Magmatic and tectonic fabrics in the Upper Jurassic La Hoya Pluton, North Patagonian Batholith (~43°S) as a record of the early stages of the Andean deformation

Fault‐Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe‐Ofqui Fault System, Southern Andes (39°S)

“…Reconstructions of crustal tectono‐magmatic activity in the intra‐arc region during the Mesozoic are scarce. Jurassic plutons could have been emplaced during a regional phase of transtensional sinistral strike‐slip, as suggested by a comparison of our Jurassic zircon U‐Pb ages to reported timing of magmatic and ductile mineral fabrics in the back‐arc region (e.g., Zaffarana et al., 2020). Similarly, Cretaceous plutons could have been emplaced during regional sinistral strike‐slip shear during the late Cretaceous, as suggested by local evidence of the Liquiñe Fault (pre‐100 ± 2 Ma, Cembrano et al., 2000), which matches a regional phase of sinistral strike‐slip reported in the back‐arc region (e.g., Oriolo et al., 2019).…”

“…The age distribution of magmatic pulses correlate well with regionally reported Jurassic, Cretaceous and Neogene tectono‐magmatic activity in the intra‐arc region (North Patagonian Batholith, e.g., H. Moreno & Lara, 2008; L. Lara & Moreno, 2004; Munizaga et al., 1988; Pankhurst et al., 1999) as well as the back‐arc region (North Patagonian Cordillera in the Argentinian Andes, e.g., Oriolo et al., 2019; Zaffarana et al., 2020). Our new zircon U‐Pb data are older than reported amphibole and biotite K‐Ar and Ar/Ar dating methods (L. Lara & Moreno, 2004; Munizaga et al., 1988).…”

“…Published studies integrating structural data, radiometric ages of synkinematic minerals, and thermochronology, document dextral and dextral-reverse kinematics along the LOFS beginning at ∼10 Ma (Figures 10a and 10b; e.g., Adriasola et al, 2005;Adriasola & Stöckhert, 2008;Cembrano et al, 1999Cembrano et al, , 2000Cembrano et al, , 2002Melnick et al, 2006;Thomson, 2002). Older dextral ductile kinematics flow has been reported from the late Cretaceous in specific N-and NE-striking faults in the back-arc region (Figures 10a and 10b; e.g., Oriolo et al, 2019;Zaffarana et al, 2020), however the relationship between Cretaceous dextral kinematics and recognized traces of the LOFS remains unclear, and we therefore rule out Cretaceous dextral kinematics. Additionally, evidence of older activity in the LOFS can be recognized east of the Liquiñe Fault, where the orientations of mylonitic foliations and lineations agree with gneissic mylonites described at other localities of the Liquiñe Fault (Figures 5a and 5b, Cembrano et al, 2000).…”