The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. In 2015, the daily episodes for each month were assembled into monthly packages, and a few new episodes were posted. Now, the blog/podcast is on an occasional schedule with diverse topics, and the Facebook Page showcases photos on Mineral Monday and Fossil Friday. Thanks for your interest!

Monday, February 10, 2014

February 10. Baikalian orogenies




Parts of Asia and Europe were also growing during the early Cambrian, if not quite on the scale of Gondwana that we talked about yesterday. The Baltic Craton, also known as the Russian or East European Platform, added a triangular block called the Timan-Pechora terrane, in what is now northwestern Russia and the adjacent Arctic Ocean. It was probably added in very late Precambrian time, possibly overlapping into the early Cambrian. The map shows this new addition outlined in green, and the red line with the cross marks is the zone where the two continents came together. This would have been a mountain range during the Cambrian, and even today, thanks to some rejuvenation, it is a range of hills.

At around the same time, very late Precambrian, the Baikalian Orogeny (named for Lake Baikal, in southern Siberia) added some small continental blocks and island arc terranes to the southern margin of Siberia – which was not at the time connected to the Baltic Shield and Europe. That’s a much later assembly, marked by the Ural Mountaina.

Most of the Baikalian “events” spanned at least 150 million years, and were largely accomplished by the time the Cambrian opened. They set the scene, provide the geography, for not just the Cambrian, but for a good bit of Paleozoic time that we’ll be discussing over the coming months.
—Richard I. Gibson

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