The Mencué Batholith: Permian episodic arcrelated magmatism in the western North Patagonian Massif, Argentina

DANIEL A. GREGORI; LEONARDO STRAZZERE; MERCEDES BARROS; BENEDINI, LEONARDO; PAULO MARCOS; JOSÉ KOSTADINOFF

INTERNATIONAL GEOLOGY REVIEW

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2020 vol. XX p. 1 - 25

0020-6814

ABSTRACTThe Mencué Batholith, western North Patagonian Massif, includes three major bodies. The MencuéGranodiorite, Cura Lauquén Granite and La Blancura Syenogranite. There are dikes of granitic andbasaltic rocks cutting the above-cited rocks.The Mencué Batholith represents several episodes of magmatism, with ages varying between 294and 239 Ma. The Mencué Granodiorite and the Cura Lauquén Granite are solid-state deformed andare S-type. They have high-K and normal calc-alkaline affinities. These rocks contain significantquantities of subduction-zone chemical components that decrease towards younger lithofacies. LaBlancura Syenogranite lack subduction zone chemical components and represent A-type granite,typical of within-plate magmatism. The partial melting of metapelites could be the process offormation of these bodies. The older lithofacies of the Mencué Batholith, found westernmost, displaya stronger deformation, but there is a progressive eastward change to younger and mildly deformedbodies and even non-deformed bodies. We conclude that the evolution of the Mencué Batholith startin the Sakmarian-Roadian (Early Permian) period. At this time, a subduction zone was active to thewest and its thermal influence affected sedimentary ormetamorphic rocks producing S-type granitesDuring the Wordian and Capitanian, (Middle Permian) periods, the Mencué Batholith was mildlydeformed, possibly in the process of the vanishing of the deformation and has a minor subductionchemical signature.Between the Wuchiapingian and Olenekia periods, the alkaline facies of the Mencué Batholithshow an absence of deformation and the characteristics of within-plate magmatism.The Early Permian magmatic events in the western North Patagonian Massif are represented bythe older bodies of the Mencué Batholith and were produced by subduction in the western marginof the Gondwanan continent.The Late Permian-Early Triassic magmatic events show a noticeable decreasing influence ofsubduction and an increasing influence of within-plate chemical components.