Geomagnetic paleointensity over 1.2 Ma from deep-tow vector magnetic data across the East Pacific Rise

Yamamoto, Michiko; Seama, Nobukazu; Isezaki, Nobuhiro

doi:10.1186/bf03351835

Cited by 10 publications

(5 citation statements)

References 38 publications

(52 reference statements)

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“…Deep-tow magnetic surveys started in the late 1970s with the development of the Deep Sea Drilling (DSDP) [Greenewalt and Taylor, 1978;Macdonald et al, 1979]. The technique was later extensively applied in surveying global mid-ocean ridges [Tivey, 1996;Perram et al, 1990;Hussenoeder et al, 1996;Pouliquen et al, 2001;Yamamoto et al, 2005]. In recent years, deep-tow magnetic data were further used in discerning hydrothermal vents and their activities [Gee et al, 2001;Tivey and Johnson, 2002;Zhu et al, 2010].…”

Section: Deep-tow Magnetic Surveysmentioning

confidence: 99%

Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349

Lin

et al. 2014

Geochem Geophys Geosyst

459

378

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Combined analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1-2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of 20 km occurred around 23.6 Ma in the East Subbasin; this timing also slightly varied along the ridge and was coeval to the onset of seafloor spreading in the Southwest Subbasin, which propagated for about 400 km southwestward from 23.6 to 21.5 Ma. The terminal age of seafloor spreading is 15 Ma in the East Subbasin and 16 Ma in the Southwest Subbasin. The full spreading rate in the East Subbasin varied largely from 20 to 80 km/Myr, but mostly decreased with time except for the period between 26.0 Ma and the ridge jump (23.6 Ma), within which the rate was the fastest at 70 km/ Myr on average. The spreading rates are not correlated, in most cases, to magnetic anomaly amplitudes that reflect basement magnetization contrasts. Shipboard magnetic measurements reveal at least one magnetic reversal in the top 100 m of basaltic layers, in addition to large vertical intensity variations. These complexities are caused by late-stage lava flows that are magnetized in a different polarity from the primary basaltic layer emplaced during the main phase of crustal accretion. Deep tow magnetic modeling also reveals this smearing in basement magnetizations by incorporating a contamination coefficient of 0.5, which partly alleviates the problem of assuming a magnetic blocking model of constant thickness and

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Section: Deep-tow Magnetic Surveysmentioning

confidence: 99%

Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349

Lin

et al. 2014

Geochem Geophys Geosyst

459

378

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“…Aeromagnetic vector profiles, where the sensor is typically mounted on a gyro-stabilized platform, have been used to estimate the spreading lineation direction and to map low-amplitude anomalies in the equatorial Pacific (Horner-Johnson and Gordon, 2003;Parker and O'Brien, 1997). Shipboard three axis magnetometers have also been used to determine the location and azimuth of magnetization contrasts in several areas (e.g., Korenaga, 1995;Seama et al, 1993;Yamamoto et al, 2005). Towed vector magnetometer systems can effectively eliminate the ship effect and resolve vector anomalies on the order of 30-50 nT (Figure 38; Gee and Cande, 2002).…”

Section: Future Directionsmentioning

confidence: 99%

Source of Oceanic Magnetic Anomalies and the Geomagnetic Polarity Timescale

Gee¹,

Kent²

2007

Treatise on Geophysics

121

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Marine magnetic anomalies (Vine, 1966; Vine and Matthews, 1963) provide a complete record of geomagnetic polarity reversals, making the agecalibrated geomagnetic polarity sequence the basis for global correlations and geochronology for the past 160 My (Figure 1). The relative widths of the magnetic polarity intervals for the Late Jurassic to Recent were determined from magnetic profiles initially by Heirtzler et al. (1968) for the Central Anomaly (Anomaly 1) to Anomaly 32 (C-sequence) and by Larson and Pitman (1972) for Anomalies M1-M22 (M-sequence). Larson and Pitman recognized that the M-sequence anomalies were bracketed by long intervals with apparently few or no reversals: the KQZ between the M-sequence and the ridge crest C-sequence of Heirtzler et al. (to which Larson Table 1 Geomagnetic polarity chrons from marine magnetic anomalies Age range (Ma) Normal polarity Chrons Age range (Ma) Reverse polarity chrons 0

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“…Several researchers have identified that tiny wiggles in marine magnetic anomaly profiles may reflect fluctuations in geomagnetic field strength (Bouligand et al., 2006; Bowers et al., 2001; Cande & Kent, 1992b; Gee et al., 1996; Pouliquen et al., 2001; Yamamoto et al., 2005). Magnetic anomaly records and marine sedimentary records show significant correlations, such as during the Brunhes chron, the past 5 Myr, or C5n.2n chron (Bowles et al., 2003; Gee et al., 2000; Li et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

Geomagnetic Field Paleointensity Spanning the Past 11 Myr From Marine Magnetic Anomalies in the Southern Hemisphere

Liu

2021

Geophysical Research Letters

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The geomagnetic field is derived from convection of its liquid outer core (Merrill & McFadden, 1995). The recognition of global geomagnetic field behavior, such as polarity reversals, allowed scientists to build Geomagnetic Polarity Time Scales (GPTS) with the most recent version published in 2020 (GPTS2020; Ogg, 2020). And global variations in geomagnetic field intensity can also provide additional dating markers (Singer, 2014). These are especially helpful when continuous paleointensity records can be correlated with sedimentary δ 18 O records, as this can establish a more robust chronology for climate change events (Richards & Andersen, 2013;Stoner et al., 2000).Sedimentary sequences can record continuous changes in relative paleointensity (RPI). However, recovering a long-time interval usually equates to a thick sedimentary column (e.g., 10 Myr corresponding to 200 m or more), which can be difficult (Valet et al., 2020). In fact, there are very few continuous sedimentary records that span the last 11 Myr. Yamazaki and Yamamoto (2018) reconstructed RPI records over the last 8 Myr from eastern equatorial Pacific Ocean sediments, which is the longest continuous sedimentary paleointensity record recovered to date. In addition, environmentally (biogenic or terrigenous) induced

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Geomagnetic paleointensity over 1.2 Ma from deep-tow vector magnetic data across the East Pacific Rise

Cited by 10 publications

References 38 publications

Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349

Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349

Source of Oceanic Magnetic Anomalies and the Geomagnetic Polarity Timescale

Geomagnetic Field Paleointensity Spanning the Past 11 Myr From Marine Magnetic Anomalies in the Southern Hemisphere

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