| 本文已被：浏览 1818次 下载 1798次 |
码上扫一扫！ |
|
|
| 海底浮岩前处理方法的实验研究 |
|
张玉祥1,2,3, 曾志刚1,2,3,4, 殷学博1,2, 齐海燕1,2, 李 禾5, 王晓媛1,2,4, 陈 帅1,2
|
|
1.中国科学院海洋研究所;2.中国科学院海洋地质与环境重点实验室;3.中国科学院大学;4.海底矿产资源评价与探测技术功能实验室, 青岛海洋科学与技术国家实验室;5.中国科学院地质与地球物理研究所
|
|
| 摘要: |
| 为了解海底浮岩气孔充填物对全岩微量元素组成的影响, 并获得有效的海底浮岩前处理方法,对冲绳海槽中部的浮岩碎成大于5 cm, 1～2 cm及小于5 mm的碎块分别进行前处理, 然后通过扫描电镜(SEM)和X射线衍射光谱(XRD)分析对清洗的效果进行观察对比。结果表明, 对大块浮岩直接清洗以及将浮岩碎成厘米级小块后清洗都难以将浮岩气孔内充填的细粒沉积物去除干净, 而对浮岩碎成毫米级(< 5 mm)颗粒后再清洗可以有效清除浮岩气孔内的充填物。本文所确定的一套有效的海底浮岩前处理方法总结如下: (1)将小于5 mm的浮岩颗粒置于超声波清洗机内用蒸馏水清洗, 每隔15 min换一次水, 直到清洗样品后的水足够清澈; (2)将样品先后浸入无水乙醇和稀盐酸溶液中, 分别去除有机质和次生碳酸盐、铁氧化物; (3)将浮岩样品置于40℃超纯水中浸泡7 d左右, 并每天换水, 直至向上层清液加硝酸银溶液无白色沉淀出现。XRD分析表明, 海底浮岩气孔中充填物的矿物组成包括斜长石、石英等。少量的气孔充填物对浮岩全岩的微量元素配分模式影响不大, 但会造成Pb、Sr 等元素含量的增加,因此可能会对浮岩全岩的Pb-Sr同位素组成造成干扰。 |
| 关键词: 海底浮岩 前处理 气孔充填物 微量元素 |
| DOI：10.11759/hykx20161114001 |
| 分类号: |
| 基金项目:国家重点基础研究发展计划(2013CB429700); 国家自然科学基金(41325021, 41306053, 41476044); 中国科学院战略先导专项(XDA11030302); 山东省泰山学者专项基金; 中国科学院、国家外国专家局创新团队国际合作伙伴计划; 青岛海洋科学与技术国家实验室鳌山人才计划; 鳌山科技创新计划项目(2015ASKJ03, 2016ASKJ13) |
|
|
|
ZHANG Yu-xiang,ZENG Zhi-gang,YIN Xue-bo,QI Hai-yan,LI He,WANG Xiao-yuan,CHEN Shuai
|
| Abstract: |
| This study was conducted to analyze the influences of sediment infillings in submarine pumice’s vesicles on whole-rock trace element compositions of pumice and to identify an effective pretreatment method for submarine pumice. The pumice obtained from the middle Okinawa Trough was pretreated after breaking it into fragments of sizes >5 cm, 1-2 cm, and <5 mm. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were conducted to observe and compare the cleaning results. Experimental results showed that direct cleaning by large pumice fragments or cleaning after the pumice was broken into centimeter-scale fragments failed to remove completely the fine-grained sediments filled in the vesicles of the pumice. However, cleaning after the pumice was crushed into millimeter-scale fragments could effectively clean up the vesicles of the pumice. This study summarized an effective pretreatment method for submarine pumice as follows: (1) clean the pumice fragments (<5 mm) using distilled water in an ultrasonic bath and change the water every 15 min until the water after cleaning the samples becomes clear enough, (2) place the fragments in anhydrous ethanol and dilute hydrochloric acid solution (0.5 mol/L) to remove organic matter and secondary carbonate and Fe oxides, respectively, and (3) place the pumice fragments in ultrapure water at 40℃ for about 7 days, with water being changed every day until the removal of chloridion. The results of SEM and XRD analyses showed that the mineral composition of the fillings in the submarine pumice’s vesicles includes plagioclase and quartz. Small amount of vesicle fillings has mild effects on the whole-rock trace element distribution pattern of pumice. However, the fillings could increase the contents of Pb and Sr and, thus, might disturb the whole-rock Pb and Sr isotopic compositions of pumice. |
| Key words: submarine pumice pretreatment vesicle fillings trace elements |