About this Research Topic
Life on Earth was punctuated by several dramatic paleoenvironmental and paleoclimatic changes leading to mass extinction linked to continental flood basalts (CFBs) and large igneous provinces (LIPs), global oceanic anoxic events (OAE), rapid climate and sea level changes and meteorite impacts. On a global basis, linking the mass extinction to LIPs volcanism has remained problematic due to insufficient accuracy in radiometric dating. In the case of the Cretaceous-Tertiary (KT) mass extinction, identifying the very short geological interval between Deccan Traps and the Meteorite impact has remained problematic and calls for new approaches. Likewise precise age control between LIPs and mass extinctions for the Jurassic/Triassic, Permo/Triassic, Mid-Permian, and end-Devonian are in need of further age refinement. This Research Topic proposes to advance high resolution age control based on integration of existing data with new approaches based on geomagnetism.
Magnetic approaches have played important roles in calibrating ages of LIPs and mass extinctions based on the record of polarity of the ancient geomagnetic field registered in continental flood basalts and marine section (i.e. magnetostratigraphy). Cyclostratigraphic studies based on spectral analysis of long-term magnetic susceptibility records from marine sediments also improved the calibration of the geological times scale and the chronological relationship between continental flood basalts and mass extinctions.
More recently, new advances in environmental magnetism offer the opportunity to link the magnetic signature of continental and marine sediments to the paleoenvironmental settings that controlled their deposition and/or to the influence of post-depositional events like diagenesis. The characterization of biomagnetite (i.e. magnetosome formed by magnetotactic bacteria) by using first order reversal curves (FORC), unmixed isothermal remanent magnetization curves, transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) spectroscopy, for example, has opened new perspectives to better constrain paleoenvironmental and diagenetic effects in marine sediments. Indeed, magnetosomes thrive typically around the oxic-anoxic transition zone and are thus very sensitive to small changes in paleoenvironmental condition (pH, temperature and alkalinity). However, environmental magnetism applied to global mass extinction events is still in its early stage and needs to be applied and tested in different geological sections worldwide to provide new robust proxies to better constrain global-scale correlations.
The main objective of this Research Topic is to integrate these recent advances into a comprehensive state of the art on the magnetic records of global paleoenvironmental and paleoclimatic changes linked to extreme geological events. Since environmental magnetism is a multidisciplinary area, the scope of this research topic includes, but is not limited to: geomagnetism, paleomagnetism, rock magnetism as well as other geological, geochemical and geophysical approaches. Attempts to link experimental data with numerical modeling are welcome. Contributors are encouraged to submit reviews, perspectives and research articles.
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