Silurian cover, late Precambrian-early Ordovician basement, and the chronology of Silurian orogenesis in the Hermitage Flexure (Newfoundland Appalachians)

Abstract

Redefining the La Poile Group as an Early-Late Silurian (429±2 Ma to 422±2 Ma) terrestrial volcanosedimentary succession and establishing its external relationships has led to its recognition as a cover sequence developed upon a basement complex. Early Silurian granites (429±2 Ma; 430±2 Ma), which are in part synchronous with the accumulation of subaerial cover deposits, are restricted to the sub-La Poile basement and have been affected, in places, by mesozonal synplutonic shear zones. Later Silurian plutons were emplaced syntectonically during regional deformation and dynamothermal metamorphism of the Silurian cover and contemporaneous remobilization of its basement. The Silurian La Poile Group and its underlying Late Precambrian-Early Ordovician basement delimit the southern extent of the medial Ordovician Dunnage Zone in the southwest Hermitage Flexure region of the Newfoundland Appalachians. -from Authors