Partitioning of localized and diffuse deformation in the Tibetan Plateau from joint inversions of geologic and geodetic observations

Abstract

The spatial complexity of continental deformation in the greater Tibetan Plateau region can be defined as the extent to which relative motion of the Indian and Asian plates is partitioned between localized slip on major faults and distributed deformation processes. Potency rates provide a quantitative metric for determining the magnitudes of on-fault and diffuse crustal deformation, which are proportional to fault slip rates and strain rates within crustal micro-plates, respectively. We simultaneously estimate micro-plate rotation rates, interseismic elastic strain accumulation, fault slip rates on major structures, and strain rates within 24 tectonic micro-plates inferred from active fault maps in the greater Tibetan Plateau region using quasi-static block models constrained by interseismic surface velocities at 608 GPS sites and 9 Late Quaternary geologic fault slip rates. The joint geodetic-geologic inversion indicates that geologic slip rates are kinematically consistent with and result from differential micro-plate motions. Estimated left-lateral slip rates on the Altyn Tagh, west-central Kunlun, and Xianshuihe faults are relatively homogeneous along strike (∼11.5, 10.5, and 12 mm/yr, respectively)

No late Quaternary strike-slip motion along the northern Karakoram fault

“…More broadly, our results show that the northern Karakoram fault does not currently form a discrete kinematic boundary within the Himalayan-Tibetan orogen between the Pamir-Karakoram region to the west and the Tibetan Plateau to the east, as assumed in many kinematic and geodynamic models (Avouac and Tapponnier, 1993;He and Chéry, 2008;Liu and Bird, 2008;Loveless and Meade, 2011;Meade, 2007;Peltzer and Saucier, 1996). Instead, the dynamics of the two regions may be partially coupled, or more likely decoupled over a broad region of diffuse deformation, a feature that future kinematic and mechanical models of recent to active deformation in the Tibetan orogen will need to take into consideration.…”

“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) He and Chéry, 2008;Liu and Bird, 2008;Loveless and Meade, 2011;Meade, 2007;Peltzer and Saucier, 1996;Thatcher, 2007;Valli et al, 2007) (Fig. 1A and B).…”

“…Thus, while rigid block models are suitable to describe the kinematics of the upper crust at decadal to millennial scales (e.g. Loveless and Meade, 2011;Meade, 2007;Thatcher, 2007), the boundaries of these blocks may not remain constant over longer intervals. This would be consistent with general models of continental deformation involving relatively weak crust with distributed deformation over geologic timescales (e.g.…”

Rates and style of Cenozoic deformation around the Gonghe Basin, northeastern Tibetan Plateau

“…Recent studies have suggested that this slip-rate gradient may be accommodated by internal deformation within the plateau and regional clockwise rotation of the Kunlun fault Kirby and Harkins, 2013), and/or that displacement is transferred northward, across the interior of northeastern Tibet, to the Haiyuan fault . A recent inversion of geodetic and geologic data suggests that slip along the Elashan and Riyueshan faults could indeed accommodate slip-rate gradients along the eastern Kunlun fault (Loveless and Meade, 2011), but this model requires relatively high rates of slip (~4-6 mm/yr) along these structures in order to accomplish complete transfer of slip. Geologic and geomorphic data suggest that right-lateral slip rates along the Elashan and Riyueshan faults are only ~1 mm/yr , such that signifi cant deformation must occur between the Kunlun and the Haiyuan faults on other structures in addition to the Elashan and Riyueshan faults .…”

Focal Mechanism Solutions of the 2008 Wenchuan earthquake sequence from P-wave polarities and SH/P amplitude ratios: new results and implications

“…These faults were relatively quiescent in seismicity (Loveless and Meade 2011;Meade 2007). Source inversions based on teleseismic data showed a pattern of double-peak energy release during rupture (e.g., Ji and Hayes 2008;Nakamura et al 2010;Zhang and Ge 2010;Zhang et al 2009).…”