Mesozoic‐Cenozoic denudation history of the Patagonian Andes (southern Chile) and its correlation to different subduction processes

Abstract

Abstract. Fission track (FT) analysis is applied to assess the

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

“…Shaded relief digital elevation modeling (Rosenau et al, 2006), regional and structural fi eld mapping (Thiele et al, 1986;SERNAGEOMIN-BRGM, 1995 1 ;Diriason et al, 1998;Arancibia et al, 1999;Lavenu and Cembrano, 1999), microstructural analyses (Cembrano et al, 1996(Cembrano et al, , 2002Arancibia et al, 1999), and Ar/Ar laser-total fusion and step-heating geochronology of synkinematic minerals (Cembrano et al, , 2002López, 2001) in deformed plutonic rocks consistently demonstrate right-lateral transpression along the LOFZ in Late Miocene to Pliocene times. This interpretation is supported by apatite and zircon fi ssion track thermochronometric data collected along the southern Andes between 41° and 47°S, indicating an episode of enhanced cooling and denudation along the LOFZ in the Late Miocene to Pliocene (Thomson et al, 2001;Thomson, 2002;Adriasola et al, 2006). When compared to plate kinematic reconstructions, the episode of denudation seems to be coeval with the arrival and subduction of the northern portions of the Chile Rise beneath Taitao Peninsula (e.g., Cande and Leslie, 1986;Ramos and Kay, 1992) and is therefore proposed to refl ect differential block uplift driven by right-lateral transpression along the LOFZ (Thomson et al, 2001;Thomson, 2002;Adriasola et al, 2006).…”

“…This interpretation is supported by apatite and zircon fi ssion track thermochronometric data collected along the southern Andes between 41° and 47°S, indicating an episode of enhanced cooling and denudation along the LOFZ in the Late Miocene to Pliocene (Thomson et al, 2001;Thomson, 2002;Adriasola et al, 2006). When compared to plate kinematic reconstructions, the episode of denudation seems to be coeval with the arrival and subduction of the northern portions of the Chile Rise beneath Taitao Peninsula (e.g., Cande and Leslie, 1986;Ramos and Kay, 1992) and is therefore proposed to refl ect differential block uplift driven by right-lateral transpression along the LOFZ (Thomson et al, 2001;Thomson, 2002;Adriasola et al, 2006).…”

“…In general, the zircon FT ages are similar to or younger than Rb-Sr, K-Ar and Ar/ Ar ages obtained from nearby outcrops (Munizaga et al, 1988;Carrasco, 1995;SERNAGEOMIN-BRGM, 1995 1 ). The zircon FT ages are interpreted to represent the time of post-emplacement cooling to temperatures of around 280±30°C (e.g., Tagami and Shimada, 1996;Thomson et al, 2001) and their locations correlate well with the distribution of the plutonic units of the NPB outlined in the geological map of SERNAGEOMIN-BRGM (1995 1 ; Fig. 2).…”

Fission track thermochronology of Neogene plutons in the Principal Andean Cordillera of central Chile (33-35°S): Implications for tectonic evolution and porphyry Cu-Mo mineralization

“…However, experimental data show that there is a wide temperature range, from 160 to 380°C, for the temperature bounds for the zircon partial annealing zone, which are strongly dependent on cooling rates and alpha radiation damage of zircon crystals (Bernet and Garver, 2005;Tagami, 2005;Reiners and Brandon, 2006). Thus, as a reasonable approximation for this work, a temperature of 280±30°C has been plotted against the zircon fission track age in study to produce a single temperature-time point on a thermal history path (e.g., Tagami and Shimada, 1996;Thomson et al, 2001;Reiners and Brandon, 2006;Adriasola and Stökhert, 2008).…”

Constraints on deformation of the Southern Andes since the Cretaceous from anisotropy of magnetic susceptibility

“…11 Thomson et al, 2001), which then propagated to the east during the early Miocene (22-18 Ma; Fosdick et al (2013) and middle to late Miocene (12-8 Ma; Thomson et al, 2001). …”