Fragments of the late Paleozoic accretionary complex in central and northern Chile: Similarities and differences as a key to decipher the complexity of the late Paleozoic to Triassic early Andean events

Abstract

Abstract The metamorphic formations that outcrop along the northern and central Chilean coast (26°–39°S) represent the late Paleozoic accretionary complex at the convergent southwestern margin of Gondwana. The characteristics of the HP-LT basal units (Western Series) and the low metamorphic-grade Eastern Series depict a homogeneous margin where the basal and frontal accretionary processes were active between the late Mississippian and the early-middle Permian, respectively. The subsequent stage (c.270–210\xa0Ma) was characterized by the tectonic and magmatism differences along a segmented margin. These changes may be triggered by the basal and frontal accretion of E- to N-MORB oceanic basalts that are present in the accretionary complexes. Both the inland location of the accretionary complexes during the transition to the Andean cycle (Late Triassic), as well as the presence of these voluminous and extended basaltic accreted formations, are consistent with the accretion of oceanic reliefs as a key factor to decipher the early Andean tectonic evolution.