Reviewing the geochemistry and petrology of the Subcordilleran Plutonic Belt, Early Jurassic magmatic arc in northern Patagonia

CLAUDIA BEATRIZ ZAFFARANA; DARIO ORTS; GLORIA GALLASTEGUI; SUÁREZ, RODRIGO JAVIER; POMA STELLA; PERNICH, SEBASTIÁN; BRENDA ARAMENDÍA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2024

0895-9811

The Subcordilleran Plutonic Belt, formed in Early Jurassic times, is a short-lived batholiththat developed during Gondwana dismembering. In our study, we analyzed both wellknownand potential new localities of the belt of plutonic rocks, considering new wholerockgeochemical data as well as data from the literature. Additionally, new geochemicaldata from five samples and one U-Pb zircon date are presented from the diorites andgranodiorites from the Cerro Catedral, at Bariloche (41°S). The obtained U-Pb age inzircon is Early Jurassic (192±1.5 Ma).The granitoids of the Subcordilleran Plutonic Belt are calc-alkaline, of medium to highpotassium. They exhibit similar alkali content than the granitoids of the Middle Jurassic-Cretaceous Patagonian Batholith, and lower alkalis than the volcanic and plutonic rocksof the Jurassic Chon Aike Silicic Large Igneous Province. These findings suggest that theSubcordilleran Plutonic Belt represents, in the region comprised within 39° and 45° S, anearly stage of the Andean arc. Our observations indicate that while some granitoids inpotential localities, such as Cerro Catedral, can now belong to the Subcordilleran PlutonicBelt, other sites, like Pilcaniyeu and Pilahue, may be associated with the plutonic faciesof the Chon Aike Province.The Subcordilleran Plutonic Belt is an example of arc magmatism that developed duringa period of major plate reorganization, along with the subduction of mature sea floorbeneath the Gondwana margin, and the latter promoted slab roll-back processes and asubduction with extension tectonic regime.