Late Mesozoic-Cenozoic apatite fission-track (AFT) cooling history of
the Greater Khingan Mountains and its implications for regional
tectonics
Abstract
Apatite fission-track (AFT) tests of clastic samples from the Greater
Khingan Mountains (GKM) in China show a center age of 260–62 Ma.
Thermal modeling of observed fission-track-length distributions shows
three stages of rapid cooling that may have been caused by extensions
between 130 and 94 Ma, 30 and 15.3 Ma, and 45 and 0 Ma, and a heating
event that may have been caused in part by changes in the subduction
direction of the Pacific plate between 64 and 45 Ma. The cumulative
exhumation since the Early Cretaceous, is approximately 3 km. The
steady-state terrain model in the three-dimensional numerical simulation
is highly consistent with the time and rate of the two-dimensional
thermal history simulation for the Early Cretaceous exhumation event.
The cooling age clusters of ~160 to 100 Ma are similar
in the GKM and Hailar-Erlian Basins. This correlation provides a
basin–mountain link for the two tectonic domains. Such a
basin–mountain coupling lasted through 100–42 Ma, as supported again
by the shared cooling ages of samples from the GKM and detritus from the
range-bounded basins on the two sides of the mountain range. We
interpreted the 130–94 Ma cooling event recorded in the GKM as a result
of crustal thickening in response to the closure of the Mongolia-Okhotsk
Ocean. An increase in the subduction velocity of the Pacific plate since
ca. 45 Ma may have created a post-arc extensional tectonic setting that
has prevailed to the present in the GKM.