Resolving uplift of the northern Andes using detrital zircon age signatures

[摘要] Upliftof the Eastern Cordillera in the northern Andes has been linked to orographic climatechange and genesis of South America?s largest river systems. The timing of initial upliftremains poorly constrained, with most estimates ranging from ca. 60 to ca. 5 Ma. New detrital zircon U-Pbages from proximal fill of the Llanos foreland basin in Colombia reveal a pronouncedmid-Cenozoic shift in provenance from an Amazonian craton source to an Andean fold-thrustbelt source. This shift corresponds with changes in detrital zircon (U-Th)/He ages,a conglomeratic unroofing sequence, and a sharp increase in foredeep accumulationrates. These nearly simultaneous changes in zircon age spectra, clast compositions,and sediment accumulation are attributable to latest Oligocene uplift of the easternflank of the Eastern Cordillera. The timing relationships suggest an early activationof the frontal thrust system, implying a long-term (up to 25 m.y.) cessation oforogenic wedge advance, potentially driven by structural inheritance and/or climatechange.

[学科分类] 地质学

[关键词] Fire safety;fatal fires;smoke alarms