Reconstructing the Late Palaeozoic – Mesozoic topographic evolution of the Chinese Tian Shan: available data and remaining uncertainties

Abstract

Abstract. The topographic evolution of continents and especially the growth and dismembering of mountain ranges plays a major role in the tectonic evolution of orogenic systems, as well as in regional or global climate changes. A large number of studies have concentrated on the description, quantification and dating of relief building in active mountain ranges. However, deciphering the topographic evolution of a continental area submitted to recurrent tectonic deformation over several hundred millions of years remains a challenge. Here we present a synthesis of the tectonic, geochronological and sedimentological data available on the intracontinental Tian Shan Range to describe its general topographic evolution from Late Palaeozoic to Early Tertiary. We show that this evolution has occurred in two very distinct geodynamic settings, initiating during the Carboniferous in an ocean subduction -continent collision tectonic context before becoming, from Early Permian, purely intra-continental. We show that during most of the Mesozoic, the topography is mostly characterized by a progressive general decrease of the relief. Nonetheless localized, recurrent deformation induced the formation of small-scale reliefs during that period. These deformations were driven by far field effects of possibly several geodynamic processes in a way that still remains to be fully understood.

Late-Paleozoic emplacement and Meso-Cenozoic reactivation of the southern Kazakhstan granitoid basement

“…However, most authors favor the Mongol-Okhotsk Orogeny and subsequent collapse as the main driving force for the Late Jurassic-Cretaceous cooling and denudation in the Altai, given the more proximal location of the Altai to the Mongol-Okhotsk collision zone. The widespread Cretaceous AFT ages and late Mesozoic cooling episode obtained for the Ili-Balkhash basement ranges are hence compatible with previous thermo-tectonic studies in the adjoining area, and are interpreted in the same context, mainly as far-field effects of the Cimmerian collisions at the southern Eurasian margin and possibly also of the MongolOkhotsk Orogeny in SE Siberia during the Jurassic-Cretaceous (Choulet et al, 2013;De Grave et al, 2007Dumitru et al, 2001;Hendrix et al, 1992;Jolivet et al, 2013b) (Fig. 8).…”

“…AFT dating and the sediment record is not always clear. Discrepancies between the sedimentological record and low-temperature thermochronological data in the Mesozoic are described by Jolivet et al (2010) for the Chinese IIi Basin, and by Jolivet et al (2013b) and Vincent and Allen (2001) for the Junggar Basin. Also, Jolivet et al (in press) demonstrate that the link between tectonic uplift and the sediment record is often not straightforward, and can be considerably modified by climate variations as in the case of the Upper Jurassic-Lower Cretaceous alluvial fan deposits of the Kalaza Formation for example.…”

“…In addition, far-field effects of the MOOB to the NE of the study area during the Jurassic-Cretaceous cannot be excluded, although its extent and influence is at present highly contested (e.g. Jolivet et al, 2010Jolivet et al, , 2013aJolivet et al, , 2013bMetelkin et al, 2010;Wilhem et al, 2012 and references therein). In the southern Altai Mountains, several AFT studies point to a Late Jurassic-Cretaceous basement cooling event, which is generally linked to both the Mongol-Okhotsk and the Cimmerian Orogeny during the Mesozoic (Cogné et al, 2005;De Grave et al, 2007Glorie et al, 2012aGlorie et al, , 2012bHalim et al, 1998;Yuan et al, 2006).…”

“…De Grave et al, 2013;Jolivet, in press;Jolivet et al, 2010Jolivet et al, , 2013b. Evidence for these reactivation episodes is often documented in the cooling histories of the exhumed basement rocks and in the sediments of the intervening basins, but the extent of these reactivation events is still under discussion (e.g.…”

Geological evolution of Central Asian Basins and the western Tien Shan Range

“…The Jurassic -Cretaceous was characterized by a general planation of the previously formed relief (e.g. Makarov 1977;Chediya 1986;Burbank et al 1999;Allen et al 2001;Cunningham et al 2003;Jolivet et al 2010Jolivet et al , 2013Jolivet et al , 2015, providing sediments to these newly forming extensional basins (Brookfield & Hashmat 2001;Klett et al 2006;Fü rsich et al 2015;Brunet et al 2017).…”