The Dabie Shan of eastern China is a ϳ200 kilometers wide mountain range with nearly 2 kilometers of relief and is an archetype of deep ultrahigh-pressure metamorphic rock exhumation. Despite its regional and petrologic importance, little is known about the low-temperature and post-orogenic evolution of the Dabie Shan. Here we present apatite and zircon (U-Th)/He (AHe and ZHe, respectively) and apatite fission-track (AFT) cooling ages from the Dabie Shan that constrain the patterns and history of exhumation over the last ϳ115 myr. On the scale of the whole orogen, ZHe and AHe ages are inversely correlated with mean elevation and are systematically younger in the core of the range. These cooling ages were converted to exhumation rates assuming steady-state erosion and accounting for topographic effects. These results indicate that, since the Eocene, flanks of the range have eroded at rates as low as 0.02 km/myr, while the range core has eroded at about 0.06 km/myr. Even in the core of the range, these recent exhumation rates are at least 10 to 20 times slower than those estimated for the initial stages of exhumation in the Triassic-Jurassic. In a 1.4 kilometer vertical transect in the core of the range, all ages are positively correlated with elevation, with ZHe ages increasing from 76 to 112 Ma, AFT from 44 to 70 Ma, and AHe from 24 to 43 Ma. We present a simple model for topographic correction of thermochronometric ages in vertical transects, using the admittance ratio (ratio of isotherm relief to topographic relief). Applied to the AHe age-elevation relationship, this yields Tertiary exhumation rates of 0.05 to 0.07 km/myr in the core of the Dabie Shan, in good agreement with regional exhumation rate patterns. Finally, age-elevation relationships for all three chronometers in the vertical transect are consistent with a constant exhumation rate of 0.06 ؎ 0.01 km/myr since the Cretaceous, with a possible modest increase in exhumation rates (as high as 0.2 km/myr) between 80 to 40 Ma. These data show no evidence for significant variations in exhumation rates over the last ϳ115 myr, as might be expected for decay of old topography or tectonic reactivation of old structures. introduction Collisional orogenies typically produce topographic and geophysical anomalies persisting several hundred million years. The post-orogenic evolution of mountain ranges and their responses to erosion and subsequent tectonic events provides insights to a variety of problems, including the deep crustal architecture of orogens, dynamics of lithospheric roots, and the erosional decay of topographic anomalies. Typically, the topographic and structural decay of an ancient mountain range is not monotonic, and

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Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. This rapid uplifting strongly contrasts with (1) the previous, rapid foreland subsidence during Early to Middle Jurassic in response to late-orogenic compression from the Qinling belt, (2) the succeeding long, slow cooling phase and relative thermal stability that occurred during the 100-45 Ma period. This rapid cooling event in the SDBAZ parallels those experienced by two adjacent upheavals of Huangling (HLUZ) and Hannan-Micang (HMUZ), with cooling rates of 2.22-3.17°C/Ma for the HLUZ in 160-126 Ma, 4.91°C/Ma for the southern HMUZ in 150-125 Ma, as well as 2.11°C/Ma for the northern HMUZ in 150-105 Ma. Comparing thermal histories among the SDBAZ, the HLUZ, the HMUZ, and the Wudang metamorphic zone (WDMZ), we infer that the Daba arcuate structural belt formed in 153-100 Ma. The combined dating data support a correlation with a low-angle arcuate south-thrusting of the Qinling orogen triggered by northward convergence of the Yangtze Craton, contemporaneously encountering rigid basement obstructions from the HLUZ and the HMUZ, respectively. Both the SDBAZ and neighboring domains additionally underwent a comparatively fast cooling and uplift since about 45 Ma.

Drilling has revealed suites of magnesian granite and diorite emplaced in Early Jurassic time (198–195 Ma) and an arc‐related low‐temperature (678 to 696°C) magmatism in NE South China Sea. These rocks have 87Sr/86Sri (0.705494 to 0.706623) and εNdt (−0.9 to +2.2) as evidence of evolved mantle‐derived magmas, coupled with enriched fluid‐mobile elements Cs to K and Pb implying involvement of subduction‐zone fluids. Another Early Jurassic granodiorite (zircon U‐Pb 187 Ma) drilled from the SW East China Sea, a magnesian high‐K calc alkaline, is comparably confined to a range of low‐temperature (~675°C) arc‐related granite, characterized by enrichment of fluid‐mobile elements and Nb‐Ta depletion. Its Sr‐Nd isotopes (87Sr/86Sri = 0.705200, εNdt = 1.1) suggest a product of evolved mantle‐derived melts. Together with detrital igneous zircons from Paleocene sequences, these observations reveal an Early Jurassic arc‐related low‐temperature (600 to 740°C) magmatism in the SW East China Sea. These arc‐related granitoids, along with those from SE Taiwan, could define an Early Jurassic NE‐SW trending Dongsha‐Talun‐Yandang magmatic arc zone along the East Asian continental margin paired with Jurassic accretionary complexes from SW Japan, East Taiwan to the West Philippines. This arc‐subduction complex assembly was associated with oblique subduction of the paleo‐Pacific slab beneath Eurasia, presumably responsible for Early Jurassic lithospheric extension in south China block.

The late Cretaceous to early Oligocene strata in the northern continental margin of the South China Sea (SCS) are significant for understanding the contemporaneous continental rifting of the margin prior to the opening of the central SCS oceanic basin. Using new seismic and drilling data, combined with previous results, we have identified three episodes of rifting from the late Cretaceous to early Oligocene based on analyses of major unconformities, tectonostratigraphic units, and sedimentary facies. The first episode of rifting that occurred only in the Pearl River Mouth (PRM) basin during the late Cretaceous to Paleocene is observed. During the early to middle Eocene, littoral-shallow lacustrine and fan-delta facies were distributed in some faulted half-grabens in the Qiongdongnan (QDN) basin, while deep lacustrine deposits widely developed in the PRM basin. During the late Eocene to early Oligocene, marine transgression propagated from the southeast into the QDN, southern PRM, and Taixinan basins. We have inferred that late Cretaceous to the middle Eocene rifting is characterized by uniform lithospheric stretching related to the retreat of the paleo-Pacific subduction zone, whereas the late Eocene to the early Oligocene rifting controlled by multiple factors is characterized by depth-dependent lithospheric extension. It is the differential rifting process that led to the differentiation in the types and distribution of source rocks in the basins of northern SCS margin.

Apatite fission-track (AFT) analyses were performed on 13 Late Palaeozoic samples in order to unravel the late-to post-Variscan evolution of the Ardennes. The dated AFT ages cover a range from 290 + 33 Ma to 168 + 12 Ma, and the mean confined track lengths correspond to a unimodal distribution, with means varying between 13.1 + 0.1 mm and 11.7 + 0.3 mm. These ages for the sedimentary rocks are clearly younger than the respective stratigraphic ages, indicative of a cooling through the apatite partial annealing zone after post-depositional complete annealing. All available AFT data (290-146 Ma) from this region might be classified as three groups, that is Ma, at least in correlation with three exhumation events. Using an inverse model, four major cooling episodes are identified from the modelled temperature-time (T-t) paths. The first rapid cooling (4.2-5.4 8C Ma 21 , 320-300 Ma) corresponds to the late-Variscan rapid thrusting that ceased at about 300 Ma. The second cooling episode (0.2-4.0 8C Ma 21 , up to 230 Ma) activated differentially, and was probably controlled by the post-Variscan transtension. The third cooling regime (0.1-0.3 8C Ma 21 , 230-45 Ma) in the Ardennes Allochthon is slow, and represents a long-term and slow exhumation. In the Brabant Parautochthon, however, it is subdivided into 0.7 8C Ma 21 (225-110 Ma) and 0.2 8C Ma 21 (110-45 Ma). The last accelerated cooling (0.7-1.1 8C Ma 21 , since 45 Ma) that affected the whole Ardennes is associated with a south-north compression during the Pyrenean phase.

Zircon U‐Pb ages of 163.8–100.4 Ma and 146.6–134.5 Ma are obtained for the granitoids from the Pearl River mouth basin, and from southern Guangdong Province, respectively. These new dating data accord well with the crystallization ages of Yanshanian granitoids broadly in the Nanling. The active continental margin of South China, as revealed by a combination of zircon U‐Pb data, underwent a key granitoid‐dominated magmatism in 165–100 Ma. Its evolution varied temporally, and spatially, registering under control of the paleo‐Pacific slab subduction. The granitoids that occurred in 165–150 Ma broadly from the South China Sea to the Nanling are preferably related to two settings from volcanic‐arc to back‐arc extension, respectively. The activities of Cretaceous granitoids migrated from the southeastern Guangdong (148–130 Ma) to the Pearl River Mouth basin (127–112 Ma), corresponding to the model of a retreating subduction. The subduction‐related granitoid magmatism in South China continued until 108–97 Ma. A tectonic transformation from slab‐subduction to extension should occur at ∼100 Ma.