Two metamorphic complexes of different lithology and structure occur in the coast ranges of central Chile. The Tanume metamorphic complex to the east belongs to a low P-T series of sillimanite-cordierite gneisses derived from a continental platform clastic sedimentary sequence and gives a whole-rock isochron age of 347 + or - 32 m.y. whereas the accreted Pichilemu complex to the west consists of stilpnomelane-bearing cherts, crossite-bearing metabasic rocks and siliceous metapelites, with an age of 311 + or - 10 m.y. Different provenance of the protoliths is indicated by the higher 87Sr/ 86Sr initial ratios of the Tanume rocks (0.7124 + or - 0.0007) relative to the Pichilemu rocks (0.7060 + or - 0.0005), which were more affected than the former by the main phase of deformation and metamorphism in the area.-R.A.H.
|Number of pages||8|
|Journal||Journal of the Geological Society|
|Publication status||Published - 1984|
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Earth and Planetary Sciences (miscellaneous)
- Environmental Science(all)