貼近世上藏有最多黃金的場所

 原文網址：https://www.uni-goettingen.de/en/3240.html?id=7808

地球上儲存最多黃金的場所並不是看管在諾科斯堡內部的美國金庫。事實上，它們隱藏在地下，而且遠遠超出一般人所能想到的深度。地球的黃金以及其他貴金屬有超過99.999%埋藏在3000公里厚的堅硬岩層之下，保存在地球的金屬核心當中，非人類所能企及。但最近，哥廷根大學的研究人員在夏威夷群島的火山岩中發現了貴金屬釕(Ru)留下的痕跡，並且確定其根源為地核。此發現發表在期刊《自然》(Nature)。

黃金並不像一般人所想的如此稀有。問題是地球超過99.999%的黃金與其他貴金屬被封存在地下大約3000公里處，也就是地核內部，遠遠不是人類可以到達的地方。圖片來源：Wikipedia/Slav4|Ariel Palmon

相較於地球的岩石地函，金屬地核含有多一點點的¹⁰⁰Ru—這是一種特殊的釕同位素。地球在45億年前形成之時，釕、金與其他貴金屬被封存在地核當中，其中的釕有一部分的來源跟今日地函裡只有一點點的釕來自不同的地方，造成地函與地核¹⁰⁰Ru的含量有差。由於這道差異極為微小，因此過去根本沒辦法偵測出來。但現在，哥廷根大學的研究人員開發出新的實驗流程，而可以解決這道問題。他們發現地表某些地方的岩漿含有特別高的¹⁰⁰Ru訊號，只能用這些岩石的根本來源為地函與地核的交界來解釋。

哥廷根大學地球化學系的Nils Messling博士解釋：「當第一批結果出爐，我們就知道挖到名副其實的『黃金』了！數據證實來自地核的物質，包括黃金與其他貴金屬，正逐漸洩漏到上方的地函當中。」

同一系的Matthias Willbold教授補充：「我們的發現顯示地核跟前人所推測的一樣並非完全孤立。同時我們也證明了有大量的超高溫地函物質，約為數十萬兆公噸的岩石會從地函與地核的邊界上升至地球表面而形成夏威夷這類的海島。」

黃金與其他貴金屬的供應並不穩定，但它們的不斐價值以及在許多領域(如：再生能源)相當重要，因此對我們來說是不可或缺的。這項結果意味著它們至少有一部分來自於地核。Messling總結：「我們觀察到的這些作用是否在過去也是如此進行仍有待證實。但是我們的發現確實可以讓我們從完全不同的視角，來理解地球內部的動力過程是如何演變的。」

 

Tapping into the World’s largest gold reserves

Earth’s largest gold reserves are not kept inside Fort Knox, the United States Bullion Depository. In fact, they are hidden much deeper in the ground than one would expect. More than 99.999% of Earth’s stores of gold and other precious metals lie buried under 3,000 km of solid rock, locked away within the Earth’s metallic core and far beyond the reaches of humankind. Now, researchers from the University of Göttingen have found traces of the precious metal Ruthenium (Ru) in volcanic rocks on the islands of Hawaii that must ultimately have come from the Earth’s core. The findings were published in Nature.

Compared to the Earth’s rocky mantle, the metallic core contains a slightly higher abundance of a particular Ru isotope: ¹⁰⁰Ru. This is because part of the Ru, which was locked in the Earth’s core together with gold and other precious metals when it formed 4.5 billion years ago, came from a different source than the scarce amount of Ru that is contained in the mantle today. These differences in ¹⁰⁰Ru are so tiny that it was impossible to detect them in the past. Now, new procedures developed by researchers at the University of Göttingen made it possible to resolve them. The unusually high ¹⁰⁰Ru signal they found in lavas on the Earth’s surface can only mean that these rocks ultimately originated from the core-mantle boundary.

Dr Nils Messling, at Göttingen University’s Department of Geochemistry, explains: “When the first results came in, we realised that we had literally struck gold! Our data confirmed that material from the core, including gold and other precious metals, is leaking into the Earth’s mantle above.” 

Professor Matthias Willbold, at the same department, adds: “Our findings not only show that the Earth’s core is not as isolated as previously assumed. We can now also prove that huge volumes of super-heated mantle material – several hundreds of quadrillion metric tonnes of rock – originate at the core-mantle boundary and rise to the Earth’s surface to form ocean islands like Hawaii.”

This means that at least some of the precarious supplies of gold and other precious metals that we rely on for their value and importance in so many sectors such as renewable energy, may have come from the Earth’s core. Messling concludes: “Whether these processes that we observe today have also been operating in the past remains to be proven. Our findings open up an entirely new perspective on the evolution of the inner dynamics of our home planet.”

原始論文：Nils Messling, Matthias Willbold, Leander Kallas, Tim Elliott, J. Godfrey Fitton, Thomas Müller, Dennis Geist. Ru and W isotope systematics in ocean island basalts reveals core leakage. Nature, 2025; DOI: 10.1038/s41586-025-09003-0

引用自：University of Göttingen. "Tapping into the World's largest gold reserves."