{"id":21734,"date":"2020-03-23T21:30:27","date_gmt":"2020-03-23T20:30:27","guid":{"rendered":"http:\/\/karmaka.de\/?p=21734"},"modified":"2020-03-25T08:19:15","modified_gmt":"2020-03-25T07:19:15","slug":"potassium-isotope-compositions-of-carbonaceous-and-ordinary-chondrites-implications-on-the-origin-of-volatile-depletion-in-the-early-solar-system","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=21734","title":{"rendered":"Potassium Isotope Compositions of Carbonaceous and Ordinary Chondrites: Implications on the Origin of Volatile Depletion in the Early Solar System<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Hannah Bloom, Katharina Lodders, Heng Chen, Chen Zhao,Zhen Tian, Piers Koefoed, M\u00e1ria K.Pet\u0151, Yun Jiang, Kun Wang (\u738b\u6606)<\/p>\n\n\n\n<p>Geochimica et Cosmochimica Acta<br>\nIn Press, Journal Pre-proof, Available online 23 March 2020<\/p>\n\n\n\n<p><a href=\"https:\/\/arxiv.org\/ftp\/arxiv\/papers\/2003\/2003.10545.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0016703720301897\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Among solar system materials there are variable degrees of depletion in moderately volatile elements (MVEs, such as Na, K, Rb, Cu, and Zn) relative to the proto-solar composition. Whether these depletions are due to nebular and\/or parent-body (asteroidal or planetary) processes is still under debate. In order to help decipher the MVE abundances in early solar system materials, we conducted a systematic study of high-precision K stable isotopic compositions of a suite of whole-rock samples of well-characterized carbonaceous and ordinary chondrites. We analyzed 16 carbonaceous chondrites (CM1-2, CO3, CV3, CR2, CK4-5 and CH3) and 28 ordinary chondrites covering petrological types 3 to 6 and chemical groups H, L, and LL. We observed significant K isotope (\u03b441K) variations (\u22121.54 to 0.70 \u2030) among the carbonaceous and ordinary chondrites. In general, the two major chondrite groups are distinct: The K isotope compositions of carbonaceous chondrites are largely higher than the Bulk Silicate Earth (BSE) value, whereas ordinary chondrites show K isotope compositions that are typically lower than the BSE value. Neither carbonaceous nor ordinary chondrites show clear\/resolvable correlations between K isotopes and chemical groups, petrological types, shock levels, cosmic-ray exposure ages, fall\/find occurrence, or terrestrial weathering. Importantly, the lack of a clear trend between K isotopes and K content among chondrites indicates that the K isotope fractionations were decoupled from the relative elemental K depletions, which is inconsistent with a single-stage partial vaporization or condensation process to account for these MVE depletion patterns among chondrites. The range of K isotope variations in the carbonaceous chondrites in this study is consistent with a four-component (chondrule, refractory inclusion, matrix and water) mixing model that is able to explain the bulk elemental and isotopic compositions of the main carbonaceous chondrite groups, but requires a fractionation in K isotopic compositions in chondrules. We propose that the major control of the isotopic compositions of group averages is condensation and\/or vaporization in pre-accretional (nebular) environments that is preserved in the compositional variation of chondrules. Parent-body processes, such as aqueous alteration, thermal metamorphism, and metasomatism, can mobilize K and affect the K isotopes in individual samples. In the case of the ordinary chondrites, the full range of K isotopic variations can only be explained by the combined effects of the size and relative abundances of chondrules, parent-body aqueous and thermal alteration, and possible sampling bias.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Hannah Bloom, Katharina Lodders, Heng Chen, Chen Zhao,Zhen Tian, Piers Koefoed, M\u00e1ria K.Pet\u0151, Yun Jiang, Kun Wang (\u738b\u6606) Geochimica et Cosmochimica Acta In Press, Journal Pre-proof, Available online 23 March 2020 PDF (OPEN ACCESS) LINK&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,583,15,18,19,12,14,72,6,23,24,7,71],"tags":[3273,1887,1124,105,1814,234,1812,3701,5103,3297,1807,3236,2992],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21734"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=21734"}],"version-history":[{"count":3,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21734\/revisions"}],"predecessor-version":[{"id":21741,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21734\/revisions\/21741"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21734"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21734"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21734"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}