Fold-Axis Parallel Extension along the Southern Ending of the Quito (Ecuadorian Andes) Fault System: Implications in River Network and Aquifer Geometry

Fold-Axis Parallel Extension along the Southern Ending of the Quito (Ecuadorian Andes) Fault System: Implications in River Network and Aquifer Geometry

Extension parallel to fold axis represents a rarely documented tectonic process that occur in different tectonic settings such as large-scale orogenic belts, mountain ranges, and thrust and fold belts. Along the Ecuadorian Andes, extensional systems have only been reported as tectonic boundaries of...

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Bibliographic Details
Published in:Geotectonics Vol. 54; no. 2; pp. 256 - 265
Main Authors: Peñafiel, L. A., Reyes, P. S. B., Alcalá, F. J., Ramírez, M. R., Cabero, A.
Format: Journal Article
Language:English
Published: Moscow Pleiades Publishing 01-03-2020
Springer Nature B.V
Subjects:
Aquifer recharge
Aquifer storage
Aquifer systems
Aquifers
Belts
Deformation
Drinking water
Earth and Environmental Science
Earth Sciences
Fault lines
Geological faults
Groundwater
Groundwater recharge
Groundwater storage
Mountains
Orogeny
River networks
Rivers
Storage conditions
Structural Geology
Tectonics
Transverse drainage
Valleys
Water supply
Ecuador
Quito fault system
fold-axis parallel extension
the aquifer geometry
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Summary:Extension parallel to fold axis represents a rarely documented tectonic process that occur in different tectonic settings such as large-scale orogenic belts, mountain ranges, and thrust and fold belts. Along the Ecuadorian Andes, extensional systems have only been reported as tectonic boundaries of local intermontane basins, pull-apart depressions and outer-arc stretching faults along hinge surfaces in compressional antiforms. The Quito fault system shows in planform view a right-stepping en-echelon arrangement which southernmost anticlinal ridge terminates as an arcuate structure locally dissected by the Saguanchi Gorge. Valley hillslopes of this transverse drainage display evidence of tectonic extension featured by several swarms of normal faults commonly dipping towards the valley bottom. Magnetotellurics sounding obtained across a N‒S line parallel to the crestline axis reveals three contiguous and distinguishable domains of which the central one shows a wedge-shaped geometry pointing down. This tectonic evidence for ongoing extensional deformation suggests that the process of fold-axis-parallel extension controlled the tectonic development and dissection of the Saguanchi Gorge across the anticlinal ridge. This episode marks a significant change in the groundwater recharge and aquifer storage conditions between the Quito basin and the inter-Andean Depression aquifer systems, currently in production to provide the potable water supply for the Quito city.
ISSN:0016-8521
1556-1976
DOI:10.1134/S0016852120020090