Yannick Branquet, Bernard Laumonier, Alain Cheilletz, Gaston Giuliani; Emeralds in the Eastern Cordillera of Colombia: Two tectonic settings for one mineralization. Geology ; 27 (7): 597–600. doi: https://doi.org/10.1130/0091-7613(1999)027<0597:EITECO>2.3.CO;2
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Colombian emeralds are formed through a hydrothermal-sedimentary process. On the western side of the Eastern Cordillera, the deposits are linked by tear faults and associated thrusts developed during a compressive tectonic phase that occurred at the time of the Eocene-Oligocene boundary, prior to the major uplift of the Cordillera during the Andean phase (middle Miocene). On the eastern side of the Cordillera, emerald mineralization occurred earlier, at the time of the Cretaceous-Tertiary boundary, during a thin-skinned extensional tectonic event linked to evaporite dissolution. This event predates the Andean phase, during which this part of the chain was folded and thrust over the Llanos foreland.