Sr-Nd isotopes data of the Neoproterozoic-Paleozoic pelites, northwest Argentina and its implications for the early Paleozoic evolution of SW Gondwana margin

MANUELA DE OLIVEIRA CARVALHO1; ANDREA BARRIENTOS; AGNES IMPICCINI; NATALIA HAUSER; MÓNICA HEILBRONT ; CLAUDIO DE MORISSON VALERIANO; APARICIO GONZALEZ PAMELA

Río Negro

Congreso; Reunión Argentina de Sedimentología; 2018

AAS

The Sr, Sm andNd isotopes results of twelve samples from the main pelitic units ofPuncoviscana complex, Mesón, Santa Victoria Groups Mojotoro Porphyry Granite arepresented. In the analyzed samples weremeasured values of 143Nd/144Nd between 0.51183 and0.5121, of 147Sm/144Nd from 0.1077 to 0.1269, of 87Sr/86Srbetween 0.7316 and 0.8295, and εNd(t) exhibit consistently negative valuesvarying from -8.7 and -15.7. These intervals plotted in an 87Sr/86Srversus εNd(t) diagram are concentrated in the field of very radiogenic data, wherethe more radiogenic values are related to the Chachapoyas Formation rocks andto the Guachos Formation, which has also the less radiogenic sample. A changeis observed in the upper units from the Puncoviscana Complex indicating theparticipation of less radiogenic sediments as compared to the lower ChachapoyasFormation.