Millennial zircons discovered at the Sierra Nevada of Santa Marta
Zircons up to 1.4 billion years old could be related to the Grenvillian belt or a cordillera formation linked to the creation of the Rodinia supercontinent which existed during the Neoproterozoic period.Bogotá D. C., 18 de noviembre de 2014 — Agencia de Noticias UN-
At the Sierra Nevada de Santa Marta and upper Province of Guajira researchers also discovered parts of this material which were dated between 250 and 360 million years old and are also related with formation of the Pangea supercontinent between the Permian and Carboniferous period.
Furthermore the most recent records, calculated between 180 and 250 million years are associated to the Triassic an Jurassic periods as well as the separation of said supercontinents.
“They are remnants of the oldest areas of the American continent after the Amazonian Shield. The importance of zircons lies in that they are oldest mineral on earth and one of the most abundant on the earth’s crust,” said UNal Geosciences doctoral candidate Alejandro Piraquive.
Piraquive calculated the age of 427 zircons for a total of 499 ages among seven samples located in areas of the Sierra Nevada de Santa Marta, the basin of the Aracataca river, the Tayrona Park and the Aguja River; as well as the upper Province of Guajira at the mountainous region also known as serranías in Colombia, of Jarara and Macuira.
“We obtained rock samples of the Sierra Nevada and the serranías”, said Piraquive whom also identified intermediate and more recent ages of other minerals of this type.
To determine the ages of the mineral the researcher gathered zircon samples with weights between three and seven kilos. Later he crushed, sieved and separated them in magnetic and gravimetric form to obtain crystals.
The samples where then covered in graphite in order to take images of the cathodoluminescence, which reveal cold light emissions from accelerated electron bombing.
“This process is indispensable to choose nuclear points and rings of material where the laser is pointed and is key for the calculation,” said Piraquive.
Finally, he carried out a statistical processing and developed probability and concordia diagrams to calculate and analyze rock ages.(Por: Fin/DSGM/DMH/AC