Caledonian strike-slip terrane accretion in W. Ireland: insights from very low-grade metamorphism (illite–chlorite crystallinity and b0 parameter)

摘要: Analysis of pelites with detrital white-micas in the Clew Bay-Galway Bay segment Irish Caledonides indicates that b0 data from whole-rock and < 2 μm fractions generally show differences smaller than errors method, irrespective (001) illite crystallinity values, probably due to metamorphic recrystallization. Intermediate pressure metamorphism Ordovician-Silurian Group slow subduction, allowing partial thermal re- equilibration before exhumation. In contrast, Croagh Patrick Laurentian shelf-sediments underwent high-pressure alteration, suggesting rapid subduction/exhumation, synchronous strike- slip faulting. The Murrisk Group, which high-intermediate an Ordovician back-arc, forms a separate terrane north also Lough Nafooey Tourmakeady groups Rosroe Formation south, low-intermediate alteration occurred. These, together Silurian North Galway may have undergone heating movement over or deposition on hot Gowlaun Detachment as Connemara Dalradian was exhumed. South consistent its inferred subduction environment. Evidence contact known buried late- post-Caledonian granitoid plutons, has been found Bay, Louisburg-Clare Island, Patrick, groups. These evidence lower-pressure surrounding country-rocks.