Publication: The recycled orogenic sand provenance from an uplifted thrust belt, Betic Cordillera, Southern Spain
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Publication Date
2003
Authors
Critelli, Salvatore
Le Pera, Emilia
Tortosa, A.
Marsaglia, Kathleen M.
Latter, Kelly K.
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
SEPM (Society for Sedimentary Geology)
Abstract
The Betic Cordillera of southern Spain represents an uplifted
foreland fold–thrust belt. Source rock types of the Betic Cordillera
include metamorphic (mainly phyllite, schist, quartzite, and
gneiss), sedimentary (siliciclastic and carbonate), volcanic (felsic to intermediate
pyroclasts), and mantle-derived (peridotite, gabbro, serpentinite,
and serpentine schist) rocks. The fluvial systems range that transect
the Betic Cordillera are the major detrital source of sediment
along the southern Spanish coast, supplying sand to beaches and offshore
depositional systems in the Alboran Sea basin.
Three key sand petrofacies derived from the Betic mountain belt
reflect the main clastic contribution of known source rocks. All the
sands are quartzolithic, ranging from quartz-rich to lithic-rich.
Fluvial systems draining the Sierra de Los Filabres, the Sierra Nevada,
the Sierra de Gador, and the Ma´laga Mountains, and their related
beaches constitute a metamorphic–sedimenticlastic quartzolithic
sand petrofacies (Qm34610 F463 Lt6269; Lm72614 Lv264
Ls26613), derived dominantly from the Nevado–Fila´bride, Alpuja´rride,
and Mala´guide complexes. This quartzolithic petrofacies extends
from northeast of Almeria to Torremolinos (southwest of Ma´laga), and
northeast of Algeciras. Only one beach sand sample, east of Cabo de
Gata, is volcanolithic. Volcanic detritus (mainly having felsitic textures)
is derived from Miocene (15–7 Ma) pyroclastic sequences cropping out
in the southeast of the chain.
This metamorphic–sedimenticlastic quartzolithic petrofacies
changes in the coastal stretch from Torremolinos to Marbella,
where drainage systems cut across the Serrania de Ronda. Here
source rock types include peridotite, gabbro, and serpentinite of the
Ronda Peridotite Massif, and metamorphic rocks of the Ma´laguide
and Alpuja´rride units. The fluvial and beach sands of this area are
quartzolithic (Qm32612 F1063 Lt58611), and include abundant
peridotite and serpentinite grains. The latter quartzolithic petrofacies
changes abruptly from Algeciras to Ca´diz, where the sand
becomes quartz-rich (Qm7765 F462 Lt1964). This sand petrofacies
is derived predominantly from recycling of sedimentary sequences,
mainly the quartzarenite turbidite units of the Gibraltar
Arc (the Algeciras Flysch). This petrofacies is characterized by
higher proportion of quartz grains and abundant sedimentary lithic
fragments (Lm163 Lv161 Ls9863).
The three onshore petrofacies plot in the recycled-orogen provenance
compositional field and the lithic to transitional to quartzose
recycled subfields of Dickinson (1985). They vary from lithic, to transitional
and quartzose depending on their source lithologies in the Betic
foreland fold–thrust belt. These actualistic petrofacies best describe the
nature and distribution of sand petrofacies derived from a collisional
fold–thrust belt where primary and recycled source rocks are interfingered.
Deep-marine turbidites of the Alboran Basin have basinwide
quartzolithic sands having close compositional relations with Betic
Cordillera onshore sand petrofacies. Comparison of detrital modes
from mainland to deep-marine environments provides a suitable
basis for interpreting the Miocene to Pleistocene sand dispersal history
in the Alboran Basin. These modern quartzolithic petrofacies
are used to interpret analogous ancient collisional sandstone petrofacies
of the Alpine orogenic belt of the western-central Mediterranean
region and of other collisional orogenic systems, as a broader
point of view.