Metamorphic evolution of the Susunai metabasites in southern Sakhalin, Russian Republic
ABSTRACT The Susunai Complex of southeast Sakhalin represents a subduction‐related accretionary complex of pelitic and basic rocks. Two stages of metamorphism are recognized: (1) a local, low‐P/T event characterized by Si‐poor calcic amphiboles; (2) a regional, high‐ P/T event characterized by pumpe...
| Published in: | Journal of Metamorphic Geology |
|---|---|
| Main Authors: | , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1997
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1525-1314.1997.tb00636.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1525-1314.1997.tb00636.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1525-1314.1997.tb00636.x |
| Summary: | ABSTRACT The Susunai Complex of southeast Sakhalin represents a subduction‐related accretionary complex of pelitic and basic rocks. Two stages of metamorphism are recognized: (1) a local, low‐P/T event characterized by Si‐poor calcic amphiboles; (2) a regional, high‐ P/T event characterized by pumpellyite, actinolite, epidote, sodic amphibole, sodic pyroxene, stilpnomelane and aragonite. The major mineral assemblages of the high‐P/T Susunai metabasites contain pumpellyite + epidote + actinolite + chlorite, epidote + actinolite + chlorite, epidote + Na‐amphibole + Na‐pyroxene + chlorite‐(‐haematite. The Na‐amphibole is commonly magnesioriebeckite. The Na‐pyroxene is jadeite‐poor aegirine to aegirine‐augite. Application of empirically and experimentally based thermobarometers suggests peak conditions of T = 250–300C, P = 4.7–6 kbar. Textural relationships in Susunai metabasite samples and a petrogenetic grid calculated for the Fe 3+ ‐rich basaltic system suggest that pressure and temperature increased during prograde metamorphism. |
|---|