Geochemical evolution of Cenozoic arc-related magmas in Southern Central and North Patagonian Andes

LITVAK, VANESA D.; IANNELLI, SOFÍA B.; FERNÁNDEZ PAZ, LUCÍA; POMA, STELLA; FOLGUERA, ANDRÉS

Concepción

Congreso; XV Congreso Geológico Chileno; 2018

Universidad de Concepción

Geochemical variations in arc-related magmas allow correlating their magmatic evolution with changes in the geodynamic context􀁒􀁉􀀃􀁗􀁋􀁈􀀃􀀤􀁑􀁇􀁈􀁄􀁑􀀃􀁖􀁘􀁅􀁇􀁘􀁆􀁗􀁌􀁒􀁑􀀃􀁝􀁒􀁑􀁈􀀑􀀃􀀷􀁋􀁌􀁖􀀃􀁚􀁒􀁕􀁎􀀃􀁉􀁒􀁆􀁘􀁖􀁈􀁖􀀃􀁒􀁑􀀃􀀦􀁈􀁑􀁒􀁝􀁒􀁌􀁆􀀃􀁗􀁌􀁐􀁈􀁖􀀏􀀃􀁆􀁒􀁐􀁓􀁄􀁕􀁌􀁑􀁊􀀃􀁊􀁈􀁒􀁆􀁋􀁈􀁐􀁌􀁆􀁄􀁏􀀃􀁈􀁙􀁒􀁏􀁘􀁗􀁌􀁒􀁑􀀃􀁒􀁉􀀃􀁄􀁕􀁆􀀐􀁕􀁈􀁏􀁄􀁗􀁈􀁇􀀃􀁓􀁕􀁒􀁇􀁘􀁆􀁗􀁖􀀃􀁗􀁋􀁕􀁒􀁘􀁊􀁋􀀃 􀁇􀁌􀁉􀁉􀁈􀁕􀁈􀁑􀁗􀀃 􀀤􀁑􀁇􀁈􀁄􀁑􀀃 􀁖􀁈􀁊􀁐􀁈􀁑􀁗􀁖􀀏􀀃 􀁌􀁑􀁆􀁏􀁘􀁇􀁌􀁑􀁊􀀃 􀁗􀁋􀁒􀁖􀁈􀀃 􀁏􀁒􀁆􀁄􀁗􀁈􀁇􀀃 􀁅􀁒􀁗􀁋􀀃 􀁌􀁑􀀃 􀁄􀀃 􀁉􀁕􀁒􀁑􀁗􀁄􀁏􀀃 􀁄􀁑􀁇􀀃 􀁌􀁑􀀃 􀁄􀀃 􀁕􀁈􀁗􀁕􀁒􀁄􀁕􀁆􀀃 􀁓􀁒􀁖􀁌􀁗􀁌􀁒􀁑􀀏􀀃 􀁗􀁒􀁊􀁈􀁗􀁋􀁈􀁕􀀃 􀁚􀁌􀁗􀁋􀀃 􀁄􀁏􀁎􀁄􀁏􀁌􀁑􀁈􀀃retroarc volcanism associated with arc dynamics. During Paleocene to middle Eocene arc magmatism along the Southern CentralAndes was constrained to the volcanic front and showed variable slab input. On the contrary, in the North Patagonian Andes,􀁌􀁑􀁗􀁕􀁄􀁓􀁏􀁄􀁗􀁈􀀃􀁄􀁏􀁎􀁄􀁏􀁌􀁑􀁈􀀐􀁏􀁌􀁎􀁈􀀃􀁐􀁄􀁊􀁐􀁄􀁖􀀃􀁄􀁕􀁈􀀃􀁕􀁈􀁊􀁌􀁖􀁗􀁈􀁕􀁈􀁇􀀃􀁌􀁑􀀃􀁗􀁋􀁈􀀃􀁕􀁈􀁗􀁕􀁒􀁄􀁕􀁆􀀃􀁝􀁒􀁑􀁈􀀑􀀃􀀥􀁜􀀃􀁏􀁄􀁗􀁈􀀃􀀨􀁒􀁆􀁈􀁑􀁈􀀃􀁗􀁒􀀃􀁐􀁌􀁇􀁇􀁏􀁈􀀃􀀲􀁏􀁌􀁊􀁒􀁆􀁈􀁑􀁈􀀃􀁗􀁌􀁐􀁈􀁖􀀏􀀃􀁏􀁒􀁚􀀃􀁙􀁒􀁏􀁘􀁐􀁈􀁖􀀃􀁒􀁉􀀃􀁄􀁕􀁆􀀃volcanism were erupted along the Andes with mostly tholeiitic composition. Arc volcanism changed to a more typical tholeiitic􀁗􀁒􀀃􀁆􀁄􀁏􀁆􀀐􀁄􀁏􀁎􀁄􀁏􀁌􀁑􀁈􀀃􀀤􀁑􀁇􀁈􀁄􀁑􀀐􀁗􀁜􀁓􀁈􀀃􀁅􀁜􀀃􀁏􀁄􀁗􀁈􀀃􀀲􀁏􀁌􀁊􀁒􀁆􀁈􀁑􀁈􀀃􀁌􀁑􀀃􀁗􀁋􀁈􀀃􀀶􀁒􀁘􀁗􀁋􀁈􀁕􀁑􀀃􀀦􀁈􀁑􀁗􀁕􀁄􀁏􀀃􀀤􀁑􀁇􀁈􀁖􀀏􀀃􀁄􀁖􀁖􀁒􀁆􀁌􀁄􀁗􀁈􀁇􀀃􀁚􀁌􀁗􀁋􀀃􀁗􀁋􀁈􀀃􀁅􀁕􀁈􀁄􀁎􀁘􀁓􀀃􀁒􀁉􀀃􀁗􀁋􀁈􀀃􀀩􀁄􀁕􀁄􀁏􀁏􀂵􀁑􀀃􀁓􀁏􀁄􀁗􀁈􀀞􀀃meanwhile, arc-derived magmas in North Patagonia still showed mostly tholeiitic composition. Arc magmatism by Miocene to􀁐􀁌􀁇􀁇􀁏􀁈􀀃􀀳􀁏􀁌􀁒􀁆􀁈􀁑􀁈􀀃􀁗􀁌􀁐􀁈􀁖􀀃􀁌􀁑􀀃􀀶􀁒􀁘􀁗􀁋􀁈􀁕􀁑􀀃􀀦􀁈􀁑􀁗􀁕􀁄􀁏􀀃􀀤􀁑􀁇􀁈􀁖􀀃􀁖􀁋􀁒􀁚􀀃􀁗􀁜􀁓􀁌􀁆􀁄􀁏􀀃􀁆􀁄􀁏􀁆􀀐􀁄􀁏􀁎􀁄􀁏􀁌􀁑􀁈􀀃􀁉􀁈􀁄􀁗􀁘􀁕􀁈􀁖􀀏􀀃􀁚􀁋􀁌􀁏􀁈􀀃􀁄􀁕􀁆􀀐􀁇􀁈􀁕􀁌􀁙􀁈􀁇􀀃􀁓􀁕􀁒􀁇􀁘􀁆􀁗􀁖􀀃􀁚􀁈􀁕􀁈􀀃􀁈􀁛􀁓􀁄􀁑􀁇􀁈􀁇􀀃to the east, associated with a progressive shallow subduction regime, developed both in the present-day Pampean-Chilean flatslabsegment (􀗾28°-33°S) and the late Miocene Payenia shallow subduction segment (􀗾33°-38°S). Particularly in the Pampean-􀀦􀁋􀁌􀁏􀁈􀁄􀁑􀀃􀁖􀁈􀁊􀁐􀁈􀁑􀁗􀀏􀀃􀁐􀁌􀁇􀁇􀁏􀁈􀀃􀀰􀁌􀁒􀁆􀁈􀁑􀁈􀀃􀁗􀁒􀀃􀁏􀁄􀁗􀁈􀀃􀀰􀁌􀁒􀁆􀁈􀁑􀁈􀀃􀁄􀁕􀁆􀀃􀁕􀁒􀁆􀁎􀁖􀀃􀁖􀁋􀁒􀁚􀀃􀁗􀁕􀁄􀁆􀁈􀀃􀁈􀁏􀁈􀁐􀁈􀁑􀁗􀁖􀀏􀀃􀁄􀁑􀁇􀀃􀀶􀁕􀀏􀀃􀀱􀁇􀀃􀁚􀁋􀁒􀁏􀁈􀀐􀁕􀁒􀁆􀁎􀀃􀁌􀁖􀁒􀁗􀁒􀁓􀁌􀁆􀀃􀁕􀁄􀁗􀁌􀁒􀁖􀀃􀁄􀁑􀁇􀀃􀁌􀁑􀀐􀁖􀁌􀁗􀁘􀀃Hf and O isotopic composition that display a trend towards an increase of crustal contributions, either by assimilation during􀁐􀁄􀁊􀁐􀁄􀀃􀁄􀁖􀁆􀁈􀁑􀁗􀀃􀁗􀁋􀁕􀁒􀁘􀁊􀁋􀀃􀁄􀀃􀁗􀁋􀁌􀁆􀁎􀀃􀁆􀁕􀁘􀁖􀁗􀀃􀁒􀁕􀀃􀁏􀁌􀁑􀁎􀁈􀁇􀀃􀁗􀁒􀀃􀁉􀁒􀁕􀁈􀁄􀁕􀁆􀀃􀁖􀁘􀁅􀁇􀁘􀁆􀁗􀁌􀁒􀁑􀀃􀁈􀁕􀁒􀁖􀁌􀁒􀁑􀀃􀁄􀁑􀁇􀀒􀁒􀁕􀀃􀁖􀁈􀁇􀁌􀁐􀁈􀁑􀁗􀀃􀁆􀁒􀁑􀁗􀁕􀁌􀁅􀁘􀁗􀁌􀁒􀁑􀁖􀀃􀁌􀁑􀁗􀁒􀀃􀁗􀁋􀁈􀀃􀁐􀁄􀁑􀁗􀁏􀁈􀀃􀁚􀁈􀁇􀁊􀁈􀀑􀀃􀀦􀁒􀁈􀁙􀁄􀁏􀀃􀁄􀁕􀁆􀀃􀁐􀁄􀁊􀁐􀁄􀁗􀁌􀁖􀁐􀀃􀁌􀁑􀀃􀀱􀁒􀁕􀁗􀁋􀀃􀀳􀁄􀁗􀁄􀁊􀁒􀁑􀁌􀁄􀀃􀁄􀁏􀁖􀁒􀀃􀁖􀁋􀁒􀁚􀁈􀁇􀀃􀁆􀁄􀁏􀁆􀀐􀁄􀁏􀁎􀁄􀁏􀁌􀁑􀁈􀀃􀁊􀁈􀁒􀁆􀁋􀁈􀁐􀁌􀁆􀁄􀁏􀀃􀁉􀁈􀁄􀁗􀁘􀁕􀁈􀁖􀀃􀁅􀁘􀁗􀀃􀁚􀁄􀁖􀀃􀁐􀁄􀁌􀁑􀁏􀁜􀀃􀁖􀁓􀁄􀁗􀁌􀁄􀁏􀁏􀁜􀀃􀁕􀁈􀁖􀁗􀁕􀁌􀁆􀁗􀁈􀁇􀀃to the main Andean axis. Overall, geochemical evolution of Cenozoic arc magmas reflects the direct influence of the variablegeodynamic parameters along Southern Central and North Patagonian Andes.