Silurian and Devonian trilobites of Central AsiaStaff: R.M. Owens & L.E. Popov [with I. Kim and O. Ivanova, Geological institute, Tashkent, Uzbekistan]
[image: Leonid Research image]
Zerafshan Range, Uzbekistan: we are getting ready for trilobite hunting.
The occurrence of the Silurian Devonian trilobites in South Tien-Shan was reported in pioneering publications by Weber from the 1930s on, but little attention was paid to this group of marine invertebrates in subsequent biostratigraphical and palaeontological studies of the region. Extensive geological mapping and exploration of Nuratau,Turkestan and Zerafshan ranges in the Uzbek part of South Tien-Shan during the last thirty years have resulted in the assembly of a representative new collection of the late Silurian to mid Devonian trilobites. In South Tien-Shan trilobites represent a relatively minor component of late Silurian shallow marine benthic assemblages in comparison to corals and rhynchonelliformean brachiopods. However, they preserve distinct biogeographic signatures linking them with contemporaneous faunas of Bohemia and South China. This permits not only the establishment of more detailed correlation of the Upper Silurian and Devonian biostratigraphical sequences in these regions, but is also helpful in the understanding of the complicated geological history of numerous small crustal fragments and remnants of Palaeozoic volcanic arcs incorporated into a tectonic collage of what is now Central Asia.
In Silurian and Lower to Middle Devonian deposits of South Tien-Shan trilobites form a relatively minor component of late Silurian shallow marine benthic assemblages, which are dominated by corals and rhynchonelliformean brachiopods. Little attention has been paid to them for more then half a century since they were first discovered and described, but during the last thirty years extensive geological mapping and exploration of the Nuratau and Turkestan ranges in the Uzbek part of southern Tien Shan has generated new collections of trilobites of the Silurian and Devonian trilobites, which are the subject of the ongoing research which is carried out in cooperation with allied geological institutions of Uzbekistan. These trilobites provide distinct biogeographic signatures, linking them with contemporaneous faunas, particularly from Bohemia. These permits not only more detailed correlation of the sequences between these regions, but also contributes to the understanding of the complex geological history of the numerous small crustal fragments and remnants of Palaeozoic volcanic arcs that are incorporated into the tectonic collage of what is now Central Asia.