Geodynamic evolution; U-Pb thermochronology; Geochronology; Northern Andes; Diffusion
Paul Andre N., Spikings Richard A., Chew David, Daly J. Stephen (2019), The effect of intra-crystal uranium zonation on apatite U-Pb thermochronology: A combined ID-TIMS and LA-MC-ICP-MS study, in Geochimica et Cosmochimica Acta
, 251, 15-35.
Paul Andre N., Spikings Richard A., Ulianov Alexey, Ovtcharova Maria (2018), High temperature (>350 °C) thermal histories of the long lived (>500 Ma) active margin of Ecuador and Colombia: Apatite, titanite and rutile U-Pb thermochronology, in Geochimica et Cosmochimica Acta
, 228, 275-300.
Spikings R, Cochrane R, Villagomez D, Lelij R, Vallejo C, Winkler W, Beate R (2015), The geological history of northwestern South America: From Pangaea to the early collision of the Caribbean Large Igneous Province (290-75 Ma), in Gondwana Research
, (1), 95-139.
Cochrane R, Spikings R, Gerdes A, Winkler W, Ulianov A, Mora A, Chiaradia M (2014), Distinguishing between in-situ and accretionary growth of continents along active margins, in Lithos
Cochrane R, Spikings R, Gerdes A, Ulianov A, Mora A, Villagomez D, Putlitz B, Chiaradia M (2014), Permo-Triassic anatexis, continental rifting and the disassembly of western Pangaea, in Lithos
Cochrane R, Spikings R, Chew D, Wotzlaw J-F, Chiaradia M, Tyrrell S, Schaltegger U, Lelij R (2014), High temperature (>350°C) thermochronology and mechanisms of Pb loss in apatite, in Geochimica et Cosmochimica Acta
The main aim of this study is to advance understanding and methodology of high-temperature U-Pb thermochronology, by applying it to accessory phases extracted from young (Mesozoic) crystalline rocks, and inverting U-Pb age data to generate continuous thermal history paths at temperatures higher than 350°C.This project will advance research into U-Pb thermochronology of titanite, apatite and rutile separated from Phanerozoic crystalline rocks, by combining i) ID-TIMS dates of a range of grain sizes, ii) laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) intra-grain dates, and iii) cathodoluminescence, back-scattered electron imaging and LA-ICP-MS trace element mapping to qualitatively and quantitatively constrain crystal heterogeneity, respectively.Thermochronological techniques have significantly contributed to our understanding of geological processes since the early 1970’s because they are capable of accurately quantifying variations in temperature, with time. Most techniques are sensitive to low temperatures (<350°C), and thus are limited to investigating the thermal histories of the upper crust. This study represents an important contribution to Earth Sciences because:i)High temperature (>350°C) U-Pb thermochronology provides earth scientists with a tool to generate continuous t-T paths for the lower and middle crust, which will significantly increase our understanding of a) how lower crustal rocks exhume to the surface (e.g. pure or simple shear during extension?), b) the tectonic stability of lower crust and cratons, and c) the tectonic history of active margins over long time periods (e.g. 500 Ma), during which they may have experienced numerous terrane collision events and a substantial quantity (e.g. >15km) of exhumation.ii)This will be the first study to combine ID-TIMS and LA-MC-ICP-MS ages of apatite, which can be used to derive theoretical thermal history paths, and assess the accuracy of those paths. Furthermore, corroboratory data from both techniques would confirm that Pb is lost by thermally activated diffusion, confirming the use of apatite U-Pb ages as thermochronometers.The Northern Andes will be used as the study region because they represent a superb natural laboratory to test the U-Pb thermochronological method. The tectonic history of the region has been extensively studied by the principal applicant and other authors, and numerous 40Ar/39Ar and lower temperature thermochronological constraints have been published. Previous studies that utilised the U-Pb thermochronological method applied it to Precambrian rocks. This study will be the first to apply it to Phanerozoic rocks, and will therefore face the challenge of generating sufficiently precise U-Pb ages from minerals with low ratios of radiogenic to common Pb.