|
Evolution of Ideas on Channel Flow and Ductile Extrusion in the Himalaya-Tibetan Plateau System |
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404, USA kvhodges{at}asu.edu
Surface and subsurface geological features of the Himalayan-Tibetan orogenic system may be explained by three sets of processes: those related to plate convergence, those related to the gravitational spreading of a fluid middle crust beneath the Tibetan Plateau, and those related to aggressive erosion along the southern margin of the plateau. In this paper, the possible relationships among the last two of these—and their tectonic manifestations—are presented in the form of a ‘Channel Flow-Extrusion’ hypothesis. This hypothesis, deriving from a series of ideas advanced by many geologists and geophysicists over the past two decades, suggests the definition of three phases in the Early Miocene-Recent history of the orogenic system. During Phase I (Early Miocene), the crust of southern Tibet was sufficiently hot and thick to enable lateral flow of a weak middle crust. To the north and east, this flow resulted in the expansion of the Tibetan Plateau. To the south, erosion at the Himalayan front permitted the mid-crustal channel to breach the surface; this process is recorded in the deformational history of the Himalayan metamorphic core and the Main Central and South Tibetan fault systems that bound it. While the lateral expansion of the plateau by mid-crustal flow has continued throughout Neogene time, some evidence suggests that extrusion across the Himalayan front waned substantially during the Middle Miocene-Early Pliocene interval (Phase II). In Middle Miocene time, large magnitude extension of the decoupled upper crust of southern Tibet led to the development of a subsidiary channel; its extrusion explains the existence of the North Himalayan gneiss domes. Phase III (Late Pliocene-Recent) has involved renewed southward extrusion of the main channel due to climatically induced increases in the erosion rate at the Himalayan range front.
This article has been cited by other articles:
 |
|
 |
|
  T. Rivers The Grenville Province as a large hot long-duration collisional orogen - insights from the spatial and thermal evolution of its orogenic fronts Geological Society, London, Special Publications, 2009; 327: 405 - 444. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Harris Channel flow and the Himalayan-Tibetan orogen: a critical review Journal of the Geological Society, 2007; 164: 511 - 523. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Grujic Channel flow and continental collision tectonics: an overview Geological Society, London, Special Publications, 2006; 268: 25 - 37. [Abstract] [PDF]
|
|
|
|
|
|
S. L. Klemperer Crustal flow in Tibet: geophysical evidence for the physical state of Tibetan lithosphere, and inferred patterns of active flow Geological Society, London, Special Publications, 2006; 268: 39 - 70. [Abstract] [PDF]
|
|
|
|
|
|
M. J. Jessup, R. D. Law, M. P. Searle, and M. S. Hubbard Structural evolution and vorticity of flow during extrusion and exhumation of the Greater Himalayan Slab, Mount Everest Massif, Tibet/Nepal: implications for orogen-scale flow partitioning Geological Society, London, Special Publications, 2006; 268: 379 - 413. [Abstract] [PDF]
|
|
|
|
|
|
R. D. Hatcher Jr. and A. J. Merschat The Appalachian Inner Piedmont: an exhumed strike-parallel, tectonically forced orogenic channel Geological Society, London, Special Publications, 2006; 268: 517 - 541. [Abstract] [PDF]
|
|
