Thermobarometric and40Ar/39Ar geochronologic constraints on Eohimalayan metamorphism in the Dinggyê area, southern Tibet

Kip Hodges, W. E. Hames, W. Olszewski, B. C. Burchfiel, L. H. Royden, Z. Chen

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

Mineral assemblages in the Dinggyê area of southern Tibet (28°N; 88°E) provide new insights regarding the poorly understood "Eohimalayan" metamorphic event in the eastern Himalayan orogen. Major element partitioning thermobarometry of pelitic rocks indicates temperatures of 750-830 K at depths of 14±3 km, consistent with the presence of kyanite, sillimanite, and andalusite schists in the area. Laser and resistance furnace40Ar/39Ar analyses of hornblendes from intercalated amphibolites yield closure ages of 25 Ma. Overlap between the probable range of Ar closure temperatures for these hornblendes and the metamorphic temperatures estimated through thermobarometry suggests that Eohimalayan metamorphism in the Dinggyê area occurred in Late Oligocene time, no more than about 10 million years before the main or "Neohimalayan" phase of metamorphism in Early to Middle Miocene time. Muscovite, biotite, and K-feldspar40Ar/39Ar ages indicate an important episode of rapid cooling between 16 and 13 Ma, which is interpreted as a signature of tectonic denudation related to movement on N-dipping extensional structures of the South Tibetan detachment system.

Original languageEnglish (US)
Pages (from-to)151-163
Number of pages13
JournalContributions to Mineralogy and Petrology
Volume117
Issue number2
DOIs
StatePublished - Jun 1994
Externally publishedYes

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Tibet
hornblende
metamorphism
closure temperature
closures
andalusite
kyanite
sillimanite
denudation
muscovite
schist
Oligocene
biotite
partitioning
laser
temperature
Miocene
Tectonics
cooling
dipping

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences(all)
  • Environmental Science(all)

Cite this

Thermobarometric and40Ar/39Ar geochronologic constraints on Eohimalayan metamorphism in the Dinggyê area, southern Tibet. / Hodges, Kip; Hames, W. E.; Olszewski, W.; Burchfiel, B. C.; Royden, L. H.; Chen, Z.

In: Contributions to Mineralogy and Petrology, Vol. 117, No. 2, 06.1994, p. 151-163.

Research output: Contribution to journalArticle

Hodges, Kip ; Hames, W. E. ; Olszewski, W. ; Burchfiel, B. C. ; Royden, L. H. ; Chen, Z. / Thermobarometric and40Ar/39Ar geochronologic constraints on Eohimalayan metamorphism in the Dinggyê area, southern Tibet. In: Contributions to Mineralogy and Petrology. 1994 ; Vol. 117, No. 2. pp. 151-163.
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