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The high elevation and rugged relief (>3 km) of the Gamburtsev Subglacial Mountains (GSM) have long been considered enigmatic. Orogenesis normally occurs near plate boundaries, not cratonic interiors, and large‐scale tectonic activity last occurred in East Antarctica during the Pan‐African (480–600 Ma). We sampled detrital apatite from Eocene sands in Prydz Bay at the terminus of the Lambert Graben, which drained a large pre‐glacial basin including the northern Gamburtsev Mountains. Apatite fission‐track and (U‐Th)/He cooling ages constrain bedrock erosion rates throughout the catchment. We double‐dated apatites to resolve individual cooling histories. Erosion was very slow, averaging 0.01–0.02 km/Myr for >250 Myr, supporting the preservation of high elevation in interior East Antarctica since at least the cessation of Permian rifting. Long‐term topographic preservation lends credence to postulated high‐elevation mountain ice caps in East Antarctica since at least the Cretaceous and to the idea that cold‐based glaciation can preserve tectonically inactive topography.

In active orogens spatial variations in exhumation rates are reflected by different cooling ages of single thermochronometers across the range, whereas temporal variations in exhumation rate are recorded in the age-elevation relationship (AER) of vertical transects. To a first order, slopes of the AER for each thermochronometer record the vertical velocity of samples relative to the relevant closure isotherm. Here we focus on the Northern Apennine chain, a tectonically active bimodal orogen characterized by paired contractional and extensional domains. We used fission-track and (U-Th)/He analysis on apatite to study vertical profiles sampled in the foredeep turbidite deposits of Oligocene-Miocene age at Mt. Cimone, Mt. Falterona and the Pratomagno ridge. The Mt. Falterona profile has been extended by using some samples from a nearby exploration well. The Pratomagno and Falterona profiles yield comparable exhumation rates, both showing an increase from values lower than 0.5 km/m.y. to values higher than 1 km/m.y. Maximum rates were reached at 3-4 Ma with subsequent exhumation apparently decreasing to rates lower than 1 km/m.y. The Cimone profile shows a significantly different exhumation history, with rates in the range of 0.3-0.4 km/m.y. at least until 3 Ma, followed by an apparent moderate increase in rates. These different exhumation histories can be explained in the light of the different structural setting of the sampled profiles. While the Pratomagno and Falterona profiles are located along the ridges of two of the Plio-Pleistocene intramontane basins that characterize the hinterland of the chain, the Cimone profile is close to the watershed and is not noticeably affected by extensional tectonics. Therefore, we propose that extensional tectonics was the likely cause of the pulse of the exhumation rates at 3-4 Ma detected in the Pratomagno and Falterona profiles. At present, a complete data set is available only for these three vertical transects, but we argue that an increase of exhumation rates is recorded in the AER from the ridges bordering all the intramontane basins and it is linked to the extensional tectonics of the basins themselves.

Syn-orogenic extension is observed in numerous convergent orogens worldwide. A number of geodynamic models have been proposed to explain this phenomenon. However, no single model can presently explain all observed tectonic, geomorphic and geologic features. One quantifiable constraint for any geodynamic model is the regional pattern and history of erosional and tectonic denudation as determined from low-temperature thermochronology. For example, if extension is attributable to wedge underplating, then horizontal material flux across the orogen should be close to zero. This leads to a spatial pattern of ages from different low temperature thermochronometers closely reflecting independently determined surface exhumation rates. Alternatively, if extension is attributable to another cause (e.g. slab rollback, orogenic collapse, slab breakoff) where frontal accretion dominates, this will lead to significant horizontal material flux within the wedge. This results in an offset of reset thermochronometers with respect to highest erosion rates in the direction of convergence. To investigate this problem, we are undertaking a detailed regional low-temperature thermochronologic study in the northern Apennines of Italy - a classic example of an active orogenic wedge undergoing syn-convergent extension. Substantial pre-existing fission-track data are augmented by new apatite (U-Th)/He cooling ages from a total of over 300 samples across the orogen. Determination of current surface exhumation rates using tectonic geomorphologic methods are being carried out in conjunction with this study. Preliminary results provide new information on the timing, rates, and spatial variations of cooling (and by proxy denudation) that would not have been possible by applying each thermochronometer in isolation. A general trend of increasing total cooling and the age of onset of accelerated cooling is observed from the prowedge (ca. 2-4 Ma) towards the core and retrowedge side (ca. 8-12 Ma) of the range. Very young cooling ages (1-3 Ma) from the Alpi Apuane core complex disrupt this pattern and indicate that late Cenozoic detachment faulting contributed significantly to extension within the northern Apennine orogenic wedge. New data currently being obtained will enable a more detailed analysis of the spatial distribution of cooling ages and provide vital new constraints for the development of geodynamic models to explain the presence of syn-orogenic extension with convergent orogens.