Diverse mineral compositions, textures, and metamorphic P-T conditions of the glaucophane-bearing rocks in the Tamayen melange, Yuli belt, eastern Taiwan

作者：Tsai Chin Ho^*; Iizuka Yoshiyuki; Ernst W G

来源：Journal of Asian Earth Sciences, 2013, 63: 218-233.

DOI：10.1016/j.jseaes.2012.09.019

• Glaucophane
• Epidote blueschist
• HP-LT metamorphism
• Amphibole zoning
• Yuli belt
• Tananao Complex

This paper presents new petrologic data for high-pressure, low-temperature (HP-LT) metamorphic rocks at Juisui. We reinterpret the so-called "Tamayen block" (Yang and Wang, 1985) or "Juisui block" (Liou, 1981; Beyssac et al., 2008) as a tectonic melange. It is not a coherent sheet but rather a mixture dominated by greenschist and pelitic schist with pods of serpentinite, epidote amphibolite, and rare blueschist. Four types of glaucophane-bearing rocks are newly recognized in this melange. Type I is in contact with greenschist lacking glaucophane and garnet. Glaucophane is present only as rare inclusions within pargasite. This type records metamorphic evolution from epidote blueschists-, epidote amphibolite-, to greenschist-facies. Type II contains characteristic zoned amphiboles from barroisite core to Mg-katophorite mantle and glaucophane rim, implying an epidote amphibolite-facies stage overprinted by an epidote blueschists-facies one. Type III includes winchite and indicates P-T conditions of about 6-8 kbar, approaching 400 degrees C. Type IV contains paragonite but lacks garnet; amphibole shows a Na-Ca core surrounded by a glaucophane rim. This type shows a high-pressure (?) epidote amphibolite-facies stage overririnted by an epidote blueschists-facies one. Amphibole zoning trends and mineral assemblages imply contradictory P-T paths for the four types of glaucophane-bearing rocks consistent with the nature of a tectonic m lange. The new P-T constraints and petrologic findings differ from previous studies (Liou et al., 1975; Beyssac et al., 2008).

• 出版日期2013-2-15
• 单位东华大学