報告題目：Sri Lankan gem Deposits- occurrence and geology（斯里蘭卡寶石礦床-產狀與地質）

報告人：Sanjeewa P.K. Malaviarachchi（院士/教授）

單位：University of Peradeniya，Sri Lanka（斯里蘭卡佩拉德尼亞大學）

報告時間：2023年12月12日（周二下午）15：00-16：30

報告地點：明辨樓C205

報告人簡介：

Dr. Sanjeewa Maalviarachchi，Academician of the Sri Lankan Academy of Sciences, completed his PhD from the Institute of Planetary Materials at Misasa, Okayama University, Japan majoring in mantle petrology, geochemistry and radiogenic isotope geology. He holds MSc from Shimane University, Japan in metamorphic petrology and BSc (Honours) from University of Peradeniya, Sri Lanka. His research interests are igneous and metamorphic petrology, hard rock geochemistry, and isotope geology. He is a professor at the Department of Geology, University of Peradeniya. Currently, he serves as a Visiting Scholar at the Institute of Geology and Geophysics, Chinese Academy of Sciences, Bejing, China.

Sanjeewa Maalviarachi教授于2023年獲得斯里蘭卡科學院院士稱號。其在日本岡山大學行星材料研究所取得博士學位，期間的研究方向為地幔巖石學、地球化學和放射成因同位素地質學。在此之前，他在日本島根大學變質巖石學理學碩士學位，在斯里蘭卡佩拉德尼亞大學獲得理學學士學位。他的研究方向包括火成巖和變質巖巖石學、巖石地球化學和同位素地質學。他是斯里蘭卡佩拉德尼亞大學地質系教授，現為中國科學院地質與地球物理研究所訪問學者。

報告內容簡介：

Sri Lanka is well known for its wide variety of gem minerals for over 2500 years. Gem discoveries in India, Madagascar, Tanzania, Mozambique etc share common geological origin with respect to the high-grade metamorphism at continental collision zone in the Gondwana, highlighting occurrences of good quality corundum, spinel, topaz, zircon, aquamarine, amethyst, gem varieties of quartz, tourmaline, chrysoberyl, zircon, beryl, garnet, sphene, topaz etc. Geologists have found similar gem minerals in eastern Antarctica, confirming the presence of a Pan-African mineral belt (originated at about 550 million years ago) from east Africa through India-Sri Lanka to Antarctica. The similarity of the geological features of these gem-bearing lithologies has been attracted internationally by both geologists and gemmologists.

Nearly all the gem formations are located in the central high-grade metamorphic terrain of the Highland Complex geological unit in Sri Lanka. The gem deposits are classified as sedimentary, metamorphic, and magmatic; the sedimentary types being the most abundant. Nearly all the gem deposits of Sri Lanka are derived from the granulite facies metamorphic rocks of the Highland Complex, clearly indicating that there were high-temperature petrological conditions (>600 °C) suitable for the formation of gemstones. Overall, the source rocks of the gem minerals are skarns, marbles, pegmatites, garnetiferous and charnockitic gneisses.

2500多年來，斯里蘭卡以其豐富多樣的寶石礦物而聞名。斯里蘭卡與印度、馬達加斯加、坦桑尼亞和莫桑比克等地的寶石礦床一樣，其成因都跟岡瓦納大陸碰撞帶的高級變質作用有著密切的關系，這些地區均分布有優質剛玉、尖晶石、黃玉、鋯石、海藍寶石、紫水晶、石英、電氣石、金綠寶石、鋯石、綠柱石、石榴石、榍石、黃玉等寶石品種。地質學家在東南極洲發現了類似的寶石礦物，證實了從東非經印度-斯里蘭卡到南極洲的泛非寶石成礦帶（起源于約5.5億年前）的存在。這些含寶石巖性地質特征的相似性在國際上受到地質學家和寶石學家的廣泛關注。

斯里蘭卡的寶石地層幾乎都位于其中部高地雜巖地體中。寶石礦床分為沉積型、變質型和巖漿型；沉積類型最為豐富。斯里蘭卡幾乎所有的寶石礦床都來源于高地雜巖的麻粒巖相變質巖，這表明該地質單元存在適合寶石形成的高溫高壓條件（>600°C）?？傮w而言，寶石礦物的源巖為矽卡巖、大理巖、偉晶巖、含石榴石以及紫蘇花崗質片麻巖。

歡迎全校師生參加！

主辦單位：

天然氣地質四川省重點實驗室

地球科學與技術學院

西南石油大學科學技術發展研究院