沉浮其中：進入地函的板塊其宿命取決於古老的構造歷史

 原文網址：https://www.whoi.edu/press-room/news-release/sink-or-swim-the-fate-of-sinking-tectonic-plates-depends-on-their-ancient-tectonic-histories/

最新發表的研究指出許久以前的構造活動在海洋板塊內部造成的岩石成分異常，會影響其沉入地函時的速度與軌跡。

本研究區域的構造背景與用到的地震站。圖片來源: Nature (2025). DOI: 10.1038/s41586-025-08754-0

地函過渡帶(mantle transition zone, MTZ)位於地下410到660公里處，這個重要區域是物質進入地函深處的必經通道。地函過渡帶分佈著一些成分為玄武岩質的大型區域，它們會造成隱沒板塊(滑到另一個板塊下方的板塊)經過這裡時減速或停止下來，而不是直接沉到下部地函。雖然之前已經在地函過渡帶看到玄武岩質的儲集區域，但它們的起源卻還是不太清楚。

由南安普敦大學的研究人員(現在任職於伍茲霍爾海洋研究所)主持的國際地震學家團隊，提出了證據顯示他們找到一塊非常厚的地函過渡帶，其只能以該區域含有許多玄武岩質的成分來解釋。這項發現意謂在某些區域，整個海洋隱沒板塊(約100公里厚)都帶有大量玄武岩質的材料。

這篇發表於期刊《自然》(Nature)的發現讓我們對於板塊的隱沒作用有更多理解。此作用能把地表的物質和揮發性元素回收到地球內部深處，使得地球數十億年來可以維持氣候的長期穩定性、大氣成分的平衡以及生命的適居性。

這項突破性的研究是VoiLA(Volatiles in the Lesser Antilles，小安地列斯群島的揮發性元素)計畫的一部分，執行此計畫的團隊在小安地列斯群島的海床裝設了34具地震儀。

「這是首次在大西洋的隱沒帶進行的大規模海底地震實驗，」Catherine Rychert博士表示。她之前是南安普敦大學的副教授，現在則任職於伍茲霍爾海洋研究所。「我們並沒有預料到會在安地列斯群島下方發現厚度異常、約有330公里的地函過渡帶，這讓我們感到相當驚訝。在全世界觀察過的過渡帶中，這種厚度也是名列前茅。雖然加勒比海本來就因為陽光與沙灘而富有盛名，但它在板塊構造學的領域現在又有了新的名號。」

「板塊具有某種『記憶』並影響到它驅動地函對流以及把物質攪回地球內部的方式，這種想法實在是很瘋狂，」Nick Harmon博士表示。他之前是南安普敦大學的副教授，現在任職於伍茲霍爾海洋研究所。

主要作者Xusong Yang之前是南安普敦大學的訪問學者，現在任職於邁阿密大學。他強調：「我們不能忽視傳承在隱沒海洋板塊內部的組成不均，這種性質可能對它進入地球內部之後最終的命運會是如何有相當大的影響。」

主持這項實驗的為之前任職於南安普敦大學的Kate Rychert博士Nick Harmon博士、倫敦帝國學院的Saskia Goes教授、卡爾斯魯爾理工學院的Andreas Reitbrock教授。經費來自NERC(英國自然環境研究委員會)與ERC(歐洲研究院)。

 

Sink or Swim: the fate of sinking tectonic plates depends on their ancient tectonic histories

Newly published research has revealed that compositional rock anomalies within oceanic plates caused by ancient tectonics influence the trajectory and speed of the plates as they plunge deep into Earth’s mantle.

Between depths of 410 and 660 kilometers lies the mantle transition zone (MTZ), a critical region acting as a gateway for materials entering Earth's deeper mantle. Large distributions of basalt rock compositions within the MTZ can cause subducting plates—ones that slide beneath other—to slow and/or stagnate within this zone, instead of descending directly into the lower mantle. Although basalt reservoirs have previously been discovered in the MTZ, their origins have remained unclear.

An international team of seismologists led by the University of Southampton (and now at the Woods Hole Oceanographic Institution) has provided evidence of an extremely thick MTZ, which can only be explained by a large basaltic rock composition, suggesting that, in certain regions, entire oceanic slabs—approximately 100 kilometers thick—can possess significant basaltic material.

The findings, published in the journal Nature, provide a greater understanding of plate subduction, which recycles surface materials and volatile elements deep into the Earth's interior, sustaining long-term climate stability, atmospheric balance, and the habitability of our planet over billions of years.

This groundbreaking research is part of the VoiLA (Volatiles in the Lesser Antilles) project, in which the team deployed 34 seismometers on the ocean floor beneath the Lesser Antilles.

"This is the first large scale ocean bottom seismic experiment conducted at an Atlantic subduction zone," said Dr. Catherine Rychert, formerly an Associate Professor at the University of Southampton and currently at the Woods Hole Oceanographic Institution. "We were very surprised to find an unexpected and exceptionally thick—approximately 330 kilometers—mantle transition zone beneath the Antilles, which makes it one of the thickest transition zones observed worldwide. Although the Caribbean is well-known for its sunshine and beaches, it now has a new claim to fame in the world of plate tectonics."

“It’s wild to think that in some ways tectonic plates have a ‘memory’ and that affects the way the plates drive mantle convection and mix material back into the Earth,” said Dr. Nick Harmon, formerly an Associate Professor at the University of Southampton and currently at the Woods Hole Oceanographic Institution.

Lead author, Dr. Xusong Yang, a former visiting scholar at the University of Southampton and currently at University of Miami, emphasized, "We cannot overlook the inherited compositional heterogeneity of subducting oceanic slabs. It may greatly influence their ultimate fate in Earth's deep interior.”

Dr. Kate Rychert and Dr. Nick Harmon, formerly of the University of Southampton, Professor Saskia Goes from Imperial College London, and Professor Andreas Reitbrock from Karlsruhe Institute of Technology, led the experiment. The experiment was funded by NERC (Natural Environment Research Council, UK) and the ERC (European Research Council).

原始論文：Xusong Yang, Yujiang Xie, Catherine A. Rychert, Nicholas Harmon, Saskia Goes, Andreas Rietbrock, Lloyd Lynch, Colin G. Macpherson, Jeroen Van Hunen, Jon Davidson, Marjorie Wilson, Robert Allen, Jenny Collier, Jamie J. Wilkinson, Timothy J. Henstock, John-Michael Kendall, Jonathan D. Blundy, Joan Latchman, Richard Robertson. Seismic imaging of a basaltic Lesser Antilles slab from ancient tectonics. Nature, 2025; DOI: 10.1038/s41586-025-08754-0

引用自：Woods Hole Oceanographic Institution. "Sink or Swim: The fate of sinking tectonic plates depends on their ancient tectonic histories."

地下「島嶼」：這些堡壘代表地下世界可能沒有那麼混亂

 原文網址：https://www.uu.nl/en/news/subterranean-islands-strongholds-in-a-potentially-less-turbulent-world

在地函深處藏有兩座跟陸塊一樣龐大的巨大「島嶼」。由烏特勒支大學發表在《自然》(Nature)的新研究顯示，相較於周圍溫度較低的隱沒板塊墳場，這兩個區域不只較為高溫，而且年代勢必也相當古老——至少有五千萬年甚至更久。這些觀察結果牴觸了一項越來越多人質疑的理論：地函是均勻混和且快速流動的說法。「地函並不如一般想法中的容易流動。」

此圖表示了板塊的隱沒過程(藍色)以及從LLSVP升起的地函柱(紅色)。組成後者的礦物顆粒比隱沒板塊大非常多。圖片來源：Utrecht University

地球表層的水可以滲到地下深處，使地核外層發生轉變

 原文網址：https://news.asu.edu/20231113-earths-surface-water-dives-deep-transforming-cores-outer-layer

數十年前，拍攝地球深處影像的地震學家辨識出一層只有幾百公里厚的構造。這圈被稱為E’層的起源長久以來都是道謎題——直到現在。

這幅示意圖顯示了由水引發的化學反應，使得二氧化矽晶體從地球外核的液態金屬中冒出來。圖片來源：Dan Shim/ASU

新研究透漏了遠古地球的呼吸方式

 原文網址：https://www.esrf.fr/home/news/general/content-news/general/new-research-reveals-earth-s-ancient-breath-.html

科學家運用歐洲同步輻射裝置(ESRF)的ID21光束線，研究古代岩漿裡的鋯石晶體所含有的磷灰石包裹體，結果揭曉了關於大氧化事件的重要訊息。這項成果發表於《自然—地球科學》(Nature Geosciences)。

用ESRF的ID21光束線測量鋯石內部的磷灰石包裹體的硫物種。大氧化事件前後，硫的能譜從還原硫(S^2-)轉變成氧化硫(S⁶⁺)。作者主張原因為被空氣置換過的沉積物滲入地函，使得岩漿的氧化還原狀態有所改變。圖片來源：ESRF

地函深處有生命的痕跡

 原文網址：https://ethz.ch/en/news-and-events/eth-news/news/2022/03/traces-of-life-in-the-earths-deep-mantle.html

By Felix Würsten

動物在5億4000萬年前的迅速發展永久改變了地球，甚至達到下部地函。由蘇黎世聯邦理工學院的研究員Andrea Giuliani主持的團隊，發現地函深處的岩石具有那次生物的迅速發展留下的痕跡。

金柏利岩是一種成分複雜的岩石，它們是從非常深的地方來到地球表面。圖中是一片富含碳酸鹽的金柏利岩薄片。圖片來源：David Swart / Messengers of the Mantle Exhibition

在中國的地下深處看到前身為太平洋海床碎片的影像

 原文網址：https://www.sciencedaily.com/releases/2020/11/201116075717.htm

研究得到的線索顯示沉入地函深處的板塊會有什麼樣的命運

By Jade Boyd

一篇新研究讓「跌入谷底」有了新的意義。地球表面是由許多塊石板組合而成，它們的底側稱為岩石圈。地震學家在中國東北方發現有塊岩石圈因為板塊隱沒作用的緣故，而被拉到地球內部400多英里(約650公里)深的地方。

上圖簡單顯示了驅動地球板塊運動(黑色箭頭)的熱對流循環(紅色箭頭)。熱流會經由地函最上層的軟流圈往隱沒帶流動。萊斯大學的電腦模型發現軟流圈在局部地方可以牽動上方的板塊，而非許多人認為的只會阻礙板塊的運動。圖片來源：Surachit/Wikimedia Commons

鑽石告訴我們地球適合居住的關鍵之一：穩定的陸地如何形成？

原文網址：https://carnegiescience.edu/node/2490

鑽石告訴我們地球適合居住的關鍵之一：穩定的陸地如何形成？

地球的陸地在板塊構造運動的摧殘下仍然可以存在許久，是生命出現在地球的重要地質條件之一，而這種穩定性取決於連在陸塊下方的地函性質。美國卡內基研究所、美國寶石學院和加拿大阿爾伯塔大學的地質學家團隊最新進行的研究顯示，鑽石可以闡明某些陸地下方具有浮力的地函是如何增厚，使得上方的陸塊可以長期處於穩定狀態。

採自獅子山的鑽石，具有含硫礦物的包裹體。圖片來源：美國寶石學院

科學家重建出許久以前消失在安地斯山下方的板塊

原文網址：http://www.uh.edu/nsm/news-events/stories/2019/0122-lost-plates.php

科學家重建出許久以前消失在安地斯山下方的板塊

安地斯山沿著南美洲西岸綿延將近7000公里(約4300英里)，是世界上最長的山脈。

John Suppe、吳恩霖和陳奕維(由左至右)發表在《自然》的論文中，描述了安地斯山脈的形成過程。

為什麼蘇門答臘大地震如此嚴重

原文網址：www.sciencedaily.com/releases/2017/05/170525141547.htm

為什麼蘇門答臘大地震如此嚴重

一組國際科學家團隊發現的證據顯示，在海床底下深處的礦物脫水現象，對2004年12月26日發生的蘇門答臘大地震的嚴重程度有相當影響。

火山弧是由混雜的岩石於深處熔融而成

原文網址：www.sciencedaily.com/releases/2017/04/170407143316.htm

火山弧是由混雜的岩石於深處熔融而成

研究改變了我們對於隱沒帶內部發生作用的理解

在海洋底部，巨大的板塊彼此之間發生碰撞及摩擦，使得其中一方潛入至另一方之下。這種稱為隱沒的強力擠壓作用是火山弧的成因。火山弧是地球某些最強烈地質事件的發源處，像是劇烈的火山噴發以及超級地震。

地質學家發現板塊如何下沉

原始網址：www.sciencedaily.com/releases/2016/11/161114124949.htm

地質學家發現板塊如何下沉

在刊登於美國國家科學院院刊(Proceedings of the National Academy of Sciences, PNAS)的論文中，聖路易斯大學的研究人員發表了關於哪些因素會造成地球板塊下沉的新說法。

聖路易斯大學的地球與大氣科學博士John Encarnacion及研究生Timothy Keenan是地球構造和硬岩地質學的專家。他們同時利用地球化學、地質年代學，結合實地野外考察來研究板塊構造的運動。

「就定義來說，板塊是具有剛性(rigidity)的。意味著其相當堅硬並且會以整體為單位來運動。因此，我們正跟腳下踩的北美板塊以每年約一英吋的速度一同往大略西邊的方向移動。」Encarnacion解釋。「但當思考是什麼原因造成了板塊移動，我把板塊比喻成浸在池水中的濕毛巾。大部分的板塊會移動是因為它們正往地球內部下沉，就像是鋪在水面的毛巾開始沉沒時會將其餘部分拖往水中一樣。」

板塊移動的平均速度大約是每年1至2英吋。最快的板塊以每年4英吋左右的速度移動，而最慢的則幾乎文風不動。由於板塊運動是地震發生的主因，因此地震學家和地質學家皆在研究板塊運動的每分細節，以對未來可能發生的地震作出更精準的預測。

「每當科學家得出意料之外的事物實際上真的有可能發生時，就能讓我們更加貼近地球運作的真實方式。 」 Encarnacion表示。「而我們對地球大尺度作用的圖像刻畫得越精細，就能幫助我們更加了解地震和火山作用的運行。此外，由於大尺度板塊運動會生成並影響礦脈的分布，因此這也能讓我們知道礦脈的起源與所在地。」

板塊運動還會以其他方式影響我們的生活：近日有人發表由於板塊運動的緣故，澳洲地圖必須要重新繪製。由於澳洲往北移動的速度相對來說快上許多，因此經過數十年後它會位移數十公分，造成GPS定位結果嚴重失準。

隱沒作用(subduction)係指板塊沉入地函的作用。它是地球板塊運動的基礎作用力之一，同時也是板塊發生移動的主要成因；然而，新生隱沒帶會如何以及在哪形成，仍然是項眾說紛紜的議題。

聖路易斯大學的地質學家於野外研究岩石，並採取樣本回實驗室進行更全面的分析來進行這項研究。

他們的工作包括了繪製地質圖：觀察並辨認岩石後，將它們給繪製在地圖上以得出這些岩石如何形成，在形成之後又遭受了何種變故。研究人員定年這些岩石樣品並探討其化學性質，以詳細得知這些遠古岩石形成時的環境條件，像是某座火成岩體是形成於夏威夷這類的火山島，亦或是深海海床。

在此研究中，Keenan和Encarnacion前往菲律賓研究此處的板塊。他們發現在兩個板塊互相遠離的分離板塊邊界(divergent plate boundary)，會迅速地因外力轉變成聚合板塊邊界(convergent boundary)，使得其中一座板塊終將開始隱沒。

這個結果令他們相當驚訝，因為分離型邊界的板塊組成物質較為軟弱，且浮力也較大使它們較不易發生隱沒作用。這項研究的發現主張，於分離板塊邊界浮力較大且軟弱的板塊物質能被外力作用而往彼此聚合，直到較古老且密度較大的板塊物質終於進入初生隱沒帶之後，後續過程便能不倚靠外力而繼續維持運作。

「我們認為我們研究的隱沒帶實際上最初是因為印度碰撞亞洲而連帶形成。印度過去曾經跟亞洲分隔兩地，但它慢慢地往北漂移最後終於跟亞洲發生碰撞。此次碰撞事件將一大塊亞洲往東南方擠出。我們認為這股推力一路傳到海洋並讓新的隱沒帶於焉形成。」

他們的發現有助於建立用來瞭解板塊如何開始下沉的模型：「在板塊互相遠離之處，板塊可以被推往彼此而讓隱沒作用發生。」

聖路易斯大學的研究人員現在想要得知他們的模型是否能適用在其他的板塊之中。

「我們認為發生在菲律賓這種由外力啟動的隱沒帶有多常見？」Encarnacion提出。「我想看看其他對古代隱沒帶的研究成果，來觀察我們的模型是否也能適用於這些隱沒帶。」

這項研究的其他研究人員包括Robert Buchwaldt, Dan Fernandez, James Mattinson, Christine Rasoazanamparany和P. Benjamin Luetkemeyer。

聖路易斯大學地球與大氣科學系結合豐富的教學資源以及實地考察經驗，在物質科學的不同領域中，包括地震學、水文學、地球化學、氣象學、環境科學，以及當代與古代氣候變遷上的研究皆享譽國際。學生同樣擁有機會直接參與教職員的研究工作，且隨著跟公家與私人機關的合作網路日趨密切，學生也能尋求在不同機關的實習機會。

研究中心包括地震中心、降水系統合作研究所、全球地球動力學計畫、環境科學中心以及量子氣象站。結合專業課程與世界級的研究讓學生有絕佳的機會去探索自身興趣，並讓他們預先瞭解畢業後可能從事的各種工作。

Geologists discover how a tectonic plate sank

In a paper published in Proceedings of the National Academy of Sciences (PNAS) Saint Louis University researchers report new information about conditions that can cause Earth's tectonic plates to sink.

John Encarnacion, Ph.D., professor of earth and atmospheric sciences at SLU, and Timothy Keenan, a graduate student, are experts in tectonics and hard rock geology, and use geochemistry and geochronology coupled with field observations to study tectonic plate movement

"A plate, by definition, has a rigidity to it. It is stiff and behaves as a unit. We are on the North American Plate and so we're moving roughly westward together about an inch a year," Encarnacion said. "But when I think about what causes most plates to move, I think about a wet towel in a pool. Most plates are moving because they are sinking into Earth like a towel laid down on a pool will start to sink dragging the rest of the towel down into the water."

Plates move, on average, an inch or two a year. The fastest plate moves at about four inches a year and the slowest isn't moving much at all. Plate motions are the main cause of earthquakes, and seismologists and geologists study the details of plate motions to make more accurate predictions of their likelihood.

"Whenever scientists can show how something that is unexpected might have actually happened, it helps to paint a more accurate picture of how Earth behaves," Encarnacion said. "And a more accurate picture of large-scale Earth processes can help us better understand earthquakes and volcanoes, as well as the origin and locations of mineral deposits, many of which are the effects and products of large-scale plate motions."

Plate movement affects our lives in other ways, too: It recently was reported that Australia needs to redraw its maps due to plate motion. Australia is moving relatively quickly northwards, and so over many decades it has traveled several feet, causing GPS locations to be significantly misaligned.

Subduction, the process by which tectonic plates sink into Earth's mantle, is a fundamental tectonic process on earth, and yet the question of where and how new subduction zones form remains a matter of debate. Subduction is the main reason tectonic plates move.

The SLU geologists' research takes them out into the field to study rocks and sample them before taking them back to the lab to be studied in more detail.

Their work involves geological mapping: looking at rocks, identifying them, plotting them on a map and figuring out how they formed and what has happened to them after they form. Researchers date rock samples and look at their chemistry to learn about the specific conditions where an ancient rock formed, such as if a volcanic rock formed in a volcanic island like Hawaii or on the deep ocean floor.

In this study, Keenan and Encarnacion traveled to the Philippines to study plates in that region. They found that a divergent plate boundary, where two plates move apart, was forcefully and rapidly turned into a convergent boundary where one plate eventually began subducting.

This is surprising because although the plate material at a divergent boundary is weak, it is also buoyant and resists subduction. The research findings suggest that buoyant but weak plate material at a divergent boundary can be forced to converge until eventually older and denser plate material enters the nascent subduction zone, which then becomes self-sustaining.

"We think that the subduction zone we studied was actually forced to start because of the collision of India with Asia. India was once separated from Asia, but it slowly drifted northwards eventually colliding with Asia. The collision pushed out large chunks of Asia to the southeast. That push, we think, pushed all the way out into the ocean and triggered the start of a new subduction zone."

Their finding supports a new model for how plates can begin to sink: "Places where plates move apart can be pushed together to start subduction."

The SLU researchers now want to learn if their model applies to other tectonic plates.

"How common was this forced initiation of a subduction zone that we think happened in the Philippines?" Encarnacion said. "I would like to see work on other ancient subduction zones to see whether our model applies to them as well."

Other researchers on the study include Robert Buchwaldt, Dan Fernandez, James Mattinson, Christine Rasoazanamparany, and P. Benjamin Luetkemeyer.

Saint Louis University's Department of Earth and Atmospheric Sciences, combines strong classroom and field-based instruction with internationally recognized research across a broad spectrum of the physical sciences, including seismology, hydrology, geochemistry, meteorology, environmental science, and the study of modern and ancient climate change. Students also have the opportunity to work directly with faculty on their research and pursue internships through a growing network of contacts in the public and private sector.

Research centers include the Earthquake Center, the Cooperative Institute for Precipitation Systems, the Global Geodynamics Program, the Center for Environmental Sciences, and Quantum WeatherTM. The fusion of academic programs with world-class research provides students with an unparalleled opportunity to explore their interests and prepare for a wide variety of careers after graduation.

原始論文：Timothy E. Keenan, John Encarnación, Robert Buchwaldt, Dan Fernandez, James Mattinson, Christine Rasoazanamparany, P. Benjamin Luetkemeyer. Rapid conversion of an oceanic spreading center to a subduction zone inferred from high-precision geochronology. Proceedings of the National Academy of Sciences, 2016; 201609999 DOI: 10.1073/pnas.1609999113

引用自：Saint Louis University Medical Center. "Geologists discover how a tectonic plate sank." ScienceDaily. ScienceDaily, 14 November 2016.