Cenozoic dextral transpressional tectonics in the northwestern Qaidam Basin, northern Tibet: Evidence from paleomagnetic and kinematic analysis of the arcuate belts
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引用次数: 0
Abstract
The mechanisms by which complex intracontinental deformation in the northern Tibetan Plateau was accommodated since the India-Asia collision remain debated. Characterization of the formation of arcuate structures in northern Tibet provides important constraints on this debate. We conducted a new paleomagnetic study on the mid- to late Miocene strata along the curved Lenghu-Nanbaxian and Eboliang-Hulushan belts of the Qaidam Basin, northern Tibet. Our results revealed that there is nonsignificant relative rotation within localities along these arcuate belts, which yielded a common mean direction of declination (D) = 3.6°, inclination (I) = 35.7° (α95 = 2.4°) after tilt correction, suggesting negligible Neogene vertical-axis rotation along the arcuate belts in the Qaidam Basin. Outcropped fault striations and the positive flower structures indicate dextral strike-slip−dominated motion along the faults since the mid- to late Miocene. By integrating the paleomagnetic results with the kinematics of these associated faults, we ruled out the possibility that these curved belts formed due to the frictional drag of the Altyn Tagh fault or due to differential shortening across the Qaidam Basin. Instead, we attribute the formation of these nonrotational arcuate belts to dextral transpressional deformation occurring within the basin since the mid- to late Miocene. Different from the orogenic belts in the northern Tibetan Plateau that absorbed postcollisional convergence through block rotation, crustal shortening, and lateral extrusion, the Qaidam Basin has also accommodated significant intracontinental deformation in the northern Tibetan Plateau through transpressional deformation within the basin. This inference underscores the importance of recognizing crustal extrusion within rigid blocks as a record of intracontinental deformation in the northern Tibetan Plateau.
期刊介绍:
The GSA Bulletin is the Society''s premier scholarly journal, published continuously since 1890. Its first editor was William John (WJ) McGee, who was responsible for establishing much of its original style and format. Fully refereed, each bimonthly issue includes 16-20 papers focusing on the most definitive, timely, and classic-style research in all earth-science disciplines. The Bulletin welcomes most contributions that are data-rich, mature studies of broad interest (i.e., of interest to more than one sub-discipline of earth science) and of lasting, archival quality. These include (but are not limited to) studies related to tectonics, structural geology, geochemistry, geophysics, hydrogeology, marine geology, paleoclimatology, planetary geology, quaternary geology/geomorphology, sedimentary geology, stratigraphy, and volcanology. The journal is committed to further developing both the scope of its content and its international profile so that it publishes the most current earth science research that will be of wide interest to geoscientists.