Near conductive cooling rates in the upper-plutonic section of crust formed at the East Pacific

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dc.contributor.authorFaak, Kathrin
dc.contributor.authorCoogan, Laurence A.
dc.contributor.authorChakraborty, Sumit
dc.date.accessioned2018-10-10T12:55:06Z
dc.date.available2018-10-10T12:55:06Z
dc.date.copyright2015en_US
dc.date.issued2015
dc.description.abstractA new geospeedometer, based on diffusion modeling of Mg in plagioclase, is used to determine cooling rates of the upper section of the lower oceanic crust formed at fast-spreading mid-ocean ridges. The investigated natural sample suites include gabbroic rocks formed at three different locations along the fast-spreading East Pacific Rise. These samples cover a depth interval of 0–840 m below the sheeted dike/gabbro boundary and therefore allow the variation of cooling rate as a function of depth within the upper plutonic sequence to be determined. We demonstrate that the cooling rates we obtained are robust (reproducible and consistent across different vertical sections at fast spreading ridges) and decrease significantly with increasing sample depth (covering almost 4 orders of magnitude, ranging from ∼1 °C y−1 for the shallowest samples to 0.0003 °C y−1 for the deepest samples). Both the absolute cooling rates, and the rate of decrease of cooling rate with depth, are consistent with conductive thermal models. In contrast, the absolute cooling rates determined from the deeper samples (>300 m below DGB), and the large decrease in cooling rate with depth are inconsistent with thermal models that include substantial cooling by off-axis hydrothermal circulation within the upper plutonic section of the crust.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.description.sponsorshipWe would like to thank Jeff Karson, Kathryn Gillis and IODP for the generous loan of samples. Stan Dosso is thanked for helping to speed up the Fortran code for the forward model and providing an inversion method to test the forward model. We thank an anonymous reviewer and the editor Tim Elliott for constructive reviews and comments that helped to improve the clarity of the paper and acknowledge support from DFGSC 166/12-1 and NSERC discovery grant 283238.en_US
dc.identifier.citationFaak, K., Coogan, L.A. & Chakraborty, S. (2015). Near conductive cooling rates in the upper-plutonic section of crust formed at the East Pacific. Earth and Planetary Science Letters, 423, 36-47. https://doi.org/10.1016/j.epsl.2015.04.025en_US
dc.identifier.urihttps://doi.org/10.1016/j.epsl.2015.04.025
dc.identifier.urihttp://hdl.handle.net/1828/10155
dc.language.isoenen_US
dc.publisherEarth and Planetary Science Lettersen_US
dc.subjectcooling rate
dc.subjectoceanic crust
dc.subjectmid-ocean ridge
dc.subjectdiffusion modeling
dc.subjectMg-in-plagioclase
dc.subject.departmentSchool of Earth and Ocean Sciences
dc.titleNear conductive cooling rates in the upper-plutonic section of crust formed at the East Pacificen_US
dc.typePostprinten_US

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