A continuous high-resolution magnetotelluric (MT) profile 5.4 km long reveals a 1- to 2-km-thick section of Neogene strata thrust beneath a crystalline range front along a gently dipping d¿collement in the Kyrgyz Tien Shan, central Asia. The imaged d¿collement links the intrabasin Akchop Hills fault, which currently accommodates ~15% of the total shortening across the central Tien Shan, to a crustal ramp that dips ~45¿ beneath the range. Bounds from the MT data on the base of the sediments and on the dip of the crustal ramp suggest >2.5--7.5 km of total shortening across the basin margin, of which at least 2.5--4.8 km clearly involves the d¿collement and the recently developed Akchop Hills fault. Thus a significant fraction of the total shortening across the margin has been accommodated by this young fault system. Combined with preliminary studies that suggest a mid-Miocene age for the base of the stratigraphic section, results drawn from the MT section indicate that shortening rates have increased since the onset of deformation, perhaps within the past 1--2 million years.