LINK<\/strong><\/a><\/p>\n\n\n\n“40Ar\/39Ar incremental heating experiments on whole\u2010rock lunar samples commonly provide evidence of varying degrees of radiogenic 40Ar (40Ar) loss. However, these experiments provide limited information about whether or not 40Ar<\/em> is preferentially lost from specific glasses, minerals, or polyphase domains. Ultraviolet laser ablation microprobe (UVLAMP) 40Ar\/39Ar dating and electron probe microanalysis of mineral clasts and polyphase melt assemblages in Apollo 17 poikilitic impact melt rock 77135 show evidence of geochemical controls on 40Ar\/39Ar dates. Potassium\u2010rich glass and K\u2010feldspar in the mesostasis are the dominant sources for Ar released during low\u2010temperature steps of published 40Ar\/39Ar release spectra for this rock, while pyroxene oikocrysts with enclosed plagioclase chadacrysts contribute Ar predominantly to intermediate\u2010 to high\u2010temperature steps. Additionally, UVLAMP analysis of a mm\u2010scale plagioclase clast demonstrates the potential to use stranded 40Ar* diffusive loss profiles to constrain the thermal evolution of lunar impact melt deposits and indicates that the melt component of 77135 cooled quickly. While some submillimeter clasts of plagioclase are distinctly older than the melt, other small clasts yield dates younger than the oldest melt components in 77135, plausibly due to subgrain fast diffusion pathways and\/or 40Ar* loss during brief episodes of reheating at high temperatures. Our data suggest that integrated petrologic and microanalytical geochronologic studies are necessary complements to bulk sample geochronologic studies in order to fully evaluate competing models for the impactor flux during the first billion years of the Moon’s evolution.”<\/p>\n","protected":false},"excerpt":{"rendered":"Cameron M. Mercer, Kip V. Hodges, Bradley L. Jolliff, Matthijs C. Van Soest, Jo\u2010Anne Wartho, John R. Weirich Meteoritics & Planetary Sciencedoi:10.1111\/maps.13240 LINK “40Ar\/39Ar incremental heating experiments on whole\u2010rock lunar samples commonly provide evidence of…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41,115],"tags":[3259,4799,2121,668,1827,1857],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17148"}],"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=17148"}],"version-history":[{"count":3,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17148\/revisions"}],"predecessor-version":[{"id":17151,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17148\/revisions\/17151"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17148"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17148"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17148"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}