Mineral inclusions in zircons of para- and orthogneiss from pre-pilot drillhole CCSD-PP1, Chinese Continental Scientific Drilling Project

Fulai Liu, Zhiqin Xu, Ikuo Katayama, Jingsui Yang, Shigenori Maruyama, J. G. Liou

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

The pre-pilot drillhole CCSD-PPI, Chinese Continental Scientific Drilling Project (CCSD), with depth of 432 m, is located in the Donghai area in the southwestern Sulu terrane. The core samples are mainly comprised of paragneiss, orthogneiss and ultramafic rock with minor intercalated layers of eclogite and phengite-bearing kyanite quartzite. All analyzed paragneiss and orthogneiss samples were overprinted on amphibolite facies retrograde metamorphism. Coesite and coesite-bearing ultrahighpressure (UHP) mineral assemblages were identified by Raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from paragneiss, eclogite and phengite-bearing kyanite quatzite samples. In the paragneiss samples, UHP mineral inclusion assemblages mainly consist of Coe + Omp+ Grt+ Phe, Coe + Jd + Phe + Ap preserved in the mantles (M) and rims (R) of zircons. These UHP mineral inclusion assemblages yield temperatures of 814-852 °C and pressures of ≥28 kbar, presenting the P-T condition of UHP peak metamorphism of these country rocks. According to the mineral inclusions and cathodoluminescence images of zircons, the orthogneisses can be divided into two types: UHP (OGI) and non-UHP (OG2). In OGI orthogneisses, low-pressure mineral inclusion assemblage, mainly consisting of Qtz + Phe +Ab +Ksp + Ap, were identified in zircon cores (C), while coesite or coesite-bearing UHP mineral inclusions were identified in the mantles (M) and rims (R) of the same zircons. These features suggest that the OG1 orthogneisses, together with the paragneisses, phengitebearing kyanite quartzite and eclogite experienced widespread UHP metamorphism in the Sulu terrane. However, in the zircons of OG2 orthogneiss samples, no UHP mineral inclusions were found. Inclusions mainly comprised Qtz + Phe + Ap and were identified in cores (C), mantles (M) and rims (R) of OG2 zircons; the cathdoluminescence images of all analyzed zircons showed clear zonings from cores to rims. These features indicate that the OG2 orthogneisses in pre-pilot drillhole CCSD-PP1 did not experience UHP metamorphism. Therefore, we should not rule out the possibility that some orthogneisses in Sulu terrane might represent relatively low-pressure granitic intrusives emplaced after the UHP event.

Original languageEnglish
Pages (from-to)199-215
Number of pages17
JournalLithos
Volume59
Issue number4
DOIs
Publication statusPublished - 2001
Externally publishedYes

Fingerprint

Chinese Continental Scientific Drilling Project
orthogneiss
Minerals
Drilling
zircon
Bearings (structural)
coesite
mineral
kyanite
eclogite
terrane
metamorphism
phengite
quartzite
mantle
low pressure
Rocks
retrograde metamorphism
Core samples
Zoning

Keywords

  • Mineral inclusions
  • Orthogneiss
  • Paragneiss
  • Pre-pilot drillhole CCSD-PP1
  • Zircons

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Mineral inclusions in zircons of para- and orthogneiss from pre-pilot drillhole CCSD-PP1, Chinese Continental Scientific Drilling Project. / Liu, Fulai; Xu, Zhiqin; Katayama, Ikuo; Yang, Jingsui; Maruyama, Shigenori; Liou, J. G.

In: Lithos, Vol. 59, No. 4, 2001, p. 199-215.

Research output: Contribution to journalArticle

Liu, Fulai ; Xu, Zhiqin ; Katayama, Ikuo ; Yang, Jingsui ; Maruyama, Shigenori ; Liou, J. G. / Mineral inclusions in zircons of para- and orthogneiss from pre-pilot drillhole CCSD-PP1, Chinese Continental Scientific Drilling Project. In: Lithos. 2001 ; Vol. 59, No. 4. pp. 199-215.
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AU - Katayama, Ikuo

AU - Yang, Jingsui

AU - Maruyama, Shigenori

AU - Liou, J. G.

PY - 2001

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N2 - The pre-pilot drillhole CCSD-PPI, Chinese Continental Scientific Drilling Project (CCSD), with depth of 432 m, is located in the Donghai area in the southwestern Sulu terrane. The core samples are mainly comprised of paragneiss, orthogneiss and ultramafic rock with minor intercalated layers of eclogite and phengite-bearing kyanite quartzite. All analyzed paragneiss and orthogneiss samples were overprinted on amphibolite facies retrograde metamorphism. Coesite and coesite-bearing ultrahighpressure (UHP) mineral assemblages were identified by Raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from paragneiss, eclogite and phengite-bearing kyanite quatzite samples. In the paragneiss samples, UHP mineral inclusion assemblages mainly consist of Coe + Omp+ Grt+ Phe, Coe + Jd + Phe + Ap preserved in the mantles (M) and rims (R) of zircons. These UHP mineral inclusion assemblages yield temperatures of 814-852 °C and pressures of ≥28 kbar, presenting the P-T condition of UHP peak metamorphism of these country rocks. According to the mineral inclusions and cathodoluminescence images of zircons, the orthogneisses can be divided into two types: UHP (OGI) and non-UHP (OG2). In OGI orthogneisses, low-pressure mineral inclusion assemblage, mainly consisting of Qtz + Phe +Ab +Ksp + Ap, were identified in zircon cores (C), while coesite or coesite-bearing UHP mineral inclusions were identified in the mantles (M) and rims (R) of the same zircons. These features suggest that the OG1 orthogneisses, together with the paragneisses, phengitebearing kyanite quartzite and eclogite experienced widespread UHP metamorphism in the Sulu terrane. However, in the zircons of OG2 orthogneiss samples, no UHP mineral inclusions were found. Inclusions mainly comprised Qtz + Phe + Ap and were identified in cores (C), mantles (M) and rims (R) of OG2 zircons; the cathdoluminescence images of all analyzed zircons showed clear zonings from cores to rims. These features indicate that the OG2 orthogneisses in pre-pilot drillhole CCSD-PP1 did not experience UHP metamorphism. Therefore, we should not rule out the possibility that some orthogneisses in Sulu terrane might represent relatively low-pressure granitic intrusives emplaced after the UHP event.

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