penetration was planned, and the expectation was to bottom in Cretaceous volcaniclastics produced by constructional volcanism on either or both Wodejebato and Pikinni. The location of Site 869, at 1 l°00.09'N, 164°45.02'E, was chosen on the seafloor adjacent to both Pikinni and Wodejebato, close enough to receive sediments shed mainly by these edifices, but far enough away so that both would contribute. It was assumed that sedimentation at an adjacent basinal hole would parallel and complement that on the atollguyot pair. For example, erosional hiatuses on the summit might be expected to produce sediments on the archipelagic apron, thus filling "missing chapters" in the geologic history provided by summit holes. Drilling at Site 869 was undertaken to address the following primary goals:1. Determining the history of volcanism on Pikinni/Wodejebato; 2. Developing a model of Cretaceous, mid-ocean guyot/atoll carbonate platform formation and evolution for the Marshall Islands; 3. Comparison of the timing and effects of fluctuations in relative sea level among Pacific guyots and relation to worldwide sea-level curves; and 4. Deciphering the cause(s) for the drowning(s) of some Marshall Islands guyots (such as Wodejebato) vs. the existence of Cenozoic reefs on nearby atolls (such as Pikinni).Two holes were drilled at Site 869, an APC/XCB hole (Hole 869A), and an RCB hole (Hole 869B), the latter located about 93 m north of the former. The operational plan was to use the APC/XCB combination to obtain relatively undisturbed cores from the upper 300 to 400 m of the sedimentary column. In analogy to Site 462, hard chert layers were expected to frustrate drilling at about 300 to 400 mbsf, and a round-trip was planned to change to an RCB bit and begin a second hole. Chert and porcellanite were encountered at much shallower depths than expected, and Hole 869A was terminated at a depth of only 166.5 mbsf. Hole 869B was washed to 140.0 mbsf and cored continuously to a total depth of 796.2 mbsf.Core recovery in Hole 869A, drilled with the APC/XCB combination, was mostly excellent, with the average being over 100% for the APC cores and 77.6% overall. In Hole 869B, recovery was variable (see "Operations" section, this chapter). ...

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High-Resolution, Whole-Core Magnetic Susceptibility Data from Leg 130, Ontong Java Plateau .

Cited by 10 publications

References 21 publications

Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Site 859

Site 869

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