The principal structural elements of the Himalayan arc can be traced more or less continuously for nearly 2500 km. It is therefore understandable that along-strike variations in structure and denudation have not received the same attention as equivalent arc-normal trends. However, it is now clear that arc segmentation can be controlled by lateral variations in the geometry of the Main Himalayan Thrust (MHT). The Bhutan Himalaya has a distinctive physiography and hosts nominal modern seismicity despite experiencing long-term strain accommodation comparable to the wider arc. This enigmatic section of the orogen presents an opportunity to test the case for local arc segmentation through applied tectonic geomorphology. By integrating low temperature thermochronology, cosmogenic radionuclide methods and quantitative geomorphometry, this study documents the spatial and temporal variability of denudation to infer partitioning of deformation across crustal structures. Laboratory methods include apatite fission track (AFT), and (U-Th)/He dating of zircon from in situ bedrock, synorogenic sediments and modern detrital samples. Additionally, 10Be concentrations from detrital quartz samples adds to a nation-wide compilation of previously published data. Results suggest prominent along- and across-strike variation in deformation within Bhutan. High normalised channel steepness and hillslope characterise a prominent east-west trending zone of elevated millennial-scale erosion rates. Here termed the Naka Zone, this geomorphic region is coincident with the estimated rupture extent of an early 18th Century great earthquake and terminates to the east in the vicinity of the Kuru Chu reentrant in the Main Central Thrust (MCT). Greater Himalaya basement rocks west of the Sakteng Klippe show a phase of rapid, monotonic cooling, the timing of which is largely latitude-dependent, consistent with exhumation above a mid-crustal ramp on the MHT ~100 km from the front followed by horizontal translation above the AFT partial annealing zone. This framework explains the decoupling of AFT ages in sampled catchments from millennial-scale erosion rates. Small catchments that straddle the MCT show bimodal distributions in single grain AFT ages, suggestive of activity on the MCT during the late Miocene. Further, central ages show a marked decrease towards Arunachel Pradesh, suggesting that in far eastern Bhutan the mid-crustal ramp extends towards the foreland, possibly invoking a lateral ramp. Synorogenic detrital thermochronometers are unreset and thus provide information on source area bedrock cooling and provenance. ZHe and AFT age distributions in the Siwaliks are bimodal. Comparisons with large modern drainage systems links a young age peak (Mio-Pliocene) to the Greater Himalaya and a dominant older age peak (Mid Miocene) to the Lesser Himalaya and points to persistent elevated topography in the range front east of Kuru Chu.
The pattern and timing of deformation in the southeast Tibet resulting from the India-Asian collision remain poorly constrained. Detailed field mapping, structural analysis and geo-thermochronogic data within a newly-defined Ludian-Zhonghejiang fold-thrust belt stretching over 120 km between the Diancang Shan and Xuelong Shan metamorphic belt in western Yunnan, China document Early Cenozoic tectonic evolution of the conjunction area between the Lanping-Simao and South China blocks. The study area is cut by two major northwest-striking, southwest-dipping brittle faults, named Ludian-Zhonghejiang fault and Tongdian fault from east to west. Kinematic measurements and indicators of S-C fabrics and striations, as well as juxtaposition of Triassic meta-sedimentary rocks overlying on Paleocene strata indicate thrusting along the Ludian-Zhonghejiang fault. Similarly, structural analysis show the Tongdian fault is also a reverse fault. Between these structures, fault-bounded Permo-Triassic and Paleocene strata are strongly deformed by upright southwest-vergent folds with axes that trend nearly parallel to the traces of the principal faults, consistent with reserve faulting related to regional NE-oriented compression. Zircon and apatite (U-Th)/He and apatite fission track ages from a Triassic granitic pluton in the hanging wall of the Ludian-Zhonghejiang thrust assisted by inverse modeling reveal a period of accelerated cooling from 50 Ma to 37 Ma, which is interpreted to record the lifespan of the fold-thrust system collaborated by the intrusive relations between magmas of ~35 Ma dated by zircon U-Pb and the fold and thrust belt. Since 37 Ma, decreasing cooling rates implies cessation of the thrusting. Early Cenozoic activity of the deformation system likely controlled deposition of the Jianchuan-Liming basin evident by coeval sediments derived from the proximal hanging wall of the fold-thrust belt. These results, together with tectonic records of contraction in east Tibet, suggest crustal shortening related to the India-Asian collision and convergence prevailed the southern and eastern part of the Tibetan Plateau, which predated Oligo-Miocene onset of extrusion tectonics in southeast Tibet.
The combination of different thermochronologic techniques on the same samples or even the same grains has become in a useful tool, to establish a complete history of the geological process that has controlled a rock, and for gaining information on sediment provenance and the exhumation of sediment source areas. Determination of crystallization and cooling ages of detrital zircon from modern river sediments is a powerful method for tracing sediment provenance and exhumation of orogenic mountain belts. In this work we explain with new examples of modern river samples from the Colombian Andes how zircon fission-track (ZFT) and U-Pb dating can be used in provenance studies to better understand the temporal association between source and depositional site and how the evolution of orogenic mountain belts from such data in a setting where large amounts of sediment are recycled from sedimentary source rocks and volcanic input may complicate the exhumational signal. Whereas the ZFT data provide information about the most recent thermal history and exhumation of the source rocks, they are complementary to U-Pb data which reflect the original zircon crystallization age and its ultimate provenance. The study contains data of detrital zircon U-Pb and zircon fission-track dating from modern river sediments of the Guatiquia and Guayuriba rivers in the eastern foothills of the EC, and the Magdalena River at Girardot on the western flank of the EC. Each individual dating technique offers unique information with respect to provenance and exhumation. We use our data to highlight certain advantages and limitations of using zircon U-Pb and FT dating in provenance studies, including the identification of original source areas, sediment recycling and the difficulty of detecting amagmatic orogens in the detrital zircon record. The data obtained in this study allows us to better understand the association between exhumation of sources and their detrital zircon signatures in modern rivers that drain a part of the EC The results obtained allowing us to make first-order observations about the provenance signal in modern rivers on the east flank of the Eastern Cordillera, our data clearly show that the zircon U-Pb age spectra of the Paleozoic through Mesozoic sedimentary section being eroded is related to sources in the Amazon Craton, the magmatic Paleozoic basement of the same EC, and exhumation of proximal Precambrian basement blocks. On the other hand, the Magdalena River sample indicates the presence of these same EC sources plus the addition of younger Permo-Triassic and Jurassic zircons derived from reworking of Upper Magdalena Valley sedimentary units and/or the crystalline basement of the CC. The ZFT data presented here complements the existing record of recent exhumation for the EC and the Magdalena River at Girardot on the western flank of the EC. Each individual dating technique offers unique information with respect to provenance and exhumation.
Fission track length histograms from sedimentary samples may contain tracks generated before the time of deposition. They may originate from various source areas with their own thermal histories. After deposition they share thermal history. Inherited tracks, mainly represented by the shortest tracks, are mixed with the young post–sedimentary tracks due to anisotropic annealing, various grain chemistry and uncertainties of measure. Inherited tracks complicate calculating the thermal history. Deconvolution from time sequence analysis  is used to separate pre–and post–depositional tracks. Deconvolution reduces the length spread caused by the uncertainties. Hereby tracks are organized according to age, the short tracks being older than the long tracks.
The evolution and denudation histories of passive margins around the world has been subject to many studies involving thermochronology over the last thirty years. This, mostly with emphasis on margins showing high elevation, low-relief plateaus. Thermochronology, and even more, multi-method thermochronology has hereby been proven to be an ideal tool to reveal information concerning the tectonic evolution of passive margins. One outcome returning from these studies, is the evidence of tectonic activity (exhumation and denudation and/or reburial) after continent break-up and the formation of the passive margin. The processes attributed to this tectonic activation are diverse, including flexural riftflank uplift, magmatic underplating, continental and oceanic far-field stress and significant climate change as the continental break-up progresses. Many uncertainties concerning the geodynamic context of (elevated) passive margins however still remain, as is discussed in a recent review by Green et al. (2018). The Araçuaí – West Congo orogen (AWCO) was formed during the Pan-African – Brasiliano orogeny (late Neoproterozoic to early Cambrian), confined in an embayment of the São Francisco – Congo craton (SFCC). During the Early Cretaceous (~130 Ma), the AWCO separated, due to the opening of the South Atlantic Ocean and the break-up of Gondwana. Today we find the eastern part of the AWCO on the African continent as the West Congo Belt (Angola, D.R. Congo, Congo Brazzaville and Gabon), and its western counterpart, the Araçuaí orogenic belt, on the South American continent (east Brazil). The Araçuaí orogen and the West Congo Belt are both bordered by the São Francisco craton to the west and the Congo craton to the east, respectively. The unique setting of this region resulted into two passive margins, with a range of structures inherited from its Proterozoic formation history, edged by cratonic domains. Furthermore, these margins have dissimilar morphology, the Brazilian margin having the typical elevated, low-relief morphology, and the Congolese margin close to sea-level. In this study we will compare the Araçuaí and the West Congo Belt in terms of their thermal history. We analysed apatite fission tracks in basement samples from transects on both side of the South Atlantic (east Brazil – D.R. Congo). The Brazilian samples reveal AFT mean ages between c. 100 and 50 Ma and mean track lengths in range 12 to 14 μm, with a majority over 13 μm. We interpreted a major denudation event around 80 Ma, which is in agreement with other studies from east Brazil. This is often correlated and attributed to a drastic change in spreading geometry of the South Atlanic around ~75 – 80 Ma. For the Congolese AFT ages, we expect at least ages related to the opening of the South Atlantic (c. 130–100 Ma). If the 80 Ma event in Brazil is linked to geometry changes in the South Atlantic, this is also expected to be found in the West Congo Belt.
New and recently published U-Pb, muscovite-biotite 40Ar/39Ar, K-feldspar MDD 40Ar/39Ar, zircon and apatite (U-Th)/He, and apatite fission-track data were compiled and inverted for a comprehensive, thermal history of southern Baffin Island, Canada. This work is a contribution to the Geo-mapping for Energy and Minerals (GEM) Baffin Island initiative and Trans-GEM synthesis of the Phanerozoic exhumation history of the Canadian Shield. Southern Baffin Island is comprised of Archean plutonic basement metamorphosed during the Trans-Hudson Orogeny. Monazite U-Pb dating on the Hall Peninsula suggest peak metamorphic conditions were at ca. 1850-1820 Ma and remained at >550ºC ca. 100 My after the thermal peak , while 40Ar/39Ar hydrous mineral ages and modeling suggest temperatures remained at >420-450ºC ca. 150-200 My after peak conditions . New apatite U-Pb age populations are in agreement and range from 1674 ± 35 Ma to 1796 ± 75 Ma (2σ), suggesting elevated post-THO temperatures at ~450ºC. During the Meso- to Neoproterozoic the Hall Peninsula region experienced prolonged slow cooling on the order of ≤0.5ºC/My until ca. 1000 Ma when cooling accelerated to ~1ºC/My due to supercontinent Rodinia assembly. Sedimentary sequences place minimum timing constraints on basement rocks being at near-surface conditions in the early Paleozoic. Preliminary results from apatite fission-track data suggest that southwest Baffin (Meta-Incognita and Hall Peninsula) was fully exhumed by Paleozoic time during basement uplift that likely exploited preexisting, regional structures. Nearby Foxe Basin sediments suggest this region of the Canadian Shield was exhumed by the Late Ordovician (ca. 450 Ma) and either remained topographically high, or experienced minor burial during subsequent continental-wide transgression and shallow marine carbonate deposition in the Silurian-Devonian. AFT data from a >1890 Ma volcanic tuff cutting the Paleoproterozoic Hoare Bay Group sediments on the easternmost Cumberland Peninsula record rapid cooling in the Jurassic. The cooling signal recorded along Cumberland Peninsula is likely due to early crustal thinning related to rifting of Greenland from mainland Canada during Pangaea breakup and aligns with a model of rift-flank uplift. AFT models are in agreement with ages of dike swarms in West Greenland given as evidence by  for the onset of rift extension. The summarized cooling history of southern Baffin Island suggests post-THO cooling rates of ~1-3ºC/My from ca. 1700-1500 Ma, followed by slow cooling and Mesoproterozoic cooling pulses at ca. 1300 Ma and ca. 1000-950 Ma, likely due to Rodinia assembly. Rocks have been at temperatures <100ºC since ca. 500 Ma.  Skipton et al., 2016, J. of Petrology, v.57(8);  Skipton et al., 2017, Lithos, v.284;  Larsen et al., 2009, J. Geol. Soc., v.166.