各位老師和同學(xué)：
應徐義剛研究員邀請，國際著(zhù)名地球物理學(xué)家、英國劍橋大學(xué)Dan Mckenzie教授本周四將順訪(fǎng)我所并做“同位素室學(xué)術(shù)報告”2018年第6次報告。歡迎大家參加并積極參與討論！
本周一下午和周三下午，Mckenzie教授將在南海海洋所和中山大學(xué)地球科學(xué)系做另外兩個(gè)報告（報告摘要見(jiàn)附件），有興趣的師生可自行前往聆聽(tīng)。
1月22日下午3：00，中科院南海海洋所（SCSIO） 題目：The structure of the oceanic lithosphere and asthenosphere
1月24日上午10：00，中山大學(xué)地球科學(xué)系（SYSU） 題目：Plate tectonics after 50 years
報告題目：Source Enrichment Processes Responsible for Isotopic Anomalies in Oceanic Island Basalts
報 告 人：Prof. Dan Peter McKenzie（劍橋大學(xué)）
報告時(shí)間：1月25日（周四）上午10:00
報告地點(diǎn)：標本樓一樓會(huì )議室
報告人簡(jiǎn)介：
Mckenzie教授，國際著(zhù)名地球物理學(xué)家，1942年生于英國切爾南特，畢業(yè)于英國劍橋大學(xué)金學(xué)院，1963年獲學(xué)士學(xué)位，1966年獲碩士和博士學(xué)位，自1965年起在劍橋大學(xué)地質(zhì)系工作至今。上世紀60～70年代，他與William J. Morgan和Xavier Le Pichon共同倡導板塊構造學(xué)說(shuō)，是板塊構造學(xué)說(shuō)的先驅之一。之后所做的地幔對流研究，是人類(lèi)對地球內部認識的開(kāi)端。發(fā)表論文200多篇，在地球物理學(xué)、大地構造學(xué)、地球化學(xué)等領(lǐng)域作出了杰出的、開(kāi)創(chuàng )性的貢獻。研究區域從地球延伸到金星和火星。
報告摘要：
Various schemes have been proposed to classify the isotopic observations from OIBs, but it is not clear whether any of them reflect the processes that produce the fractionation between parent and daughter elements. The obvious way forward is to use the correlation between isotopic ratios and elemental concentrations to extract the composition of the enriched material. But doing so is not straightforward for several reasons.
The mantle is surprisingly inhomogeneous, and, if more than two sources contribute to the composition of the melt, it is difficult to use the observations to disentangle the effects of magma mixing. Some of the larger oceanic islands are underlain by plumes, where the upwelling velocities reach 0.5 m/a. Therefore the composition of the material undergoing melting may change on a time scale as short as 10,000a. Another problem concerns the accuracy of the isotopic measurements, which may need to be made on samples as small as individual olivine melt inclusions.
The necessary measurements have now been made on a number of sample suites, in particular on post-glacial basalts from Iceland erupted in the last 10 ka. These show that the centre of Iceland is dominated by EMORB enrichment, in contrast to magmas from the far northeast and southwest, which have signatures like those of basalts from Reunion and model ages of about 400 Ma. The Icelandic data shows the importance of determining the composition of the enriching material from magmas that are erupted in a limited area in a short time interval. In SW Iceland there is no correlation between elemental concentrations and isotopic ratios from whole rock samples, but there is between ion probe measurements on melt inclusions.