Restrepo-Moremo,S.A., Foster,D.A., Stockli,D.F. and Parra-Sanchez（aの頭に´）,L.N.(2009): Long-term erosion and exhumation of the “Altiplano Antioqueno（後のnの頭に〜）”, Northern Andes (Colombia) from apatite (U-Th)/He thermochronology. Earth and Planetary Science Letters, 278, 1-12.

『燐灰石（U-Th）/He熱年代測定法による北部アンデス（コロンビア）の『アンチオケーニョ高原』の長期的浸食と削剥』

『Abstract
　The Antioqueno（後のnの頭に〜） Plateau (AP) in the northern Cordillera Central, Colombia, is the largest high elevation erosional surface in the Northern Andes. Apatite (U-Th)/He thermochronometry (AHe) of samples collected from two elevation profiles spanning 〜2 km of exhumed crustal sections reveal the long-term erosional exhumation of the AP. sample profiles exhibit AHe ages that increase with elevation from ca. 22 Ma (〜760 m) at the bottom of regional scarps to ca. 49 Ma (〜2350 m) on top of the AP. A marked inflection point in age versus elevation data at ca. 25 Ma defines the bottom of the exhumed post-Oligocene He partial retention zone (He-PRZ). Elevation-invariant ages below ca. 25 Ma record the onset of rapid exhumation and surface uplift of the AP that led to river incision. A subtle change in slope within the He-PRZ, ca. 41 Ma, is interpreted as a less intense, exhumation-related cooling episode. These two exhumation pulses coincide with the Proto-Andina and Pre-Andina orogenic phases previously proposed for the Colombian Andes, and are synchronous with tectonically driven exhumation events reported for the Peruvian, Bolivian and Argentinean Andes, and for some orogenic systems in the Caribbean. The pulses are correlated with variations in the rates of convergence between Nazca (Farallon) and South America documented for the Middle Eocene and the Late Oligocene suggesting continental-scale controls on uplift and denudation throughout the Andean range. AHe data provide an average erosion rate of 〜0.04 mm/yr for the last 25 million years. Erosion rates during the exhumation pulses were in the order of 〜0.2-0.4 mm/yr. Similarity between AHe profiles indicates the whole AP was uplifted and exhumed as a coherent structural block, corroborating previous structural evidence for the rigidity and coherence of this crustal block in the Northern Andes. Our results are in agreement with tectonostratigraphic data in the Magdalena and Cauca basins and with proposed scenarios for paleogeographic evolution in the Northern Andes.

Keywords: (U-Th)/He dating; relict landscape; morphotectonics; erosion/exhumation rates; Northern Andes; Antioqueno（後のnの頭に〜） Plateau』

1. Introduction
2. Study site: the Antioqueno（後のnの頭に〜） Plateau
　2.1. Physiographic and geologic overview
　2.2. The Antioqueno（後のnの頭に〜） Plateau
　2.3. Tectonic setting
3. Apatite (U-Th)/He thermochronology
4. Methods
5. Results
6. Discussion and interpretation
Acknowledgements
Appendix A. Supplementary data
References

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