Magnetostratigraphy of Leg 108 Advanced Hydraulic Piston Cores

Tauxe, Lisa; Valet, Jean‐Pierre; Bloemendal, Jan

doi:10.2973/odp.proc.sr.108.154.1989

Cited by 19 publications

(21 citation statements)

References 5 publications

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“…Inclinations after demagnetization are widely scattered, but they remained biased toward negative directions. Similar steeply inclined overprints affecting DSDP and ODP cores have been reported by Barton and Bloemendal (1986), Bleil (1989), Tauxe et al (1989), and Hounslow et al (1990). Hall and Sager (1990) interpreted a similar overprint affecting Leg 116 sediments as a drilling-induced remanence related to the core barrel, which they found to be intensely magnetized.…”

Section: Pass-through Cryogenic Magnetometersupporting

confidence: 56%

Magnetic Diagenesis, Organic Input, Interstitial Water Chemistry, and Paleomagnetic Record of the Carbonate Sequence on the Ontong Java Plateau

Musgrave¹,

Delaney²,

Stax³

et al. 1993

Proceedings of the Ocean Drilling Program

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Shipboard paleomagnetic studies on Ocean Drilling Program Leg 130 were plagued by a severe reduction in the remanence intensity, which affected sediments below a sharply defined onset at sub-bottom depths of 50 mbsf or less. This loss of intensity was accompanied by a reduction in magnetic stability and consequent loss of polarity and paleolatitude information. Viscous remanent magnetization and drilling-induced remanences contributed high-coercivity overprints, further obscuring the greatly diminished primary magnetization. The depth at which the reduction in intensity occurred correlates with the organic carbon content of the sediments, and a further relationship is present between intensity downhole and the level of sulfate reduction. This implies that loss of intensity is related to the microbial reduction of magnetite. Reduction of sulfate results in the generation of a magnetic iron sulfide, which appears to be the carrier of the high-coercivity overprints. Oxidation and drying of the sediment after sampling leads to partial destruction of this sulfide, and complete decomposition occurs at temperatures below 300°C. These features identify the magnetic sulfide as the metastable phase, greigite. Varying inputs of organic material in past times, presumably reflecting both latitude and climatic changes, resulted in varying degrees of reduction, which are now reflected in differences in magnetic intensity, degree of overprinting, and survival of primary magnetization. The highest reduction levels result in the almost total dissolution of magnetite, and the weak surviving remanence is dominated by greigite. At lower reduction states, multidomain magnetite persists together with greigite. Still-less-reducing conditions in turn cause the survival of fine-grained, single-domain magnetite, and then of hematite.An earlier paleomagnetic study of Ontong Java Plateau sediments from Deep Sea Drilling Project Leg 30 produced a paleolatitude curve that differed significantly from other records of Pacific paleolatitude. It is likely that the samples in this earlier study also carried high-coercivity overprints, which biased the results. Those samples from Leg 130 that appear to preserve a primary magnetization yielded paleolatitudes consistent with expected Pacific Plate motion.

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Section: Pass-through Cryogenic Magnetometersupporting

confidence: 56%

Magnetic Diagenesis, Organic Input, Interstitial Water Chemistry, and Paleomagnetic Record of the Carbonate Sequence on the Ontong Java Plateau

Musgrave¹,

Delaney²,

Stax³

et al. 1993

Proceedings of the Ocean Drilling Program

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“…Comparison of discrete sample measurements with the longcore measurements revealed that the coring-induced moment was strongest in the outer parts of the core (Bleil, 1989). Similar results were reported by Tauxe et al (1989) and Hall and Sager (1990). The latter authors indicated that the presence of overprints with positive and negative inclinations implied that the coring-induced moments were probably caused by the remanence of the core barrels.…”

Section: Review Of Previous Worksupporting

confidence: 73%

Coring-induced magnetization of recovered sediment

Fuller¹,

Hastedt²,

Herr³

1998

Proceedings of the Ocean Drilling Program, 157 Scientific Results

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Shipboard measurements of archived advanced piston corer (APC) cores during Leg 157 revealed a preponderance of radially inward-directed magnetization. The nature of the radial magnetization was investigated with tests on a wash core. The coring-induced magnetization has higher coercivity than a simple isothermal remanent magnetization (IRM). Well-lithified samples do not have this coring-induced, high-coercivity contamination. The coring-induced moment, therefore, appears to be related to the coring or recovery process in relatively poorly lithified sediments.The magnetic fields of bottom-hole assemblies (BHAs), APC barrels, and APC cutting shoes were measured as possible source fields for the drill moments. Fields of tens of mT were found in the core barrels, with fields only 1 order of magnitude smaller at the cutting edge of the shoes. The fields associated with the BHAs were weaker and fell off rapidly on the scale length of the drill bit. The coring-induced magnetization appears to be caused by the mechanical disturbance of sediments during coring, pull-out, or passage up the drill string in the presence of the field of the APC barrel.

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“…The Reunion Subchron, at about 2 Ma (just older than the Olduvai Subchron), was originally recognized in oceanic magnetic profiles (as a very small but persistent anomaly called "X" by Heirtzler et al, 1968) and from basalt lava flows on Reunion Island (McDougall and Watkins, 1973). Magnetostratigraphic studies from oceanic sediments recovered from DSDP-ODP drilling often show some evidence for the Reunion interval (e.g., Tauxe et al, 1989), but no detailed magnetostratigraphic record of this subchron is presently available. In contrast, Clement and Kent (1987) provided a detailed record, from sediments cored in the North Atlantic (Site 609, Leg 94), of two other magnetic features of normal polarity between the Olduvai and Jaramillo subchrons.…”

Section: Introductionmentioning

confidence: 99%

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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Magnetostratigraphy of Leg 108 Advanced Hydraulic Piston Cores

Cited by 19 publications

References 5 publications

Magnetic Diagenesis, Organic Input, Interstitial Water Chemistry, and Paleomagnetic Record of the Carbonate Sequence on the Ontong Java Plateau

Magnetic Diagenesis, Organic Input, Interstitial Water Chemistry, and Paleomagnetic Record of the Carbonate Sequence on the Ontong Java Plateau

Coring-induced magnetization of recovered sediment

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

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