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Thermochronology and tectonics of the circum-Maracaibo region, and experimental analysis of the usefulness of multi-domain diffusion thermochronology

Applicant Spikings Richard A.
Number 129497
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 01.05.2010 - 31.05.2013
Approved amount 239'480.00
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All Disciplines (2)

Discipline
Geochronology
Mineralogy

Keywords (7)

Colombia; Venezuela; Thermochronology; Tectonics; multi-domain diffusion; U-Pb Thermochronology; 40Ar/39Ar thermochronology

Lay Summary (English)

Lead
Lay summary
This proposal aims to i) use innovative geochronological and thermochronological methods to investigate the response of continental crust to collision and accretion within geologically distinct regions of the circum-Maracaibo region, and ii) to test the validity of the multi-domain diffusion (MDD) model to derive accurate, continuous thermal history solutions for alkali feldspars using the 40Ar/39Ar method.The Maracaibo Triangular Block (MTB) provides a well exposed section of rocks that permit the processes of continent-continent and continent-ocean arc/plateau collision and accretion to be studied, and any concluding models will be useful analogues for interpreting geological observations in other locations where continental plates have grown via the collision and accretion of oceanic and continental crust. Geochronological and thermochronological data will be used to construct semi-continuous thermal history paths and a temporally constrained tectonic framework. Zircon U-Pb LA-ICP-MS ages will provide a baseline to interpret the thermochronological data. High temperature (>300°C; apatite and titanite U-Pb; hornblende, white mica and biotite 40Ar/39Ar) thermochronological methods will be used to extract thermal history paths from Precambrian and Palaeozoic granitoids. Lower temperature thermochronological methods (<300°C; alkali feldspar 40Ar/39Ar, zircon and apatite fission-track analysis, zircon and apatite (U-Th)/He analysis) will be used to provide quantitative information about i) the response of the north western South American Plate to Pacific active margin tectonics, and ii) the collision of the Caribbean Plate against the north-western South American Plate at 75-73 Ma. Our interpretations will be used to understand how the margins of continental plates respond to collision and accretion events, and to develop models for the Phanerozoic geological evolution of north-western South America.The long, protracted cooling history of basement sequences provides an excellent opportunity to test the MDD model via a detailed investigation of the distribution of radiogenic 40Ar within single alkali feldspar crystals. We intend to utilise a CO2-IR laser equipped with a 2-wavelength, co-axial optical pyrometer and state-of-the-art 193nm UV excimer to perform both laser heating and in-situ ablation of the same, chemically unaltered alkali feldspar crystal to obtain diffusion data. Cyclical step-heating and in-situ analyses of the same crystal would represent the most direct method of attempting to match radiogenic daughter isotope concentrations yielded by both gas extraction methods, and therefore represents a direct test of the MDD model.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Vertical tectonics at a continental crust-oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia
Villagomez Diego, Spikings Richard, Mora Andres, Guzman Georgina, Ojeda German, Cortez Elisabeth, Van der Lelij Roelant (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.
Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate Boundary Zone
Van der Lelij Roelant, Spikings Richard, Kerr Andrew, Kounov Alexandre, Cosca Michael, Chew David, Villagomez Diego (2010), Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate Boundary Zone, in Tectonics, 29, 1-30.

Collaboration

Group / person Country
Types of collaboration
Goethe University Germany (Europe)
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
10th Swiss Geoscience Meeting 16.11.2012 Bern
9th Swiss Geoscience Meeting 11.11.2011 Zurich
XIV Congreso Latinoamericano de Geologia, Colombia 10.08.2011 Medellin, Colombia
European Geophysical Uniion 05.04.2011 Vienna
GSA Penrose Meeting: Neotectonics of Arc-Continent Collision 12.01.2011 Manizales (Colombia)
12th International Conference on Thermochronology. 10.08.2010 Glasgow
Conference: European Geophysical Union 20.04.2010 Vienna
Conference: Circum Caribbean and North Andean Tectonomagmatic Evolution: Impacts on Palaeoclimate and Resource Formation 02.06.2009 Cardiff


Awards

Title Year
ELSTE prize 2010

Associated projects

Number Title Start Funding scheme
134443 Thermochronology and Tectonics of the Northern Andes (Colombia and Ecuador) 01.04.2011 Project funding
119871 Thermochronology and tectonics of the Northern Andes (Colombia and Ecuador) 01.04.2008 Project funding

Abstract

This proposal seeks funding for three years for one PhD student to pursue two main aims: i) to use innovative geochronological and thermochronological methods to investigate the response of continental crust to collision and accretion by establishing semi-continuous thermal and exhumation histories for geologically distinct regions of the circum-Maracaibo region within the north western South American Plate, and ii) to test the validity of the multi-domain diffusion (MDD) model to derive accurate, continuous thermal history solutions for alkali feldspars that have experienced long (>400 Ma), protracted cooling histories, using the 40Ar/39Ar method.The response of continental crust to collision and accretion (AIM i): The Maracaibo Triangular Block (MTB) provides an extremely well exposed section of rocks that permit the processes of continent-continent and continent-ocean arc/plateau 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. New Guinea. This proposal intends to target specific basement provinces within the MTB, which are (figure 1): i) the transpressive orogen of the Merida Andes (Venezuela), ii) the Santander Massif (Colombia), iii) The Perija Andes (Venezuela), and iv) the triangular, fault bounded Sierra Nevada de Santa Marta (Colombia). The MTB resides within the zone of interaction between the Caribbean, Nazca and South American Plates. Despite the fact that the enormous hydrocarbon reserves of the Lake Maracaibo region render it the most economically productive region of South America, there is a paucity of knowledge of the tectonic history of its basement provinces, which hinders our attempts to i) understand the relationships between tectonics and sedimentation within the MTB, and ii) assess the relative roles played by tectonic forces that originated at the Pacific and Caribbean margins, since the late Cretaceous.Geochronological and thermochronological data will be combined with published geochemical and structural data to construct semi-continuous thermal history paths and a temporally constrained tectonic framework. Zircon U/Pb LA-ICP-MS ages will provide a baseline to interpret the thermochronological data. High temperature (>300°C; apatite and titanite U/Pb; hornblende, white mica and biotite 40Ar/39Ar) thermochronological methods will be used to extract plausible thermal history paths from Precambrian and Palaeozoic granitoids, potentially revealing information about i) the amalgamation of eastern Rodinia, ii) the opening of the Iapetus ocean and the evolution of a cordilleran type margin along the South American Plate, and iii) the timing of suturing of continental terranes, ending with the amalgamation of western Pangea in the Carboniferous. Lower temperature thermochronological methods (<300°C; alkali feldspar 40Ar/39Ar, zircon and apatite fission-track analysis, zircon and apatite (U-Th)/He analysis) will be used to provide quantitative information about i) the response of the far north western South American Plate to Pacific active margin tectonics since the Jurassic, and ii) the collision of the Caribbean Cretaceous Oceanic Province against the north western South American Plate at 75-73 Ma (Vallejo et al., 2006) and subsequent prolonged collision between those provinces. Our interpretations will be combined with previous Andean studies to understand further how the margins of continental plates respond to collision and accretion events, and to develop models for the Phanerozoic geological evolution of the north western South American plate margin.The planned research is complementary to other projects within the Dept. of Mineralogy, University of Geneva, which address the tectonic evolution of the central and northern Andes from 16°S (southern Peru) to the northern plate boundary. These projects aim to understand genetic links between tectonics, the composition of the crust, magmatism and metallogenesis.Testing the validity of the multi-domain diffusion model (AIM ii): The long, protracted cooling history of basement sequences within the MTB, combined with state-of-the-art analytical facilities in Geneva, provides an excellent opportunity to test the MDD model via a detailed investigation of the distribution of radiogenic 40Ar within single alkali feldspar crystals. The MDD method is the only documented method for generating continuous thermal history profiles over the temperature range of 350-150°C (alkali feldspars). However, despite the fact that the MDD model has yielded sensible and useful results (including previous work by the applicant), the technique is contested and very few experimental tests of the assumptions behind the model have been performed. We intend to utilise a CO2-IR laser equipped with a 2-wavelength, co-axial optical pyrometer (temperature precision ±2-3%) and state-of-the-art 193nm UV excimer to perform both laser heating and in-situ ablation of the same, chemically unaltered alkali feldspar crystal to obtain diffusion data. Cyclical step-heating and in-situ analyses of the same crystal would represent the most direct method of attempting to match radiogenic daughter isotope concentrations yielded by both gas extraction methods, and therefore represents a direct test of the MDD model.The project is already active and commenced on 1st April, 2009 with the employment of a PhD candidate (Roelant Van der Lelij). However, the financial situation of the Department of Mineralogy is such that it can not pay Roelant’s salary after 31st March, 2010, and funds are requested for three years, starting on the 1st April, 2010. Roelant is an excellent student, has demonstrated a high level of laboratory skill and innovation and is an ideal candidate to carry out the proposed research.
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