Coupled U–Pb dating and Hf isotopic analysis of detrital zircons from Bayan Obo Group in Inner Mongolia: Constraints on the evolution of the Bayan Obo rift belt

Chen

et al. 2019

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The Eastern Kunlun Range in north Tibet, located along the northern margin of the eastern Tethyan orogenic system, records evidence for continental break‐up and ocean development in the Neoproterozoic, Paleozoic‐early Mesozoic subduction and continental collision, Mesozoic intracontinental extension, and Cenozoic contractional deformation. The Kunlun region is marked by active left‐lateral strike‐slip deformation of Kunlun fault system, one of the major intracontinental strike‐slip faults in Tibet that developed in response India‐Asia. To better constrain the tectonic evolution of the Eastern Kunlun Range and the closure of the various Kunlun oceans, we conducted detailed investigation integrating new geologic mapping, geochronology, and whole‐rock geochemistry with a synthesis of existing datasets across north Tibet. The Eastern Kunlun Range experienced three major deformation events in the Neoproterozoic, early Paleozoic, and Late Paleozoic‐early Mesozoic, which were associated with collision of the Proto‐, Paleo‐, and Neo‐Kunlun arcs, respectively. Our new detrital zircon analyses from Mesoproterozoic‐Cenozoic strata constrain stratigraphic age and sediment provenance and highlight the importance of three periods of arc activity. Our stratigraphic synthesis, including new field observations, provides new insights into connections between sediment dispersal and changes in tectonism and paleogeography. Miocene‐to‐present strike‐slip activity on the Kunlun fault and the associated strain pattern can be explained by clockwise rotation of the Kunlun fault and its wall rock as a bookshelf‐fault system, which has been proposed for northern Tibet as a result of distributed north‐south right‐lateral shear. The development of this fault system was facilitated by the presence of a Triassic suture that provided a preexisting weakness.

Section: Discussionmentioning

confidence: 83%

Tectonics of the Eastern Kunlun Range: Cenozoic Reactivation of a Paleozoic‐Early Mesozoic Orogen

Chen

et al. 2019

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“…The upper section of the Baoyintu Group is dominated by quartz schist, interbedded with quartzite and lamellar marble lens; however, a thrust fault between these two units exists (Inner Mongolia BGMR, ). Following the latest Paleoproterozoic event, near‐continuous Mesoproterozoic‐Neoproterozoic sedimentation of the Bayan Obo Group is observed (Inner Mongolia BGMR, ; Zhou et al, , ; Zhou, Hu, et al, ; Zhou, Wang, et al, ). The strata can be divided into three distinct successions: the Changcheng (i.e., late Paleoproterozoic), Jixian (i.e., early Mesoproterozoic), and Qingbaikou (i.e., early Neoproterozoic; Liu et al, ; Sun et al, ; Wan et al, ; Zhou et al, ; Zhou, Hu, et al, ; Zhou, Wang, et al, ).…”

Section: Regional Geologymentioning

confidence: 99%

“…Simplified geologic map of the northern margin of the North China craton, modified from Inner Mongolia BGMR () and Zhou et al (, ), Zhou, Hu, et al (), and Zhou, Wang, et al (). Shown in the map are locations of north marginal rift system.…”

Section: Introductionmentioning

confidence: 99%

A 1.9‐Ga Mélange Along the Northern Margin of the North China Craton: Implications for the Assembly of Columbia Supercontinent

Zhou

et al. 2018

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The involvement and location of the Neoarchean-Paleoproterozoic North China craton in the supercontinent Columbia remains enigmatic, and the tectonic history along its margins impacts our understanding of connections between North China and other continents. Here we present structural observations from a Paleoproterozoic mélange that is located along its northern margin and that we refer to as the Bayan Obo mélange. It is composed of a structurally complex tectonic mixture of metapelites and metasedimentary rocks mixed with exotic blocks of ultramafic-mafic rocks, metabasalts, metacarbonate and alkaline rocks, and tonalite-trondhjemite gneisses. New zircon geochronology of the various constituent blocks suggest that it formed, and was subsequently deformed, at ca. 1.9 Ga. The oldest intramélange blocks are 2.45-to 2.54-Ga tonalite-trondhjemite-granodiorite rocks and granitoids that signify the stabilization of the northern North China in the Neoarchean-Paleoproterozoic. A ca. 2.45-Ga plagiogranite block probably originated by partial melting of the older tonalite-trondhjemite-granodiorite rocks. We suggest that this mélange formed in a sedimentary setting near the subduction trench, on the basis of mixing of upper and lower plate volcanic rocks and textural relationships.

“…Han et al, 2020;Kusky & Li, 2003;Kusky et al, 2007Kusky et al, , 2016Wan, Windley, Xiao, Feng, & Zhang, 2015;. Meso-to Neoproterozoic continental and/or passive margin deposits were deposited on top following orogeny, such as the Bayan Obo Group in the northern North China and Tuolai Group in the Qilian Shan (e.g., C. Wu et al, 2017Wu et al, , 2018Zhou et al, 2018;.…”

Section: Proterozoic Rocksmentioning

confidence: 99%

Punctuated Orogeny During the Assembly of Asia: Tectonostratigraphic Evolution of the North China Craton and the Qilian Shan From the Paleoproterozoic to Early Paleozoic

Yin

et al. 2021

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Asian and the Tethyan oceanic domains are separated by the Tarim and North China cratons whose geologic histories are critical for deciphering the interactions of the two orogenic systems to the north and south. A major obstacle for establishing the geologic history of Tarim and North China cratons is that the two tectonic entities are currently bounded by Cenozoic structures along the southern margin of the Tian Shan and the northern margin of the Tibetan plateau (Figure 1). These structures have either reactivated or strongly modified the earlier tectonic configurations of the region (e.g., Yin & Nie, 1996). For example, Cenozoic structures that bound the southern margin of Tarim and North China cratons overprinted Mesozoic extensional basins (X.