Models of how high elevations formed across Tibet predict: (a) the continuous thickening of a “viscous sheet”; (b) time-dependent, oblique stepwise growth; and (c) synchronous deformation across Tibet that accompanied collision. Our new observations may shed light on this issue. Here, we use ⁴⁰Ar/³⁹Ar and (U-Th)/He thermochronology from massifs in the hanging walls of thrust structures along the Kunlun Belt, the first-order orogenic range at the northern Tibetan margin, to elucidate the exhumation history. The results show that these massifs, and hence the plateau margin, were subject to slow, steady exhumation during the Early Cenozoic, followed by a pulse of accelerated exhumation during 40–35 Ma. The exhumation rate increases westward (from ~0.22 to 0.34 and 0.5 mm/yr). The two-fold increase in exhumation in the western part (0.5 mm/yr) compared to the eastern part suggests westward increases in exhumation and compressional stress along the Kunlun Belt. We relate these observations to the mechanisms responsible for the oblique stepwise rise of Tibet. After collision, oblique subduction beneath Kunlun caused stronger compressional deformation in the western part than in the eastern part, resulting in differential growth and lateral extrusion.

The Taihangshan Mountain Belt, in the central North China Craton, represents an important crustal and tectonic boundary. To explore the complex tectonic evolution of this area during the Mesozoic–Cenozoic, we gathered zircon and apatite (U–Th)/He thermochronology data along a vertical transect (elevation of 630−1584 m) of the northern part of the Taihang Mountain Belt. From our data, we observed three separate rapid cooling phases that occurred at 100 Ma, 50−40 Ma and 27 Ma. Combined with previously published geochronological ages, we suggest that the uplift of the Taihang Mountain Belt initiated during the Jurassic and experienced multiphase rapid uplift from the Cretaceous to the Cenozoic. The early Cretaceous rapid cooling/uplifting events are widespread in the North China Craton and are caused by the collision between the Okhotomorsk Block and the East Asian continental margin. The Eocene and Oligocene rapid cooling events correspond to the initial rifting and thermal subsidence of the Bohai Bay Basin, indicating a coupling between the creation of basins and mountains.

Lithospheric destruction of the North China Craton (NCC) is a prominent phenomenon during the Mesozoic, but the timing and process are still in dispute. Furthermore, whether the Yangtze Craton (YTC) was also destructed is controversial. Twenty samples collected from the NCC and YTC were subjected to high‐resolution⁴⁰Ar/³⁹Ar geochronological and thermochronological studies. Average cooling rates of 450–150°C were estimated, showing that a rapid cooling event (~12°C/Ma) occurred on the NCC but not on the YTC during the Late Mesozoic. Crustal thickness can be roughly estimated by using pure conductive cooling showing that the crust of the NCC in the Jurassic was thicker than in the Cretaceous. Nonlinear cooling histories and cooling rates obtained by using multidomain diffusion theory show that the upper crusts of NCC and YTC had different cooling patterns during the Mesozoic. Combined with the sedimentation rates on the NCC, we argue that lithospheric thinning of the NCC began in the northern portion at ~140–135 Ma and peaked in the central and eastern portions at ~125–100 Ma, at a cooling rate of ~9.6°C/Ma. In contrast, the YTC cooled gently during 200–75 Ma at a rate of ~1.2°C/Ma, implying that the lithospheric thinning did not happen there during this time. Pure conductive cooling suggests that the crust of the YTC in the Late Triassic was thicker than the NCC in the Cretaceous; therefore, we argue that the lithospheric destruction in the YTC might have occurred after ~75 Ma.

It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. ⁴⁰Ar/³⁹Ar incremental heating results on groundmass selected from the samples show that the age spectra are meaningless geologically. However, singe crystal total fusions of CO₂ lasing on the sanidine separates could yield rational ⁴⁰Ar/³⁹Ar results and distinguish their sources in this study. Timing on three formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this paper. The lowermost portion of the Chawan Formation gives an age of 113.7±0.3 Ma; the lower part of the Xishantou Formation was formed 116.4±0.4 Ma ago and the bottom of the Gaowu Formation took its shape at 118.4±0.4 Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations.