1,721,166 research outputs found
Low-temperature thermochronological evolution along a Chilean transect between 23° and 24° latitude south: a proxy of prolonged subduction along the Andean continental margin
No full textExhumation of the western Qinling mountain range and the building of the northeastern margin of the Tibetan Plateau
No full textThis study presents new apatite fission-track data collected from intrusive and sedimentary rocks of the western Qinling mountain range. Results show a large range of data, with ages spanning from Upper Jurassic to Oligocene. No particular age-elevation relationships have been detected. Thermal modelling shows clearly that the region was affected by a nearly steady-state slow cooling starting from the Jurassic. This is particularly true for samples collected north of the West Qinling Fault whereas samples collected to the south show a re-heating event, followed by enhanced exhumation. As a whole, these data testify that the studied part of the western Qinling region was relatively stable for a long period and relatively insensitive to the tectonics related to the growth of the Tibetan Plateau. The present-day relief is mainly the result of transtensional tectonics that occurred in the Eocene
Sedimentary vs. tectonic burial and exhumation along the Apennines (Italy)
No full textWe review the burial-exhumation history of sedimentary units along the Apennines, focussing on paleo-thermal and thermochronological data derived from organic matter optical analyses, X-ray diffraction of clay-rich sediments, fission-track and (U-Th)/He dating.
In the Northern Apennines, burial conditions and timing of exhumation progressively decreases eastwards from the inner towards the outer zones and through the nappes from the lowermost to the uppermost unit. Apart from large outcrops of metamorphic rocks well exposed in Tuscany, most of the rocks of the Northern Apennines reached only diagenetic conditions. In the Central Apennines paleo-thermal and thermochronological data indicate a substantial low sedimentary and tectonic burial testifying minor amounts of orogenic shortening with a prevailing thick-skinned structural style and scarce exhumation when compared to the Northern and Southern Apennines. In the Southern Apennines, thermal indicators record exhumation of sedimentary units in the axial zone of the chain from depths locally in excess of 4 km (Lagonegro Unit and Monte Alpi structure). Apatite fission-track data indicate that exhumation marks the late tectonic stages (younger than 10 Ma) of chain evolution, probably initiating with the buttressing of the allochthonous wedge against the thickening passive margin of Adria microplate. On the other hand, higher structural units (derived from Apenninic platform deformation) show variable amounts of burial along the strike of the chain (increasing from Lucania to North Calabria border). In Eastern Sicily thermal maturity decreases from hinterland to foreland as a result of less severe thermal evolution and/or tectonic loading apart from the Peloritani Mts. in the hinterland that subdued two different phases of exhumation: the first between 35-20 Ma and the second younger than 15 Ma. Accretionary prism made up of Sub-ligurian unit (namely Sicilidi) in the footwall of the Peloritani Mts. mainly exhumed in Burdigalian times (17-19 Ma) from depths of a few kilometers. Frontal thrust stack derived from late deformation of Mesozoic passive margin successions mainly exhumed in Tortonian-Pliocene times from depths of about three kilometers. Syn-orogenic siliciclastics (mainly thrust-top basins) generally show low thermal maturity testifying scarce burial apart from those at the rear of the chain (on top of the Peloritani Mts) that are thermally imprinted by out-of-sequence reactivation in Serravalian times followed by fast exhumation in extensional regime
Widespread Late Eocene-Oligocene orogen-parallel strike-slip deformation in northwestern Anatolia and Thrace—implications for the interpretation of the North Anatolian and other associated transcurrent fault system
No full textApatite Fission Track Signatures of the Ross Sea Ice Flows During the Last Glacial Maximum
No full textThe catchment for the Ross Sea ice includes both the East and the West Antarctic ice sheets, but the mass balance is a direct response to climate change. Our work is aimed to reconstruct the ice flows after the Last Glacial Maximum and is based on apatite fission track data from samples collected from 18 piston cores across the Ross Sea embayment. Fission track ages have been divided into meaningful populations and then compared with bedrock ages from West and East Antarctica. Furthermore, fission track lengths have been measured on each population and then compared through forward modeling with thermal histories derived from literature. The widespread presence of apatites with cooling ages of about 30–40 Ma reveals a main exhumation phase of the Transantarctic Mountains during the Oligocene associated to the last phases of the West Antarctic Rift System. Furthermore, the presence of key marker apatites (e.g., younger than 21 Ma or older than 230 Ma) allows to identify the Central High as a major ice flow divide
Rapid early-middle Miocene exhumation of the Kazdağ Massif: implication for the Neogene tectonics of western Anatolia
No full textRapid early-middle Miocene exhumation of the Kazdag metamophic core complex (Western Anatolia)
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