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| Cretaceous Normal Superchron | |
|---|---|
| Name | Cretaceous Normal Superchron |
| Type | geomagnetic chron |
| Period | Cretaceous |
| Start | ~121 Ma |
| End | ~83 Ma |
| Duration | ~38 Ma |
| Primary method | palaeomagnetism |
Cretaceous Normal Superchron The Cretaceous Normal Superchron was an extended interval of predominantly normal geomagnetic polarity during the Cretaceous Period. It is recognized in marine magnetic anomaly charts, continental volcanic records, and reversal stratigraphy, and has been pivotal for studies in palaeomagnetism, plate tectonics, and Mesozoic geodynamics.
The interval is documented across datasets from the Ocean Drilling Program, Integrated Ocean Drilling Program, International Ocean Discovery Program, Deep Sea Drilling Project, and continental studies led by institutions such as the Smithsonian Institution and the United States Geological Survey. Key figures associated with its identification include Vine–Matthews–Morley hypothesis proponents and researchers from the Scripps Institution of Oceanography and Lamont–Doherty Earth Observatory. Correlations rely on magnetic anomaly profiles tied to stratigraphic markers like the Glen Rose Formation, North Atlantic Igneous Province, and sections studied by teams from the Geological Society of America and the European Geosciences Union.
Radiometric and biostratigraphic calibration has constrained the interval to roughly 121–83 million years ago, with age controls provided by labs at the USGS Geologic Division, Geological Survey of Canada, and universities including University of Cambridge and University of California, Berkeley. Key dating methods employed include argon–argon dating at facilities affiliated with Massachusetts Institute of Technology and uranium–lead geochronology from researchers at Stanford University and the University of Oxford. International committees such as the International Commission on Stratigraphy and the ICS have integrated these calibrations into global chronostratigraphic charts.
Magnetic anomaly maps produced using data from the Joint Oceanographic Institutions for Deep Earth Sampling and processed by groups at NOAA and NASA show long-wavelength, low-frequency reversal behavior. Paleomagnetic signatures from volcanic provinces like the Deccan Traps analogues, the Caribbean Large Igneous Province, and the Ontong Java Plateau exhibit stable normal inclinations and declinations recorded by laboratories at the Max Planck Institute for Chemistry and CNRS. Studies published in journals associated with the American Geophysical Union and the Royal Society describe reduced reversal rates, elevated paleointensity estimates from specimens curated at the Natural History Museum, London and methodological advances from the European Research Council.
Hypotheses implicate core–mantle interactions studied by researchers at the Princeton Plasma Physics Laboratory and the Goddard Space Flight Center, with mantle plume activity linked to events like the Ontong Java Plateau emplacement and hotspot tracks studied by teams at the University of Hawaii. Computational geodynamo models developed at Los Alamos National Laboratory, ETH Zurich, and Caltech explore influences from lower mantle heterogeneities recognized in seismic tomography produced by the Incorporated Research Institutions for Seismology and the Seismological Society of America. Proposed mechanisms include changes in convective vigour, inner core growth scenarios advanced at Columbia University, and flux expulsion processes discussed in conferences held by the American Geophysical Union.
Marine magnetic anomaly identification uses grids compiled by the International Hydrographic Organization and processed by teams at Woods Hole Oceanographic Institution, while continental lava flows and sedimentary magnetostratigraphy have been analyzed by researchers at Yale University and the University of Tokyo. Paleontological biostratigraphy from the International Paleontological Association and isotope stratigraphy efforts involving GEOTRACES and laboratories in the French National Centre for Scientific Research help anchor magnetic polarity records. Key field sections include exposures in the Western Interior Seaway region, South Atlantic margins studied by the British Geological Survey, and Arctic sequences sampled by the Norwegian Polar Institute.
The superchron coincides with major tectonic reorganizations such as the opening of the South Atlantic Ocean and seafloor spreading events documented by teams at Universidade de São Paulo and the University of Cape Town. Links to large igneous provinces, sea-level fluctuations tracked by the International Ocean Discovery Program, and evolutionary turnovers recorded by curators at the American Museum of Natural History and the Natural History Museum, London suggest complex interactions among mantle dynamics, ocean circulation studied at Scripps Institution of Oceanography, and climate proxies held by researchers at the Woods Hole Oceanographic Institution.
The extended polarity stability provided a low-reversal-rate framework used by plate reconstructions from groups at Paleomap Project contributors and software teams at GPlates for modelling Mesozoic plate motions with input from the US Antarctic Program. Paleoclimate reconstructions leveraging data synthesized by the Intergovernmental Panel on Climate Change and isotope labs at Lamont–Doherty Earth Observatory use the superchron interval to test links between geomagnetic field behaviour, cosmic ray flux models from European Space Agency datasets, and potential effects on cloud nucleation debated at the Royal Meteorological Society.
Category:Geomagnetism Category:Cretaceous