loading page

Double-dating applied to provenance study in actual rivers in the foothills of the Eastern Cordillera Colombia
  • +1
  • Cindy URUEÑA,
  • Matthias Bernet,
  • Mauricio Ibañez,
  • Jimmy Muñoz
Cindy URUEÑA

Corresponding Author:[email protected]

Author Profile
Matthias Bernet
Author Profile
Mauricio Ibañez
Author Profile
Jimmy Muñoz
Author Profile

Abstract

The combination of different thermochronologic techniques on the same samples or even the same grains has become in a useful tool, to establish a complete history of the geological process that has controlled a rock, and for gaining information on sediment provenance and the exhumation of sediment source areas. Determination of crystallization and cooling ages of detrital zircon from modern river sediments is a powerful method for tracing sediment provenance and exhumation of orogenic mountain belts. In this work we explain with new examples of modern river samples from the Colombian Andes how zircon fission-track (ZFT) and U-Pb dating can be used in provenance studies to better understand the temporal association between source and depositional site and how the evolution of orogenic mountain belts from such data in a setting where large amounts of sediment are recycled from sedimentary source rocks and volcanic input may complicate the exhumational signal. Whereas the ZFT data provide information about the most recent thermal history and exhumation of the source rocks, they are complementary to U-Pb data which reflect the original zircon crystallization age and its ultimate provenance. The study contains data of detrital zircon U-Pb and zircon fission-track dating from modern river sediments of the Guatiquia and Guayuriba rivers in the eastern foothills of the EC, and the Magdalena River at Girardot on the western flank of the EC. Each individual dating technique offers unique information with respect to provenance and exhumation. We use our data to highlight certain advantages and limitations of using zircon U-Pb and FT dating in provenance studies, including the identification of original source areas, sediment recycling and the difficulty of detecting amagmatic orogens in the detrital zircon record. The data obtained in this study allows us to better understand the association between exhumation of sources and their detrital zircon signatures in modern rivers that drain a part of the EC The results obtained allowing us to make first-order observations about the provenance signal in modern rivers on the east flank of the Eastern Cordillera, our data clearly show that the zircon U-Pb age spectra of the Paleozoic through Mesozoic sedimentary section being eroded is related to sources in the Amazon Craton, the magmatic Paleozoic basement of the same EC, and exhumation of proximal Precambrian basement blocks. On the other hand, the Magdalena River sample indicates the presence of these same EC sources plus the addition of younger Permo-Triassic and Jurassic zircons derived from reworking of Upper Magdalena Valley sedimentary units and/or the crystalline basement of the CC. The ZFT data presented here complements the existing record of recent exhumation for the EC and the Magdalena River at Girardot on the western flank of the EC. Each individual dating technique offers unique information with respect to provenance and exhumation.