| 摘要: |
| 1992年冲绳海槽地质调查时,在134站(126°56′7″E,27°30′0″N)共采集到3件玄武岩样品,其中1件取自134站表层样,另外2件取自134站柱状样中的118-143cm处和193- 218cm处(刀口位置)。通过对上述3件玄武岩样品的岩相学、岩石化学组成、稀土元素和微量元素和锶同位素比值分析研究,认为本区玄武岩具多期次喷发特征,早期喷发形成的玄武岩中单斜辉石质量分数较低,晚期喷发形成的玄武岩中单斜辉石质量分数相对较高,表明了单斜辉石为晚期结晶堆积产物。本区玄武岩稀土配分模式与岛弧拉斑玄武岩基本一致,其87Sr与86Sr质量分数比值m(87Sr)/m(86Sr)为0.7046,亦与岛弧拉斑玄武岩相当。最后利用Rb-Sr丰度特征确定本区的地壳厚度为19-24 km。 |
| 关键词: 冲绳海槽 玄武岩 构造背景 |
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| 基金项目:国家自然科学基金资助项目(49903003) |
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| Petrology and geochenistry of the basalt from the middle part of Okinawa |
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| Abstract: |
| During the survey of the Okinawa Through in 1992, three basalt samples were collected from 134 site (126°56′7"E, 27°30′0"N), one sample from surface layer, two samples from the sample column (1181～43 cm, 193～218). The studies of the mineralogy, petrochemistry and REE, trace elements, Smisotope of the basalt smaples suggest that the basalts from several eruption tems. In former erupted basalt the content of monopyroxene is low, in later erupted basalt the content of monopyroxene is contrary, it indicates that the monopyroxene is the result of crystal piling. The rare earth elements is like the tholeiite, the ratio of 87Sr/86Sr is 0.7046 is also like the tholeiite. Through of the content of Rb-Sr confirming that the thickness of the lithosphere is 19～24 km. |
| Key words: Okinawa Through tholeiite structure background |
