Rights statement: This is the author’s version of a work that was accepted for publication in Palaeogeography, Palaeoclimatology, Palaeoecology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Palaeogeography, Palaeoclimatology, Palaeoecology, 567, 2021 DOI: 10.1016/j.palaeo.2021.110225
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - A geomagnetic polarity stratigraphy for the Middle and Upper Ordovician
AU - Hounslow, M.W.
AU - Harris, S.E.
AU - Wójcik, K.
AU - Nawrocki, J.
AU - Ratcliffe, K.T.
AU - Woodcock, N.H.
AU - Montgomery, P.
N1 - This is the author’s version of a work that was accepted for publication in Palaeogeography, Palaeoclimatology, Palaeoecology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Palaeogeography, Palaeoclimatology, Palaeoecology, 567, 2021 DOI: 10.1016/j.palaeo.2021.110225
PY - 2021/4/1
Y1 - 2021/4/1
N2 - Magnetostratigraphic studies of the Ordovician provide evidence for the nature of core-mantle boundary interactions, and provide means for dating and correlation across differing environmental regimes. We provide new magnetostratigraphic data from the Middle and Upper Ordovician, compiling this into a polarity chronostratigraphic scale for the Dapingian to Hirnantian interval. The new data are derived from the Backside Beck and Cheney Longville sections in Britain, the Mójcza section in Poland and two cores from Poland and Lithuania. The chronology is provided by existing biostratigraphy, principally based on chitinozoans and conodonts for the Ordovician. Correlations between sections are supported by carbon isotope stratigraphy linked to Baltic isotopic zonations, along with lithological and local magnetic susceptibility correlations in Polish cores. The palaeomagnetic signal is carried by both haematite and magnetite, with haematite dominating in red-coloured lithologies (marls and limestones) and magnetite in non-red mudstones and limestones. A positive reversal test (class C) in the Cheney Longville section and positive fold tests in the Backside Beck section provide validation of the isolation of a primary palaeomagnetic signal. Palaeomagnetic directions from cores were re-oriented using Kiaman-age and Brunhes overprints. These new datasets in combination with existing Middle Ordovician data provides a near-complete magnetic polarity chronostratigraphic scale through the Middle and Upper Ordovician. Brief normal-polarity magnetozones extend well into the later parts of what has been considered the Moyero Superchron, which started in the late Tremadocian. Reversal frequencies for the mid and late Ordovician are 1.7 and 1.5 Myr−1 respectively, although that for the late Ordovician may be an underestimate.
AB - Magnetostratigraphic studies of the Ordovician provide evidence for the nature of core-mantle boundary interactions, and provide means for dating and correlation across differing environmental regimes. We provide new magnetostratigraphic data from the Middle and Upper Ordovician, compiling this into a polarity chronostratigraphic scale for the Dapingian to Hirnantian interval. The new data are derived from the Backside Beck and Cheney Longville sections in Britain, the Mójcza section in Poland and two cores from Poland and Lithuania. The chronology is provided by existing biostratigraphy, principally based on chitinozoans and conodonts for the Ordovician. Correlations between sections are supported by carbon isotope stratigraphy linked to Baltic isotopic zonations, along with lithological and local magnetic susceptibility correlations in Polish cores. The palaeomagnetic signal is carried by both haematite and magnetite, with haematite dominating in red-coloured lithologies (marls and limestones) and magnetite in non-red mudstones and limestones. A positive reversal test (class C) in the Cheney Longville section and positive fold tests in the Backside Beck section provide validation of the isolation of a primary palaeomagnetic signal. Palaeomagnetic directions from cores were re-oriented using Kiaman-age and Brunhes overprints. These new datasets in combination with existing Middle Ordovician data provides a near-complete magnetic polarity chronostratigraphic scale through the Middle and Upper Ordovician. Brief normal-polarity magnetozones extend well into the later parts of what has been considered the Moyero Superchron, which started in the late Tremadocian. Reversal frequencies for the mid and late Ordovician are 1.7 and 1.5 Myr−1 respectively, although that for the late Ordovician may be an underestimate.
KW - Chronostratigraphy
KW - Magnetostratigraphy
KW - Moyero
KW - Palaeomagnetic
KW - Reversal frequency
KW - Superchron
U2 - 10.1016/j.palaeo.2021.110225
DO - 10.1016/j.palaeo.2021.110225
M3 - Journal article
VL - 567
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
SN - 0031-0182
M1 - 110225
ER -