Petrological and mineralogical contrasts of basic lithologies between eclogite and non–eclogite units along the Kokuryo River of the Sanbagawa belt, Central Shikoku, Japan

Serpentinite mélanges occur as thin horizons up to 350 m thick within coherent schists of the Nishisonogi unit of the Nagasaki Metamorphic Complex located in western Kyushu, which represent serpentinite‐hosted exhumation channels within a Cretaceous subduction complex. This study gives the petrography of coherent schists and various tectonic block types embedded in serpentinite or chlorite‐actinolite schist of the mélange. The P–T conditions recorded in these rocks were compared, to clarify a possible exhumation process and style of the Nishisonogi unit. In the mélange, two types of tectonic blocks were recognized based on peak temperature conditions: a lower temperature type (400–590°C) and a higher temperature type (780–830°C), the latter of which shows temperatures higher than those of the coherent schists (370–450°C). The garnet glaucophanite in the coherent schists shows a prograde pressure increment from 0.9 to 2.3 GPa. The serpentinite mélange comprises tectonic blocks with peak temperatures higher than those of the coherent schists, indicating that blocks from the deep structural levels of the lower‐plate underwent tectonic mixing into the mélange during exhumation. Ultrahigh‐pressure (UHP) conditions have not been recorded either in the coherent schists or in the serpentinite mélanges, although microdiamonds have been reported from the Yukinoura mélange located at the western margin of the Nishisonogi unit (Nishiyama et al., Scientific Reports, 2020, 10, 11645). A possible correlation between the Nishisonogi unit and other HP metamorphic rocks or belts (Renge rocks, Suo Belt and Sanbagawa Belt) was examined to conclude that the Nishisonogi unit is a unique paleo‐subduction complex in terms of the coexistence of HP subduction complex with intercalated serpentinite mélanges and a UHP mélange derived from the slab‐mantle interface.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

customersupport@researchsolutions.com

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Petrological and mineralogical contrasts of basic lithologies between eclogite and non–eclogite units along the Kokuryo River of the Sanbagawa belt, Central Shikoku, Japan

Cited by 2 publications

References 72 publications

Local CO2 variation and evolution of metamorphic fluid at the lithologic boundary recorded in Sanbagawa metamorphic rocks, Central Shikoku, Japan

Local CO2 variation and evolution of metamorphic fluid at the lithologic boundary recorded in Sanbagawa metamorphic rocks, Central Shikoku, Japan

Significance of serpentinite‐hosted exhumation channels in a palaeo‐subduction complex, Nishisonogi unit, Nagasaki Metamorphic Complex: P–T trajectories of mélange blocks and coherent schists

Contact Info

Product

Resources

About