@article{WiederkehrSudoBousquetetal.2009,
  author    = {Wiederkehr, Michael and Sudo, Masafumi and Bousquet, Romain and Berger, Alfons and Schmid, Stefan M.},
  title     = {Alpine orogenic evolution from subduction to collisional thermal overprint : the Ar-40/Ar-39 age constraints from the Valaisan Ocean, central Alps},
  issn      = {0278-7407},
  doi       = {10.1029/2009tc002496},
  year      = {2009},
  abstract  = {The investigated HP/LT metasedimentary units of the Valaisan and adjacent European domains occupy a key position in the Alpine belt for understanding the transition from early subduction-related HP/LT metamorphism to collision-related Barrovian overprint and the evolution of mountain belts in general. The timing of high-pressure metamorphism, subsequent retrogression and following Barrow-type overprint was studied by Ar-40/Ar-39 dating of biotite and several white mica generations that are well characterized in terms of mineral chemistry, texture and associated mineral assemblages. Four distinct age populations of white mica record peak pressure conditions (42-40 Ma) and several stages of subsequent retrograde metamorphic evolution (36-25 Ma). Biotite isotopic analyses yield consistent apparent ages that cluster around 18-16 Ma for the Barrow-type thermal overprint. The recorded isotopic data reveal a significant time gap in the order of some 20 Ma between subduction-related HP/LT metamorphism and collision-related Barrovian overprint, supporting the notion of a polymetamorphic evolution associated with a bimodal P-T path.},
  language  = {en}
}
@article{OzawaTagamiListancoetal.2004,
  author    = {Ozawa, Ayako and Tagami, Takahiro and Listanco, Eddie L. and Arpa, Carmencita B. and Sudo, Masafumi},
  title     = {Initiation and propagation of subduction along the Philippine Trench : evidence from the temporal and spatial distribution of volcanoes},
  issn      = {1367-9120},
  year      = {2004},
  abstract  = {K-Ar ages of 37 samples collected from the Bicol peninsula, the Luzon island, Philippines, were determined by the unspiked sensitivity method in order to constrain the timing of initiation of subduction along the Philippine Trench. The measured K-Ar ages range from 0 to 7 Ma with two old outliers of 27 and 43 Ma. Together with K-Ar ages previously reported on volcanics in Leyte and eastern Mindanao, subduction volcanism has likely propagated from north to south: similar to 6.6 Ma in Bicol and similar to 3.5 Ma in Leyte and its vicinity. The temporal and spatial distribution suggests that the subduction volcanism started earlier in the north than in the south. This is consistent with the southern propagation of subduction along the Philippine Trench from similar to 8 Ma. (C) 2003 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{OzawaTagamiSudo2004,
  author    = {Ozawa, Ayako and Tagami, T. and Sudo, Masafumi},
  title     = {K-Ar geochronology of the temporal change of eruptive style in the eastern Izu peninsula, central Japan},
  issn      = {1038-4871},
  year      = {2004},
  abstract  = {A recent K-Ar study elucidated that eruptive style in the eastern Izu peninsula changed from polygenetic to monogenetic volcano at 0.3-0.2 Ma. To narrow down the time of change, we determined 10 K-Ar ages on Togasayama Andesite of Amagi volcano, the youngest polygenetic volcano in the area, and Togasayama Monogenetic Volcano, one of the oldest monogenetic volcanoes in the area, which overlies a part of the Togasayama Andesite. Dating results showed that the Togasayama Andesite effused at least from 0.34 to 0.20 Ma, whereas the Togasayama Monogenetic Volcano erupted at 0.26- 0.29 Ma, suggesting that the northern part of the Togasayama Andesite effused after the eruption of the Togasayama Monogenetic Volcano. Considering previous data, it is therefore inferred that change of eruptive style in the eastern Izu area occurred during the period 0.29-0.20 Ma, with considerable overlap of both polygenetic and monogenetic volcanism},
  language  = {en}
}