LINK<\/strong><\/a><\/p>\n“Northwest Africa (NWA) 7325 is an anomalous achondrite that experienced episodes of large-degree melt extraction and interaction with melt under reducing conditions. Its composition led to speculations about a Mercurian origin and provoked a series of studies of this meteorite. We present the noble gas composition, and results of 40Ar\/39Ar and 129I-129Xe studies of whole rock splits of NWA 7325. The light noble gases are dominated by cosmogenic isotopes. 21Ne and 38Ar cosmic-ray exposure ages are 25.6 and 18.9 Ma, respectively, when calculated with a nominal whole rock composition. This 38Ar age is in reasonable agreement with a cosmic-ray exposure age of 17.5 Ma derived in our 40Ar\/39Ar dating study. Due to the low K-content of 19 \u00b1 1 ppm and high Ca-content of approximately 12.40 \u00b1 0.15 wt%, no reliable 40Ar\/39Ar age could be determined. The integrated age strongly depends on the choice of an initial 40Ar\/36Ar ratio. An air-like component is dominant in lower temperature extractions and assuming air 40Ar\/36Ar for the trapped component results in a calculated integrated age of 3200 \u00b1 260 (1\u03c3) Ma. This may represent the upper age limit for a major reheating event affecting the K-Ar system. Results of 129I-129Xe dating give no useful chronological information, i.e., no isochron is observed. Considering the highest 129Xe*\/128XeI ratio as equivalent to a lower age limit, we calculate an I-Xe age of about 4536 Ma. In addition, elevated 129Xe\/132Xe ratios of up to 1.65 \u00b1 0.18 in higher temperature extractions indicate an early formation of NWA 7325, with subsequent disturbance of the I-Xe system.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Hopp, J., Schr\u00f6ter, N., Pravdivtseva, O., Meyer, H.-P., Trieloff, M. and Ott, U. Meteorit Planet Sci. doi:10.1111\/maps.13062 LINK “Northwest Africa (NWA) 7325 is an anomalous achondrite that experienced episodes of large-degree melt extraction and interaction…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28,69,506,139,507],"tags":[4411,1849,378,2400,1861,2285],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14413"}],"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=14413"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14413\/revisions"}],"predecessor-version":[{"id":14414,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14413\/revisions\/14414"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14413"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}