000078320 001__ 78320
000078320 005__ 20200117221647.0
000078320 0247_ $$2doi$$a10.1016/j.gca.2018.03.009
000078320 0248_ $$2sideral$$a105299
000078320 037__ $$aART-2018-105299
000078320 041__ $$aeng
000078320 100__ $$aNichols, C.I.O.
000078320 245__ $$aMicrostructural and paleomagnetic insight into the cooling history of the IAB parent body
000078320 260__ $$c2018
000078320 5060_ $$aAccess copy available to the general public$$fUnrestricted
000078320 5203_ $$aThe IABs represent one of only two groups of iron meteorites that did not form by fractional crystallization of liquid Fe-Ni in the core of a differentiated planetesimal. Instead, they are believed to originate from a partially differentiated body that was severely disrupted by one or more impacts during its early history. We present a detailed microstructural and paleomagnetic study of the Odessa and Toluca IAB meteorites, with a view to further constraining the complex history of the IAB parent body. X-ray photoemission electron microscopy and energy dispersive spectroscopy were used to generate high-resolution Ni/Fe maps. The crystallographic architecture of Odessa was analysed using electron backscatter diffraction. Paleomagnetic signals and the magnetic properties of several microstructures were also assessed using X-ray magnetic circular dichroism. Odessa exhibits a complex series of microstructures, requiring an unusual evolution during slow cooling. A conventional Widmanstätten microstructure, consisting of multiple generations of kamacite lamellae surrounded by M-shaped diffusion profiles, developed via continuous precipitation to temperatures below ~400 °C. Multiple generations of pearlitic plessite nucleated from kamacite/taenite (T > 400 °C) and tetrataenite rim/taenite interfaces (T < 400 °C), via a process of discontinuous precipitation. Rounded rafts of Ni-rich taenite, observed within some regions of pearlitic plessite, are shown to have the same crystallographic orientation as the parental taenite, and a non-standard orientation relationship with the enclosing kamacite. Contrary to current theories, these rafts cannot have formed by coarsening of pre-existing pearlitic plessite. A new bowing mechanism is proposed, whereby rafts of Ni-enriched taenite form between advancing lobes of an irregular reaction front during discontinuous precipitation. Subsequent coarsening leads to the growth of the taenite rafts, and the partial or complete removal of pearlite lamellae, resulting in spheroidised plessite with a crystallographic architecture matching the experimental observations. We find no evidence for a strong magnetic field on the IAB parent body, suggesting it did not have an active core dynamo at the time of cloudy zone formation. This supports the prediction that the IAB parent body was unable to form a significant core due to the redistribution of metal during an earlier impact event.
000078320 536__ $$9info:eu-repo/grantAgreement/ES/MINECO-FSE-FEDER/MAT2014-53921-R$$9info:eu-repo/grantAgreement/EC/FP7/320750/EU/Nanopaleomagnetism: a multiscale approach to paleomagnetic analysis of geological materials/NanoPaleoMag$$9info:eu-repo/grantAgreement/EC/FP7/312284/EU/Coordinated Access to Lightsources to Promote Standards and Optimization/CALIPSO$$9info:eu-repo/grantAgreement/ES/DGA-FSE-FEDER/IMANA-E34
000078320 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttp://creativecommons.org/licenses/by/3.0/es/
000078320 590__ $$a4.258$$b2018
000078320 591__ $$aGEOCHEMISTRY & GEOPHYSICS$$b10 / 84 = 0.119$$c2018$$dQ1$$eT1
000078320 592__ $$a2.49$$b2018
000078320 593__ $$aGeochemistry and Petrology$$c2018$$dQ1
000078320 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion
000078320 700__ $$aKrakow, R.
000078320 700__ $$0(orcid)0000-0002-0901-8341$$aHerrero-Albillos, J.$$uUniversidad de Zaragoza
000078320 700__ $$aKronast, F.
000078320 700__ $$aNorthwood-Smith, G.
000078320 700__ $$aHarrison, R.J.
000078320 7102_ $$12003$$2395$$aUniversidad de Zaragoza$$bDpto. Física Materia Condensa.$$cÁrea Física Materia Condensada
000078320 773__ $$g229 (2018), 1-19$$pGeochim. cosmochim. acta$$tGEOCHIMICA ET COSMOCHIMICA ACTA$$x0016-7037
000078320 8564_ $$s1894403$$uhttps://zaguan.unizar.es/record/78320/files/texto_completo.pdf$$yVersión publicada
000078320 8564_ $$s93965$$uhttps://zaguan.unizar.es/record/78320/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada
000078320 909CO $$ooai:zaguan.unizar.es:78320$$particulos$$pdriver
000078320 951__ $$a2020-01-17-22:07:22
000078320 980__ $$aARTICLE