HR: 1340h
AN: T13A-1130    [Abstracts]
TI: Calibration of Pre-M25 Marine Magnetic Anomalies: Magnetic Polarity Composite of ýLate Callovian Through Kimmeridgian
AU: * Przybylski, P A
EM: paprzyby@purdue.edu
AF: Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47906, United States
AU: Ogg, J G
EM: jogg@purdue.edu
AF: Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47906, United States
AB: Ammonite-zoned successions have yielded a composite magnetic polarity pattern ýspanning latest Callovian (lamberti ammonite Zone) through Late Kimmeridgian ýý(acanthicum Zone) that confirms marine magnetic anomalies M37 through to M24 ýinterpreted by deep-tow and other magnetic surveys in the western Pacific. This pattern ýwas constructed after thermal demagnetization of over 1000 samples from over 30 ýsections in Poland, British Isles, France and Spain. Polish sections include thick ýammonite-zoned limestone formations of the Krakow-Czestochowa-Wielun Upland and ýHoly-Cross Mountains. British limestone and clay formations were investigated in ýEngland (Dorset and Yorkshire) and in Scotland (the Isle of Skye). The sections include ýcandidates for the global stratotypes for the Callovian–Oxfordian and Oxfordian–ýKimmeridgian stage boundaries. All British and most of the Polish-French-Spanish ýsections are calibrated to ammonite biostratigraphy at the subzone level (Boreal-ýSubboreal realm and Sub-Mediterranean realm, respectively) and to regional sequence ýstratigraphy. The independent Boreal-Subboreal and Sub-Mediterranean composites of ýmagnetic polarity are consistent, and the main features of the modeled pre-M25 marine ýmagnetics can be calibrated. ý The Callovian–Oxfordian boundary (base of Quenstedtoceras mariae Zone) occurs in a ýnarrow normal-polarity subzone correlated to polarity subchron M36a of the western ýPacific magnetic polarity pattern. The beginning of the Middle and the Late Oxfordian ýsubstages as defined in the Sub-Mediterranean province in Poland correspond ýapproximately to M33 and M29 of the Pacific M-sequence. The placement of the ýOxfordian- Kimmeridgian boundary in the Sub-Boreal ammonite zonation (base of ýPictonia baylei Zone) is at the beginning of the M27r polarity zone. This is significantly ýolder than the traditional placement of the Oxfordian–Kimmeridgian boundary in the ýSub-Mediterranean zonation (base of Sutneria platynota Zone) near the base of the M25r ýpolarity zone.ý This project is a collaboration with A. Wierzbowski, M. Lewandowski, E. Glowniak, J. ýGutowski, P. Ziolkowski, M. Sidorczuk, and Z. Zlonkiewicz (Poland); A. Coe and J. ýWright, (England); and N. Nowaczyk (Germany)ý
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 8157 Plate motions: past (3040)
DE: 9609 Mesozoic
SC: Tectonophysics [T]
MN: 2007 Fall Meeting