【摘要】：為了揭示沖繩海槽西南端流紋巖成因,利用電子探針和LA-ICP-MS對該流紋巖中角閃石進行了主量和微量元素測定。所有角閃石主量元素成分變化范圍小,晶體化學(xué)特征主要表現(xiàn)為:CaB1.60,CaA=0,(Na+K)A0.33,NaB介于0.23~0.39之間,均為鈣質(zhì)鎂閃石。微量元素以富集Sc、V、Cr、Co、Ni和REE,虧損Rb、Sr、Ba、Zr、Th、U和Pb為特征,這些元素的富集與虧損與復(fù)雜的類質(zhì)同象作用有關(guān)。由角閃石溫壓計得出其結(jié)晶時的溫度范圍為775~839℃,壓力為0.12GPa,大致相當(dāng)于4km的深度。角閃石的成因礦物學(xué)研究顯示該流紋巖中角閃石為殼-�；旌铣梢�,進一步表明沖繩海槽南部流紋巖由幔源玄武質(zhì)巖漿與殼源長英質(zhì)巖漿混合形成的中基性巖漿在淺層巖漿房中結(jié)晶分異而形成,且殼幔混合源很可能是沖繩海槽西南端火山巖巖漿的主要來源。
[Abstract]:In order to reveal the origin of rhyolite at the southwest end of Okinawa trough, the major and trace elements of amphibole in the rhyolite were determined by electron probe and LA-ICP-MS. The major element composition of all amphibole varies in a small range. The main crystal chemical characteristics of the amphibole are as follows: 1: CaB1.60 (CaA0) and (Na K) A0.33 (NaB) between 0.23 and 0.39, all of which are calcareous magnesite. The enrichment of trace elements is characterized by enrichment of Sc,V,Cr,Co,Ni and REE, depleted Rb,Sr,Ba,Zr,Th,U and Pb. The enrichment of these elements is related to the deficiency and complex isomorphism. The crystallization temperature range of amphibole temperature and pressure is 775 ~ 839 鈩，

本文編號：2212648