TAHAMÍ GEOPARK PROJECT
Geology · Culture · Community
1.5 billion years of history in the Central Mountain Range of Colombia
Geological history of the Tahamí Geopark project, Antioquia .
GEOLOGICAL HISTORY
This landscape not only tells stories of the Quaternary, the Cenozoic, the Mesozoic and the Paleozoic; it also holds the memory of the ancient Proterozoic, when the oldest foundations of our Earth were consolidated.
East of the Palestina and Otú faults, in the Chibcha Terrane, some of the oldest rocks in the entire region outcrop: the San Lucas Gneiss, whose crystallization age has been dated by U-Pb at 1.501 billion years (Ordóñez et al., 2009), the oldest recorded to date in the Colombian Andes, according to the authors. This rock was subsequently subjected to a metamorphic event approximately 1.124 billion years ago (Clavijo et al., 2008), also confirmed by U-Pb dating.
These rocks, witnesses to the Grenville orogenic events, provide evidence of geological processes that occurred long before the formation of the Andes, when the mountains rose on the ancient supercontinent Rodinia. Later, during the Jurassic period, these rocks were intruded by igneous bodies such as the Segovia Batholith, marking a new stage in the tectonic history of the region.
West of the Palestine and Otu faults, in the Tahamí Terrane, lie rocks that record a complex metamorphic history. These rocks, metamorphosed during the Triassic (approximately 240 million years ago), originated from sediments deposited in a marine environment during the Early Paleozoic, including limestones formed long before the assembly of the supercontinent Pangaea.
This ancient basement was subsequently intruded by plutonic rocks, in particular by the large Antioquian Batholith, of Cretaceous–Lower Tertiary age, which outcrops widely in this region (Restrepo JJ & Toussaint JF, 1988; Toussaint JF & Restrepo JJ, 2020).
All these rocks were later deformed and uplifted during the Andean Orogenesis.
When exposed at the surface, they were eroded, forming the current landscape where three large plateaus separated by escarpments can be observed. These plateaus have a relief of rounded hills and are cut by deep canyons (Arias A. 1995, Surfaces of Erosion). The geopark territory is located in the Lower Plateau.
Geological history in the Proterozoic
In the eastern sector of the Tahamí Geopark Project, towards the geological domain of the Chibcha Terrane, very old rocks outcrop, represented by the San Lucas Gneiss. This unit records crystallization ages close to 1.5 billion years, corresponding to the Mesoproterozoic, and was subsequently affected by metamorphic events related to the Grenvillian orogeny, linked to the evolution and assembly of the supercontinent Rodinia (Ordóñez-Carmona et al., 2009; Cuadros et al., 2014).
These rocks form part of the metamorphic basement of the Serranía de San Lucas, at the northern end of the Central Cordillera of Colombia. They are composed mainly of quartz-feldspathic and biotite gneisses, with local presence of amphibolites, marbles and other metamorphic rocks, and preserve the record of tectonic and metamorphic processes that occurred long before the formation of the present Andes (Bogotá & Aluja, 1981; Feininger, Barrero & Castro, 1972; Cuadros et al., 2014).
The subsequent evolution of this ancient basement was marked by further episodes of deformation, metamorphism, and magmatism. Different Paleozoic and Mesozoic igneous bodies intruded sectors of the region, including units attributed to the Carboniferous, Permian, and Jurassic periods, demonstrating that this part of the territory was reactivated and transformed repeatedly throughout geological time.
The area is also traversed or bounded by important regional tectonic structures. These include the Palestina Fault and the Otú–Pericos Fault System, as well as the Cimitarra Fault and other minor structures. These faults participate in the contact and transition between different geological domains, including the Tahamí and Chibcha terranes, and are fundamental elements for understanding the complex tectonic construction of the Cordillera Central (Feininger, 1970; Feininger, Barrero & Castro, 1972; Restrepo & Toussaint, 2020).
Thus, the San Lucas Gneiss represents a window into the oldest stages of regional geological history: a record of approximately 1.5 billion years, predating the formation of the Andes and bearing witness to continents, oceans, and tectonic processes profoundly different from those we observe today.
THE PRESENT
This geological story is not over and the forces of the Earth continue to act, producing earthquakes, landslides and floods, erosion, phenomena that are now increased by climate change.
It is essential that we are aware of our geological past in order to prevent and mitigate risks in the present and in the future.
TECTONIC CONTEXT
The Tahamí Terrain covers a large part of the northern Central Mountain Range, with small blocks present on the western flank of the southern Central Mountain Range.
This terrain consists primarily of metamorphic rocks intruded by plutons ranging in age from the Triassic to the Paleogene, and minor Mesozoic sedimentary sequences. It includes greenschists, graphite-muscovite-quartz schists, quartzites, and marbles, as well as higher-grade rocks such as migmatites and amphibolites, and granulites in high-grade areas (Restrepo & Toussaint, 1985; Rodríguez et al., 2005). Syntectonic orthogneisses, such as the Samaná, Abejorral, Naranjal, and Palmitas gneisses, have been dated to approximately 240 Ma (Villagómez, 2010; Cochrane, 2013; Restrepo et al., 2011; Vinasco et al., 2006; Ibañez-Mejia et al., 2008).
What is a tectonostratigraphic terrain?
“A geological entity of regional extent that is limited by faults and is characterized by a geological history different from the geological history of the adjacent entities.” (Berg et al., 1978; Coney et al., 1980; and others).
VIDEOS ABOUT IGNEOUS ROCKS LIKE THE BATHOLITH
VIDEOS ABOUT METAMORPHIC ROCKS
THE WATERFALLS
Natural waterfalls are one of the landscape elements that best unite tourism and geology.
