LINK<\/strong><\/a><\/p>\n\n\n\n“Baddeleyite (monoclinic-ZrO2) is a key accessory mineral for dating mafic rocks and tracing magmatic and impact processes. Although its crystal structure is highly sensitive to pressure\u2013temperature (P-T) conditions, integrated studies linking microstructural response of lunar baddeleyite to P-T histories and Pb-Pb ages remain limited. Here we integrate in-situ Pb-Pb dating with high-resolution electron backscatter diffraction (EBSD) analysis of baddeleyite grains in two lunar gabbroic breccia meteorites, Northwest Africa 773 and 3333. Based on crystallographic and petrographic characteristics, baddeleyite grains are classified into five groups, reflecting diverse P-T histories. A notable finding is widespread preservation of cubic heritage baddeleyite, despite relatively lower-T records recorded by coexisting silicates. This feature is attributed to elevated shock pressures that depress stability fields of high-T ZrO2 polymorphs, modification of phase stability by impurities (e.g., Ti and Fe), and grains experienced high-T conditions prior to incorporation into their present host rocks. Clast-hosted baddeleyite yields a coherent weighted mean Pb-Pb age of 3100\u202f\u00b1\u202f8.5\u202fMa (n\u202f=\u202f9), interpreted as the primary magmatic crystallization age, whereas matrix-hosted grains show a broader age distribution around\u202f\u223c3.1\u202fGa. Two matrix-hosted grains associated with impact melt veins yield a younger age of 2941\u202f\u00b1\u202f20\u202fMa, consistent with later\u202f\u223c2.9\u202fGa thermal modification. The absence of a systematic relationship between Pb-Pb age and microstructural type suggests that ZrO2 phase transformations alone do not exert a first-order control on Pb mobility. Instead, heterogeneous propagation of pressure and temperature during shock metamorphism, together with the intensity and duration of thermal events, appears to govern isotopic disturbance. These results highlight the importance of integrated microstructural and geochronological approaches for reconstructing complex lunar thermal histories.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Liying Huang, Lee Francis White, Xuchao Zhao, Mahesh Anand, Muhammad Zeeshan Mughal, Yuchen Xu, Yang Liu, Yongliao Zou Geochimica et Cosmochimica Acta, in Press, Journal Pre-proof, Available online 9 September 2026 LINK “Baddeleyite (monoclinic-ZrO2) is…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[2661,1827,2238,4499,2260,649],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/42536"}],"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=42536"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/42536\/revisions"}],"predecessor-version":[{"id":42538,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/42536\/revisions\/42538"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=42536"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=42536"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=42536"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}