Contact metamorphism of the Daulet Suite by solid-state emplacement of the Kokchetav UHP-HP metamorphic slab

Masaru Terabayashi, Tsutomu Ota, Hiroshi Yamamoto, Yoshiyuki Kaneko

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The andalusite-sillimanite-type low-pressure Daulet Suite underlies the Kokchetav ultrahigh-pressure-high-pressure (UHP-HP) massif of northern Kazakhstan. The Daulet Suite is composed of pelitic-psammitic gneisses or schists an quartz schist with minor amounts of metacarbonate and metabasite. About 300 thin sections were examined from the, Daulet metapelites: rocks were divided into two mineral zones. Zone A is characterized by andalusite + cordierite + biotite, and zone B by sillimanite + cordierite + biotite with excess K-feldspar, quartz, and plagioclase in both zones. K-feldspar appears with andalusite at lower temperatures than the first formation of sillimanite. Pressure-temperature conditions of the Daulet metamorphism range from 580 to 680°C at a nearly constant pressure of ∼2 kbar. Comparison of compositions of solid-solution minerals with a buffered assemblage indicates that the metamorphic grade increases towards the boundary with the overlying UHP-HP unit. Detailed mapping revealed that the primary structure of both the Kokchetav UHP-HP massif and its surrounding units is subhorizontal; the UHP-HP unit has been thrust over the Daulet Suite with a top-to-the-north movement. The thermal structure of the Daulet Suite is subhorizontal and metamoorphic grade increases upwards-i.e., toward the boundary with the UHP-HP unit-whereas the thermobaric maximum of the UHP-HP unit occurs at an intermediate structural level, The upward increase in metamorphic grade within the Daulet Suite implies contact metamorphism by the tectonic juxtaposition of the "hot" Kokchetav UHP-HP unit at shallow crustal levels.

Original languageEnglish
Pages (from-to)819-830
Number of pages12
JournalInternational Geology Review
Volume44
Issue number9
Publication statusPublished - Sep 2002
Externally publishedYes

Fingerprint

contact metamorphism
slab
emplacement
andalusite
sillimanite
cordierite
schist
feldspar
biotite
quartz
solid state
metabasite
metapelite
thermal structure
mineral
solid solution
thin section
low pressure
plagioclase
metamorphism

ASJC Scopus subject areas

  • Geology

Cite this

Contact metamorphism of the Daulet Suite by solid-state emplacement of the Kokchetav UHP-HP metamorphic slab. / Terabayashi, Masaru; Ota, Tsutomu; Yamamoto, Hiroshi; Kaneko, Yoshiyuki.

In: International Geology Review, Vol. 44, No. 9, 09.2002, p. 819-830.

Research output: Contribution to journalArticle

Terabayashi, Masaru ; Ota, Tsutomu ; Yamamoto, Hiroshi ; Kaneko, Yoshiyuki. / Contact metamorphism of the Daulet Suite by solid-state emplacement of the Kokchetav UHP-HP metamorphic slab. In: International Geology Review. 2002 ; Vol. 44, No. 9. pp. 819-830.
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