PROVENANCE OF PRE- AND CARBONIFEROUS SEQUENCES OF THE ESQUELARROYO PESCADO-TEPUEL REGIONS (ARGENTINE, PATAGONIA): A COMBINED U-Pb AND Hf ISOTOPE STUDY OF DETRITAL ZIRCONS AND CONSTRAINTS ON DEPOSITIONAL SETTING

NORBERTO JAVIER URIZ; CARLOS CINGOLANI; TABOADA ARTURO; JONATAN ARIEL ARNOL; BASEI, MIGUEL ANGELO STIPP; ABRE, PAULINA; GABRIELA SOLEDAD COELHO DOS SANTOS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2022

0895-9811

Provenance and stratigraphic age of Devonian pre-glacial (Esquel and ArroyoPescado formations) and Carboniferous glacial (Valle Chico Formation)metasedimentary units exposed in the southwestern sector of the North PatagonianArgentine region are analysed by sedimentary petrology and combined U?Pb and Lu-Hfisotope on detrital zircons. Additionally, one sample of the Jaramillo Formation(Tepuel Group) was used to compare and correlate with the post-Devonian deposits inthe type-area of the Tepuel basin.Petrographic analyses show that the samples of the Esquel Formation aredistributed between the transitional arc and dissected arc fields for the QmFL diagramand dissected arc and recycled orogen in the QFL triangle. The samples of the ArroyoPescado Formatión plot in the transitional arc field and samples of the Valle ChicoFormation are located in dissected arc and recycled lithic fields of the QmFL diagramand within the dissected arc and recycled orogen fields in the QFL triangle. Finally, thesample of the Jaramillo Formation it?s in the transitional arc field.Manuscript File Click here to view linked References2Detrital zircons of the Esquel Formation shown U-Pb age distribution withdominance of Famatinian, Pampean-Brazilian and Mesoproterozoic ages, whereas theArroyo Pescado Formation displays an important concentration of Mesoproterozoicages. On the other hand, the Valle Chico Formation comprises a main input of postFamatinian or Chanic (Devonian) ages and Gondwanic (Carboniferous) ages are alsorecorded. The Jaramillo Formation differs from the rest of the samples analyzed in theremarkable unimodal concentration of U-Pb Gondwanic ages (Carboniferous) and thescarce documentation of ages older than Famatinian. The maximum sedimentation ageis Pridolian (Upper Silurian) for the Esquel Formation, Visean (Mississipian) for theValle Chico Formation and for Jaramillo Formation. The age is restricted to theFamatinian cycle for the Arroyo Pescado Formation. Hf isotope studies show aremarkable juvenile character for most of the analysed zircons and a small differencebetween the U-Pb age and Hf TDM registered for each crystal. Likewise, the importantparticipation of TDM Mesoproterozic ages is noteworthy. These records are equivalent tothose identified in different units of the Paleozoic of the Patagonian region and theMalvinas Islands, where the Mesoproterozoic detrital zircons with positive values ofεHf (t) and juvenile character are present. The depocentres recorded by the Esquel andArroyo Pescado units probably derived from the same source areas, but the variation inthe participation of U-Pb age records of their contributions indicate that the depocentresfilling has been developed in a diachronous facies. Combined U?Pb ages and initial Hfisotope compositions of single zircons obtained here, suggests that the North Patagonianand Deseado/Malvinas Massifs could be the main source areas for pre-Glacial andGlacial studied units. Remote areas cannot be ruled out, but are difficult to reconcilewith our data