A new mechanism for stable viscous remanent magnetization and overprinting during long magnetic polarity intervals

Moon, Tom; Merrill, Ronald T.

doi:10.1029/gl013i008p00737

Cited by 43 publications

(23 citation statements)

References 12 publications

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“…Studies of secondary fluid inclusions and burial histories from apatite and zircon fission‐track cooling ages should be helpful. Additional studies of TVRM acquisition during long polarity intervals [e.g., Moon and Merrill, 1986] might also be productive.…”

Section: Discussionmentioning

confidence: 99%

The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

Elmore

McCabe

1991

Reviews of Geophysics

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Section: Discussionmentioning

confidence: 99%

The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

Elmore

McCabe

1991

Reviews of Geophysics

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“…During the last few years there has, unfortunately, been little improvement in the available data from the stable cratonic areas of the major Gondwanan continents, with the notable exception of Australia, for which there has been both re-sampling and re-analysis (Embleton 1981;Idnurm 1985aIdnurm ,b 1986. In fact, most advances have resulted in an increasing appreciation of the complexities of the magnetic processes, even when only time is involved (Moon and Merrill 1986). This has resulted in the elimination, or at least questioning, of the reliability of most previously accepted observations.…”

Section: Continental Palaeomagnetismmentioning

confidence: 99%

Gondwanaland and the evolution of the Indian Ocean

Tarling¹

1988

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In regions, such as the Indian Ocean, where geophysical data are largely lacking, reconstructions must be a compromise, allowing for the evolution of 'passive' margins and the inclusion of remanent continental blocks that are now isolated within the oceanic basins. Sea-floor spreading anomalies are re-examined in the context of the foregoing considerations, and emphasis is placed on the need to match anomalies that formed within the same transform segments. Despite subsequent attempts, it is considered that Norton and Sclater's (1979) configuration of Gondwanaland and its Mesozoic-Tertiary breakup only need small, but significant modifications. These allow for the inclusion of small, but critically located continental units between the major continental blocks. Only age differences are proposed for most of their anomaly 16 reconstruction, now largely corresponding to anomaly 20 times. No changes are proposed to Norton and Sclater's reconstruction for anomaly 34 times. Alterations to older reconstructions are mainly to allow for the inclusion of the Kerguelen, Gaussberg and Broken Ridges between India and Antarctica, and for the Agulhas-Falkland (Malvinas) Plateaux between Africa and Antarctica. The revised Gondwanaland reconstruction for early-middle Jurassic times appears to be more consistent with the geological and geophysical evidence, particularly reducing the need for differential motions of Sri Lanka and of the West Antarctic Peninsula. A review of the palaeomagnetic data indicates caution in the ability of extant data to distinguish between most reconstructions proposed during the last decade; considerable re-sampling and re-evaluation are required to adequately test between such Gondwanan models.

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“…As all other evidence indicates that the sequence is older than the Brunhes, we must conclude that the overprint signal has a high coercivity. Moon and Merrill (1986) showed that high coercivity VRM can occur, and there always remains the possibility that the high coercivity overprint is partly of post-depositional chemical origin. Below the estimated position of the B/M boundary, the records at both Sites 821 and 820 are too poor to merit any sort of polarity interpretation.…”

Section: Polarity At Sites 821 and 820mentioning

confidence: 99%

Magnetic Stratigraphy and Characterization of Sediments from the Northeast Margin of Australia and Their Relationship to Environmental Change during the Quaternary

Barton¹,

Omarzai²,

Alexer³

et al. 1993

Proceedings of the Ocean Drilling Program

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This study is a synthesis of paleomagnetic and mineral magnetic results for Sites 819 through 823 of Ocean Drilling Program (ODP) Leg 133, which lie on a transect from the outer edge of the Great Barrier Reef (GBR) down the continental slope to the bottom of the Queensland Trough. Because of viscous remagnetization and pervasive overprinting, few reversal boundaries can be identified in these extremely high-resolution Quaternary sequences. Some of the magnetic instability, and the differences in the quality of the paleomagnetic signal among sites, can be explained in terms of the dissolution of primary iron oxides in the high near-surface geochemical gradients.Well-defined changes in magnetic properties, notably susceptibility, reflect responses to glacio-eustatic sea-level fluctuations and changes in slope sedimentation processes resulting from formation of the GBR. Susceptibility can be used to correlate between adjacent holes at a given site to an accuracy of about 20 cm. Among-site correlation of susceptibility is also possible for certain parts of the sequences and permits (tentative) extension of the reversal chronology. The reversal boundaries that can be identified are generally compatible with the calcareous nannofossil biostratigraphy and demonstrate a high level of biostratigraphic consistency among sites. A revised chronology based on an optimum match with the susceptibility stratigraphy is presented.Throughout most of the sequences there is a strong inverse correlation both between magnetic susceptibility and calcium carbonate content, and between susceptibility and δ 18 O. In the upper, post-GBR, sections a more complicated type of magnetic response occurs during glacial maxima and subsequent transgressions, resulting in a positive correlation between susceptibility and 6 O.Prior to and during formation of the outer-reef barrier, the sediments have relatively uniform magnetic properties showing multidomain behavior and displaying cyclic variations in susceptibility related to sea-level change. The susceptibility oscillations are controlled more by carbonate dilution than by variation in terrigenous influx. Establishment of the outer reef between 1.01 and 0.76 Ma restricted the supply of sediment to the slope, causing a four-fold reduction in sedimentation rates and a transition from prograding to aggrading seismic geometries (see other chapters in this volume). The Brunhes/Matuyama boundary and the end of the transition period mark a change to lower and more subdued susceptibility oscillations with higher carbonate contents. The major change in magnetic properties comes at about 0.4 Ma in the aggrading sequence, which contains prominent sharp susceptibility peaks associated with glacial cycles, with distinctive single-domain magnetite and mixed single-domain/superparamagnetic characteristics. Bacterial magnetite has been found in the sediments, particularly where there are high susceptibility peaks, but its importance has not yet been assessed. A possible explanation for the characteristic ...

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A new mechanism for stable viscous remanent magnetization and overprinting during long magnetic polarity intervals

Abstract: A neW.. mechanism by which viscous remanent magnetization, VRM, can be acquired is Proposed. This VRM probably is the major cause of overprinting during long magnetic polarity intervals.

Cited by 43 publications

References 12 publications

The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

Gondwanaland and the evolution of the Indian Ocean

Magnetic Stratigraphy and Characterization of Sediments from the Northeast Margin of Australia and Their Relationship to Environmental Change during the Quaternary

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