原文網址：https://cmns.umd.edu/news-events/news/researchers-solve-one-earths-ancient-volcanic-mysteries
新研究追查距今1億2000萬年前發生的「超級火山爆發」其源頭為何，結果讓我們對於地球複雜的地質歷史有了新的觀點。
由馬里蘭大學與夏威夷大學領導的地質學家團隊串連了逐條線索，終於找出地球歷史上規模最大的火山噴發之一其源頭來自太平洋的深處。
Val Finlayson (左)與Paulo Galvan在2013年的研究航次中從深海取得的岩石樣品。 圖片來源：Val Finlayson.
在2025年4月30日發表於期刊《自然》(Nature)的文章中，研究團隊揭示了位於南太平洋的一連串海底火山，以及地球上最大的火山高原——翁通-爪哇高原(Ontong-Java
Plateau)都是由同一個海底熱點形成。
「在此之前，我們對於太平洋以及位在其中的火山只有極為片段的圖像，」此研究的通訊作者Val
Finlayson表示，她是馬里蘭大學地質科學系的助理教授。「但是我們的研究首次清楚地證明太平洋南邊較年輕的火山系統，與西邊較古老的系統之間有所連結。這道發現讓我們對於太平洋海盆是如何經過數億年的演變，而成為現今樣貌的歷史有了更加完整的理解。」
熱點是指高溫且化學組成特殊的物質從地球深處往上升，而在地表形成火山的區域。科學家多年以來猜測南太平洋的路易威爾熱點不但形成了與其同名的海底火山鏈，也形成了現今位在所羅門群島北方的海底、年代為1億2000萬年的翁通-爪哇高原。雖然前人曾經試著建立太平洋海床移動過程的理論與模型，進而解釋這兩個大型地質特徵的關聯，但還是沒辦法給出肯定的答案。
「大部分可以證明路易威爾海底火山鏈與翁通-爪哇高原之間有關的實體證據都消失了，因為路易威爾熱點的軌跡有部分已經隱沒、也就是被推到太平洋周遭的板塊下方，」Finlayson表示。「我們必須從另外一道存在許久的熱點軌跡——一群位於海底深處的火山取出數億年前的樣品，才有證據指出我們目前對於太平洋板塊演變的模型需要重新審視。」
Finlayson與團隊發現薩摩亞附近的一連串海底山，年代比此區域的火山應有的年代還要老，這是他們的第一項突破。從此處取得古老的岩石樣品並分析年代與化學組成之後，研究人員的結論認為這些火山是路易威爾熱點留下的一段年代非常久遠的軌跡。Finlayson表示這些軌跡就像是以火山為形式的「足跡」，當地殼(板塊)在熱點上方移動的時候，就會形成這類火山軌跡。
「我們可以追蹤這些『足跡』的時空分布，」Finlayson解釋。「越遠離還在活動的熱點，這些足跡的年代就會更加古老。就像你走在沙灘上，遠方的足跡會漸漸淡去，但還是可以看出這些足跡都是源自於你。幸虧有這份新的證據，我們才能修正目前太平洋板塊如何移動的模型，並且更加瞭解過去數億年來的海床移動過程。」
Finlayson團隊目前的計畫是運用他們改良過的模型，來深入了解其他散佈在海床或露出海面的古代火山構造。由於現今許多太平洋島國坐落在火山高原或海底火山鏈的頂部，Finlayson希望她的成果可以進一步了解這些國家的根基。此外，她也相信團隊的發現有助於科學家之後對火山活動和地質演化了解得更深，不只是在太平洋地區，也包括世界各地。
「雖然我們解開了一道謎題，但還有數不盡的謎題有待解決。這項發現讓我們對於太平洋及其火山活動的歷史有了更加精確的認識，並且幫助我們深入了解此處發生的火山作用類型及動力學，」Finlayson表示。「我們對於地球動盪的過去所學到的任何新事物，都有助於我們更加了解這顆活力旺盛、我們稱作家園的星球。」
Researchers solve
one of Earth’s ancient volcanic mysteries
A new study
traces a 120-million-year-old “super-eruption” to its source, offering new
insights into Earth’s complex geological history.
Geologists led by the University of Maryland and the
University of Hawaiʻi finally connected the dots between one of the largest
volcanic eruptions in Earth’s history and its source deep beneath the Pacific
Ocean.
In a paper published in the journal Nature on April 30, 2025, the team
revealed that the same underwater hotspot created both a chain of underwater
volcanoes in the southern Pacific region and the massive Ontong-Java Plateau,
the largest volcanic platform on Earth.
“Up until now, we’ve had this extremely disconnected
picture of the Pacific and its volcanoes,” said the study’s corresponding
author Val Finlayson, an assistant research scientist in UMD’s Department of
Geology. “But for the first time, we’re able to make a clear connection between
the younger southern and older western Pacific volcanic systems. It’s a
discovery that gives us a more complete history of how the Pacific Ocean basin
has evolved over millions of years to become what it is today.”
For years, scientists wondered whether the southern
Pacific Ocean’s Louisville hotspot—an area where hot and chemically distinct
material from deep inside the Earth rises to the surface to create
volcanoes—formed both the underwater mountain chain bearing its name and the
120-million-year-old Ontong-Java Plateau, a submerged seafloor platform located
what is now north of the Solomon Islands. Previous theories and models on how
the Pacific seafloor moved attempted to explain the connection between the two
major geological features but failed to provide a definitive answer.
“Much of the physical evidence for a connection between
Louisville and Ontong-Java has disappeared because part of the Louisville
hotspot track was subducted, or pushed, under tectonic plates in the Pacific
region,” Finlayson said. “We had to sample deeply submerged volcanoes from a
different long-lived hotspot track to find evidence from tens of millions of
years ago that suggested our models for the Pacific plate needed revision.”
Finlayson and her team made their first breakthrough
when they discovered a series of underwater mountains near Samoa that were much
older than expected for volcanoes in the area. By analyzing the age and
chemical makeup of ancient rock samples taken from the area, the researchers
concluded that these mountains were part of a much older segment of the
Louisville volcanic track, which Finlayson compared to a volcano’s
“footprints.” As the Earth’s crust (tectonic plates) moves over hotspots, they
form these volcanic tracks.
“We can track these ‘footprints’ across time and
space,” Finlayson explained. “The footprints get progressively older as you
move away from an active hot spot, similar to how your own footprints will fade
away in the sand as you walk. But you can still tell that these prints belong
to the same source. Thanks to this new evidence, we were able to revise current
models of Pacific plate motion and gain a better understanding of how the
seafloor has moved over millions of years.”
Finlayson’s team now plans to apply their improved
models to better understand other ancient volcanic features scattered across
the ocean floor and above its surface. As many Pacific island nations currently
sit atop volcanic platforms and underwater volcanic chains, Finlayson hopes
that her work furthers understanding of the very foundations of those countries.
She also believes that her team’s discovery will help scientists develop a
better understanding of volcanism and geological evolution, not just in the
Pacific region, but around the world.
“We’ve solved one mystery, but there are countless
more waiting to be unraveled. This finding offers us a more accurate history of
the Pacific and its volcanic activity and helps us understand more about the
dynamics and style of volcanism that occurs there,” Finlayson said. “Everything
new we learn about the Earth’s tumultuous past helps us better understand the
dynamic planet we live on today.”
原始論文：Konter, J.G.,
Finlayson, V.A., Konrad, K. et al. Pacific hotspots reveal a
Louisville–Ontong Java Nui tectonic link. Nature, 2025
DOI: 10.1038/s41586-025-08889-0
引用自：University of Maryland. "One of Earth's
ancient volcanic mysteries solved."
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