The Otú Norte or Otú-Pericos Fault () is an inactive sinistral oblique strike-slip fault in the department of Antioquia in northern Colombia. The fault has a total length of and runs along an average north-northwest to south-southeast strike of 346.4 ± 8, cross-cutting the northern part of the Central Ranges of the Colombian Andes. Together with the parallel Bagre Norte Fault the fault separates the Central Ranges from its northeasternmost continuation, the Serranía de San Lucas.
Etymology The fault was by Feininger et al. in 1972 named after Otú Airport in vereda Otú in Remedios, Antioquia.Consorcio GSG, 2015, p.168
Description The Otú Norte Fault crosses the northern part of the Central Ranges of the Colombian Andes. The fault strikes north-northwest to south-southeast and appears to branch off the Palestina Fault. The Otú Fault extends in a northwest direction to near Nechí, where it is covered by young Quaternary deposits. The sinistral oblique reverse fault separates blocks of totally dissimilar geology and lithology; the metamorphic Precambrian San Lucas Complex and Jurassic igneous rocks (diorites) of the Segovia Batholith on the east are juxtaposed against the Cretaceous Santa Isabel Stock and Paleozoic quartz-feldspar gneisses and quartzitic arc rocks of the Cajamarca Complex on the west.Fonseca et al., 2011, p.40Fonseca et al., 2011, p.64 Just west of Remedios, the fault forms the contact between the Cretaceous Antioquia and Jurassic Segovia Batholiths.Geological Map of Antioquia, 1999 The northern end apparently splays into several faults that cross the Nechí River.Paris et al., 2000, p.28
Activity A rate of less than per year is estimated for the fault, considered inactive. Displaced Quaternary terraces as high as are reported and the fault offsets the Tertiary erosion surface of the Central Ranges.Paris et al., 2000, p.29 A total displacement of the fault has been estimated at .Álvarez et al., 2007, p.49
Economic importance
The fault separates two major gold mining areas in Antioquia; the Segovia-Remedios mining district and La Ye mine in the east,Segovia-Remedios mining districtMining Atlas - La Ye and the placer deposits of Gramalote and Cisneros in the west.Mining Atlas - GramaloteMining Technology - Cisneros North of Zaragoza, the fault underlies the El Limón mine.Mining Atlas - El Limón Antioquia produces 50% of all gold in Colombia.Fonseca et al., 2011, p.126
The ductile zone of the fault produced mylonites in mainly the amphibolite facies of the Segovia Batholith.Álvarez et al., 2007, p.47 This ductile behavior was later overprinted by fragile tectonics, leaving cataclasis and fault breccias in the fault zone as well as striations in the quartz of the batholith. These deformations are interpreted as second grade Riedel shears.Álvarez et al., 2007, p.48
See also
List of earthquakes in Colombia Romeral Fault System Bagre Norte Fault
References
Bibliography
Maps
Further reading