Continental tectonics

1. Sedimentary evolution of the Tajik basin and implications for the tectonics of the Pamir Plateau

Significance:

As the western extension of the Tibetan Plateau, the Pamir is rather poorly understood, yet is important in understanding collisional tectonics due to its unique sub-surface structures. We explore the tectonic evolution of the Pamir by studying the thick foreland successions in the eastern Tajik Basin.

Research methods:

• Lithofacies analysis to resolve depositional environments;

• Magnetostratigraphy to constrain depositional ages;

• Detrital zircon U-Pb age and mudstone εNd provenance to determine source terranes;

• Low-temperature thermochronology (AFT & ZFT) to explore source terrane exhumation history;

• Carbonate stable isotopes to infer topographic and environmental evolution.

Main conclusions:

• The coarse-grained clastic rocks in the eastern Tajik Basin were deposited between ~20 and 8 Ma;

• Multiple proxies suggest deformation and surface uplift of the North Pamir during the middle–late Miocene;

• Detrital fission-track data record multiple Mesozoic–Cenozoic tectonics of the Pamir.

2. Late Cretaceous–Oligocene evolution of the Hoh Xil Basin, Central Tibet

Significance:

The Hoh Xil Basin in the north-central Tibetan Plateau is one of the most inaccessible regions on the plateau and most poorly understood. The evolution of the basin is, however, essential to understanding the outward and upward growth history of the Tibetan Plateau due to its critical location.

Research methods:

• Lithofacies analysis of five long sedimentary sections across the western Hoh Xil Basin, for the first time;

• Detrital zircon U-Pb age provenance analysis;

• Carbonate stable isotopes for strata correlations and environmental interpretation.

Main conclusions:

• The west and east Hoh Xil was a unified basin with similar stratigraphic evolution and tectonic settings;

• The unified Hoh Xil experienced a transition from a foreland basin to a hinterland basin in the early Eocene, e.g., ~50 Ma;

• This study provides evidence for far-field deformation associated with the India-Asia collision, as well as a method for plateau outward growth.

3. Other studies

• Jurassic successive terrane collisions in central Tibet (Geosphere, 2019)

Mesozoic tectonism, prior to the Cenozoic India-Asia collision, is important to understand the formation of the Tibetan Plateau. This study applied lithofacies and provenance analyses to demonstrate complex terrane assemblages in central Tibet, as well as constrained the initial timing of the Lhasa-Qiangtang collision at ca. 163 Ma.

• Latest Cretaceous–Paleogene drainage evolution of the Missouri River (Tectonics, 2018)

The unique badland landscape in the northern Great Plains of western North Dakota exposes good Cretaceous–Miocene stratigraphic sections. The provenance information recorded in these strata reflects four episodes of tectonic and magmatic activity in the central North American Cordillera. This study also demonstrates the feasibility of using far-away depositional records to infer orogenesis.

• Early Mesozoic evolution of the northeastern Tibetan Plateau (JAES, 2014)

The closure of the eastern Paleo-Tethys Ocean has been suggested as a Mediterranean style, which is, however, lacking sedimentary evidence. This research focused on the Triassic deep marine flysch deposits in northeastern Tibet. The results of this work provide sedimentary evidence for poorly documented back-arc rifting in geological records, which is a typical component of Mediterranean-style subduction and collision.

4. Other related studies

• Middle-late Miocene rapid exhumation of the southern Qilian Shan and implications for propagation of the Tibetan Plateau (Meng et al., Tectonophysics, 2020)

• Cenozoic drainage evolution of the Rio Grande paleoriver recorded in detrital zircons in south Texas (Fan et al., Int. Geol. Rev., 2018)

• Early Mesozoic structural evolution of the eastern West Qinling, northwest China (Wu et al., Tectonophysics, 2014)

• Detrital zircon evidence for the linkage of the South China block with Gondwanaland in early Palaeozoic time (Duan et al., Geological Magazine, 2012)

• Multiple controls on rift basin sedimentation in volcanic settings: Insights from the anatomy of a small Early Cretaceous basin in the Yanshan belt, northern North China (Wei et al., GSA Bulletin, 2012)

• Subaqueous gravity flow sedimentation: theoretical studies and field identification (Li et al., Acta Sedimentologica Sinica, 2012)

• Geological characteristics of unconformities in Mesoproterozoic successions in the northern margin of North China Block and their tectonic implications (Qu et al., Earth Science Frontiers, 2010)

• The deep-time research by chromatometry: an example from the Cenomanian to Turonian stages of the Cretaceous, Gongza section, Southern Tibet (Li et al., Earth Science Frontiers, 2009)

• Sedimentary significance of the autochthonous glauconite in stromatolitic limestones of the Mesoproterozoic Tieling Formation in Jixian, Tianjin, North China (Zhou et al., Geological Bulletin of China, 2009)

• Original analysis of the spindle-shaped cracks in the fine clastic rocks of the Precambrian: an example from the Changcheng Group of the eastern part of Yanshan area (Li et al., Geoscience, 2008)