Low‐Temperature Thermochronology of the Chatkal‐Kurama Terrane (Uzbekistan‐Tajikistan): Insights Into the Meso‐Cenozoic Thermal History of the Western Tian Shan. Issue 10 (27th October 2018)

• Record Type: Journal Article
• Authors: Jepson, Gilby; Glorie, Stijn; Konopelko, Dmitry; Gillespie, Jack; Danišík, Martin; Mirkamalov, Rustam; Mamadjanov, Yunus; Collins, Alan S.
• Is Part Of: Tectonics. Volume 37:Issue 10(2018)
• Page Start: 3954
• Page End: 3969
• Publication Date: 2018-10-27
• Subjects: tectonics -- thermochronology -- apatite fission track -- Tian Shan -- Uzbekistan -- Tajikistan; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2017TC004878
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: The Chatkal‐Kurama terrane represents a key region in understanding the tectonic evolution of the western Tian Shan. In this contribution, we present new thermochronological data (zircon [U‐Th‐Sm]/He, apatite fission track, and apatite [U‐Th‐Sm]/He) and the associated thermal history models for 30 igneous samples from the Chatkal‐Kurama terrane within Uzbekistan and Tajikistan (west of the Talas‐Fergana Fault) and integrate our data with published data from the central Tian Shan (east of the Talas‐Fergana Fault). The Chatkal‐Kurama terrane experienced a phase of rapid cooling during the Triassic‐Jurassic at ca. 225–190 Ma, which we interpret as a far‐field response to the closure of the Palaeo‐Asian Ocean or the accretion of the Qiangtang terrane on to the Eurasian margin. In the Late Jurassic to the Early Cretaceous, the Chatkal‐Kurama terrane experienced a period of tectonic stability and denudation, before transitioning into a period of marine incursions of the Paratethys Sea. In contrast, fast cooling is recorded for the Kyrgyz central Tian Shan to the east of the Talas‐Fergana Fault. The differing thermal histories at either side of the Talas‐Fergana Fault suggest that the fault induced a topographic divide during the Late Jurassic‐Early Cretaceous, with high relief in the east (Kyrgyz Tian Shan) and low relief to the west (Uzbek‐Tajik Tian Shan). Finally, the Chatkal‐Kurama terrane experienced renewed tectonic activity since ca. 30 Ma, related with the distant India‐Eurasia collision and Pamir indentation. The Cenozoic reactivation induced crustal tilting of the Chatkal‐Kurama terrane, progressively exposing deeper rocks to the southwest. Plain Language Summary: The Chatkal‐Kurama terrane is the westernmost extent of the Tian Shan and one of the largest intracontinental mountain ranges in the world. The classical view of the plate tectonic paradigm implies that the majority of mountain building occurs at the margins of tectonic plates. Major ranges such as the Andes, the Himalaya, and the Rocky Mountains all form along the boundaries between major tectonic plates. However, the existence of major mountain ranges far from any modern plate boundary, such as the Tian Shan in Central Asia, forces us to consider how these intracontinental systems fit within the Earth system. These areas represent a unique challenge due to the complex nature of the tectonics, featuring multiple phases of deformation in response to far‐field stress propagated from the plate margins into the continental interior. By using thermochronology in an intracontinental setting, such as the Chatkal‐Kurama terrane, we aim to explore this complicated cooling history of the mountain ranges in this area and how that relates to the mountain growth in an intracontinental setting. Key Points: Three thermal events: (1) Triassic‐Early Jurassic cooling and exhumation, (2) Late Jurassic‐Cretaceous quiescence, and (3) rapid Block tilting of the Chatkal‐Kurama terrane identified by the geospatial relationship of the thermochronological data The integration of the data from this study with published data from the Tian Shan, to produce an exhumation model for the Tian Shan