A clockwise P‐T‐t-D path of the northern Patagonia basement: implications for the Permian evolution of the Panthalassan margin of Gondwana

ABSTRACT

The geologic evolution of the Gondwanide orogen recorded during the late Palaeozoic along the Panthalassan border of Gondwana is related to an active continental margin, though it is still debatable whether it was built by collision or accretion. To disentangle its orogenic processes and provide constraints on the orogen type, we characterize the physicochemical conditions of metamorphism and associated deformation of the Mina Gonzalito Metamorphic Complex from northern Patagonia (41°28’30” S-65°40’30” W). New field mapping and comprehensive petrochronologic analysis constrain the evolution of a thick-skinned fold and thrust belt in a retroarc setting, which is spatially and temporally related to the geometry and kinematics of the right-lateral reverse El Jagüelito ductile shear zone. Metamorphic evolution resulted in a clockwise P‐T‐t-D path reflecting three stages of continuously changing P-T conditions under high-pressure (8.0–9.9 kbar) amphibolite facies (540–680°C) during a single-phase progressive ductile deformation event. Monazite ages ranging from 303 ± 5 to 252 ± 6 Ma account for the single-phase regional tectono-metamorphic event spanning ~ 50 My. Our results, integrated with regional data, led to interpreting the late Palaeozoic Gondwanide orogen developed along the Panthalassan margin of Gondwana as accretionary in advancing-mode.

Graphical Abstract

KEYWORDS:

• Geothermobarometry
• petrochronology
• monazite
• late Palaeozoic

Acknowledgments

We are deeply indebted to Ana María Sato and Ricardo Varela for all the help and support through the years they have given us, especially to P. D. González and M. Naipauer. We sincerely thank Lilian Carpintero, owner of the Santa Auriciana farm, for allowing us access to their farm and for their hospitality during our fieldwork. We also thank the three anonymous reviewers and the editor-in-chief of IJR for their valuable comments and contributions to improving the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2024.2375727.

Notes

1. Whole-rock geochemical analyses of the samples are available upon request from the corresponding author.

Additional information

Funding

This work was supported by the SEGEMAR; Universidad Nacional de Río Negro under Grant PI-UNRN-2021-40-A-959; Ministerio de Ciencia, Tecnología e Innovación Productiva, Agencia Nacional de Promoción Científica y Tecnológica under Grant FONCYT-PICT-2021-01081, and CONICET under Grant PIP-11220200100099CO.