Low-temperature viscous magnetization of multidomain magnetite: Evidence for disaccommodation contribution

Muxworthy, Adrian R.; Williams, Wyn

doi:10.1016/j.jmmm.2006.03.052

Cited by 10 publications

(7 citation statements)

References 31 publications

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“…Generally the samples displayed a logarithmic dependency (Figure 6) over the measurement time (∼10 min) in agreement with previous studies (Muxworthy and Williams, 2006b). The samples displayed a range of estimates for Figure 6 for sample H3.…”

Section: Viscosity Measurementssupporting

confidence: 90%

“…non-magnetic effects, which can alter the magnetisation, e.g., disaccommodation (Moskowitz, 1985;Muxworthy and Williams, 2006b), which can lead to VRM acquisition behavior that is not explained by Equation (4) (Lowrie and Kent, 1978;Tivey and Johnson, 1984); it will likely lead to an overestimate of t A . Such processes would be expected to have greater effects on older VRMs.…”

Section: Domain State Mineralogy and Viscous Acquisitionmentioning

confidence: 99%

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Testing the use of viscous remanent magnetisation to date flood events

2015

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Using erratics associated with large flood events, this paper assesses whether their viscous remanent magnetisation (VRM) can be used to date the flood events. We tested this method using flood erratics from three large events: (1) the Late Pleistocene Bonneville mega-flood in Idaho, USA, (∼14-18 ka), (2) the 1918 A.D. Mt. Katla, Iceland, eruption and associated jökulhaup (meltwater flood) at Mýrdalssandur, and (3) the Markarfljót jökulhaup due to an earlier eruption of Mt. Katla (∼2.5 ka). We measured 236 specimens, 66 of which yielded clear identifiable and measurable viscous magnetisation signals from erratics with clustered VRM directions. From the VRM unblocking temperatures, age estimates were made. The age estimate for the most recent event (Mýrdalssandur) worked well, with a median estimated age of 80 years (with individual erratic estimates distributed between 61-105 years) compared to the known age of 91 years. The ages of the other two events were over-estimated. The estimates for Markarfljót [15 ka (7-33 ka)] were based on the results of just one erratic. For the Bonneville flood the estimates were too old, however, this locality had the largest uncertainty in the ambient temperature used in the age determination; the VRM acquired is strongly dependent on the ambient temperature, the older the event the greater the uncertainty. Southern Idaho currently has hot summers, with average summer maximum temperatures of ∼31 • C, but a mean annual temperature of only ∼ 9 • C. It is suggested that the VRM dating method works best for recent events (<2-3 ka) where the ambient temperature history can be constrained.

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Section: Viscosity Measurementssupporting

confidence: 90%

Section: Domain State Mineralogy and Viscous Acquisitionmentioning

confidence: 99%

Testing the use of viscous remanent magnetisation to date flood events

2015

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“…The viscous magnetization of MD magnetite has been well investigated [e.g., Muxworthy and Williams , 2006a, 2006b; Williams and Muxworthy , 2006]. For the case of the BCY loess unit L1, the multiple mineral parameters have provided several lines of evidence for the coarse‐grained nature of the remanence carriers (e.g., large PSD or MD magnetite particles of detrital origin).…”

Section: Discussionmentioning

confidence: 99%

Paleomagnetic and mineral magnetic investigation of the Baicaoyuan loess‐paleosol sequence of the western Chinese Loess Plateau over the last glacial‐interglacial cycle and its geological implications

Deng

2008

Geochem Geophys Geosyst

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[1] Closely spaced paleomagnetic and mineral magnetic studies were conducted on the Baicaoyuan (BCY) loess-paleosol sequence since the last interglacial in the western Chinese Loess Plateau. The multiproxy records of mineral magnetic parameters clearly indicate loess-paleosol alternations with the fine structure of pedostratigraphy over the last glacial-interglacial cycle. However, the paleomagnetic results reveal the absence of any short-lived geomagnetic excursions in the BCY section. This absence could be interpreted by two alternative mechanisms, such as magnetic overprinting and discontinuous sedimentation. The absence of the Mono Lake and Laschamp excursions in the loess unit L1 is probably due to the viscous overprinting of the remanence carried by coarse-grained magnetite of eolian origin and/or to the episodic nature of loess accumulation during the last glacial period. However, discontinuous sediment accumulation may more probably lead to the absence of the Blake excursion in the last interglacial soil S1 as well as of the Mono Lake and Laschamp excursions in the last glacial loess L1 at the BCY section. Together with previously published paleomagnetic results from other sections over the Loess Plateau, the findings probably further indicate the discontinuous nature of loess accumulation in the western Loess Plateau, where sedimentation of the last interglacial soil may be episodic at the timescale equivalent to the duration of the Blake geomagnetic excursion (4-6 ka), much longer than the timescale for episodic loess sedimentation in the last glacial loess of both the western and eastern Loess Plateau due to the reduced sediment accumulation rate compared to that during the last glacial period. Thus, sediments with relatively high sedimentation rate in some parts of the western Loess Plateau do not consistently guarantee the faithful recording of high-frequency geomagnetic variations.

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“…Magnetite percentage was calculated considering a value of 660 Â 10 À6 m 3 kg À1 for pure multidomain magnetite [Maher, 1988]. The ARM/ IRM ratio is a common magnetic grain size proxy, which is proportional to the relative content of single domain (SD) particles e.g., for equidimensional magnetite, the (30-100 nm grain size range) and pseudo-single domain (PSD) magnetite (i.e., the 100 nm-1 mm size range) [Muxworthy and Williams, 2006].…”

Section: Environmental Magnetic Analysesmentioning

confidence: 99%

Formation of magnetite‐enriched zones in and offshore of a mesotidal estuarine lagoon: An environmental magnetic study of Tauranga Harbour and Bay of Plenty, New Zealand

Badesab

Dobeneck

Bryan

et al. 2012

Geochem Geophys Geosyst

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[1] Magnetic iron minerals are widespread and indicative sediment constituents in estuarine, coastal and shelf systems. We combine environmental magnetic, sedimentological and numerical methods to identify magnetite-enriched placer-like zones in a complex coastal system and delineate their formation mechanisms. Magnetic susceptibility and remanence measurements on 245 surficial sediment samples collected in and around Tauranga Harbour, the largest barrier-enclosed tidal estuary of New Zealand, reveal several discrete enrichment zones controlled by local hydrodynamic conditions. Active magnetite enrichment takes place in tidal channels, which feed into two coast-parallel nearshore magnetite-enriched belts centered at water depths of 6-10 m and 10-20 m. A close correlation between magnetite content and magnetic grain size was found, where higher susceptibility values are associated within coarser magnetic crystal sizes. Two key mechanisms for magnetite enrichment are identified. First, tide-induced residual currents primarily enable magnetite enrichment within the estuarine channel network. A coast-parallel, fine sand magnetite enrichment belt in water depths of less than 10 m along the barrier island has a strong decrease in magnetite ©2012. American Geophysical Union. All Rights Reserved.1 of 20 content away from the southern tidal inlet and is apparently related to active coast-parallel transport combined with mobilizing surf zone processes. A second, less pronounced, but more uniform magnetite enrichment belt at 10-20 m water depth is composed of non-mobile, medium-coarse-grained relict sands, which have been reworked during post-glacial sea level transgression. We demonstrate the potential of magnetic methods to reveal and differentiate coastal magnetite enrichment patterns and investigate their formative mechanisms.

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Low-temperature viscous magnetization of multidomain magnetite: Evidence for disaccommodation contribution

Cited by 10 publications

References 31 publications

Testing the use of viscous remanent magnetisation to date flood events

Testing the use of viscous remanent magnetisation to date flood events

Paleomagnetic and mineral magnetic investigation of the Baicaoyuan loess‐paleosol sequence of the western Chinese Loess Plateau over the last glacial‐interglacial cycle and its geological implications

Formation of magnetite‐enriched zones in and offshore of a mesotidal estuarine lagoon: An environmental magnetic study of Tauranga Harbour and Bay of Plenty, New Zealand

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