LINK<\/strong><\/a><\/p>\n“Cosmic spherules collected from deep sea sediments of the Indian Ocean having different textures such as scoriaceous (4), relict-bearing (16), porphyritic (35) and barred olivine (2) were investigated for petrography, as well as high precision oxygen isotopic studies on olivine grains using secondary ion mass spectrometry (SIMS). The oxide FeO\/MgO ratios of large olivines (> 20\u03bcm) in cosmic spherules have low values similar to those seen in the olivines of carbonaceous chondrite chondrules, rather than matching the compositions of matrix. The oxygen isotope compositions of olivines in cosmic spherules have a wide range of \u03b418O, \u03b417O and \u039417O values as follows: \u22129 to 40\u2030, \u221213 to 22\u2030 and -11 to 6\u2030. Our results suggest that the oxygen isotope compositions of the scoriaceous, relict-bearing, porphyritic and barred spherules show provenance related to the carbonaceous (CM, CV, CO and CR) chondrites. The different types of spherules that has experienced varied atmospheric heating during entry has not significantly altered the \u039417O values. However, one of the relict-bearing spherules with a large relict grain has \u039417O = 5.7\u2030, suggesting that it is derived from 16O-poor material that is not recognized in the meteorite record. A majority of the spherules have \u039417O ranging from \u22124 to \u22122\u2030, similar to values in chondrules from carbonaceous chondrites, signifying that chondrules of carbonaceous chondrites are the major contributors to the flux of micrometeorites, with an insignificant fraction derived from ordinary chondrites. Furthermore, barred spherule data shows that during atmospheric entry an increase in \u223c10\u2030 of \u03b418O value surges \u039417O value by \u223c1\u2030.”<\/p>\n","protected":false},"excerpt":{"rendered":"
N.G. Rudraswami, M. Shyam Prasad, R.H. Jones, K. Nagashima Geochimica et Cosmochimica Acta In Press, Accepted Manuscript, Available online 28 August 2016 LINK “Cosmic spherules collected from deep sea sediments of the Indian Ocean having…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,56],"tags":[106,362,1381,327],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/9690"}],"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=9690"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/9690\/revisions"}],"predecessor-version":[{"id":9691,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/9690\/revisions\/9691"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9690"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9690"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}