Andrés Mora
Ecopetrol
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Andrés Mora.
Geology | 2011
David W. Farris; Carlos Jaramillo; Germán Bayona; Sergio A. Restrepo-Moreno; Camilo Montes; Agustín Cardona; Andrés Mora; Robert J. Speakman; Michael D. Glascock; Victor A. Valencia
Tectonic collision between South America and Panama began at 23–25 Ma. The collision is significant because it ultimately led to development of the Panamanian Isthmus, which in turn had wide-ranging oceanic, climatic, biologic, and tectonic implications. Within the Panama Canal Zone, volcanic activity transitioned from hydrous mantle-wedge−derived arc magmatism to localized extensional arc magmatism at 24 Ma, and overall marks a permanent change in arc evolution. We interpret the arc geochemical change to result from fracturing of the Panama block during initial collision with South America. Fracturing of the Panama block led to localized crustal extension, normal faulting, sedimentary basin formation, and extensional magmatism in the Canal Basin and Bocas del Toro. Synchronous with this change, both Panama and inboard South America experienced a broad episode of exhumation indicated by (U-Th)/He and fission-track thermochronology coupled with changing geographic patterns of sedimentary deposition in the Colombian Eastern Cordillera and Llanos Basin. Such observations allow for construction of a new tectonic model of the South America–Panama collision, northern Andes uplift and Panama orocline formation. Finally, synchroneity of Panama arc chemical changes and linked uplift indicates that onset of collision and Isthmus formation began earlier than commonly assumed.
Geological Society of America Bulletin | 2008
Andrés Mora; Mauricio Parra; Manfred R. Strecker; Edward R. Sobel; H. Hooghiemstra; Vladimir Torres; Jaime Vallejo Jaramillo
New apatite fission-track data, paleoelevation estimates from paleobotany, and recently acquired geological data from the Eastern Cordillera of Colombia document the onset of increased exhumation rates in the northeastern Andes at ca. 3 Ma. The Eastern Cordillera forms an efficient orographic barrier that intercepts moisture-laden winds sourced in the Amazon lowlands, leading to high rainfall and erosion gradients across the eastern flank of the range. In contrast, the drier leeward western flank is characterized by lower rates of deformation and exhumation. In light of the geological evolution of the Eastern Cordillera, the combination of these data sets suggests that the orographic barrier reached a critical elevation between ca. 6 and ca. 3 Ma, which ultimately led to protracted, yet more focused erosion along the eastern flank. Sequentially restored structural cross sections across the eastern flank of the Eastern Cordillera indicate that shortening rates also have increased during the past 3 Ma. From fission-track and structural cross-section balancing, we infer that accelerated exhumation led to increasing tectonic rates on the eastern flank, creating a pronounced topographic and structural asymmetry in the Eastern Cordillera. The tectonic and climatic evolution of this orogen thus makes it a prime example of the importance of climatic forcing on tectonic processes.
Geological Society of America Bulletin | 2010
Brian K. Horton; Joel E. Saylor; Junsheng Nie; Andrés Mora; Mauricio Parra; Andrés Reyes-Harker; Daniel F. Stockli
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analyses of 29 samples from the Eastern Cordillera of Colombia reveal the origin of northern Andean basement and patterns of sedimentation during Paleozoic subsidence, Jurassic–Early Cretaceous extension, Late Cretaceous postrift subsidence, and Cenozoic shortening and foreland-basin evolution. U-Pb geochronological results indicate that presumed Precambrian basement is mainly a product of early Paleozoic magmatism (520–420 Ma) potentially linked to subduction and possible collision. Inherited zircons provide evidence for Mesoproterozoic tectonomagmatic events at 1200–1000 Ma during Grenville-age orogenesis. Detrital zircon U-Pb ages for Paleozoic strata show derivation from Andean basement, syn depositional magmatic sources (420–380 Ma), and distal sources of chiefl y Mesoproterozoic basement (1650–900 Ma) in the Amazonian craton (Guyana shield) to the east or in possible continental terranes along the western margin of South America. Sedimentation during Jurassic–Early Cretaceous rifting is expressed in detrital zircon age spectra as Andean basement sources, recycled Paleozoic contributions, and igneous sources of Carboniferous–Permian (310–250 Ma) and Late Triassic–Early Jurassic (220–180 Ma) origin. Detrital zircon provenance during continued Cretaceous extension and postrift thermal subsidence recorded the elimination of Andean basement sources and increased infl uence of craton-derived drainage systems providing mainly Paleoproterozoic and Mesoproterozoic (2050–950 Ma) grains. By Eocene time, zircons from the Guyana shield (1850–1350 Ma) dominated the detrital signal in the easternmost Eastern Cordillera. In contrast, coeval Eocene deposits in the axial Eastern Cordillera contain Late Cretaceous–Paleocene (90–55 Ma), Jurassic (190–150 Ma), and limited Permian–Triassic (280–220 Ma) zircons recording initial uplift and exhumation of principally Mesozoic magmatic-arc rocks to the west in the Central Cordillera. Oligocene–Miocene sandstones of the proximal Llanos foreland basin document uplift-induced exhumation of the Eastern Cordillera fold-thrust belt and recycling of the Paleogene cover succession rich in both arc-derived detritus (dominantly 180– 40 Ma) and shield-derived sediments (mostly 1850–950 Ma). Late Miocene–Pliocene erosion into the underlying Cretaceous section is evidenced by elimination of Mesozoic– Cenozoic zircons and increased proportions of 1650–900 Ma zircons emblematic of Cretaceous strata.
Gsa Today | 2010
Brian K. Horton; Mauricio Parra; Joel E. Saylor; Junsheng Nie; Andrés Mora; Vladimir Torres; Daniel F. Stockli; Manfred R. Strecker
Uplift of the Eastern Cordillera in the northern Andes has been linked to orographic climate change and genesis of South America’s largest river systems. The timing of initial uplift remains poorly constrained, with most estimates ranging from ca. 60 to ca. 5 Ma. New detrital zircon U-Pb ages from proximal fill of the Llanos foreland basin in Colombia reveal a pronounced mid-Cenozoic shift in provenance from an Amazonian craton source to an Andean fold-thrust belt source. This shift corresponds with changes in detrital zircon (U-Th)/He ages, a conglomeratic unroofing sequence, and a sharp increase in foredeep accumulation rates. These nearly simultaneous changes in zircon age spectra, clast compositions, and sediment accumulation are attributable to latest Oligocene uplift of the eastern flank of the Eastern Cordillera. The timing relationships suggest an early activation of the frontal thrust system, implying a long-term (up to 25 m.y.) cessation of orogenic wedge advance, potentially driven by structural inheritance and/or climate change. INTRODUCTION Surface uplift of the Eastern Cordillera in the northern Andes has had a profound effect on orographic climate change (Mora et al., 2008), growth of large continental drainage systems (Fig. 1) (Amazon, Orinoco, and Magdalena rivers; Hoorn et al., 1995; Díaz de Gamero, 1996), and biologic evolution of neotropical rainforests (Hooghiemstra and Van der Hammen, 1998; Jaramillo et al., 2006). Most estimates for the onset of uplift along the eastern flank of the Colombian Andes (Fig. 2) range from Paleocene to Pliocene time (Van der Hammen et al., 1973; Dengo and Covey, 1993; Cooper et al., 1995; Bayona et al., 2008; Parra et al., 2009a). Initial uplift has proven difficult to constrain by conventional methods. First, recent zircon fission track data provide a minimum age but do not uniquely pinpoint the precise onset of earliest uplift-induced exhumation (Parra et al., 2009b). Second, insights from synorogenic growth strata are commonly limited by inadequate exposure, poor seismic resolution, and GSA Today, v. 20, no. 7, doi: 10.1130/GSATG76A.1 minimal variation in stratal dip (e.g., Toro et al., 2004). Third, clastic compositional records of erosional unroofing are hindered by the uniformly high-maturity (quartz-dominated) sand compositions imposed by intense tropical weathering (e.g., Johnsson et al., 1988). In this study, we utilize U-Pb and (U-Th)/He ages of detrital zircon grains from the Colombian Andes to demonstrate that initial uplift-induced exhumation along the eastern flank of the fold-thrust belt had commenced by ca. 26–23 Ma. Timing relationships revealed by geochronological data coincide with shifts in conglomerate clast compositions and sediment accumulation rates and provide new insights into the pace of orogenic wedge advance. GEOLOGIC SETTING The Eastern Cordillera of Colombia forms a 1–4-km-high orographic barrier separating the intermontane Magdalena Valley from the Llanos foreland basin (Fig. 2). The 100–200-kmwide range is bounded by a frontal thrust system consisting of inverted normal faults and newly formed fold-thrust structures (Cooper et al., 1995; Mora et al., 2006). Following Jurassic– Early Cretaceous rifting, Andean orogenesis began with latest Cretaceous–Paleocene shortening in the Central Cordillera and early foreland basin evolution in the present-day Magdalena Figure 1. Map of South America showing main river systems (Magdalena, Orinoco, Amazon, and Parana) and Precambrian crustal provinces of the Amazonian craton (after Cordani et al., 2000; Chew et al., 2007).
AAPG Bulletin | 2010
Andrés Mora; Brian K. Horton; Andrés Mesa; Jorge Rubiano; Richard A. Ketcham; Mauricio Parra; Vladimir Blanco; Diego Garcia; Daniel F. Stockli
Previously unreleased fission-track results and regional structural relationships are used to interpret the migration of deformation during Cenozoic orogenesis in the Eastern Cordillera (Cordillera Oriental) of the Colombian Andes. Low-temperature thermochronological results are based on apatite and zircon fission-track analyses of 41 samples collected along vertical and horizontal transects across the Eastern Cordillera at 4–7N latitude. Inverse modeling of fission-track results helps delimit the most probable cooling histories caused by exhumation linked to upper-crustal deformation. These inverse models are constrained by known structural geometries, chronostratigraphy, biostratigraphy, and vitrinite reflectance data. Fission-track data and modeling results indicate a close correspondence in the timing and style of deformation along the western and eastern flanks of the Eastern Cordillera. East-directed fold-thrust deformation along the eastern boundary with the Llanos foreland basin was underway by the late Oligocene and early Miocene. Similarly, west-directed fold-thrust structures along the western boundary with the intermontane middle Magdalena Valley Basin became active at approximately the same time. Less well known is the time of initial shortening within the axial segment of the Eastern Cordillera; although fission-track results suggest active exhumation by the early Miocene, shortening may have commenced much earlier during the late Eocene. Timing relationships for the Eastern Cordillera have important implications for the generation, migration, and accumulation of petroleum in the middle Magdalena Valley intermontane basin and the Llanos foreland basin. Our study provides a regional context to assess the timing of structural trap development and improve exploration and development of new and existing reservoirs in Colombia and analogous fold-thrust systems elsewhere.
Geology | 2012
Mauricio Parra; Andrés Mora; Cristina Lopez; Luis Ernesto Rojas; Brian K. Horton
Low-temperature thermochronometry and crosscutting relationships identified in newly released reflection seismic data reveal a previously unrecognized zone of early Andean shortening in Colombia. Apatite fission-track data and thermal modeling help define a 60–50 Ma onset of rapid exhumation along the present boundary between the Magdalena Valley hinterland basin and Eastern Cordillera thrust belt. Subsurface angular unconformities localized above fold-thrust structures indicate Paleogene deposition in a wedge-top depozone containing doubly vergent reverse faults. Retrodeformation of a cross section based on interpreted seismic profiles and thermochronometric data indicates Paleocene to Early Eocene shortening and exhumation occurred through simultaneous activation of east- and west-directed reverse faults across a broad orogenic front. Subsequent deformation focused along west-directed inversion structures. These relationships reveal that deformation operated in a disparate manner, rather than following a systematic progression from hinterland to foreland. The northern Andes also exemplify the potential effects of hinterland sediment loading and fault strength on deformation advance in contractional orogens.
Geological Society of America Bulletin | 2012
Joel E. Saylor; Daniel F. Stockli; Brian K. Horton; Junsheng Nie; Andrés Mora
Lag time is the difference between the closure age of a thermochronologic system and the depositional age of host strata. Lag-time analysis of sedimentary basin fi ll provides insight into the exhumation history of adjacent eroded orogens. In a case study of the Paleogene Floresta basin in the Eastern Cordillera fold-thrust belt of Colombia, variations in lag time refl ect changes in both sediment source areas and exhumation patterns. However, near-zero lag times can be produced by either syndepositional volcanism or rapid exhumation. We applied U-Pb geochronology and (U-Th)/He (ZHe) thermochronology to individual zircon grains and identifi ed zircons of volcanic origin as those for which the U-Pb age is within the 2σ uncertainty of their ZHe age. Consistent discrimination of young ZHe ages as the products of either rapid exhumation or volcanism reveals three stages in the history of the northern Andean hinterland. (1) Early to late Paleocene: The appearance of syndepositional and Mesozoic volcanic zircons marks the initial infl ux of magmatic arc detritus. (2) Middle to late Eocene: Near-zero lag times point to rapid, regionally extensive exhumation attributable to thrust-induced uplift of the Magdalena Valley basement. (3) Late Eocene to late Oligocene: Increased lag time is interpreted as recycling of shallowly buried foreland-basin strata possibly due to movement on basinbounding thrust systems. The presence of volcanic zircons with ZHe ages younger than or indistinguishable from the youngest exhumationally cooled zircons underscores the need for double dating to reliably identify volcanic infl uence in detrital thermochronology datasets. These data highlight the utility of double-dated ZHe results for extracting tectonic histories and reliably excluding volcanic zircons from lag-time analysis.
Geological Society of America Bulletin | 2010
Andrés Mora; Mauricio Parra; Manfred R. Strecker; Edward R. Sobel; Gerold Zeilinger; Carlos Jaramillo; Silane Da Silva; Mauricio Blanco
We decipher the geometry, timing, and kinematics of deformation of a region in the eastern foothills of the Eastern Cordillera of Colombia. We assess the influence of inherited structural fabrics, changes in basin geometry, erosional denudation, and the characteristics of the tectonic stress field with respect to the evolution of the structural styles of the deformation front in the Eastern Cordillera. Detailed structural and geomorphic mapping of an area of ∼5000 km 2 , analysis of seismic-reflection profiles, cross-section balancing, tectonic stress-field indicators, and new apatite fission-track data are used to characterize the partitioning of Late Cenozoic deformation in the eastern foothills of the Eastern Cordillera of Colombia. During the late Miocene–Pliocene, in the Eastern Cordillera, deformation migrated from inverted master normal faults to low-elevation, low-amplitude structures in the foreland. However, this shift in the locus of deformation was not spatially uniform. The deformation front is wider in a northern sector of the Cordilleran foothills, where sedimentary units are thicker, and shortening is perpendicular to the structures. This shortening direction is identical to the direction of the greatest horizontal stress S Hmax as seen in borehole breakouts. During the late Miocene–Pliocene, basement ranges are passively uplifted by younger, more frontal thrusts. The eastern foothills of the Eastern Cordillera thus reveal a complex combination of factors responsible for the structural styles and partitioning of active deformation in an inversion orogen. Over time, the most important factor changes, from the role of inherited structural fabrics to the geometries of basin fills.
The Journal of Geology | 2013
Joel E. Saylor; Jennifer N. Knowles; Brian K. Horton; Junsheng Nie; Andrés Mora
Detrital zircon U-Pb geochronology is widely used in reconstructing sedimentary provenance, sediment dispersal pathways, and tectonic histories. These applications implicitly assume that sample age distributions from sedimentary basins closely match the zircon age populations within the drainage catchments of the eroding source region. However, recent studies question this largely untested assumption. Here we compare detrital zircon data from unconsolidated sand samples from two modern rivers in the Colombian foreland with data from Mesozoic-Cenozoic sedimentary strata exposed in their respective Andean catchments (∼1500 km2). We forward model the expected detrital zircon age distribution from each mountainous catchment by integrating age data from all exposed sedimentary units into two modeled age distributions: one assuming equal contributions from each formation and one in which each formation’s contribution is proportional to its exposure area within the catchment. Multiple statistical methods show that the area-proportional models most closely match the modern river data. We further test the ability to estimate the contributing source areas by iteratively solving for formation exposure areas to minimize the misfit between the model and the modern river data. The results show a robust correlation between modeled and observed source areas when considered at the epoch level and a qualitative correlation when considered at the formation level. We conclude that detrital zircon age populations of the Colombian foreland basin fill accurately reflect mixing of their Andean sources, in proportions roughly equal to their exposed areas within each catchment. We further conclude that the approximate relative exposure areas of contributing sources can be estimated from detrital zircon analyses. These results highlight the need for consideration of variations in the exposure area rather than solely the presence or absence of competing sediment sources in detrital zircon provenance studies.
Gsa Today | 2012
Gabriel Veloza; Richard H. Styron; Michael D. Taylor; Andrés Mora
We present a publicly available database of active structures for the northern Andes based on the literature, our own field mapping, interpretation of digital elevation models, earthquakes, and the regional velocity field obtained from Global Positioning System (GPS) studies. The “Active Tectonics of the Andes” database (ATA v.1.0) is a digital archive of more than 400 active faults available in a variety of digital formats for use by the scientific and teaching communities. ATA v.1.0 is an open-source archive that is updateable based on new results obtained by the scientific community, and it should prove useful to scientists, teachers, policy makers, and the general population. We use ATA v.1.0 in combination with surface velocities from GPS to evaluate the regional kinematics of faulting in northwest South America. In particular, we find that the development of active strike-slip systems is controlled, in part, by the degree of convergence obliquity between subducting oceanic plates and South America.