Timing of tectonic events in the Alpujárride Complex, Betic Cordillera, southern Spain
J.P. Platt
S.P. Kelley
A. Carter
M. Orozco
10.6084/m9.figshare.3454256.v1
https://geolsoc.figshare.com/articles/dataset/Timing_of_tectonic_events_in_the_Alpuj_rride_Complex_Betic_Cordillera_southern_Spain/3454256
<p>Ar–Ar and fission-track dating from four low-grade sections in the Alpujárride Complex sheds light on the timing of the early
contractional history of these high-pressure metamorphic units, and their subsequent exhumation during the early Miocene extensional
collapse of the Betic orogen. White mica grains from the lowest-grade rocks yield partly reset detrital Ar–Ar ages; where
deformation and recrystallization are more intense, however, they yield reproducible ages as old as <em>c</em>. 48 Ma, which we interpret as the approximate timing of the main contractional event and associated high-pressure metamorphism
in these units. Rocks from slightly higher-grade sections give reproducible Ar–Ar ages between 30 and 40 Ma, but these younger
ages probably reflect the interplay of growth and cooling in fine-grained micas heated to between 300 °C and 400 °C during
prograde metamorphism. In each of the four areas studied the low-grade rocks are separated by an extensional detachment or
shear zone from medium-grade rocks below. In two areas these detachments have been folded around major overturned north-vergent
folds. Ar–Ar data from structurally below the detachments, and fission-track ages from all structural levels, indicate the
onset of significant cooling in the early Miocene, which corresponds to the age of the extensional event. The folds must therefore
be early Miocene or younger.
</p>
2016-06-21 12:00:17
tectonic events
Alpuj árride Complex
White mica grains
Betic Cordillera
prograde metamorphism
extensional detachment
40 Ma
contractional history
Betic orogen
extensional event
Miocene extensional collapse
48 Ma
contractional event
Ar
shear zone
Geology