Magnetic polarity zonation and European paleomagnetic poles for the Upper Jurassic

Piotr A Przybylski, Purdue University

Abstract

The goal of this research was to resolve some important questions about stratigraphy and tectonics of the Upper Jurassic, a fascinating period in the history of our planet. During the Middle to Upper Jurassic (about 160Ma), when the supercontinent Pangaea was split into new continents, the present Pacific plate was formed and the spreading in the Atlantic and Indian oceans was initiated. The magnetic record of this spreading in form of the pre-M25 marine magnetic anomalies remained uncalibrated due to the incomplete magnetic polarity results obtained from some Middle and Upper Jurassic outcrops. In addition, there remains considerable uncertainty about both the paleolatitude and rotational history of the European plate during the Middle to Upper Jurassic. The sparse paleomagnetic data in this interval have either yielded apparent poles with unacceptably large confidence limits, or fail to agree with each other. The verification of the above presented problems was done by obtaining more magnetostratigraphic samples from new sections in thick ammonite-rich limestone formations of southern Poland (Polish Jura Chain, Holy-Cross Mountains) and extracting the paleomagnetic directions using the newest magnetometer technology and analytical methods. This Polish paleomagnetic work was combined with the re-analysis of well-dated magnetostratigraphy segments that were previously obtained from Britain (Dorset, Yorkshire, the Isle of Skye), south-eastern France (Crussol, Valence), Spain (north-eastern Iberian Range) and western Germany (Plettenberg, Swabian Alb). The results of this interdisciplinary research project, which combines magnetostratigraphy, paleomagnetism, biostratigraphy, marine magnetic anomaly records and cyclostratigraphy are summarized below.

Degree

Ph.D.

Advisors

Zinsmeister, Purdue University.

Subject Area

Geology|Geophysics|Paleontology|Marine Geology|Geophysical engineering

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