How Much Did the Colombian Andes Rise by the Collision of the Caribbean Oceanic Plateau?

• Published in: Geophysical research letters 2021-04, Vol.48 (7), p.n/a
• Main Authors: León, Santiago, Monsalve, Gaspar, Bustamante, Camilo
• Format: Article
• Language: English
• Subjects: Andean orogeny; arc magmatism; Caribbean oceanic plateau collision; mountain building; paleotopography; trace element geochemistry
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL093362

The quantification of topographic growth at convergent margins is of primary importance to assessing the linkages between tectonic processes and landscape evolution. Traditionally, this task has relied on the applicability of conventional paleobotanical and isotopic methods to estimate paleoelevations, which is not always straightforward. Here, we use recent calibrations based on trace elements of arc‐related magmatic rocks to estimate crustal thickening and surface uplift of the northern Colombian Andes during the early Andean orogeny at ca. 70‐60 Ma. Increased Sr/Y and (La/Yb)N ratios of arc‐related intrusives suggest a ∼20 km crustal thickening that was probably accompanied by an isostatically compensated topographic uplift of up to ∼2 km along the proto‐Central Cordillera and the Santa Marta Range. This kilometer‐scale uplift was coeval with a regional shift from marine to continental deposition in foreland basins and was triggered by the collision of the Caribbean oceanic plateau. Plain Language Summary Quantifying the history of mountain building is primordial for our knowledge of how Earth's landscape, and the associated effects on climate and biodiversity, evolves in response to tectonic processes. As thickening of the Earth's crust is compensated in most orogenic systems by topographic growth (i.e., isostatic compensation), we can estimate how high mountains were in ancient times by tracking changes in crustal thickness. Here, we use trace element Sr/Y and La/Yb ratios of magmatic rocks, which allow documenting a crustal thickening of ∼20 km in the northern Colombian Andes at ∼70–60 Ma, that was likely accompanied by a topographic uplift of up to ∼2 km. Such period of mountain growth is consistent with the transition from marine to continental accumulation settings in foreland basins. Our results demonstrate the primary role that the collision of thick oceanic crust plays on mountain building in convergent margins. Key Points The Colombian Andes underwent ∼20 km of crustal thickening at ∼70‐60 Ma, suggested by an increase in Sr/Y and (La/Yb)N ratios of arc rocks A surface uplift up to ∼2 km of the proto‐Central Cordillera was accompanied by a regional transition from marine to fluvial settings Collision of thick and buoyant oceanic crust contributes to mountain building along convergent margins such as the Colombian Andes