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south to 18 Ma in the north; the exhumation rates increase in the same direction. Such
an age pattern can be explained by: (1) A piggy-back thrust tectonics in which footwall
burial and hangingwall exhumation propagated towards north. (2) Since the Karakul-
Mazar belt may behaved as a rigid block during the Tertiary, deformation was probably
confined to the margins of the belt, e.g. to the right-lateral Markansu fault to the north
of the belt. (3) The whole belt may be rotated around a horizontal axis with normal
faulting in the south and thrusting in the north. (4) Cretaceous collision south of the
Pamirs led to further compression and induced renewed continental subduction of the
Karakul-Mazar belt beneath the Central Pamirs and thermally influenced the apatite
annealing zone in the Karakul lake area.
(b) The Central Pamiran Qiangtang block is characterised by a Tertiary anticlinorium
and constitute the Muzkol and Sares domes. The basement rocks exposed in the domes
are interpreted as the Triassic/Jurassic Karakul-Mazar/Sonpan-Ganze accretionary
wedge rocks (Schwab et al. in press). During the Tertiary, these rocks were strongly
deformed and metamorphosed to upper amphibolite facies conditions with local
migmatisation. Rb/Sr whole rock-muscovite ages from two gneiss samples of the Sares
dome yielded 37 and 30 Ma. Emplacement ages of Tertiary melts seem to be episodic:
An earlier phase with subalkaline intrusions is of Early Oligocene age (~33 Ma) and a
later phase with aplitic dykes of Late Miocene ages (~14-11 Ma). Metamorphic
hornblende and biotite Ar/Ar cooling ages cover ~28-14 Ma. Tertiary melt generation is
also documented by widespread basalt dyke occurrence in the domes with Ar/Ar
whole rock ages at ~20 Ma. Apatite and zircon fission track ages range from 20 to 15
Ma. The Tertiary anticlinorium is not only characterised by penetrative resetting of
nearly all mineral chronometers, but also shows very fast exhumation rates. Between
22 and 15 Ma cooling rates increased to > 40°C/Ma and in some cases (e.g. P15) all
mineral ages are reset to ~15 Ma. Tertiary intramontane basins along the margins of
the dome contain coarse grained conglomerates mainly composed of weakly
metamorphosed carbonatic and dolomitic clasts of the Mesozoic cover sequence of the
dome. Reset zircons of sediments from a basin south of the dome yielded ages of 20 to
19 Ma. Basalts cutting through the section are preliminarily interpreted as of within
plate origin. They yielded ~20 Ma Ar/Ar whole rock ages. K/Ar sericite ages range
from 33 to 14 Ma and increase away from the dome (from north to south). The older
K/Ar sericite ages (>25 Ma) are interpreted to be partly reset. Dome exhumation
between 25 to 15 Ma seem to have heated the Palaeogene sedimentary basin.
(c) The southernmost samples evaluated for their low-T history are Cretaceous
intrusions attributed to the Shyok arc. At least since Miocene the northernmost South
Pamirs was strongly deformed along the right lateral splays of the Karakoram fault. The
transpressional faults seem to be responsible for exhumation at 11-10 Ma. From Late
Miocene to Recent, final cooling of the samples was at rates of 5-16°C/Ma.
(d) A coeval Late Miocene (11-10 Ma) denudation is indicated in the southernmost Tien
Shan by apatite fission track data on granitoids. There, exhumation was probably
induced in response to crustal thickening along major thrust faults and dextral
transpressional strike slip faults.
In the Central Pamirs, future work has to determine if metamorphism, melt generation
and deformation occurred in two major phases, namely in Early Oligocene and Early
Miocene, and if exhumation in the whole Pamirs was a constant steady-state Tertiary
process, or with distinct accelerated exhumation phases, e.g. at the beginning of the
Middle and Late Miocene.