【摘要】 <正>冲绳海槽中分布有大量的浮岩,在这一带进行的底质调查获得了不少样品.这是一种很特殊的岩石,虽然进行了一定的研究,至今仍有许多问题没有得到圆满的解决.岩石外观很突出的特点是色浅(浅灰白～白色),质轻(干样比重为0.5—0.7),性脆,疏松,均一,断面粗糙.在电镜下观察具泡沫状气孔构造(见图1、2).状似海绵,孔洞互通,因此具有很强的吸水性,吸水饱和之后,比重大于1.这也是它能沉于海底的原因.更多还原

【Abstract】 The studied pumice is a special kind of rocks, its colour is very light and the specific gravity is small. It was not found frequently in the nature, but distributed widely in Okinawa Trough.The chemical characteristics of the pumice is of lowest alkalinity in a acidic-alkalinity series. According to its characteristics of geochemistry, mineralogy, petrology and its special environment, the authors considered that thepumice is formed by mixing of eruptive magma and steam with sea water. So it has the characteristics both of magmatite and sedimentary and may be a transitional kind of them.更多还原