Int J Earth Sci (Geol Rundsch) (2017) 106:1991–2003
Late Paleozoic deformation and exhumation in the Sierras
Ar‑feldspar dating constraints
· Sebastián Oriolo
· Jeff Benowitz
· Klaus Wemmer
· Paul Layer
Received: 20 March 2016 / Accepted: 18 September 2016 / Published online: 28 September 2016
© Springer-Verlag Berlin Heidelberg 2016
Argon diffusion in feldspar has been widely applied to con-
strain the cooling and exhumation history of magmatic and
metamorphic rocks (e.g., Burgess et al. 1992; Meert et al.
2001; Streepey et al. 2002; Cassata et al. 2009). It has been
also used to date sub-greenschist events as well as authi-
genic growth of feldspars (e.g., Spötl et al. 1998; McLaren
and Dunlap 2006; Mark et al. 2008; Mortimer et al. 2012).
The closure temperature of this geochronological system
is, however, a matter of discussion. Instead of having a sin-
gle closure temperature (Dodson 1973), feldspars present
multiple diffusion domains that can be potentially useful to
reconstruct more complex cooling histories (Lovera et al.
1989; Burgess et al. 1992; Spötl et al. 1998; Sherlock et al.
2005; Mark et al. 2008; Benowitz et al. 2011, 2012, 2014).
Ar feldspar methods constitute an impor-
tant tool to ﬁll the gap between high- and low-temperature
thermochronometers between approximately 300–150 °C
(McDougall and Harrison 1999; Streepey et al. 2002; Cas-
sata et al. 2009), providing powerful insights into thermal
evolution of complex tectonic settings like the Sierras Pam-
peanas in Argentina.
The Sierras Pampeanas constitute a morphotectonic
unit, which is located in the Andean foreland of the Pam-
pean ﬂat-slab segment between 27°S and 33°S (Fig. 1). It
is made up of mostly magmatic and metamorphic rocks of
late Proterozoic-Paleozoic ages (e.g.; Caminos 1979; Gor-
dillo and Lencinas 1979; Sims et al. 1998; Casquet et al.
2001; Steenken et al. 2006; Siegesmund et al. 2010). Dur-
ing the late Devonian, the collision of the Chilenia micro-
continent to the west of the Sierras Pampeanas gave rise
to the Chanic/Achalian Orogeny (e.g., Sims et al. 1998;
Steenken et al. 2010; Willner et al. 2011), which was suc-
ceeded by subduction along the proto-Andean margin.
Ar feldspar data obtained
from the Sierras Pampeanas are presented, ﬁlling the gap
between available high- (>~300 °C) and low-temperature
(<~150 °C) thermochronological data. Results show Silu-
rian–Devonian exhumation related to the late stages of
the Famatinian/Ocloyic Orogeny for the Sierra de Pocho
and the Sierra de Pie de Palo regions, whereas the Sier-
ras de San Luis and the Sierra de Comechingones regions
record exhumation during the Carboniferous. Comparison
between new and available data points to a Carboniferous
tectonic event in the Sierras Pampeanas, which represents
a key period to constrain the early evolution of the proto-
Andean margin of Gondwana. This event was probably
transtensional and played a major role during the evolution
of the Paganzo Basin as well as during the emplacement of
alkaline magmatism in the retroarc.
Keywords Carboniferous · Paganzo Basin · Andean
foreland · Pampean ﬂat-slab segment · Crustal exhumation
Electronic supplementary material The online version of this
article (doi:10.1007/s00531-016-1403-3) contains supplementary
material, which is available to authorized users.
* Stefan Löbens
Geoscience Centre, University of Göttingen,
Goldschmidtstr. 3, 37077 Göttingen, Germany
Department of Geology and Geophysics, University
of Alaska, 900 Yukon Drive, Fairbanks, AK 99775, USA