Tom McCann, 2017. "The Jurassic of the Western Tien Shan:: The Central Kyzylkum Region, Uzbekistan", Geological Evolution of Central Asian Basins and the Western Tien Shan Range, M.-F Brunet, T. McCann, E. R. Sobel
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The Sarbatyr inlier in the Kyzylkum area, Uzbekistan contains rare outcrops of Jurassic (Bajocian–Bathonian) rocks which form part of the Kuduksarbatyr Formation. Six facies are differentiated in the general succession, ranging from conglomerates to mudstones. The coarser sediments were deposited in a distal alluvial fan setting, which interdigitated with nearshore/lagoonal marine sediments rich in fossil fragments and glauconite. The overall succession provides evidence of varying sea-levels over time, with three distinct ‘transgressive’ events being noted. Two global transgressive events have been recognized in the Bajocian with another significant event at the Bajocian–Bathonian boundary. While it is possible that the events recognized within the Sarbatyr succession correspond to these global events, the effects of local tectonic activity must also be taken into account. The re-examination of the sediments of the Kuduksarbatyr Formation extends the marine influence on sedimentation through to the Bathonian (previous interpretations suggested that the area was continental).
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The geological evolution of Central Asia commenced with the formation of a complex Precambrian–Palaeozoic orogen. Cimmerian blocks were then accreted to the southern margin in the Mesozoic, leading to tectonic reactivation of older structures and discrete episodes of basin formation. The Indian and Arabian blocks collided with Asia in the Cenozoic, leading to renewed structural reactivation, intracontinental deformation and basin development.
This complex evolution resulted in the present-day setting of an elongated Tien Shan range flanked by large Mesozoic–Cenozoic sedimentary basins with smaller intramontane basins distributed within the range.
This volume presents multidisciplinary results and reviews from research groups in Europe and Central Asia that focus on the western part of the Tien Shan and some of the adjacent large sedimentary basins. These works elucidate the Late Palaeozoic–Cenozoic tectono-sedimentary evolution of the area. Emphasis is given to the collision of terranes and continents and the ensuing fault reactivations. The impact of climatic changes on sedimentation is also examined.