Eclogite xenoliths from stockdale kimberlite,Kansas |
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| Authors: | Henry O A Meyer Douglas G Brookins |
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| Institution: | (1) Planetology Branch, National Aeronautics and Space Administration, Goddard Space Flight Center, 20771 Greenbelt, Md., USA;(2) Department of Geology, Kansas State University, 66502 Manhattan, Kansas, USA;(3) Present address: Department of Geosciences, Purdue University, 47907 Lafayette, Indiana, USA;(4) Present address: Department of Geology, University of New Mexico, 87106 Albuquerque, New Mexico, USA |
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| Abstract: | Six kimberlite pipes of late Cretaceous or Tertiary age occur in Riley Co., east-central Kansas. Within the pipes xenoliths of local sedimentary and exotic igneous rocks are common, especially in the Stockdale pipe. Igneous rocks which occur as xenoliths include granite, gabbro, metagabbro, pyroxenite and eclogite. In the eclogites omphacitic clinopyroxene (approx. Di52Jd24mol%) and pyropic garnet (approx. Py47Al35Gr12mol%) are the predominant minerals with subordinate amounts of rutile and sulphides (pyrrotite-pentlandite (?)-chalcopyrite). Interstitial kaersutitic amphibole is a minor constituent. The eclogites are chemically equivalent to olivine-basalt. The texture, composition and mineralogy of the eclogites from Kansas are similar to those of eclogites from kimberlite pipes in South Africa and Siberia. Whereas the rocks from these latter localities display a range in composition, those examined to date from Kansas are of fairly restricted composition. Furthermore it seems probable that the eclogites from Stockdale formed under limited P-T conditions within the mantle. This is the first record of such eclogites on the North American continent. |
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