Late Ediacaran magnetostratigraphy of Baltica: Evidence for Magnetic Field Hyperactivity?

Bazhenov, Mikhail L.; Levashova, Natalia M.; Meert, Joseph G.; Голованова, И. В.; Данукалов, К. Н.; Fedorova, Natalia M.

doi:10.1016/j.epsl.2015.12.015

Cited by 52 publications

(38 citation statements)

References 56 publications

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“…Among the alternative explanations for the apparent rapid polar wander, recent attention has focused on the nature of the Earth's magnetic field during the Ediacaran to Middle Cambrian. Evidence for frequent reversals of the magnetic field during this interval come from studies in Siberia (Pavlov and Gallet, 2000;Gallet et al, 2003;Shatsillo et al, 2015), Baltica (Levashova et al, 2013;Meert, 2014;Bazhenov et al, 2016) and China (Yin, 2002).…”

Section: Magnetic Field Behaviour In the Ediacaran-cambrianmentioning

confidence: 99%

Rapid changes of magnetic Field polarity in the late Ediacaran: Linking the Cambrian evolutionary radiation and increased UV-B radiation

Meert¹,

Levashova

Bazhenov

et al. 2016

Gondwana Research

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Novelty in the biological world is the culmination of genetic changes often triggered by the physical environment. The most radical phase of biological evolution took place during the Cambrian Evolutionary Radiation (CER). Prior to the CER, bacterial matgrounds and associated communities of Ediacaran organisms dominated the shallow seafloor. Near the end of the Ediacaran Period, ~550 million years ago, many soft-bodied biota went extinct. In the Early Cambrian, animals with the ability to burrow vertically altered the ecology of the seafloor and biomineralization became commonplace. Here we link the terminal Ediacaran extinction, the Cambrian substrate revolution and the diversification of biomineralizing organisms to changes associated with the reversal frequency of the Earth's magnetic field. Beginning around 550 Ma and continuing through much of the Cambrian, the Earth's magnetic field was rapidly reversing. Models, and limited paleointensity studies, indicate that rapid reversals are a feature of an overall weaker dipole. A weakened dipole reduces the dimensions of the magnetosphere that provides a barrier to incoming cosmic radiation. Here we show that the environmental effects of that collapse include increased dosing of UVB radiation into the shallow marine environment. Increased UVB radiation in the shallow marine environment provided selective pressure favoring organisms that could detect and avoid UVB damage by burrowing vertically, moving up or down in the water column, growing protective shells and other 'flight from light' mechanisms. These changes took place in advance of the CER, but effectively cleared the ecological space for the subsequent changes in the later Cambrian. IntroductionBiological innovation on the Earth is interconnected with changes in atmospheric composition, hydrospheric modification, eustatic sea level changes, plate tectonic activity, climate change, and other events (e.g., asteroid or comet impacts) that lead to changes in biotic diversity, ecologic interactions, and ultimately to community evolution (Boucot, 1990;Knoll, 2011;Meert and Lieberman, 2008). Arguably, one of the most important periods of biological innovation took place over a relatively short time interval commonly known as the

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Section: Magnetic Field Behaviour In the Ediacaran-cambrianmentioning

confidence: 99%

Rapid changes of magnetic Field polarity in the late Ediacaran: Linking the Cambrian evolutionary radiation and increased UV-B radiation

Meert¹,

Levashova

Bazhenov

et al. 2016

Gondwana Research

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“…today, (ii) true polar wander (TPW) events where the entire lithosphere rotates to accommodate a change in global moment of inertia, or (iii) the absence of a stable GAD field, including the possibility of an equatorial dipole or "hyper" frequent polarity reversals [Abrajevitch and Van der Voo, 2010;Halls et al, 2015;Bazhenov et al, 2016].…”

Section: 1002/2016gl068858mentioning

confidence: 99%

“…Despite these advances, however, several important discrepancies in Neoproterozoic paleogeography persist, including the history of Rodinia [Evans, 2013;Li et al, 2013] and a growing number of anomalous poles in the Ediacaran [Kirschvink et al, 1997;Abrajevitch and Van der Voo, 2010;Halls et al, 2015;Bono and Tarduno, 2015;Klein et al, 2015;Bazhenov et al, 2016] and Cryogenian [Maloof et al, 2006;Swanson-Hysell et al, 2012]. Anomalous APWPs have been interpreted as either (i) rapid plate motions much faster than any occurring…”

Section: Introductionmentioning

confidence: 99%

Simulating 2 Ga of geodynamo history

Driscoll

2016

Geophysical Research Letters

111

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The paleomagnetic record indicates the geodynamo has been active over much of Earth history with surprisingly little trend in paleointensity. Variability, however, is expected from models that predict a sharp increase in intensity following inner core nucleation (ICN) and implied by Neoproterozoic anomalies that hint at a highly variable field over several hundred million years. Here we demonstrate with a suite of numerical dynamos driven by a new thermal evolution model that the geodynamo could have transitioned from a multipolar to dipolar regime around 1.7 Ga, then to a weak‐field dynamo around 1.0 Ga, and finally to a strong‐field dipole following ICN around 650 Ma that is maintained to the present day. The occurrence of a weak‐field geodynamo in the Neoproterozoic may be consistent with the observed anomalous apparent polar wander paths and reversal behavior. Recovery to a dipolar geodynamo in the Phanerozoic could be a signature of inner core nucleation. Index terms: 1507, 1560, and 1521.

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“…The explosion of life in the Early Cambrian period at ~530 Ma has been associated with growth of Earth's inner core, the supposed strengthening of the dipole geomagnetic field, and the resulting thickening of Earth's atmosphere (Doglioni et al, ), although there is little evidence for strengthening of the geomagnetic field at this time (e.g., Biggin et al, ). On the other hand, the Late Ediacaran and Early Cambrian periods (~550 and ~530 Ma, respectively) may have been times of unusually high polarity reversal frequency (Bazhenov et al, ; Pavlov & Gallet, ), although precise estimates of reversal frequency are elusive due to poorly constrained age control in stratigraphic sections where the reversals were recorded. Meert et al () proposed that high reversal frequency (up to ~20 reversals/Myr) at this time would have been associated with low geomagnetic field intensity that therefore lowered shielding from UVR, which created an evolutionary advantage for burrowing and shelled organisms.…”

Section: Introductionmentioning

confidence: 99%

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

Channell

Vigliotti

2019

Reviews of Geophysics

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It has long been speculated that biological evolution was influenced by ultraviolet radiation (UVR) reaching the Earth's surface, despite imprecise knowledge of the timing of both UVR flux and evolutionary events. The past strength of Earth's dipole field provides a proxy for UVR flux because of its role in maintaining stratospheric ozone. The timing of Quaternary evolutionary events has become better constrained by fossil finds, improved radiometric dating, use of dung fungi as proxies for herbivore populations, and improved ages for nodes in human phylogeny from human mitochondrial DNA and Y chromosomes. The demise of Neanderthals at ~41 ka can now be closely tied to the intensity minimum associated with the Laschamp magnetic excursion, and the survival of anatomically modern humans can be attributed to differences in the aryl hydrocarbon receptor that has a key role in the evolutionary response to UVR flux. Fossil occurrences and dung‐fungal proxies in Australia indicate that episodes of Late Quaternary extinction of mammalian megafauna occurred close to the Laschamp and Blake magnetic excursions. Fossil and dung fungal evidence for the age of the Late Quaternary extinction in North America (and Europe) coincide with a prominent decline in geomagnetic field intensity at ~13 ka. Over the last ~200 kyr, phylogeny based on mitochondrial DNA and Y chromosomes in modern humans yields nodes and bifurcations in evolution corresponding to geomagnetic intensity minima, which supports the proposition that UVR reaching Earth's surface influenced mammalian evolution with the loci of extinction controlled by the geometry of stratospheric ozone depletion.

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Late Ediacaran magnetostratigraphy of Baltica: Evidence for Magnetic Field Hyperactivity?

Cited by 52 publications

References 56 publications

Rapid changes of magnetic Field polarity in the late Ediacaran: Linking the Cambrian evolutionary radiation and increased UV-B radiation

Rapid changes of magnetic Field polarity in the late Ediacaran: Linking the Cambrian evolutionary radiation and increased UV-B radiation

Simulating 2 Ga of geodynamo history

The Role of Geomagnetic Field Intensity in Late Quaternary Evolution of Humans and Large Mammals

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