Application of Detrital Zircon U-Pb Geochronology to Surface and Subsurface Correlations of Provenance, Paleodrainage, and Tecto
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Research Paper GEOSPHERE Application of detrital zircon U-Pb geochronology to surface and subsurface correlations of provenance, paleodrainage, and GEOSPHERE; v. 11, no. 6 tectonics of the Middle Magdalena Valley Basin of Colombia doi:10.1130/GES01251.1 Brian K. Horton1, Veronica J. Anderson1, Victor Caballero2, Joel E. Saylor3, Junsheng Nie4, Mauricio Parra2,5, and Andrés Mora2 10 figures; 2 supplemental files 1Institute for Geophysics and Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78712, USA 2Ecopetrol, Instituto Colombiano del Petróleo, Bucaramanga, Colombia 3Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204, USA CORRESPONDENCE: [email protected] 4MOE Key Laboratory of Western China’s Environmental Systems, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 73000, China 5Institute of Energy and Environment, University of São Paulo, 05508-010 São Paulo, SP, Brazil CITATION: Horton, B.K., Anderson, V.J., Caballero, V., Saylor, J.E., Nie, J., Parra, M., and Mora, A., 2015, Application of detrital zircon U-Pb geochronol- ogy to surface and subsurface correlations of prov- ABSTRACT Provenance shifts of mid-Paleocene and latest Eocene–earliest Oligocene enance, paleodrainage, and tectonics of the Middle age are consistent with incipient uplift of the flanking Central Cordillera and Magdalena Valley Basin of Colombia: Geosphere, v. 11, no. 6, p. 1790–1811, doi:10.1130/GES01251.1. Detrital zircon U-Pb geochronology has been used extensively to develop Eastern Cordillera, respectively. However, a well-documented phase of latest provenance histories for surface outcrops of key stratigraphic localities within Paleocene–middle Eocene beveling of basement uplifts in the Middle Magda- Received 17 August 2015 sedimentary basins. However, many basins lack sufficiently continuous and lena Valley Basin appears to be largely aliased in the detrital record. Moreover, Revision received 13 September 2015 widespread exposures of complete successions to evaluate proposed long- despite the proximity of the magmatic arc, there is insufficient syndeposi- Accepted 2 October 2015 term tectonic histories, stratigraphic correlations, and paleodrainage patterns tional evidence for a proposed Paleogene pulse of magmatism and, in this Published online 12 November 2015 within individual basins. Here, we demonstrate the utility of subsurface detri- case, limited utility of U-Pb ages in pinpointing precise depositional (strati- tal zircon U-Pb analysis by integrating ages from three key wells (21 subsur- graphic) ages. face samples) with previously reported data from six exposed intervals (90 U-Pb age spectra for Oligocene through Pliocene basin fill underscore surface samples) within a single basin. Samples from the 5–10-km-thick clastic complex along-strike (north-south) and cross-strike (east-west) variations re- successions span several structural blocks over an ~300 × 50 km swath of flective of compartmentalized transverse deposystems demarcated by point- the Middle Magdalena Valley Basin, a north-trending intermontane basin in source contributions from the Central Cordillera and Eastern Cordillera. The the northern Andes of Colombia. Available U-Pb age distributions for mod- late Miocene appearance of 100–0 Ma grains and a regional switch to broad, ern rivers highlight the distinctive signatures of several competing sediment multimodal age distributions suggest the initial integration of the longitu- sources, including two major contiguous ranges (Central Cordillera and East- dinal proto–Magdalena River, linking the Middle Magdalena Valley Basin ern Cordillera) and two localized block uplifts (Santander Massif and San with southern headwaters in the Upper Magdalena Valley and likely driving Lucas range). U-Pb results from Jurassic through Neogene stratigraphic units increased sedimentation rates farther north in the offshore Magdalena sub- spanning the nine surface and subsurface sites, including several type locali- marine fan of the southern Caribbean margin. ties, enable comparisons of provenance shifts at specific sites and spatial vari- ations among key stratigraphic intervals across multiple sites. Distinctive age populations for the Andean magmatic arc, retroarc fold- INTRODUCTION thrust belt, and South American craton facilitate correlation of stratigraphic units and reconstruction of the long-term provenance and tectonic evolution Although advances in detrital zircon U-Pb geochronology have fueled a re- of the Middle Magdalena Valley Basin. Nearly all surface and subsurface lo- surgence in sediment provenance studies, subsurface and intrabasinal applica- calities show up-section changes in age spectra consistent with (1) Jurassic tions remain limited. Rapid data acquisition through laser-ablation–inductively growth of extensional subbasins fed by local igneous sources, (2) Cretaceous coupled plasma–mass spectrometry (LA-ICP-MS) has propelled U-Pb analyses deposition in an extensive postrift setting, and (3) protracted Cenozoic growth of sand-sized zircon grains to the forefront of provenance studies seeking to of basin-bounding ranges during Andean crustal shortening. Subsurface sam- discriminate among potential source regions (e.g., Dickinson and Gehrels, ples augment surface samples, highlighting their utility in developing regional 2008; Nie et al., 2012; Gehrels, 2014). Further applications for sedimentary For permission to copy, contact Copyright source-to-sink relationships, the timing of paleodrainage integration, and tec- basin analysis include assessments of: (1) the relative volumetric contribu- Permissions, GSA, or [email protected]. tonic reconstructions. tions from known sources in modern watersheds (Saylor et al., 2013); (2) the © 2015 Geological Society of America GEOSPHERE | Volume 11 | Number 6 Horton et al. | Provenance and paleogeographic reconstruction of the Magdalena Valley, northern Andes Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/6/1790/4333662/1790.pdf 1790 by guest on 27 September 2021 Research Paper complex mixing and downstream dilution of source signals within modern Silva et al., 2013; Bayona et al., 2013; Reyes-Harker et al., 2015). Alternative sce- rivers (Amidon et al., 2005; Link et al., 2005; Zhang et al., 2012; He et al., 2014); narios propose a north-flowing proto–Magdalena River developing in middle (3) large-scale paleodrainage patterns, including the onset and evolution of to late Miocene time (Hoorn et al., 1995, 2010). Evolution of the Middle Magda- major paleorivers (Davis et al., 2010; Dickinson et al., 2012; Mackey et al., 2012; lena Valley Basin drainage systems and establishment of a through-going Blum and Pecha, 2014); and (4) absolute ages of stratigraphic units (Fildani Magdalena River also directly affected sediment accumulation and offshore et al., 2003; DeCelles et al., 2007; Dickinson and Gehrels, 2009; Horton et al., hydrocarbon prospectivity of the Magdalena delta in the Caribbean Sea. 2015). Although accurate ages for syndepositional volcanic zircons clearly im- Further uncertainties center on potential basin responses to the important re- prove chronostratigraphic correlations, U-Pb geochronology may provide a gional phases of Mesozoic extension and Cenozoic shortening in the northern- viable correlation tool on the basis of comparable age distributions (e.g., Rain- most Andes, as well as critical transitions involving focused basement uplift bird et al., 2007; Lawton et al., 2010; Beranek et al., 2013; Lewis and Sircombe, and punctuated magmatism (e.g., Colletta et al., 1990; Dengo and Covey, 1993; 2013), an approach that could considerably enhance subsurface investigations. Gómez et al., 2003, 2005a, 2005b; Horton et al., 2010a; Bayona et al., 2012; Parra Despite the wide range of applications, complexities over multiple scales et al., 2012; Nie et al., 2012; Saylor et al., 2012a, 2012b; Caballero et al., 2013a, highlight various difficulties in pinpointing sediment source regions, recon- 2013b; Reyes-Harker et al., 2015). Here, we present U-Pb ages of detrital zircons for structing paleodrainage patterns, and correlating stratigraphic units. Whereas 21 subsurface samples of Mesozoic–Cenozoic basin fill, and we integrate these most basin-scale studies focus on temporal provenance shifts registered within data with results from 83 surface outcrop samples and seven modern river key stratigraphic sections, uncertainties persist over the effectiveness of signal samples to help correlate the provenance and tectonic histories of surface and transmission from source to sink. These issues can include (1) uneven con- sub surface basin fill. tributions from source areas, (2) storage, buffering, or recycling within drain- age systems, and (3) potential sequestration due to intrabasinal variations in hydrodynamics or depositional environments (e.g., Métivier and Gaudemer, GEOLOGIC AND STRATIGRAPHIC FRAMEWORK 1999; DeGraaff-Surpless et al., 2003; Allen, 2008; Lawrence et al., 2011; Saylor et al., 2013; Latrubesse, 2015). In river-dominated basins, many of these po- The Middle Magdalena Valley Basin is a long-lived sedimentary basin that tential problems can be minimized by sampling a range of depositional sub- has recorded uplift and exhumation of the major ranges and block uplifts of the envi ron ments over a sufficiently large region (e.g., Potter, 1978; Ingersoll, 1990; northernmost Andes at 4°N–7°N (Fig. 1). Modern