A New Middle to Late Jurassic Geomagnetic Polarity Time Scale (GPTS) From a Multiscale Marine Magnetic Anomaly Survey of the Pacific Jurassic Quiet Zone

Tominaga, Masako; Tivey, Maurice A.; Sager, William W.

doi:10.1029/2020jb021136

Cited by 7 publications

(2 citation statements)

References 143 publications

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“…Between ~150 Ma and ~110 Ma, Larson and Chase (1972) revealed that there are reversal periods sandwiched between periods of normal polarity (KQZ and the Jurassic Quiet Zone, JQZ). In fact, during the JQZ, geomagnetic reversals were frequent and the geomagnetic intensity was weak, as shown by MMA (e.g., Tominaga et al, 2021) and the absolute paleomagnetic intensity (paleointensity) of volcanic rocks (e.g., Tauxe et al, 2013). Larson and Pitman (1972) pointed out that the CNS corresponded in time to the KQZ of previous studies (e.g., Helsley and Steiner, 1968), designating C34n as the KQZ.…”

Section: Its Discoverymentioning

confidence: 80%

The Cretaceous Normal Superchron: A Mini-Review of Its Discovery, Short Reversal Events, Paleointensity, Paleosecular Variations, Paleoenvironment, Volcanism, and Mechanism

Yoshimura

2022

Front. Earth Sci.

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The Cretaceous Normal Superchron (CNS) was first defined in the 1960s to explain the Cretaceous Quiet Zone in marine magnetic anomaly profiles, which includes no or fewer geomagnetic reversals. This ∼37 million years period is considered the most unique and extreme geomagnetic feature for the last 160 Myr. Superchrons may be caused by the geodynamo operating at peak efficiency with a unique heat flux at the core-mantle boundary (CMB). Previous studies suggest that the CNS is a sign of the connection between Earth’s interior and surface. During the CNS, the geomagnetic intensity may have fluctuated significantly, and the average may have changed with time, and the paleosecular variations had unique features. The warm climate around the CNS may have been caused by volcanic activity associated with active mantle convection. Such mantle convection increases heat flux at the CMB during the CNS, but geodynamo simulations predict small heat flux, which are inconsistent. This discrepancy may be resolved by the growth and collapse of a superplume or by an increase and decrease in the subduction flux.

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Section: Its Discoverymentioning

confidence: 80%

The Cretaceous Normal Superchron: A Mini-Review of Its Discovery, Short Reversal Events, Paleointensity, Paleosecular Variations, Paleoenvironment, Volcanism, and Mechanism

Yoshimura

2022

Front. Earth Sci.

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“…Over timescales of ∼10 5 –10 8 years, the geomagnetic field's intensity appears to display an inverse relationship with its polarity reversal frequency (Driscoll & Olson, 2009; Glatzmaier et al., 1999; Hawkins et al., 2021; Tarduno & Cottrell, 2005; Tauxe, 2006; Tauxe & Hartl, 1997; Valet et al., 2005), which may represent a fundamental property of the geodynamo (Smirnov et al., 2017). Although low field intensities during frequent reversals have been widely recognized (e.g., Biggin et al., 2012; McElhinny & Larson, 2003; Tauxe et al., 2013; Tominaga et al., 2021), the geomagnetic field behaviors during long intervals of nearly no polarity reversals, that is, superchrons, remain poorly characterized and understood (e.g., Brandt et al., 2021; Cottrell et al., 2008; Zhang et al., 2021). In particular, it is not well known as to whether geomagnetic field strength stayed persistently strong/weak or exhibited some form of variations during a superchron.…”

Section: Introductionmentioning

confidence: 99%

Salient Changes of Earth's Magnetic Field Toward the End of Cretaceous Normal Superchron (CNS)

Liu,

Li,

Richter

2024

JGR Solid Earth

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Changes in Earth's magnetic field during the Cretaceous Normal Superchron (CNS) spanning ∼121 Ma to ∼84 Ma hold important clues about the geodynamo evolution. Canonical models predict a persistently strong geomagnetic field with low variability during CNS, which, however, has not been observed in the available absolute paleointensity data and seafloor marine magnetic anomaly (MMA) records. The lack of relative paleointensity (RPI) data across CNS further impedes tests of model predictions. Here, we present a ∼9‐Myr (∼94–∼85 Ma) RPI record from a Turonian to Santonian hemipelagic succession from IODP Site U1512 offshore southern Australia. Detailed paleomagnetic and rock magnetic analyses demonstrate that the ratio of natural remanent magnetization (NRM) demagnetized at 20 mT over magnetic susceptibility (MS), that is, NRM20mT/MS, as a reliable proxy for the RPI of the Upper Cretaceous succession. The new RPI record shows marked changes in both intensity and variability at ∼90.8 Ma. Also, the 6 Myr‐long (∼94–∼88 Ma), near‐continuous, ∼1.2 kyr‐resolution RPI record exhibits a strong positive correlation between field intensity and variability. Assuming this correlation holds for the entire CNS, an extrapolated RPI curve for the entire CNS is obtained by integrating the positive correlation with field variability estimates from the MMA data. The extrapolated RPI curve shows a strong and highly variable field in the middle CNS but a weak and stable field at its beginning and ending. These features imply a much more dynamic geodynamo than previously thought, and provide crucial benchmarks for unraveling the geodynamo evolution during CNS.

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Extraction of Marine Magnetic Anomalies Under Magmatic Disturbances Based on an Anisotropic Elliptical Directional Filter

Wang

Liu

2022

Pure Appl. Geophys.

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A New Middle to Late Jurassic Geomagnetic Polarity Time Scale (GPTS) From a Multiscale Marine Magnetic Anomaly Survey of the Pacific Jurassic Quiet Zone

Cited by 7 publications

References 143 publications

The Cretaceous Normal Superchron: A Mini-Review of Its Discovery, Short Reversal Events, Paleointensity, Paleosecular Variations, Paleoenvironment, Volcanism, and Mechanism

The Cretaceous Normal Superchron: A Mini-Review of Its Discovery, Short Reversal Events, Paleointensity, Paleosecular Variations, Paleoenvironment, Volcanism, and Mechanism

Salient Changes of Earth's Magnetic Field Toward the End of Cretaceous Normal Superchron (CNS)

Extraction of Marine Magnetic Anomalies Under Magmatic Disturbances Based on an Anisotropic Elliptical Directional Filter

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