TY  - JOUR
A1  - Zhang, Yang
A1  - Huang, Wentao
A1  - Huang, Baochun
A1  - van Hinsbergen, Douwe J. J.
A1  - Yang, Tao
A1  - Dupont-Nivet, Guillaume
A1  - Guo, Zhaojie
T1  - 53-43Ma Deformation of Eastern Tibet Revealed by Three Stages of Tectonic Rotation in the Gongjue Basin
JF  - Journal of geophysical research : Solid earth
N2  - The Gongjue basin from the eastern Qiangtang terrane is located in the transition region where the regional structural lineation curves from east-west-oriented in Tibet to north-south-oriented in Yunnan. In this study, we sampled the red beds in the basin from the lower Gongjue to upper Ranmugou formations for the first time covering the entire stratigraphic profile. The stratigraphic ages are bracketed within 53-43Ma by new detrital zircon U-Pb ages constraining the maximum deposition age to 52.51.5Ma. Rock magnetic and petrographic studies indicate that detrital magnetite and hematite are the magnetic carriers. Positive reversals and fold tests demonstrate that the characteristic remanent magnetization has a primary origin. The Gongjue and Ranmugou formations yield mean characteristic remanent magnetization directions of D-s/I-s=31.0 degrees/21.3 degrees and D-s/I-s=15.9 degrees/22.0 degrees, respectively. The magnetic inclination of these characteristic remanent magnetizations is significantly shallowed compared to the expected inclination for the locality. However, the elongation/inclination correction method does not provide a meaningful correction, likely because of syn-depositional rotation. Rotations relative to the Eurasian apparent polar wander path occurred in three stages: Stage I, 33.33.4 degrees clockwise rotation during the deposition of the Gongjue and lower Ranmugou formations; Stage II, 26.93.7 degrees counterclockwise rotation during deposition of the lower and middle Ranmugou formation; and Stage III, 17.73.3 degrees clockwise rotation after 43Ma. The complex rotation history recorded in the basin is possibly linked to sinistral shear along the Qiangtang block during India indentation into Asia and the early stage of the extrusion of the northwestern Indochina blocks away from eastern Tibet.
KW  - eastern Qiangtang terrane
KW  - Gongjue basin
KW  - paleomagnetism
KW  - inclination shallowing
KW  - rotation
Y1  - 2018
U6  - https://doi.org/10.1002/2018JB015443
SN  - 2169-9313
SN  - 2169-9356
VL  - 123
IS  - 5
SP  - 3320
EP  - 3338
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bougeois, Laurie
A1  - Dupont-Nivet, Guillaume
A1  - de Rafelis, Marc
A1  - Tindall, Julia C.
A1  - Proust, Jean-Noel
A1  - Reichart, Gert-Jan
A1  - de Nooijer, Lennart J.
A1  - Guo, Zhaojie
A1  - Ormukov, Cholponbelk
T1  - Asian monsoons and aridification response to Paleogene sea retreat and Neogene westerly shielding indicated by seasonality in Paratethys oysters
JF  - Earth and planetary science letters
N2  - Asian climate patterns, characterised by highly seasonal monsoons and continentality, are thought to originate in the Eocene epoch (56 to 34 million years ago - Ma) in response to global climate, Tibetan Plateau uplift and the disappearance of the giant Proto-Paratethys sea formerly extending over Eurasia. The influence of this sea on Asian climate has hitherto not been constrained by proxy records despite being recognised as a major driver by climate models. We report here strongly seasonal records preserved in annual lamina of Eocene oysters from the Proto-Paratethys with sedimentological and numerical data showing that monsoons were not dampened by the sea and that aridification was modulated by westerly moisture sourced from the sea. Hot and arid summers despite the presence of the sea suggest a strong anticyclonic zone at Central Asian latitudes and an orographic effect from the emerging Tibetan Plateau. Westerly moisture precipitating during cold and wetter winters appear to have decreased in two steps. First in response to the late Eocene (34-37 Ma) sea retreat; second by the orogeny of the Tian Shan and Pamir ranges shielding the westerlies after 25 Ma. Paleogene sea retreat and Neogene westerly shielding thus provide two successive mechanisms forcing coeval Asian desertification and biotic crises.
KW  - Eocene monsoon
KW  - aridification
KW  - Paratethys sea
KW  - Central Asia
KW  - seasonality
KW  - bivalves
Y1  - 2018
U6  - https://doi.org/10.1016/j.epsl.2017.12.036
SN  - 0012-821X
SN  - 1385-013X
VL  - 485
SP  - 99
EP  - 110
PB  - Elsevier
CY  - Amsterdam
ER  -