Antioquia Batholith

The batholith was named after Antioquia by Botero in 1942, after various authors as Boussignault in 1825, Ospina in 1911, Scheibe in 1933 and Posada in 1936 mentioned its existence. == Geology ==

The batholith varies in composition between hornblende-biotite tonalite to granodiorite, with lateral variations between gabbro to granite. Common minerals are hornblende, quartz, plagioclase, K-feldspar, biotite and amphibole, with traces of epidote, chlorite and sphene. in the east of San Jerónimo, around Belmira, in Don Matías, Girardota, Gómez Plata, Entrerríos, Carolina del Príncipe, Barbosa, Santo Domingo, and Santa Rosa de Osos. Because of profound weathering, outcrops are scarce and restricted to riverbeds, and at El Peñón de Guatapé. To the northwest of the urban center of Santa Rosa de los Osos, bauxite mineralizations of the batholith are found. Origin The batholith intruded the Triassic San Isidro Granulite, Ceja Gneiss and Medellín Amphibolite, In certain places, the batholith is overlain by the El Vergel Beds, alluvium and other Quaternary deposits. • Balseadero Fault • Biscocho Fault • Caldera Fault • Miraflores Fault • Monteloro Fault • Nare Fault Age A 2019 summary of ages obtained for the batholith show that the batholith formed in a protracted manner from 97 to 58 million years ago (Ma), that is from the Late Cretaceous to the Paleocene. For the main part of the intrusion there is a best estimate of the age between 71 ± 1.2 and 77 ± 1.7 Ma, suggesting an intrusion age near the boundary of the Campanian and Maastrichtian. == Hydrology ==

The Medellín River cross-cuts the batholith from southwest to northeast, where it flows in the Porce River. The following reservoirs are situated entirely on the batholith: • Miraflores Reservoir • Las Playas Reservoir • Guatapé Reservoir • Río Grande Reservoir • San Lorenzo Reservoir • Troneras Reservoir == References ==