TY - JOUR
T1 - A Late Miocene acceleration of exhumation in the Himalayan crystalline core
AU - Wobus, Cameron
AU - Pringle, Malcolm
AU - Whipple, Kelin
AU - Hodges, Kip
N1 - Funding Information:
This work was supported by NSF Tectonics grant EAR-008758 to KVH and KXW. Additional support was provided by a CIRES postdoctoral fellowship to CWW. We thank Ajay Sitaula and Himalayan Experience for logistical support, and Bill Olszewski for laboratory support. The manuscript benefited from the comments of two anonymous reviewers.
PY - 2008/5/15
Y1 - 2008/5/15
N2 - Unraveling the relative roles of erosion and tectonics in shaping the modern topography of active orogens requires datasets documenting spatial and temporal patterns of exhumation, surface uplift and climatic forcing throughout orogenic growth. Here we report the results of biotite 40Ar/39Ar incremental heating and single-grain laser-fusion experiments from a nearly vertical, ∼ 1000 m age-elevation transect in the central Nepalese Himalaya. Age-elevation relationships constructed from these data suggest very slow cooling in this part of the Himalayan crystalline core during the Early Miocene, accelerating to only moderate rates at ∼ 10 Ma. If we assume purely vertical exhumation and a steady-state thermal structure, the exhumation rates implied by these data are ≪ 0.1 mm/yr prior to 10 Ma and ∼ 0.5 mm/yr from ∼ 10-7 Ma. The acceleration in cooling rate at 10 Ma requires a change in kinematics that may be linked to large-scale changes in climate, or to more local tectonic perturbations. Although we do not presently have enough data to assess the relative roles of regional vs. local drivers, these data provide a new constraint on exhumation through the Miocene that must be honored by any model of Himalayan evolution.
AB - Unraveling the relative roles of erosion and tectonics in shaping the modern topography of active orogens requires datasets documenting spatial and temporal patterns of exhumation, surface uplift and climatic forcing throughout orogenic growth. Here we report the results of biotite 40Ar/39Ar incremental heating and single-grain laser-fusion experiments from a nearly vertical, ∼ 1000 m age-elevation transect in the central Nepalese Himalaya. Age-elevation relationships constructed from these data suggest very slow cooling in this part of the Himalayan crystalline core during the Early Miocene, accelerating to only moderate rates at ∼ 10 Ma. If we assume purely vertical exhumation and a steady-state thermal structure, the exhumation rates implied by these data are ≪ 0.1 mm/yr prior to 10 Ma and ∼ 0.5 mm/yr from ∼ 10-7 Ma. The acceleration in cooling rate at 10 Ma requires a change in kinematics that may be linked to large-scale changes in climate, or to more local tectonic perturbations. Although we do not presently have enough data to assess the relative roles of regional vs. local drivers, these data provide a new constraint on exhumation through the Miocene that must be honored by any model of Himalayan evolution.
KW - Himalaya
KW - argon thermochronology
KW - climate
KW - tectonics
UR - http://www.scopus.com/inward/record.url?scp=43049131051&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=43049131051&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2008.02.019
DO - 10.1016/j.epsl.2008.02.019
M3 - Article
AN - SCOPUS:43049131051
VL - 269
SP - 1
EP - 10
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
IS - 1-2
ER -