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Thermochronology and Tectonics of the Northern Andes (Colombia and Ecuador)

English title Thermochronology and Tectonics of the Northern Andes (Colombia and Ecuador)
Applicant Spikings Richard A.
Number 134443
Funding scheme Project funding
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geochronology
Start/End 01.04.2011 - 31.03.2013
Approved amount 152'575.00
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All Disciplines (2)

Discipline
Geochronology
Geology

Keywords (6)

U-Pb thermochronology; Ar/Ar thermochronology; Tectonics; Andes; Colombia; Ecuador

Lay Summary (English)

Lead
Lay summary
Plate margin within the Tethys-Pacific Wilson cycle with respect to the onset of subduction and its interruption by accreting island arcs. The proposed science is considered to be important because:South AmericanThe main aims of the study are: i) to determine the timing of amalgamation of western Pangea and its effect on rock uplift and exhumation along the relict South American Plate margin, ii) to determine the timing of the disassembly of western Pangea, the opening of the western Tethys Ocean and the timing of crustal anatexis, and to iii) constrain the evolution of the

 

A) The Northern Andean Segment (north of 5°S) provides an extremely well exposed section of rocks that permit the processes of continent-continent and continent-oceanic arc collision and accretion to be studied, and hence any concluding models will represent useful analogues for interpreting geological observations in other locations where continental plates have grown via the collision and accretion of oceanic and continental crust, e.g. the northern and eastern margins of Australia.

 

B) The significant hydrocarbon reserves of the north-western Amazon basin, along with extensive porphyry related metal deposits within the Andes render the Northern Andean Segment economically important, although they are under-exploited due to a paucity of knowledge of the geological evolution of the region.

 

A wide disparity exists in the documented evolution of the Palaeozoic-Mesozoic rocks within Ecuador and Colombia, despite the fact that they continuously crop-out along-strike, throughout both countries. These differences render it difficult to compare geochronological and stratigraphic information from different regions and hence coherent models for the Palaeozoic - early Cretaceous evolution of the entire Northern Andean Segment have not been proposed. Extensive mapping by the British Geological Survey during 1986-1992 divided the Palaeozoic - Mesozoic rocks of Ecuador (Eastern Cordillera) into four N-S trending terranes (Litherland et al., 1994). However, more recently Pratt et al. (2005) proposed an autochthonous geological model for the same rocks. Palaeozoic - Mesozoic rocks of the Central Cordillera of Colombia are thought to form a single allochthonous terrane (the Tahami Terrane; Toussaint and Restrepo, 1994; Figure 1), which accreted against the Precambrian shield during the Cretaceous. These contrasting models form the core of the proposal and originate because of a paucity of quantitative data, resulting in few temporal constraints.

Ar) thermochronological methods will be used to extract plausible thermal history paths from Precambrian gneisses, Paleozoic metasedimentary rocks, Triassic migmatites and Jurassic granitoids to assess the pre-Andean exhumation history of the NW SOAM Plate margin during continental disassembly, and subsequent active margin processes such as island arc accretion.39Ar/40This proposal requests funds to complete the post-graduate studies of Ryan Cochrane, which requires analyses of samples already collected from well-exposed sections of Precambrian - Mesozoic rocks within Ecuador and Colombia, and funds for one additional field season. Geochronological (ID-TIMS and LA-ICPMS), geochemical (XRF and ICP-MS) and isotopic tracing (Hf and Nd) data will be used to construct a temporal and tectonic framework for several sections. High temperature (>350°C; apatite and titanite U-Pb; hornblende and white mica

The acquired data and interpretations will be used to develop a model for the Palaeozoic - early Cretaceous geological evolution of the NW SOAM plate margin. We intend to obtain data from both Ecuador and Colombia to test the likelihood of diachroneity during the amalgamation and disassembly of Pangea, as well as during the interruption of the Pacific active margin by the collision of an intra-oceanic arc system.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Tectonic history of the Central and Western cordilleras of Colombia, a Thermochronological study
Villagomez Diego (2012), Tectonic history of the Central and Western cordilleras of Colombia, a Thermochronological study, in Lithos, 160(1), 228-249.
Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia
Villagomez D, Spikings R, Magna T, Kammer A, Winkler W, Beltran A (2011), Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia, in LITHOS, 125(3-4), 875-896.
Vertical tectonics at a continental crust-oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia
Villagomez D, Spikings R, Mora A, Guzman G, Ojeda G, Cortes E, van der Lelij R (2011), Vertical tectonics at a continental crust-oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia, in TECTONICS, 30, 1-18.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
9th Swiss Geoscience Meeting 11.11.2011 Zurich
Invited seminar at the Federal University of Ecuador (EPN) 10.09.2011 Quito, Ecuador
14th Latin American Congress 29.08.2011 Medellin
Europeasn Union Geosciences 03.04.2011 Vienna


Knowledge transfer events



Self-organised

Title Date Place
Seminar at the Ecuadorian Geological Survey 09.09.2011 Quito, Ecuador

Associated projects

Number Title Start Funding scheme
107596 Accretionary and post-accretionary cooling, exhumation and tectonic history of the central and western Andes of Colombia 01.04.2005 Project funding
128146 Upgrading the 40Ar/39Ar facility at the University of Geneva 01.01.2010 R'EQUIP
119871 Thermochronology and tectonics of the Northern Andes (Colombia and Ecuador) 01.04.2008 Project funding
129497 Thermochronology and tectonics of the circum-Maracaibo region, and experimental analysis of the usefulness of multi-domain diffusion thermochronology 01.05.2010 Project funding
146332 Advancing U-Pb high temperature thermochronology by combining single grain and intra-grain dating 01.04.2013 Project funding

Abstract

This proposal requests funds for 24 months for one PhD student to use innovative geochronological and thermochronological methods to study the Palaeozoic-early Cretaceous geological history of the NW South American (SOAM) Plate margin. The continental margin of the South American Plate in Ecuador and Colombia (north of 5°S; Figure 1) has experienced at least one complete Wilson cycle since ~600 Ma with the opening and closure of the Rheic Ocean, and it currently sits within the active margin stage of the Tethys-Pacific Wilson cycle. This project has already been funded for 24 months (expiring 01/04/11), and involves a single PhD student. We request funds for an extension of 24 months.The main aims of the study are: i) to determine the timing of amalgamation of western Pangea and its effect on rock uplift and exhumation along the relict SOAM Plate margin, ii) to determine the timing of the disassembly of western Pangea, the opening of the western Tethys Ocean and the timing of crustal anatexis, and to iii) constrain the evolution of the SOAM Plate margin within the Tethys-Pacific Wilson cycle with respect to the onset of subduction and its interruption by accreting island arcs. The proposed science is considered to be important because:A) The Northern Andean Segment (north of 5°S) provides an extremely well exposed section of rocks that permit the processes of continent-continent and continent-oceanic arc collision and accretion to be studied, and hence any concluding models will represent useful analogues for interpreting geological observations in other locations where continental plates have grown via the collision and accretion of oceanic and continental crust, e.g. the northern and eastern margins of Australia.B) The significant hydrocarbon reserves of the north-western Amazon basin, along with extensive porphyry related metal deposits within the Andes render the Northern Andean Segment economically important, although they are under-exploited due to a paucity of knowledge of the geological evolution of the region.A wide disparity exists in the documented evolution of the Palaeozoic-Mesozoic rocks within Ecuador and Colombia, despite the fact that they continuously crop-out along-strike, throughout both countries. These differences render it difficult to compare geochronological and stratigraphic information from different regions and hence coherent models for the Palaeozoic - early Cretaceous evolution of the entire Northern Andean Segment have not been proposed. Extensive mapping by the British Geological Survey during 1986-1992 divided the Palaeozoic - Mesozoic rocks of Ecuador (Eastern Cordillera) into four N-S trending terranes (Litherland et al., 1994). However, more recently Pratt et al. (2005) proposed an autochthonous geological model for the same rocks. Palaeozoic - Mesozoic rocks of the Central Cordillera of Colombia are thought to form a single allochthonous terrane (the Tahami Terrane; Toussaint and Restrepo, 1994; Figure 1), which accreted against the Precambrian shield during the Cretaceous. These contrasting models form the core of the proposal and originate because of a paucity of quantitative data, resulting in few temporal constraints.This proposal requests funds to complete the post-graduate studies of Ryan Cochrane, which requires analyses of samples already collected from well-exposed sections of Precambrian - Mesozoic rocks within Ecuador and Colombia, and funds for one additional field season. Geochronological (ID-TIMS and LA-ICPMS), geochemical (XRF and ICP-MS) and isotopic tracing (Hf and Nd) data will be used to construct a temporal and tectonic framework for several sections. High temperature (>350°C; apatite and titanite U-Pb; hornblende and white mica 40Ar/39Ar) thermochronological methods will be used to extract plausible thermal history paths from Precambrian gneisses, Paleozoic metasedimentary rocks, Triassic migmatites and Jurassic granitoids to assess the pre-Andean exhumation history of the NW SOAM Plate margin during continental disassembly, and subsequent active margin processes such as island arc accretion.The acquired data and interpretations will be used to develop a model for the Palaeozoic - early Cretaceous geological evolution of the NW SOAM plate margin. We intend to obtain data from both Ecuador and Colombia to test the likelihood of diachroneity during the amalgamation and disassembly of Pangea, as well as during the interruption of the Pacific active margin by the collision of an intra-oceanic arc system. This project is complementary to SNF project 200021_129497 (thermochronology and tectonics of the circum-Maracaibo region; commenced on April 1st 2010), and is a continuation of SNF project 200020_119871.
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