Ediacaran Thermal Disturbance in the NW Amazonian Craton: Insights from Zircon and Apatite U–Pb Geochronology of the Guaviare Complex, Colombia
Abstract
The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, and subsequent thermal events. Zircon U–Pb data define a dominant concordant population at ca. 1.30 Ga, interpreted as the crystallization age of an igneous protolith. This age is consistent with Mesoproterozoic A-type magmatism previously recognized in the region and consistent with emplacement under intracratonic extensional conditions, as suggested by previous studies. A limited number of discordant zircon analyses indicate Pb loss and/or partial isotopic resetting between ~1.0 and 0.6 Ga, although no well-defined metamorphic zircon population is identified. Meanwhile, apatite U–Pb analyses from key samples yield consistent lower intercept ages between 633 ± 16 Ma and 543 ± 8 Ma, indicating a widespread Ediacaran thermal disturbance that may have affected the Guaviare Complex, temporally overlapping with alkaline magmatism in the northwestern Amazonian Craton, including the San José del Guaviare Nepheline Syenite. However, alternative mechanisms such as fluid-assisted Pb mobility, regional reheating, or prolonged cooling cannot be excluded. Finally, the combined zircon–apatite dataset highlights the value of multi-chronometer approaches for resolving complex thermal histories in cratonic domains.
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BibTeX
@article{perez2026ediacaran,
title = {{Ediacaran Thermal Disturbance in the NW Amazonian Craton: Insights from Zircon and Apatite U–Pb Geochronology of the Guaviare Complex, Colombia}},
author = {Amed Bonilla Pérez and Nathan Cogné and Carlos Alfonso Zafra Mejía},
journal = {Geosciences},
year = {2026},
month = oct,
doi = {10.3390/geosciences16040154},
url = {https://hal.science/hal-05806246v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Ediacaran Thermal Disturbance in the NW Amazonian Craton: Insights from Zircon and Apatite U–Pb Geochronology of the Guaviare Complex, Colombia
AU - Amed Bonilla Pérez
AU - Nathan Cogné
AU - Carlos Alfonso Zafra Mejía
PY - 2026
DA - 2026/10/28
JO - Geosciences
DO - 10.3390/geosciences16040154
UR - https://hal.science/hal-05806246v1
AB - The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, and subsequent thermal events. Zircon U–Pb data define a dominant concordant population at ca. 1.30 Ga, interpreted as the crystallization age of an igneous protolith. This age is consistent with Mesoproterozoic A-type magmatism previously recognized in the region and consistent with emplacement under intracratonic extensional conditions, as suggested by previous studies. A limited number of discordant zircon analyses indicate Pb loss and/or partial isotopic resetting between ~1.0 and 0.6 Ga, although no well-defined metamorphic zircon population is identified. Meanwhile, apatite U–Pb analyses from key samples yield consistent lower intercept ages between 633 ± 16 Ma and 543 ± 8 Ma, indicating a widespread Ediacaran thermal disturbance that may have affected the Guaviare Complex, temporally overlapping with alkaline magmatism in the northwestern Amazonian Craton, including the San José del Guaviare Nepheline Syenite. However, alternative mechanisms such as fluid-assisted Pb mobility, regional reheating, or prolonged cooling cannot be excluded. Finally, the combined zircon–apatite dataset highlights the value of multi-chronometer approaches for resolving complex thermal histories in cratonic domains.
SN - 2076-3263
ER -