Detrital zircon typology and U/Pb geochronology for the Miocene Ladrilleros-Juanchaco sedimentary sequence, Equatorial Pacific (Colombia)New constraints on provenance and paleogeography in northwestern South America.

  1. Osorio-Granada, E.
  2. Restrepo-Moreno, S.A.
  3. Muñoz-Valencia, J.A.
  4. Trejos-Tamayo, R.A.
  5. Pardo-Trujillo, A.
  6. Barbosa-Espitia, A.A.
Journal:
Geologica acta: an international earth science journal

ISSN: 1695-6133

Year of publication: 2017

Volume: 15

Issue: 3

Pages: 201-215

Type: Article

DOI: 10.1344/GEOLOGICAACTA2017.15.3.4 DIALNET GOOGLE SCHOLAR lock_openOpen access editor

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Abstract

Typology and internal texture analyses were performed on detrital zircons obtained from the Miocene sandstones of the Ladrilleros-Juanchaco sedimentary sequence (Colombia, Equatorial Pacific). This analysis was complemented with zircon U/Pb dating to identify typology-age associations as indicators of provenance of these sediments. Our results show that zircons with S and P dominant typology have internal structures/zoning that indicate mostly igneous and possibly some metamorphic origins. Morphometric results suggest little transport from source areas. Both typology and U/Pb data point to the Western Cordillera as the main source of the detrital materials of this sedimentary sequence. A paleogeographic reconstruction shows that during Late Miocene times there were significant portions of the Western Cordillera uplifted, eroding away and acting as a fluvio-topographic barrier blocking sediments from the Central Cordillera to reach the Pacific basins. Miocene plutons at the axis of the Western Cordillera were also probably exhumed and played a role as geomorphologically active massifs. This study demonstrates that typologic analysis on detrital zircon grains is a powerful tool as indicator of provenance and paleogeography in complex litho-tectonic areas where overlapping U/Pb signatures can lead to contradictory results.

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Funding information

This work was carried out with support from the Instituto de Investigaciones en Esratigrafía (IIES) and the Research Group in Stratigraphy and Volcanology (GIEV-Cumanday) at Universidad de Caldas (Colombia). Institutional support from the National Hydrocarbons Agency (ANH, Colombia), Universidad Nacional de Colombia Sede Medellín. We are grateful to the personnel at the LaserCrhon Laboratory of the University of Arizona. We greatly appreciate the comments and suggestions from Yamirka Rojas-Agramonte and Javier Fernández-Suárez, whose input significantly improved the quality of the manuscript.

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