ORCID Profile
0000-0002-1634-8998
Current Organisations
The University of Edinburgh
,
University of Glasgow
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Publisher: Elsevier BV
Date: 09-2021
Publisher: Wiley
Date: 11-12-2022
DOI: 10.1111/MAPS.13934
Abstract: To better understand volcanism on planetary bodies other than the Earth, the quantification of physical processes is needed. Here, the petrogenesis of the achondrite Martian Yamato (Y) nakhlites (Y 000593, Y 000749, and Y 000802) is reinvestigated via quantitative analysis of augite (high‐Ca clinopyroxene) phenocrysts: crystal size distribution (CSD), spatial distribution patterns (SDP), and electron backscatter diffraction (EBSD). Results from CSD and EBSD quantitative data sets show augite to have continuous uninterrupted growth resulting in calculated minimum magma chamber residence times of either 88–117 ± 6 yr or 9–12 yr. All s les exhibit low‐intensity S‐LS type crystallographic preferred orientation. Directional strain is observed across all s les with intracrystalline misorientation patterns indicative of (100)[001]:(001)[100] (Y 000593 and Y 000802) and {110} or {110} 1 / 2 (Y 000749) slip systems. SDP results indicate phenocryst‐bearing crystal‐clustered rock signatures. Combined findings from this work show that the Yamato nakhlites formed on Mars as in idual low‐viscosity lava flows or sills. This study shows that through combining these different quantitative techniques over multiple s les, one can more effectively compare and interpret resulting data to gain a more robust, geologically contextualized petrogenetic understanding of the rock suite being studied. The techniques used in this study should be equally applicable to igneous achondrites from other parent bodies.
Publisher: Springer Science and Business Media LLC
Date: 07-08-2008
DOI: 10.1038/NATURE07138
Abstract: The subduction of oceanic plateaux, which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood-basalt provinces, is an important factor in many current models of plate motion and provides a potential mechanism for triggering plate reorganization. To evaluate such models, it is essential to decipher the history of the collision between the largest and thickest of the world's oceanic plateaux, the Ontong Java plateau, and the Australian plate, but this has been hindered by poor constraints for the arrival of the plateau at the Melanesian trench. Here we present (40)Ar-(39)Ar geochronological data on hotspot volcanoes in eastern Australian that reveal a strong link between collision of the Greenland-sized Ontong Java plateau with the Melanesian arc and motion of the Australian plate. The new ages define a short-lived period of reduced northward plate motion between 26 and 23 Myr ago, coincident with an eastward offset in the contemporaneous tracks of seamount chains in the Tasman Sea east of Australia. These features record a brief westward deflection of the Australian plate as the plateau entered and choked the Melanesian trench 26 Myr ago. From 23 Myr ago, Australia returned to a rapid northerly trajectory at roughly the same time that southwest-directed subduction began along the Trobriand trough. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the Pacific plate, including the archetypal Hawaiian chain, and thus provide strong evidence that immense oceanic plateaux, like the Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale.
Publisher: Informa UK Limited
Date: 04-2008
Publisher: Springer Science and Business Media LLC
Date: 21-12-2012
DOI: 10.1038/NGEO1677
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-09-2019
Abstract: Evidence for impact-generated water on Mars ~633 Ma ago predicts two craters at the nakhlite meteorite’s ejection site.
Publisher: Elsevier BV
Date: 02-2011
Publisher: Informa UK Limited
Date: 02-2007
Publisher: Geological Society of London
Date: 03-2012
Publisher: Springer Science and Business Media LLC
Date: 25-11-2012
DOI: 10.1038/NGEO1638
Publisher: American Geophysical Union (AGU)
Date: 09-2013
DOI: 10.1002/TECT.20084
Publisher: Informa UK Limited
Date: 08-2008
Publisher: Informa UK Limited
Date: 03-10-2017
Publisher: Elsevier BV
Date: 08-2019
Publisher: American Geophysical Union (AGU)
Date: 10-2018
DOI: 10.1029/2018GC007821
Publisher: American Geophysical Union (AGU)
Date: 06-2022
DOI: 10.1029/2021JE007082
Abstract: Deformation is a near ubiquitous process that is observed within nearly all naturally forming rocks. Electron backscatter diffraction (EBSD) is a technique that enables slip‐systems (a form of plastic deformation) to be inferred from intracrystalline misorientations at a comparable scale to the representative CPO analysis (≥300 crystals for the nakhlites). Extensive laboratory and studies on naturally occurring s les have identified preferential mantle condition extrinsic parameters for specific slip‐system signatures within olivine and clinopyroxene. Intracrystalline misorientation patterns for olivine and augite (high Ca‐clinopyroxene) for 16 different Martian nakhlite meteorites (21 sections) were analyzed and assessed against these known parameters. Investigation of high and low deformation regions within the nakhlites revealed a shift in intracrystalline misorientation patterns for 10 of the 21 sections. Interpreted as both shock (high deformations) and emplacement (low deformation) signatures, the observed variations in deformation patterns for the two main regimes of deformation indicate heterogeneous s ling of the nakhlite source crater. Our findings indicate that shock deformation is prevalent throughout the nakhlites, and that great care needs to be taken when interpreting intracrystalline misorientations of crystals within apparent lower deformation regions.
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 03-2014
Publisher: Wiley
Date: 28-06-2018
DOI: 10.1111/MAPS.13136
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Benjamin Cohen.