Geochronology and facies analysis of subaqueous volcanism of lower ordovician, Famatinian arc, Argentina

ARMAS, P.,; CRISTOFOLINI, E.,; OTAMENDI, JUAN ENRIQUE; TIBALDI, A.; BARZOLA, M.,; CAMILLETTI, G.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018

0895-9811

The Chuschín formation is asedimentary-volcanic succession of the Famatina System associated with subduction-relatedarc magmatism. This formation developed along the western margin of Gondwanaduring the early and middle Ordovician. The interpretation of the Chuschínformation is significant for the understanding of the Famatinian arc. Thisstudy provides a detailed facies analysis, which allows characterizing thedeposits as well as defining some of the characteristics of the volcanism andsedimentation. Coherent, autoclastic, peperitic, pyroclastic and volcaniclasticfacies were recognized between the different volcanic facies. Thecharacteristics and relationships between these facies indicate events ofeffusive subaqueous volcanism as well as explosive volcanism showingpredominantly high temperature features. Both types of volcanism are interbeddedwith volcanogenic deposits and epiclastic sediment that are associated mainlywith turbidity currents. The magmatic and volcanic rocks are dominantlysubalkaline, weakly peraluminous and silicic. Two new U-Pb zirconcrystallization ages on volcanic rocks from the Chuschín Formation show thatthis section of the Famatinian arc formed between 463 and 469 Ma (Middle Ordovician).