Callovian (Upper Middle Jurassic) magnetostratigraphy: A composite polarity pattern from France, Britain and Germany, and its correlation to the Pacific marine magnetic anomaly model
Abstract
Callovian strata from sixteen exposures across western Europe produced a nearly continuous composite geomagnetic polarity reference sequence spanning the latest Bathonian (Clydoniceras discus Zone) through the entire Callovian and into the earliest Oxfordian (Quenstedtoceras mariae zone). This sequence is compiled from multi-section sequences from France and England, a section in southern Germany, and a section on the Isle of Skye (Scotland). These sections are calibrated with ammonite biostratigraphy, brachiopod associations and sequence stratigraphy. Over 400 oriented core samples were subjected to progressive thermal demagnetization and filtered according to magnetic behavior; the highest quality suite produced mean paleopoles of 67.3°N, 174.8°E (δp: 5.0, dm: 7.6) for the English composite, 80.4°N, 137.4°E (δp: 2.7. dm: 3.6) for the French composite, 48°N, 137°E (δp: 8.0, dm: 13.8) on the Isle of Skye and 81.8°N, 171.1°E (δp: 7.6, dm: 10.1) in Southern Germany. The composite polarity pattern for the Callovian shows a trend of longer durations for the normally oriented zones that is interrupted by three clusters of Chrons dominated by their reversed-polarity. The observed Chron duration in addition to the overall trend in orientation mirrors the pattern found from M37 through M39 in the pre-M29 geomagnetic polarity block models based on marine magnetic anomaly analyses from the Pacific Ocean, with the Callovian-Oxfordian boundary occurring within anomaly M37n (tentatively within M37n.1n) and the Callovian-Bathonian boundary falling within M39n.
Degree
M.S.
Advisors
Ogg, Purdue University.
Subject Area
Geology|Geophysics
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