Closure Time of the Junggar‐Balkhash Ocean: Constraints From Late Paleozoic Volcano‐Sedimentary Sequences in the Barleik Mountains, West Junggar, NW China. Issue 12 (5th December 2017)

• Record Type: Journal Article
• Authors: Liu, Bo; Han, Bao‐Fu; Chen, Jia‐Fu; Ren, Rong; Zheng, Bo; Wang, Zeng‐Zhen; Feng, Li‐Xia
• Is Part Of: Tectonics. Volume 36:Issue 12(2017)
• Page Start: 2823
• Page End: 2845
• Publication Date: 2017-12-05
• Subjects: West Junggar terrane -- Central Asian Orogenic Belt -- Junggar‐Balkhash Ocean -- detrital zircon -- sedimentology -- timing of closure; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1002/2017TC004606
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: The Junggar‐Balkhash Ocean was a major branch of the southern Paleo‐Asian Ocean. The timing of its closure is important for understanding the history of the Central Asian Orogenic Belt. New sedimentological and geochronological data from the Late Paleozoic volcano‐sedimentary sequences in the Barleik Mountains of West Junggar, NW China, help to constrain the closure time of the Junggar‐Balkhash Ocean. Tielieketi Formation (Fm) is dominated by littoral sediments, but its upper glauconite‐bearing sandstone is interpreted to deposit rapidly in a shallow‐water shelf setting. By contrast, Heishantou Fm consists chiefly of volcanic rocks, conformably overlying or in fault contact with Tielieketi Fm. Molaoba Fm is composed of parallel‐stratified fine sandstone and sandy conglomerate with graded bedding, typical of nonmarine, fluvial deposition. This formation unconformably overlies the Tielieketi and Heishantou formations and is conformably covered by Kalagang Fm characterized by a continental bimodal volcanic association. The youngest U‐Pb ages of detrital zircons from sandstones and zircon U‐Pb ages from volcanic rocks suggest that the Tielieketi, Heishantou, Molaoba, and Kalagang formations were deposited during the Famennian‐Tournaisian, Tournaisian‐early Bashkirian, Gzhelian, and Asselian‐Sakmarian, respectively. The absence of upper Bashkirian to Kasimovian was likely caused by tectonic uplifting of the West Junggar terrane. This is compatible with the occurrence of coeval stitching plutons in the West Junggar and adjacent areas. The Junggar‐Balkhash Ocean should be finally closed before the Gzhelian, slightly later or concurrent with that of other ocean domains of the southern Paleo‐Asian Ocean. Key Points: Sandstone and conglomerate of the Molaoba Formation were deposited in a fluvial environment during the Gzhelian (Pennsylvanian) Absence of upper Bashkirian‐Kasimovian (Pennsylvanian) resulted from uplifting of the West Junggar terrane Closure of Junggar‐Balkhash Ocean occurred before the Gzhelian, nearly coeval with that of other oceans in the southern Paleo‐Asian Ocean