Keywords
paleomagnetism
paleotectonic reconstructions
Tethys paleoocean
Middle Jurassic
Section
Abstract
We present the first paleomagnetic results of the Middle Jurassic volcanogenic-sedimentary rocks of the NW Caucasus — the Chataltapa Formation (Aalenian-Bajocian), the Mount Indyuk Formation (Aalenian), and the Porphyrites series (Bajocian) belonging to the Greater Caucasus tectonic megazone. The purpose of our work was to determine the paleolatitude position in the Middle Jurassic of the NW Caucasus tectonic block and to estimate the width of the northern branch of the Tethys paleoocean. As a result of paleomagnetic analysis, we identified a pre-folding bipolar component of natural remanent magnetization, mean direction for all three formations: D=18.8° I=34.1° k=114.2 α95=11.6° By averaging the virtual geomagnetic poles of the formations, the paleomagnetic pole of Bajocian for the NW Caucasus was calculated (Plat=60.1°, Plong=181.5° A95=12.8°). According to this result, the tectonic block was located in the Bajocian at tropical latitudes of the northern hemisphere (19 +/− 13°). All the studied rocks exhibited extensive remagnetization processes, probably corresponding to the post-Eocene Alpine orogeny. With the help of the obtained data and some published paleomagnetic poles for the Middle Jurassic rocks of the Caucasus and Turkey, the width of the northern branch of the Tethys Ocean is estimated; according to these data, it was not less than 1500 km.
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