火山岩握有地球深部活動的資訊

原文網址：www.sciencedaily.com/releases/2015/11/151124170253.htm

 

Volcanic rocks hold clues to Earth's interior

火山岩握有地球深部活動的資訊

The journey for volcanic rocks found on many volcanic islands began deep within Earth.

Brought to Earth's surface in eruptions of deep volcanic material, these rocks hold clues as to what is going on deep beneath Earth's surface.

火山岩自地球深處啟程，歷經漫漫長路，自火山深部噴發後才能在許多海島上為我們所見。也因此它們帶有地表之下十分深處正在進行何種活動的資訊。

Studies of rocks found on certain volcanic islands, known as ocean island basalts, revealed that although these erupted rocks originate from Earth's interior, they are not the same chemically.

科學家詳細研究某些火山島嶼上這種稱作洋島玄武岩(ocean island basalt)的岩石後，發現雖然這些岩石都是源自地球深處，然而它們的化學性質卻不盡相同。

According to a group of current and former researchers at Arizona State University, the key to unlocking this complex, geochemical puzzle rests in a model of mantle dynamics consisting of plumes -- upwelling's of abnormally hot rock within Earth's mantle -- that originate in the lower mantle and physically interact with chemically distinct piles of material.

由一群現任與曾經任職於亞利桑那州立大學的研究人員組成的團隊，表示解開這道複雜地球化學謎題的關鍵在於有考量到地函柱的地函動力學模型之中。地函柱是在地函中因為異常高熱而上湧的岩石，它們源自下部地函，會跟地函中化學性質不同的區域產生物理交互作用。

The team revealed that this theoretical model of material transport can easily produce the chemical variability observed at hotspot volcanoes (such as Hawaii) around the world.

研究團隊顯示我們在世界各地不同熱點火山(hotspot volcano，如夏威夷)觀察到的岩石化學性質變化，可以利用此理論模型架構出的地函物質輸送模式來輕易產生。

"This model provides a platform for understanding links between the physics and chemistry that formed our modern world as well as habitable planets elsewhere," says Curtis Williams, lead author of the study whose results are published in the Nov. 24 issue of the journal Nature Communications.

「這個模型提供的平台不只能讓我們了解物理化學作用彼此之間的鏈結如何形塑我們居住的世界，它同樣也能適用於某處適合我們生存的星球。」第一作者Curtis Williams說，他們的研究成果刊登於11/24的《自然通訊》（Nature Communications）。

Basalts collected from ocean islands such as Hawaii and those collected from mid-ocean ridges (that erupt at spreading centers deep below oceans) may look similar to the naked eye; however, in detail their trace elements and isotopic compositions can be quite distinct. These differences provide valuable insight into the chemical structure and temporal evolution of Earth's interior.

從夏威夷這類的海洋島嶼和中洋脊(在海床因板塊張裂而噴發的火山)取得的玄武岩，雖然由肉眼看來兩者之間十分相似，但仔細分析便會發現它們的稀有元素含量和同位素組成之間有天壤地別的差異。這些差異提供了一扇珍貴的窗口，讓我們有機會一窺地球內部不同化學成分的空間分布，以及它們如何隨著時間演變。

"In particular, it means that Earth's mantle -- the hot rock below Earth's crust but above the planet's iron core -- is compositionally heterogeneous. Understanding when and where these heterogeneities are formed and how they are transported through the mantle directly relates to the initial composition of Earth and how it has evolved to its current, habitable state," said Williams, a postdoc at UC Davis.

「尤其重要的是，這代表地球地函(位於地殼之下，鐵質地核之上的熾熱岩石)的成分是不均勻的。瞭解這種不均勻性質是何時何地發展出來，以及它如何散播到地函各處，跟我們想要得知地球最初成分為何，和地球如何演化成目前的適居狀態這些問題之間有著直接關係。」加州大學戴維斯分校的博士後研究員Williams說。

While a graduate student in ASU's School of Earth and Space Exploration, Williams and faculty members Allen McNamara and Ed Garnero conceived a study to further understand how chemical complexities that exist deep inside Earth are transported to the surface and erupt as intraplate volcanism (such as that which formed the Hawaiian islands). Along with fellow graduate student Mingming Li and Professional Research Associate Matthijs van Soest, the researchers depict a model Earth, where in its interior resides distinct reservoirs of mantle material that may have formed during the earliest stages of Earth's evolution.

還是亞利桑那州立大學地球與太空探索學院的研究生時，Williams與系所中的同仁Allen McNamara和Ed Garnero合作，深入探討地球深處的化學複雜性是如何傳送至表面，並以板塊內火山活動(intraplate volcanism，夏威夷火山即為一例)的形式噴發。在同樣是研究生的Mingming Li和專業副研究員Matthijs van Soest的協助下，研究人員建構出一個地球模型，其內部有數個地方在地球演化最初期時便已經擁有性質特異的地函物質。

Employing such reservoirs into their models is supported by geophysical observations of two, continent-sized regions -- one below the Pacific Ocean and one below parts of the Atlantic Ocean and Africa -- sitting atop the core-mantle boundary.

將這種儲庫納入模型當中是有地球物理觀測數據支持的。目前觀測結果顯示在太平洋下方，以及在部分大西洋至非洲下方，分別有兩個陸塊般大小的不均勻帶覆於核幔邊界之上。

"In the last several years, we have witnessed a sharpening of the focus knob on seismic imaging of Earth's deep interior. We have learned that the two large anomalous structures at the base of the mantle behave as if they are compositionally distinct. That is, we are talking about different stuff compared to the surrounding mantle. These represent the largest internal anomalies in Earth of unknown chemistry and origin," said Garnero.

「在最近這幾年，我們目睹到地球內部地震成像的清晰程度正不斷提高。我們體認到地函底部有兩處巨大的異常構造，從它們的行為看起來它們是由截然不同的成分組成。精確來說，我們討論的便是與周遭地函性質大異其趣的那些東西。這些區塊代表著地函之中我們仍未知曉其化學性質與起源的最大異常帶。」Garnero說。

These chemically distinct regions also underlie a majority of hotspot volcanism, via hot mantle plumes from the top of the piles to Earth's surface, suggesting a potential link between these ancient, chemically distinct regions and the chemistry of hotspot volcanism.

在大型熱點火山下方也常常會有這些化學異常帶，它們可能是從深部異常帶的頂端藉由高熱地函柱而來到地表。這顯示在古老化學異常帶與熱點火山化學性質之間可能具有某種潛在關聯。

To test the validity of their model, Williams and coauthors compare their predictions of the variability of the ratios of helium isotopes (helium-3 and helium-4) in plumes to that observed in ocean island basalts.

為了測試他們模型的可信度，Williams和共同作者比較模型預估的地函柱氦同位素比(氦-3和氦-4)變化值，以及從洋島玄武岩中得到的觀測值。

3He is a so-called primordial isotope found in Earth's mantle. It was created before Earth was formed and is thought to have become entrapped within Earth during planetary formation. Today, it is not being added to Earth's inventory at a significant rate, unlike 4He, which accumulates over time.

氦-3是一種可以從地函中發現的原生同位素(primordial isotope)。這種同位素是在地球誕生之前就已經形成，一般認為它們會在行星形成過程當中被困在地球當中。在今日，他們進入地球的速率非常緩慢，而非像氦-4一樣會隨著時間逐漸累積。

Williams explained: "The ratio of helium-3 to helium-4 in mid-ocean ridge basalts are globally characterized by a narrow range of small values and are thought to sample a relatively homogenous upper mantle. On the other hand, ocean island basalts display a much wider range, from small to very large, providing evidence that they are derived from different source regions and are thought to sample the lower mantle either partially or in its entirety."

Williams解釋：「在全球各地中洋脊玄武岩中的氦-3對氦-4比例都集中於非常窄的一段範圍之內，而我們認為它們代表了相對性質較為均一的上部地函的樣品。另一方面，洋島玄武岩的氦同位素比卻呈現出大範圍的變動，值可以從很小到很大。這證明了它們的來源並不相同，我們認為它們可能有部分或著整體都是來自下部地函。」

The variability of 3He to 4He in ocean island basalts is not only observed between different hotspots, but temporally within the different-aged lavas of a single hotspot track.

洋島玄武岩中的氦-3對氦-4變化不只可在不同熱點產生的玄武岩之間觀察到，就算是在同一熱點造成的火山序列中，不同年代的熔岩之間也會有此差異。

"The reservoirs and dynamics associated with this variability had remained unclear and was the primary motivation behind the study presented here," said Williams.

「這種多樣性之所以產生的來源與動力學仍未明朗，而這也是我們呈現在此的研究背後的主要動機。」Williams說。

引用自：Arizona State University. "Volcanic rocks hold clues to Earth's interior." ScienceDaily. ScienceDaily, 24 November 2015.

地函柱引發板塊運動？

原文網址：www.sciencedaily.com/releases/2015/11/151111143225.htm

Plate tectonics thanks to plumes?

地函柱引發板塊運動？

"Knowing what a chicken looks like and what all the chickens before it looked like doesn't help us to understand the egg," says Taras Gerya. The ETH Professor of Geophysics uses this metaphor to address plate tectonics and the early history of the Earth. The Earth's lithosphere is divided into several plates that are in constant motion, and today's geologists have a good understanding of what drives these plate movements: heavier ocean plates are submerged beneath lighter continental plates along what are known as subduction zones. Once the movement has begun, it is perpetuated due to the weight of the dense subducting plate.

「知道一隻雞以及牠列祖列宗的長相並不能讓我們認識雞蛋的模樣。」Taras Gerya說。這名蘇黎世聯邦理工學院(ETH)地球物理學系的教授以此比喻板塊運動和地球早期的歷史。地球岩石圈分裂成好幾塊會不斷運動的板塊。現今的地質學家對驅動板塊移動的作用力已有相當瞭解：密度較高的海洋板塊沿著隱沒帶沉沒至較輕的大陸板塊之下。一旦此運動開始進行，隱沒板塊的重量便會使之維持下去。

But just as in the past, earth scientists still do not understand what triggered plate tectonics in the first place, nor how the first subduction zone was formed. A weak spot in the Earth's lithosphere was necessary in order for parts of the Earth's crust to begin their descent into the Earth's mantle. Was this weak spot caused by a gigantic meteorite that effectively smashed a hole in the Earth's lithosphere? Or did mantle convection forces shatter the lithosphere into moving parts?

但跟過去的地球科學家一樣，我們現在仍然不瞭解一開始是什麼觸發了板塊運動，而隱沒帶又是如何形成。我們所知的是地球岩石圈必然出現了一個軟弱區域，才能使部分的地球地殼開始沉入地函。這個軟弱區域會是因為一次巨型隕石撞擊，在地球岩石圈重重擊出一個大坑而形成嗎？或者是地函對流將岩石圈碎裂成好幾塊能自由移動的碎片？

Venus as a model

以金星作為模型

Gerya is not satisfied with any of these potential explanations. "It's not trivial to draw conclusions about what set the tectonic movements in motion," he says. The ETH professor therefore set out to find a new, plausible explanation.

Gerya對這些可能的解釋都不甚滿意。「得出是什麼開啟了能夠持續運作的板塊運動可是件至關重要的事。」他說。這位ETH的教授因此計畫要找出一套可行的新解釋。

Among other things, he found inspiration in studies about the surface of the planet Venus, which has never had plate tectonics. Gerya observed (and modelled) huge, crater-like circles (coronae) on Venus that may also have existed on the Earth's surface in the early period (Precambrian) of the Earth's history before plate tectonics even began. These structures could indicate that mantle plumes once rose from Venus' iron core to the outer layer, thus softening and weakening the planet's surface. Plumes form in the deep interior of the planet. They rise up to the lithosphere, bringing with them hot partially molten mantle material that causes the lithosphere to weaken and deform. Halted by the resistance of the hard lithosphere, the material begins to spread, taking on a mushroom-like shape.

除了其他方面之外，他也從關於金星地表的研究中得到了不少啟發。Gerya觀察到(並模擬)金星上有著像隕石坑般的巨大圓形構造(冕狀物，coronae)。由於這顆星球從未發生板塊運動，因此在板塊運動發生前的早期(前寒武紀)地球地表，也可能存在著類似構造。這種構造象徵著有地函柱(plume)從金星的鐵質地核往上升至星球外層，因而軟化並弱化了行星地表。地函柱在金星深處形成，往上移動而與岩石圈接觸。它們攜帶的炙熱部分熔融地函會弱化岩石圈並使其變形。在被堅硬的岩石圈阻擋之後，這些熱物質會往外擴散，而形成蘑菇狀的外觀。

Such plumes also likely existed in the Earth's interior and could have created the weaknesses in the Earth's lithosphere needed to initiate plate tectonics on Earth.

這種地函柱也可能會存在於地球內部，並形成啟動板塊運動所需，存在於岩石圈之內的軟弱區域。

Mantle plumes create weaknesses

地函柱創造軟弱區域

The ETH geophysicist worked with his team to develop new computer models that he then used to investigate this idea for the first time in high resolution and in 3D. The corresponding publication has recently been published in Nature.

ETH的地球物理學家與他的團隊發展出一套新的電腦模型，讓他首度能在3D高解析度系統下探討上述想法。相關結果近日發表於期刊《自然》(Nature)之中。

The simulations show that mantle plumes and the weaknesses they create could have actually initiated the first subduction zones.

模擬結果顯示出地函柱與其造成的軟弱區域真的能夠促使第一個隱沒帶形成。

In the simulations, the plume weakens the overlying lithosphere and forms a circular, thinning weak point with a diameter of several dozen to hundreds of kilometres. This is stretched over time by the supply of hot material from the deep mantle. "In order to make a ring larger, you have to break it," explains the researcher. This also applies to the Earth's surface: the ring-shaped weaknesses can (in the model) only be enlarged and subducted if the margins are torn.

在模擬過程當中，地函柱會弱化上覆的岩石圈，並在其中形成一層薄薄的環形軟弱區域，直徑可從數十至數百公里不等。隨著深部地函不斷提供熱物質，它會開始往外擴展。「若要將一個環拉得更大，你非得扯斷它不可。」研究人員解釋。此觀點也能套用在地球表面：(模擬中)唯有這道環形弱點的邊緣被撕裂後，它才能往外擴張並且發生隱沒。

Water lubricates the plate margin

水分潤滑了板塊邊緣

The tears spread throughout the lithosphere, large slabs of the heavier rigid lithosphere plunge into the soft mantle, and the first plate margins emerge. The tension created by the plunging slabs ultimately sets the plates in motion. They plunge, well lubricated by the buried seawater of the ocean above. Subduction has begun -- and with it, plate tectonics. "Water acts as a lubricant and is an absolute necessity in the initiation of a self-sustaining subduction," says Gerya.

這些裂縫會延伸至岩石圈各處，造成密度較高的堅硬岩石圈斷塊往下沉至柔軟的地函當中。第一道板塊邊界就此誕生。而下沉板塊造成的拉力最後會使得整個板塊跟著移動。在下沉的過程當中，上方海水會隨之埋入而達到潤滑效果，使整個過程進行得更加順利。隱沒作用於焉開始，隨之而來的是板塊運動開始運作。「在啟動可以永續運作的隱沒作用的過程中，水的潤滑絕對是項不可或缺的要素。」

In their simulations, the researchers compare different temperature conditions and lithosphere states. They came to the conclusion that plume-induced plate tectonics could plausibly develop under the conditions that prevailed in the Precambrian around three billion years ago. Back then the Earth's lithosphere was already thick and cool, but the mantle was still very hot, providing enough energy to significantly weaken the lithosphere above the plumes.

研究人員在模擬過程當中，比較不同溫度條件和岩石圈狀態會有何差異。他們得出的結論顯示30億年前前寒物紀時期的地球，可以達到發生由地函柱引發的板塊運動所需的條件。那時地球岩石圈雖然已經達到一定厚度且冷卻下來，然而地函仍然相當熾熱，能夠提供使地函柱之上的岩石圈弱化至一定程度需要的能量。

Had the lithosphere instead being thin and warm, and therefore soft, the simulations show that a ring-shaped rapidly descending structure called drip would simply have formed around the plume head. While this would have steadily sunk into the mantle, it would not have caused the soft lithosphere to subduct and tear and therefore would not have produced plate margins. Likewise, the computer simulations showed that under today's conditions, where there is less temperature difference between lithosphere and plume material, plume-induced subduction is hard to initiate because the lithosphere is already too rigid and the plumes are barely able to weaken it sufficiently.

模擬結果顯示假如岩石圈的厚度較薄、溫度較高，因此較為軟弱， 則僅會在地函柱頭附近形成一種會迅速下沉，稱作drip的環狀構造。由於這種構造會穩定地往下沉入地函，因此它不會撕裂軟弱的岩石圈並造成隱沒作用，板塊邊界也不會形成。同樣地，電腦模擬也顯示在目前岩石圈以及地函柱物質之間溫差較小的狀態下，由於岩石圈已經太過堅硬使得地函柱不足以大幅弱化它，因此難以發生由地函柱引發的隱沒作用。

Dominant mechanism

主要機制

"Our new models explain how plate tectonics came about," says the geophysicist. Plume activity was enough to give rise to today's plate mosaic. He calls the power of the plumes the dominant trigger for global plate tectonics.

「我們的新模型解釋了板塊運動如何開始。」這名地球物理學家說。他聲稱地函柱的力量便是啟動地球板塊運動的主因，也造就了今日我們所見的片片板塊。

The simulations can also explain how so-called triple junctions, i.e. zones in which three plates come together, are nucleated by multi-directional stretching of the lithosphere induced by plumes. One such example of a triple junction can be found in the Horn of Africa where Ethiopia, Eritrea and Djibouti meet.

這項模擬也能解釋三向聯結構造(triple junction，三個板塊交接的地區)是如何因為地函柱造成岩石圈往多重方向拉伸，使得不同板塊交接而形成。在衣索比亞、厄利垂亞、吉布地三國交界的非洲之角即可看到三向聯結構造中的一例。

A possible plume-weakened zone analogous to a starting point for global plate tectonics likely exists in the modern world: the researchers see such a zone in the Caribbean plate. Its shape, location and spread correspond largely to the new model simulations.

今日，在世界上可能還存在著類似地球板塊運動的起始地點，由地函柱產生的軟弱帶。研究人員在加勒比板塊中看到一個這樣的區域，它的形狀、位置以及逐漸擴張都相當符合這個新模型的模擬結果。

Indeed it is arguably impossible to prove how global plate tectonics started on Earth based solely on observations: there is no geophysical and only a small amount of geological data from the Earth's early years, and laboratory experiments are not possible for extremely large-scale and very long-term tectonic processes, says the ETH researcher. "Computer models are therefore the only way we can reproduce and understand the events of the Earth's early history."

我們的確能說幾乎不可能僅靠觀察來證明地球上的板塊運動是如何開始。我們無法得到地球早年歲月時的地球物理資料，而地質證據也是吉光片羽。同樣地，實驗室試驗不可能重現如此大規模且極度長期的構造運動過程。「因此電腦模擬是我們僅剩的唯一方法，可以重現並瞭解地球早期究竟有何事件發生。」這位ETH的研究人員說。

引用自：ETH Zurich. "Plate tectonics thanks to plumes?." ScienceDaily. ScienceDaily, 11 November 2015. 

原文網址：www.sciencedaily.com/releases/2015/11/151103140444.htm

Diamonds may not be so rare as once thought

鑽石或許並不如之前認為的那般稀有

Chemical model shows a simpler deep Earth formation

化學模型顯示出鑽石在地球深處的簡易形成方法

Diamonds may not be as rare as once believed, but this finding in a new Johns Hopkins University research report won't mean deep discounts at local jewelry stores.

鑽石也許並不像之前咸信的如此稀有，然而這起約翰·霍普金斯大學新研究報告中的發現，並不代表你家附近珠寶店的鑽石價格會暴跌。

"Diamond formation in the deep Earth, the very deep Earth, may be a more common process than we thought," said Johns Hopkins geochemist Dimitri A. Sverjensky, whose article co-written with doctoral student Fang Huang appears today in the online journal Nature Communications. The report says the results 'constitute a new quantitative theory of diamond formation,' but that does not mean it will be easier to find gem-quality diamonds and bring them to market.

「鑽石於地球深處，非常非常深處形成的過程也許比我們認為得更常發生。」約翰·霍普金斯大學的地球化學家Dimitri A. Sverjensky說。他和他的博士班學生Fang Huang合撰的文章今日刊登於期刊《自然通訊》(Nature Communications)線上版。這篇報告寫道他們的結果「建構了一套可用來解釋鑽石如何形成的新型數量化理論」，但這並不代表找到並銷售寶石等級的鑽石會變得易如反掌。

For one thing, the prevalence of diamonds near the Earth's surface -- where they can be mined -- still depends on relatively rare volcanic magma eruptions that raise them from the depths where they form. For another, the diamonds being considered in these studies are not necessarily the stuff of engagement rings, unless the recipient is equipped with a microscope. Most are only a few microns across and are not visible to the unaided eye.

一方面來說，要在地表附近形成鑽石含量豐富而能供人類開採的礦藏，仍然要靠某些相當罕見，能將鑽石從它們形成的地球深處帶至地表的火山爆發事件。另一方面，這篇研究中所指的鑽石並不全然像訂婚鑽戒上的那般光彩奪目，除非收下的人配有顯微鏡。這些鑽石大都只有幾微米的大小，絕非肉眼可見。

Using a chemical model, Sverjensky and Huang found that these precious stones could be born in a natural chemical reaction that is simpler than the two main processes that up to now have been understood to produce diamonds. Specifically, their model -- yet to be tested with actual materials -- shows that diamonds can form with an increase in acidity during interaction between water and rock.

利用化學模擬方法，Sverjensky 和Huang發現這些珍稀的寶石能在某種自然發生的化學反應中形成，這種反應遠較目前為止所知，另外兩種形成鑽石的主要機制簡單許多。準確來說，雖然還未經實物驗證，他們的模型顯示水與岩石反應的過程中，酸度提高會使鑽石形成。

The common understanding up to now has been that diamonds are formed in the movement of fluid by the oxidation of methane or the chemical reduction of carbon dioxide. Oxidation results in a higher oxidation state, or a gain of electrons. Reduction means a lower oxidation state, and collectively the two are known as 'redox' reactions.

迄今，一般我們認為鑽石是由於液體流動的過程中，發生甲烷氧化或者二氧化碳還原而形成。氧化會提高物質的氧化態，或者可說是讓它失去電子；還原則會降低氧化碳，兩者通常合稱為氧化還原反應。

"It was always hard to explain why the redox reactions took place," said Sverjensky, a professor in the Morton K. Blaustein Department of Earth and Planetary Sciences in the university's Krieger School of Arts and Sciences. The reactions require different types of fluids to be moving through the rocks encountering environments with different oxidation states.

「要解釋氧化還原反應為何發生總是一件很難的事。」Sverjensky說，他是約翰·霍普金斯大學克里格藝術科學學院，地球與行星科學系的教授。這類反應需要不同流體在岩石中流動時，遇到氧化態有所差異的環境才會發生。

The new research showed that water could produce diamonds as its pH falls naturally -- that is, as it becomes more acidic -- while moving from one type of rock to another, Sverjensky said.

Sverjensky說，這項新研究顯示水在不同種類岩石之間流動時，在pH值自然下降(也就是變得更加酸性)的過程中，鑽石就會從中產生。

The finding is one of many in about the last 25 years that expands scientists' understanding of how pervasive diamonds may be, Sverjensky said.

Sverjensky說，包含此發現，科學家過去25年來已經從許多研究中愈加瞭解鑽石的分布其實是多麼廣泛。

"The more people look, the more they're finding diamonds in different rock types now," Sverjensky said. "I think everybody would agree there's more and more environments of diamond formation being discovered."

「人們愈去探討，他們就在愈多種岩石中發現鑽石。」Sverjensky說。「我想現在大家都同意會有愈來愈多的環境被發現有鑽石形成於其中。」

Nobody has yet put a number on the greater abundance of diamonds, but Sverjensky said scientists are working on that with chemical models. It's impossible to physically explore the great depths at which diamonds are created: roughly 90 to 120 miles below the Earth's surface at intense pressure and at temperatures about 1,650 to 2,000 degrees Fahrenheit.

雖然尚未有人發現由此成因而形成的豐富鑽石礦藏，Sverjensky說科學家可以利用化學模型來進行相關研究。目前人類還無法實際去探索鑽石形成的深度，它們位於地表之下140至200公里，在那裏壓力相當地大，而溫度可高達900至1100℃。

The deepest drilling exploration ever made was about 8 or 9 miles below the surface, he said.

他說，人類曾鑽到最深的地方也只不過是地表之下13至15公里。

If the study doesn't shake the diamond markets, it promises to help shed light on fluid movement in the deep Earth, which helps account for the carbon cycle on which all life on the planet depends.

即使這篇研究並沒有撼動鑽石市場，至少它肯定會讓我們對液體在地球深部是如何流動有更多的瞭解，而這與地球上所有生物依存的碳循環息息相關。

"Fluids are the key link between the shallow and the deep Earth," Sverjensky said. "That's why it's important."

「液體是連結地球深部和淺部的關鍵角色。」Sverjensky說。「這就是它為何如此重要的原因。」

This research was supported by grants from the Sloan Foundation through the Deep Carbon Observatory (Reservoirs and Fluxes and Extreme Physics and Chemistry programs) and by a U.S. Energy Department grant, DE-FG-02-96ER-14616.

本研究的贊助來自於斯隆基金會的深碳觀測計畫(Deep Carbon Observatory)下的子計畫，「儲量與通量」以及「極端物理化學條件」；另外一份則來自美國能源局計畫編號DE-FG-02-96ER-14616。

引用自：Johns Hopkins University. "Diamonds may not be so rare as once thought: Chemical model shows a simpler deep Earth formation." ScienceDaily. ScienceDaily, 3 November 2015. 

深海熱泉會移除海洋中的碳

原文網址：www.sciencedaily.com/releases/2015/11/151102143735.htm

Deep-sea hydrothermal vents have carbon-removing properties

深海熱泉會移除海洋中的碳

University of Georgia Skidaway Institute of Oceanography scientist Aron Stubbins joined a team of researchers to determine how hydrothermal vents influence ocean carbon storage. The results of their study were recently published in the journal Nature Geoscience.

喬治亞大學斯基德维海洋研究所的科學家Aron Stubbins參與的研究團隊探討深海熱泉對海洋碳儲量會有何影響。他們的結果近日發表於期刊《自然－地質科學》之上。

Hydrothermal vents are hotspots of activity on the otherwise dark, cold ocean floor. Since their discovery, scientists have been intrigued by these deep ocean ecosystems, studying their potential role in the evolution of life and their influence upon today's ocean.

深海熱泉(hydrothermal vent)為既暗又冷的海床上少數活動劇烈的熱點。自從發現它們以來，科學家便對熱泉周邊的深海生態系統深感興趣，進行了無數研究以瞭解它們在生物演化上的地位，以及對現今海洋的影響。

Stubbins and his colleagues were most interested in the way the vents' extremely high temperatures and pressure affect dissolved organic carbon. Oceanic dissolved organic carbon is a massive carbon store that helps regulate the level of carbon dioxide in the atmosphere -- and the global climate.

Stubbins和他的同僚最感興趣的是極端高溫高壓的熱泉環境會如何影響溶解性有機碳。海洋的溶解性有機碳是座巨大的碳儲存庫，因此有助於調控大氣中的二氧化碳濃度，進一步影響全球氣候。

Originally, the researchers thought the vents might be a source of the dissolved organic carbon. Their research showed just the opposite.

起初，研究人員預計熱泉可能會是溶解性有機碳的來源之一，但研究結果呈現出來的卻恰好相反。

Lead scientist Jeffrey Hawkes, currently a postdoctoral fellow at Uppsala University in Sweden, directed an experiment in which the researchers heated water in a laboratory to 380 degrees Celsius (716 degrees Fahrenheit) in a scientific pressure cooker to mimic the effect of ocean water passing through hydrothermal vents.

現為瑞典烏普薩拉大學博士後研究員的Jeffrey Hawkes為此研究的主要研究人員，他於實驗室中利用高壓鍋具將海水加熱至380℃，來模擬海水經過熱泉系統時的情境，並觀察過程中會發生何種效應。

The results revealed that dissolved organic carbon is efficiently removed from ocean water when heated. The organic molecules are broken down and the carbon converted to carbon dioxide.

結果顯示海水加熱後會從中移除大多數的溶解性有機碳。這些有機分子被分解掉之後，其中的碳元素會轉變成二氧化碳。

The entire ocean volume circulates through hydrothermal vents about every 40 million years. This is a very long time, much longer than the timeframes over which current climate change is occurring, Stubbins explained. It is also much longer than the average lifetime of dissolved organic molecules in the ocean, which generally circulate for thousands of years, not millions.

若要讓所有海水都流經熱泉系統大約要花費4000萬年。Stubbins解釋說這是一段耗時甚久的歷程，跟眼下正發生的氣候變遷時間尺度相比而言要長得多。而這跟海洋中溶解性有機分子平均存在的時間相比也長了許多，它們通常以數千年的時間尺度循環，而非數百萬年。

"However, there may be extreme survivor molecules that persist and store carbon in the oceans for millions of years," Stubbins said. "Eventually, even these hardiest of survivor molecules will meet a fiery end as they circulate through vent systems."

「然而，或許海洋中存在有某些可稱作終極生存者的分子，它們能夠持有並儲存碳原子長達數百萬年。」Stubbins說。「然而，即便是所有分子中最頑強的倖存者，最終它們還是會在流經熱泉系統時燃燒殆盡。」

Hawkes conducted the work while at the Research Group for Marine Geochemistry, University of Oldenburg, Germany. The study's co-authors also included Pamela Rossel and Thorsten Dittmar, University of Oldenburg; David Butterfield, University of Washington; Douglas Connelly and Eric Achterberg, University of Southampton, United Kingdom; Andrea Koschinsky, Jacobs University, Germany; Valerie Chavagnac, Université de Toulouse, France; and Christian Hansen and Wolfgang Bach, University of Bremen, Germany.

Hawkes於他在參與德國奧爾登堡大學海洋地質化學研究團隊時進行了這項研究計畫。共同作者包括Pamela Rossel和Thorsten Dittmar(奧爾登堡大學)、David Butterfield(美國華盛頓大學)、Douglas Connelly和Eric Achterberg(英國南安普敦大學)、Andrea Koschinsky(雅德國各布大學)、Valerie Chavagnac(法國土魯斯大學)、Christian Hansen和Wolfgang Bach(德國不來梅大學)。

引用自：University of Georgia. "Deep-sea hydrothermal vents have carbon-removing properties." ScienceDaily. ScienceDaily, 2 November 2015.