Chronicling Climate in Rings and Rocks
If you have ever assembled a large jigsaw puzzle, you know how difficult a task it can be, especially if the picture you are putting together is unclear or if pieces are missing. The process becomes even harder without a table or puzzle mat to display and support all the pieces during the building process.
Earth’s deep history might be the biggest puzzle geologists try to put together—and it’s not an easy job. Geologists use isotope geochronology, a method that relies on the predictable decay of isotopes of radioactive elements, to determine when a particular rock formed, and they apply this information to establish the timing of past geologic events. However, isolated pieces of rock do not tell the complete picture of Earth’s history. Just as each piece of a puzzle has a shape and color pattern matching the pieces around it, in geochronology, age-dated rocks must be matched with other rocks of similar age and isotopic composition to tell the history of Earth clearly and accurately. It is much easier to make these matches when you have an appropriate puzzle mat on which to reconstruct the geologic history.
Over the past few years, a group of early-career Colombian scientists from the Semillero de Geocronologia Uniandes (Geochronology Incubator at the University of the Andes) have collected all existing pieces of geochronology information about Colombia’s rocky landscape to build the Colombian Geochronological Database (CGD). This database serves as a mat for geochronologists interested in fitting the geology of Colombia, which spans more than 1.1 million square kilometers, into the puzzle that is the geologic history of the northern Andes [Rodriguez-Corcho et al., 2021].
A Box of Unsorted Pieces
Colombia comprises a mosaic of five major geographical regions: the Amazon, Andean, Caribbean, Orinoco, and Pacific. Although these regions share common biological and geographic features, they do not necessarily share the same geologic history.
Figure 1 shows a different layout, delineated on the basis of distinct rocks: the result of different geological events that took place (and are still taking place) not only at the surface but also in the crust and mantle. For example, the eastern and southeastern regions (Amazon and Orinoco geographical regions) contain rocks from the Guiana craton, which extends to Venezuela and Brazil, and group together the oldest rocks (roughly 1 billion years old) in northern South America. The Western Cordillera region (Pacific geographical region) comprises a collage of rocks, some of them formed in the bottom of the sea, which crashed against the South American continent and were elevated above sea level by geological forces. When each of these events took place and how long each lasted are big-picture questions that isotope geochronology can answer.
Four years ago, undergraduates at the Semillero de Geocronologia Uniandes in Bogotá, Colombia, began investigating the status of the geochronological research in Colombia, motivated by the question of how much is known about the ages of Colombia’s rocks. This group of students, most of whom graduated during the development of the project but continued working on it, was led by professor Yamirka Rojas-Agramonte and was assisted by Colombian graduate students at universities all over the world.
The team found that the existing geochronological information had been previously compiled in published geochronological databases [Gómez-Tapias et al., 2015; Millward and Verdugo, 1981; Restrepo, 1983; Maya, 1992; Calvache, 1988]. Nevertheless, these databases had several limitations. First, they did not provide clear insights on the regional geology and tectonics of Colombia and the northern Andes region through all geologic time. They were not all contained in a digital format, none of them were available for easy public access, and they were not organized under a consistent format (e.g., the locations of some samples were described by colloquial names for businesses or other landmarks that no longer existed). Also, none of the databases had enough data to construct representative statistical figures for use in regional-scale geologic interpretations.
In other words, although these databases preserved the geochronological information of Colombia, they were like boxes of unsorted puzzle pieces. What was needed was a resource in which pieces that fit together—rocks of similar ages—could be kept in place, showing where most of the available information is concentrated and where the gaps are.
The Need for a Puzzle Mat
The lack of a common framework in which to view Colombia’s geologic history motivated the creation of the CGD. The CGD allows geochronologists to recognize significant events in Colombia’s geologic past that may have regional or even global tectonic and geodynamic significance.
For example, by providing a peer-reviewed timeline for major tectonic events recorded in the rocks of Colombia, the CGD allows geologists to understand when plate tectonic processes along northwestern South America have resulted in the creation of new crust (through processes like arc magmatism, crustal melting, and continental rifting), the preservation of old crust (through processes such as continent-continent or arc-continent collision), or the destruction of crust. These are relevant questions for researchers studying the evolution of mountains and active tectonic processes.
The CGD also aids in assessing the effects of societal events on geological research. For example, Colombia’s long-lasting, violent internal political conflict between the government and guerilla forces has hindered access to places in the southern (Amazonia), western (Pacific), and eastern (Llanos) regions of the country, resulting in data gaps in those areas. The only way to collect samples for geochronological studies is to gather them during fieldwork. The CGD enables scientists to visualize where the conflict has left these gaps and to plan future fieldwork to fill them. Although the internal conflict persists (and has even worsened in certain areas amid the COVID-19 pandemic), with the signing of the 2016 peace agreement and now with the development of the CGD, the new generation of geoscientists is optimistic about the challenges and opportunities to come.
An Example of ICON Science
CGD is an example of global and regional scientific collaboration fulfilling the values of ICON science. ICON, a term coined in 2019 by the U.S. Department of Energy, refers to efforts that integrate processes across disciplines and scales (I), coordinate consistent protocols to produce interoperable data (C), openly exchange data (O), and network efforts in data collection (N).
The CGD was designed primarily by following the approach used by Bruce Eglington in developing DateView, a user-friendly freeware geochronology database system that offers well-organized data storage and easy retrieval [Eglington, 2004]. Project members also developed a consistent workflow to compile, filter, and interpret all geochronological data related to Colombia’s geology published between 1962 and 2021. This task required the team to review each of the available data sets and analyze the type and quality of data they contained, an effort led by Rojas-Agramonte and carried out by students at different stages in their early careers with assistance from expert scientist mentors. In total, this work amounted to reviewing 342 references, of which 283—including peer-reviewed papers and bachelor’s, master’s, and doctoral theses—met the minimum criteria to be included. References were discarded if they lacked geological information related to the samples studied or if samples didn’t have the correct coordinates.
In August 2021, the CGD launched a public web page featuring an interactive map and other useful tools for data accessibility (Figure 2). The site will be updated routinely and will allow researchers to contribute by uploading their geochronology data. Behind the website, there will be a team of volunteer scientists and experts in geochronology and Colombian geology who will review and assess the quality of the contributions, using the criteria mentioned above.
For the moment, the database includes data from Colombia exclusively, but the CGD team plans to expand its network and include data from other Latin American countries by training scientists from those countries to compile their data in the CGD. To further network and to increase the usefulness and accessibility of the data in the CGD, these data will be uploaded into global data sets, such as the PANGAEA project.
With the creation of this Colombian geological puzzle mat, researchers can easily see their data in a larger context, and they can see where their efforts are most needed to fill in the gaps. Furthermore, seeing all available data assembled in one place may yield new insights into the big picture of Colombia’s geological history.
I thank Yamirka Rojas Agramonte, Andres Felipe Rodriguez-Corcho, Johana A. Barrera-Gonzalez, and Maria Paula Marroquin-Gomes for actively collaborating on the writing stages of this article. Sarah Bonilla-Correa, David Izquierdo-Camacho, Sofia M. Delgado-Balaguera, David Cartwright-Buitrago, Maria D. Muñoz-Granados, William G. Carantón-Mateus, Alejandro Corrales-García, Andrés F. Laverde-Martinez, Aura Cuervo-Gómez, Marco A. Rodriguez-Ruiz, Juan P. Marin-Jaramillo, Nicole Salazar-Cuellar, Laura C. Esquivel-Arenales, Maria E. Daroca, A. Sofía Carvajal, Ana M. Perea-Pescador, Juan D. Solano-Acosta, Sergio Diaz, Alejandro Guillen, German Bayona, Agustín Cardona-Molina, Bruce Eglington, and Camilo Montes assisted in assembling the Colombian Geochronological Database.
Calvache, M. L. (1988), Catálogo de las edades isotópicas del vulcanismo Neógeno–Cuaternario de Colombia. Sector sur. volcán Doña Juana hasta la frontera con Ecuador, Ingeominas informe interno, Ingeominas, Bogotá.
Eglington, B. (2004), DateView: A windows geochronology database, Comput. Geosci., 30, 847–858, https://doi.org/10.1016/j.cageo.2004.06.002.
Gómez-Tapias, J., et al. (2015), Compilando la geología de Colombia: Una visión a 2015, Publ. Geol. Espec. 33, Serv. Geol. Colomb., Bogotá.
Maya, M. (1992), Catálogo de dataciones isotópicas en Colombia, Bol. Geol. Ingeominas, 32, 1–3.
Millward, D., and G. Verdugo (1981), Catalogue of radiometric age dates in Colombia, March 1981: Informe Mision Geologica Britanica, Ingeominas, Bogotá.
Restrepo, J. J. (1983), Compilación de edades radiométricas de Colombia: Departamentos andinos hasta 1982, Bol. Cienc. Tierra, 78, 201–245.
Rodriguez-Corcho, A. F., et al. (2021), The Colombian geochronological database (CGD), Int. Geol. Rev., 29, 1–35, https://doi.org/10.1080/00206814.2021.1954556.
Carolina Ortiz-Guerrero (email@example.com), University of Florida, Gainesville