兩起火山噴發事件引發了古典時代晚期的社會危機

原文網址：www.sciencedaily.com/releases/2016/04/160419083247.htm

Two volcanoes trigger crises of the late antiquity

兩起火山噴發事件引發了古典時代晚期的社會危機

International team of climate researchers reconstruct global cooling in the reign of emperor Justinian

由國際氣候學家組成的團隊重建了於查士丁尼一世統治時期發生的全球冷化事件

Contemporary chroniclers wrote about a "mystery cloud" which dimmed the light of the sun above the Mediterranean in the years 536 and 537 CE. Tree rings testify poor growing conditions over the whole Northern Hemisphere -- the years from 536 CE onward seem to have been overshadowed by an unusual natural phenomenon. Social crises including the first European plague pandemic beginning in 541, are associated with this phenomenon. Only recently have researchers found conclusive proof of a volcanic origin of the 536 solar dimming, based on traces of volcanic sulfur from two major eruptions newly dated to 536 CE and 540 CE in ice cores from Greenland and Antarctica.

同時期的編年史學者於文獻中寫道，西元536年到537年地中海上空因「神秘雲霧」的籠罩而變得天昏地暗。樹輪紀錄證實了當時整個北半球的植物皆處於相當惡劣的生長情況，顯然自西元536年起北半球便因一種不尋常的自然現象而蒙上了一層陰影。包括始於西元541年歐陸史上首次發生的瘟疫大流行在內，種種的社會危機似乎都跟此現象有所關聯。科學家直到最近才發現決定性的證據證明西元536年陽光變得昏暗是由火山造成。這些證據來自於格陵蘭和南極的冰芯，其中含有最新定出年代為西元536年和540年，由兩次大型火山噴發出的火山硫磺造成的痕跡。

An international team of climate scientists led by Dr. Matthew Toohey at the GEOMAR Helmholtz Centre for Ocean Research Kiel and Prof. Dr. Kirstin Krüger of the University of Oslo (UiO), with financial support from the Centre for Earth Evolution and Dynamics (CEED) at the UiO, has investigated the time period using the new ice core data, historical evidence and climate models. As they write in the international journal Climatic Change, the impact of the volcanic double event of 536/540 on Northern Hemisphere climate was stronger than any other documented or reconstructed event of the past 1200 years. "One of the eruptions would have led to a significant cooling of Earth's surface. Two of them, so close in time, caused what is probably the coldest decade of the past 2000 years," says Dr. Matthew Toohey from GEOMAR, lead author of the study today at a press conference at the annual EGU Meeting in Vienna where he presented the results.

由德國基爾的萊布尼茨海洋科學研究所的 Matthew Toohey博士，以及奧斯陸大學的Kirstin Krüger博士領導的國際氣侯學家團隊，在奧斯陸大學地球演化及動力學中心的資助之下，利用新的冰芯資料、歷史證據以及氣候模型來調查這段時期究竟發生了什麼事件。就他們發表於國際期刊《氣候變遷》(Climatic Change)的論文，在536年和540年發生的兩次火山爆發對北半球氣候造成的影響之大，在過去1200年以來有文獻紀錄或重建出來的所有事件中，沒有任何一個可以與之相提並論。「這兩次火山噴發中的任何一者其強度便足以劇烈冷卻地表。而這兩次發生的間距如此之短，恐怕造成了過去2000年以來最冷的10年。」此研究的第一作者，萊布尼茨海洋科學研究所的 Matthew Toohey說。今日他於舉辦在維也納的歐洲地質年會上的記者會中發表他們的成果。

To simulate the impact of the 536 and 540 eruptions, the scientists used the available data from ice cores and the descriptions of the solar dimming from contemporary scholars. With this data they estimated the magnitude of the eruptions and their approximate locations on Earth, and then simulated the spread and impacts of the aerosol clouds resulting from the volcanic injection of sulfur into the stratosphere. This revealed that following the eruptions, the solar radiation at Earth's surface was strongly reduced over the Northern Hemisphere for several years, and caused decreases in the hemispheric average temperature of up to 2 degrees Celsius.

為了模擬536年和540年火山爆發造成的影響，科學家利用了自冰芯中取得的數據，以及當時學者描述的陽光變弱現象。他們憑藉這些資料來推測這兩起噴發事件的規模以及發生在地球上的大致位置，接著他們模擬由火山爆發而進入平流層中的硫磺在形成氣膠雲霧後會如何擴散，以及造成何種影響。結果顯示火山噴發之後，北半球照射至地表的太陽輻射會大幅降低數年之久，因此使北半球均溫下降了多達攝氏2度。

The relationship between the "mystery cloud" of 536 and the transition from Antiquity to the Middle Ages is an issue of great popular interest. Volcanic eruptions in the more recent past have impacted human societies. For example, in 1815 the Indonesian volcano Tambora hurled so much ash and sulfur into the atmosphere that the year 1816 became known as "the year without summer" in Europe and North America, where unusually low temperatures led to crop failures and famines. For eruptions of the more distance past, connections between eruptions and societal impacts become less clear.

536年的「神秘雲霧」以及歷史同時從古典時期進入中世紀，兩者之間的關聯是許多人相當感興趣的議題。距今較不遠的火山爆發事件確實曾對人類社會造成了重大影響。舉例來說，1815年印尼的坦博拉火山往大氣中拋出的火山灰及硫磺其量之多，使得1816年成為歐洲以及北美洲眾人所知的「夏天消失的一年」，當時不尋常的低溫造成這些地方作物歉收以及飢荒爆發。但對於更遙遠之前的火山噴發事件來說，火山爆發與社會動盪之間的關聯就不是那麼清楚。

Toohey and his colleagues used their climate model simulations to directly estimate the impact of the eruptions on agriculture in Europe, and identified Northern Europe and in particular Scandinavia as the most likely locations to have suffered under the cold conditions after the eruptions. This result supports the theory of a connection between the eruptions and archaeological evidence of a large-scale societal crisis in Scandinavia in the 6th century. "Each one of the eruptions of 536/540 would have strongly impacted societies, and it happened twice within four years," says co-author Prof. Dr. Kirstin Krüger from the University of Oslo.

Toohey 和他的同僚利用他們建立的氣候來直接預估這兩次火山爆發影響歐洲農業的程度，他們發現在歐陸北端以及部份的斯堪地那維亞是噴發過後最因環境變冷而深受其害的地區。這些結果也支持了一項理論，其認為考古證據顯示出6世紀斯堪地那維亞發生的大規模社會危機，跟火山爆發之間有一定的關聯。「536年和540年的火山噴發事件中的任何一次都能對社會造成重大影響，更別說它們倆發生的間距僅僅相隔4年。」奧斯陸大學的共同作者Kirstin Krüger博士說。

Which volcanoes exactly were responsible for these aerosols clouds is still enigmatic. "Several candidates are being discussed, including volcanoes in Central America, Indonesia and North America. Future studies will be necessary to show the exact source of the aerosol clouds of 536/540," says Dr. Toohey.

究竟是哪座火山造成了這些氣膠雲霧仍然沒有解答。「我們討論到的一些候選者包括了位於中美洲、印尼和北美的火山。未來的研究勢必能準確找出536年和540年氣膠雲霧的來源。」Toohey.博士說。

引用自：Helmholtz Centre for Ocean Research Kiel (GEOMAR). "Two volcanoes trigger crises of the late antiquity: International team of climate researchers reconstruct global cooling in the reign of emperor Justinian." ScienceDaily. ScienceDaily, 19 April 2016. 

地球在數百萬年中逐漸發生的氣候變遷跟火山有重大關聯

原文網址：www.sciencedaily.com/releases/2016/04/160421150056.htm

Volcanoes tied to shifts in Earth's climate over millions of years

地球在數百萬年中逐漸發生的氣候變遷跟火山有重大關聯

A new study in the April 22 edition of Science reveals that volcanic activity associated with the plate-tectonic movement of continents may be responsible for climatic shifts from hot to cold over tens and hundreds of millions of years throughout much of Earth's history.

在地球歷史上的許多時期，都曾發生氣候於數千萬年至數億年間由酷熱逐漸轉變成嚴寒的現象。4月22日發表在《科學》(Science)期刊上的新研究顯示，這或許跟大陸板塊移動時伴隨產生的火山活動大有關係。

The study, led by researchers at The University of Texas at Austin Jackson School of Geosciences, addresses why the Earth has fluctuated from periods when the planet was covered in ice to times when even the polar regions were ice-free.

此篇由德克薩斯大學奧斯汀分校傑克遜地球科學院的研究人員領導的研究，提出了可能的成因來解釋這個問題：地球為何會在整顆星球被冰封的時期，與連極區都未見一絲冰霜的時期之間來回變化。

The study explores very long-term shifts in Earth's baseline climate, not short-term or human-induced climate change.

這篇研究探討了地球的基準氣候(baseline climate)在相當長的一段時間中如何變化，而非短期或者人為導致的氣候變遷。

Lead researcher Ryan McKenzie said the team found that periods when volcanoes along continental arcs were more active coincided with warmer, or greenhouse, conditions over the past 720 million years. Conversely, periods when continental arc volcanos were less active coincided with colder, or icehouse, conditions.

率領此研究的 Ryan McKenzie說研究團隊發現自過去的7億2000萬年以來，當陸弧(continental arc)中的火山活動較為活躍時，也是氣候較溫暖的時期，此時的地球處於溫室(greenhouse)環境。反之，當陸弧火山活動趨緩時，此時的氣候就較為寒冷，地球便處於冰室(icehouse)環境。

Continental volcanic arc systems such as the Andes Mountains are created at active continental margins where two tectonic plates meet and the oceanic plate descends under the continental plate, forming a subduction zone. When this happens, magma mixes with carbon trapped in the Earth's crust and releases carbon dioxide (CO2) gas into the atmosphere when volcanoes in the system erupt.

當兩個板塊之間彼此擠壓，海洋板塊下沉至大陸板塊之下而形成隱沒帶時，在上方的活動型大陸邊緣便會有陸弧系統生成，現今的安地斯山脈即為一例。此構造環境形成後，當陸弧系統中的火山爆發時，就會噴發出混有地殼內部的碳的岩漿，並釋放二氧化碳氣體至大氣中。

"Continental arc systems are plumbed through the Earth's crust and they tend to interact with carbon reservoir rock preserved beneath the surface," said McKenzie, who began the work as a postdoctoral researcher at the Jackson School and finished the study at Yale University.

「陸弧系統會貫穿地殼，因此它們有相當大的機會能跟保存在地表下方岩石中的碳儲存庫之間發生交互作用。」 McKenzie說。他在傑克遜地球科學院擔任博士後研究員時開始進行這項研究，之後在耶魯大學任職時完成。

Scientist have long known that the amount of carbon dioxide in the atmosphere influences the Earth's climate, McKenzie said. The unanswered question is what caused the fluctuations in CO2 observed in the geologic record. Other theories have suggested that geological forces such as mountain building have, at different times in the planet's history, introduced large amounts of new material to the Earth's surface, and weathering of that material has drawn CO2 out of the atmosphere. The new study points to the amount of CO2 being released into the atmosphere, rather than the amount removed from it, as the primary driver of Earth's climate.

McKenzie說長久以來科學家就已經知道大氣中的二氧化碳含量會影響地球氣候。然而從地質紀錄中觀察到的二氧化碳含量變化究竟是由什麼原因所造成，仍尚未有人可以回答。某些理論認為在地球歷史的不同時期，像是造山運動之類的地質營力會將大量的新鮮岩石帶到地球表面，這些物質遭受風化作用時便會從大氣中吸收二氧化碳。但是，此篇新研究指出驅動地球氣候變化的動力是釋放至大氣中二氧化碳的多寡，而非被吸收的量有多少。

Using nearly 200 published studies and their own fieldwork and data, researchers created a global database to reconstruct the volcanic history of continental margins over the past 720 million years.

利用將近200篇已發表的研究，以及研究團隊自身的野外工作和資料，他們創建了一個資料庫可以用來重建過去7億2000萬年以來全球大陸邊緣的火山活動史。

"We studied sedimentary basins next to former volcanic arcs, which were eroded away over hundreds of millions of years," said co-author Brian Horton, a professor in the Jackson School's Department of Geological Sciences. "The distinguishing part of our study is that we looked at a very long geologic record -- 720 million years -- through multiple greenhouse-icehouse events."

「由於火山弧會在數億年的時光中被慢慢侵蝕殆盡，因此我們研究了過往位於它們附近的沉積盆地。」任職於傑克遜地球科學院的共同作者 Brian Horton說。「我們這篇研究裡最突出的一部份是我們觀察了地球在歷經多次溫室—冰室事件後而留下來的一段相當長期的地質紀錄，時間長達7億2000萬年。」

Specifically, researchers looked at the uranium-lead crystallization ages of the mineral zircon, which is largely created during continental volcanic arc activity. Zircon is less common in other types of volcanic settings, such as hot spots like Hawaii or island arc volcanoes such as the Marianas, so the mineral can be used to track continental arc volcanism. For the study, they looked at data for roughly 120,000 zircon grains from thousands of samples across the globe.

精確而言，研究人員探討的是鋯石礦物顆粒的鈾鉛結晶年代，這些礦物多半是在陸弧火山活動時產生出來的。鋯石很少在其他類型的火山構造環境中看到，像是夏威夷所處的熱點(hotspot)以及馬里亞納群島位於的火山島弧(island arc)，因 此這種礦物便能夠用來追蹤陸弧的火山活動。為了進行這項研究，研究人員從全世界蒐集到的數千個樣品裡，將近12萬顆的鋯石顆粒中探討他們需要的資訊。

"We're looking at changes in zircon production on various continents throughout Earth's history and seeing how the changes correspond with the various icehouse and greenhouse transitions," McKenzie said. "Ultimately, we find that during intervals of high zircon production we have greenhouse conditions, and as zircon production diminishes, we see a shift into our icehouse conditions."

「我們想要知道地球歷史上各個陸塊產生鋯石的速率是如何改變，並且觀察這些變化如何對應至溫室地球及冰室地球之間的多次轉換。」McKenzie說。「最後我們發現在鋯石產量較高的時期，地球便處於溫室環境；而隨著鋯石產量逐漸下滑，我們看到地球也逐漸轉變成冰室環境。」

The cooler icehouse periods tended to correlate with the assembly of the Earth's supercontinents, which was a time of diminished continental volcanism, Horton said. The warmer greenhouse periods correlated with continental breakup, a time of enhanced continental volcanism.

Horton說較為寒冷的冰室時期傾向對應至當地球陸地組合成超大陸的時期，此時陸地的火山活動較為平靜。而較為溫暖的溫室時期則對應至大陸分裂時，此時陸地的火山活動較為活躍。

Jackson School researchers Shannon Loomis and Daniel Stockli, Yale University's Noah Planavsky, and Rice University's Cin-Ty Lee also worked on the study. The research was funded by the National Science Foundation.

傑克遜地球科學院的研究人員 Shannon Loomis和Daniel Stockli、耶魯大學的 Noah Planavsky以及萊斯大學的 Cin-Ty Lee 也共同參與了此研究。研究由美國國家科學基金會贊助。

引用自：University of Texas at Austin. "Volcanoes tied to shifts in Earth's climate over millions of years." ScienceDaily. ScienceDaily, 21 April 2016. 

化學風化控制了河川的侵蝕速率

原始網址：www.sciencedaily.com/releases/2016/04/160414095555.htm

Chemical weathering controls erosion rates in rivers

化學風化控制了河川的侵蝕速率

Chemical weathering can control how susceptible bedrock in river beds is to erosion, according to new research. In addition to explaining how climate can influence landscape erosion rates, the results also may improve scientists' ability to interpret and predict feedbacks between erosion, plate tectonics and Earth's climate.

根據新的研究顯示，化學風化可以控制河床的岩石有多容易受到侵蝕作用影響。除了解釋氣候會如何影響地表的侵蝕速率之外，研究結果或許也能讓科學家對於侵蝕作用、板塊構造運動和地球氣候彼此之間的交互作用做出更準確的分析和預測。

The research, led by The University of Texas at Austin, was published in Nature on April 14, 2016.

這項由德州大學奧斯汀分校領導的研究成果刊登於2016年4月14日的《自然》(Nature)期刊上。

"Our research presents a specific, process-based mechanism to explain how and why river erosion depends on climate, and also perhaps why previous studies have found conflicting sensitivities to climate in different landscapes," said Brendan Murphy, a Ph.D. student at The University of Texas Jackson School of Geosciences who led the research.

「我們在研究成果中呈現的精確流程化機制，不僅可以用來解釋氣候如何影響河川侵蝕作用，以及兩者之間的因果關係，或許也能告訴我們為何在之前的研究中，河川侵蝕作用受氣候的影響程度在不同地景中並不一致。」德州大學奧斯汀分校地球科學院，主持此研究的博士生Brendan Murphy說。

Murphy conducted the research with Joel Johnson, a professor in the Jackson School's Department of Geological Sciences, Nicole Gasparini of Tulane University and Leonard Sklar of San Francisco State University.

Murphy偕同德州大學奧斯汀分校地球科學院的教授Joel Johnson、杜蘭大學的Nicole Gasparini以及舊金山州立大學的Leonard Sklar進行了此篇研究。

Chemical weathering occurs when minerals in rock react with water. These chemical reactions physically weaken rock by altering its structure. Rocks in streambeds then become more susceptible to erosion by physical processes, such as impacts by sediment carried in flowing water.

化學風化發生在當礦物與水接觸而發生反應時，這些化學作用會改變岩石的結構而弱化其物理強度。河床上的岩石因此變得更容易遭受物理過程所導致的侵蝕作用，像是流水中攜帶的沉積物顆粒造成的衝擊。

It has been established that chemical weathering influences rock strength, Murphy said. But scientists have lacked data on the extent to which chemical weathering influences river erosion. To explore the issue, the team travelled to the Big Island of Hawaii, where the bedrock is made entirely of volcanic basalt, to collect data on chemical weathering, rock strength, and erosion rates in streams across wet and dry regions of the island.

Murphy說科學家早已確認化學風化會影響岩石強度，但他們在化學風化對河川侵蝕的影響程度究竟有多深這方面並未擁有足夠的資料。為了深究這項議題，研究團隊前往夏威夷的大島(Big Island)。此地的岩石幾乎都是由火山噴發出來的玄武岩構成。研究團隊蒐集了這座島上乾燥與濕潤區域中各溪流流域內的化學風化、岩石強度以及侵蝕速率的資料。

"Hawaii is a simple, natural laboratory for studying how climate controls river erosion because it has uniform lithology and a very extreme precipitation gradient," Murphy said. "We went to investigate if the local precipitation rate was changing the rock strength in the rivers and then looked for a mechanism to explain it."

「在研究氣候如何控制河川侵蝕作用時，夏威夷可視為一座相當單純的天然實驗室。這是因為這座島上各地的岩石組成相當一致，然而降水梯度(precipitation gradient)則相當極端。」Murphy說。「我們前去調查當地的降雨量是否會影響河川中岩石的強度，接著再探討可以解釋其箇中緣由的機制。」

They measured the strength of the rock using a Schmidt hammer, a device that measures surface hardness in the field, and also analyzed the chemistry and density of rock samples back in the lab to determine the influence of chemical weathering.

他們利用施密特錘(Schmidt hammer)來測量岩石的強度，這是一種可以在野外量測岩石表面硬度的裝置；並且將岩石樣本帶回實驗室分析它們的化學性質和密度，以得知化學風化的影響程度。

Consistent with their hypothesis, they found that bedrock was more chemically weathered and physically weaker where local precipitation rates were greater. More significant, Murphy said, was their finding that locations of high precipitation could maintain high erosion rates despite continuously exposing "fresh rock" -- rock that was previously below the eroded surface and is not chemically altered.

他們發現在降雨量較高的地區，河床岩石的化學風化程度就越高且物理強度越脆弱，這點與他們的假設相符。Murphy說更重要的是，他們發現在降雨量高的地區，儘管「新鮮岩石」—也就是之前位於受侵蝕的表面之下，化學性質尚未改變的岩石—會不斷地出露在地表，侵蝕速率卻仍能維持在高檔。

Fresh bedrock weathers rapidly when exposed at the surface, which weakens rock and allows it to be efficiently eroded by the river, the researchers found.

研究人員發現新鮮的底岩一旦暴露於地表就會迅速地遭受風化，這使得岩石變得脆弱而讓河川能夠進行高效率的侵蝕作用。

"This presents a positive feedback allowing river streambeds to maintain high weathering rates, weaker rock, and high erosion rates," Murphy said.

「在此呈現出的正回饋效應使得河床可以維持在高風化速率、岩石強度弱化以及高侵蝕速率的狀態。」Murphy說。

Based on their findings, the researchers modified a numerical model that describes how rivers cut into a landscape, Johnson said, finding that chemical weathering data drastically improved their ability to predict patterns of river incision.

Johnson說研究人員根據他們的成果，修改了之前用來描述河川如何切割地表的數值模型，而他們發現這些關於化學風化的數據可以大幅精進模型預測河川侵蝕模式的能力。

"Once we included the climate effect demonstrating that the chemical weathering is weakening the bedrock and making it more erodible, we can do a much better job of matching the pattern and rates of incision that occur across this landscape." Johnson said.

「我們一將化學風化作用使岩石弱化以及更易侵蝕的氣候效應囊括進模型當中，就能使模擬結果更符合研究中地貌的侵蝕速率與模式。」Johnson說。

Even though researchers examined only a single rock type, Murphy said that the mechanism linking chemical weathering to rock strength and erosion should apply to all types of rock. Understanding the relationship between erosion and chemical weathering can help tease out the role climate has on sculpting landscapes and influencing global cycles, Murphy said.

即便研究人員只探討了單一岩石種類組成下的情況，Murphy說化學風化跟岩石強度和侵蝕作用之間的關聯應該可以適用於所有的岩石類別。他也表示了解侵蝕作用和化學風化之間的關係，有助於我們釐清氣候在形塑地表的作用中扮演了何種腳色，以及氣候如何影響全球物質的循環。

"The ability to better understand how landscapes erode is important, because bedrock erosion affects chemical weathering, which is a major component of the global carbon cycle and can influence global climate by the removal of carbon dioxide from the atmosphere," Murphy said. "The ability to model landscape evolution and how climate plays into it is important for tying these larger global cycles together."

「更加了解地表如何遭受侵蝕是件相當重要的事，這是因為岩石的侵蝕作用會影響化學風化，而化學風化在全球碳循環中位處至關重要的一環，它會將二氧化碳從大氣中移除進而影響全球氣候。」Murphy說。「若我們要嘗試將不同的大型全球循環系統整合在一起，那麼可以更精確地模擬地貌演變及氣候在其中所占地位的能力便相當重要。」

The research was funded by the National Science Foundation and a Tulane Research Enhancement grant.

這項研究由國家科學基金會以及杜蘭大學研究發展津貼贊助。

引用自：University of Texas at Austin. "Chemical weathering controls erosion rates in rivers." ScienceDaily. ScienceDaily, 14 April 2016. 

兩座超大陸之間的關聯

原文網址：www.sciencedaily.com/releases/2016/04/160412091348.htm

Links within two supercontinents

兩座超大陸之間的關聯

A University of Wyoming researcher contributed to a paper that has apparently solved an age-old riddle of how constituent continents were arranged in two Precambrian supercontinents -- then known as Nuna-Columbia and Rodinia. It's a finding that may have future economic implications for mining companies.
懷俄明州立大學的一位研究人員撰寫的論文似乎解開了一個年代久遠的問題：前寒武紀的兩座超大陸—哥倫比亞大陸(Nuna-Columbia)和羅迪尼亞大陸(Rodinia)的位置是如何分布的。對礦業公司而言這項發現未來或許具有經濟上的潛在利用價值。

Specifically, the article describes a technique Kevin Chamberlain, a UW research professor in the Department of Geology and Geophysics, and other researchers used to test reconstructions of ancient continents. The paper argues that the rocks or crust now exposed in southern Siberia were once connected to northern North America for nearly a quarter of the Earth's history. Those two continental blocks now form the cores of the modern continents of Asia and North America.

具體來說，這篇論文內容記述的是懷俄明州立大學地質與地球物理學系的教授，Kevin Chamberlain和其他研究人員用來重建這兩座古代大陸時所用的技術。這篇論文主張現今在西伯利亞南方出露的岩石或地殼曾跟北美北方相連，時間長達將近地球歷史的四分之一。而現今這兩個古陸塊則構成了亞洲大陸和北美大陸的核心。

Chamberlain was co-author of the paper, titled "Long-Lived Connection between Southern Siberia and Northern Laurentia in the Proterozoic," that appeared in today's (April 11) online issue of Nature Geoscience. The monthly multi-disciplinary journal focuses on bringing together top-quality research across the entire spectrum of the Earth sciences, along with relevant work in related areas. The journal's content reflects all the disciplines within the geosciences, encompassing field work, modeling and theoretical studies.

這篇題名為「原生代時西伯利亞大陸南部和勞倫大陸北部之間曾相連許久(Long-Lived Connection between Southern Siberia and Northern Laurentia in the Proterozoic)」的論文刊登在今日(4月11日)的《自然—地質科學》(Nature Geoscience)線上版，共同作者之一為Chamberlain。這本跨領域的科學月刊著重在彙整地球科學各分野中品質最佳的研究，以及其他有關領域中與地球科學相關的研究成果。此期刊的內容呈現出地質學家進行研究時會用到的各種方法，包含野外調查、電腦模擬及理論方面的研究。

"The article highlights a technique that our project has been using to test pre-Pangea or ancient continental reconstructions," Chamberlain says. "We have been using the ages, orientations and paleo-magnetic characteristics of short-lived (1 million to 10 million years in duration) igneous, mafic dike swarms as piercing points to determine nearest-neighbor continents in the past."

「此篇文章的內容側重在我們計畫中用來嘗試重建前盤古大陸以及古代大陸時用的方法。」 Chamberlain說。「我們將在短時間內(100萬至1000萬年)形成的基性火成岩脈群作為銜接點，並利用它們的年代、方位及古地磁特性來找出在過去曾緊密相連的大陸。」

Mafic dikes are dark-colored rocks or minerals that are in a dike formation, which is a sheet of rock that formed in a fracture in a pre-existing rock body. Chamberlain says mafic dikes, like those studied in the paper, can be found in Wyoming. Mafic dikes in the state include the black vein that can be seen in Mount Moran in the Teton Range; the black, horizontal band on the east face of Medicine Bow Peak; and those that crisscross the Granitic Mountains in central Wyoming.

基性岩脈是以脈絡狀分布的暗色岩石或礦物，這種岩體通常形成於更早之前即存在的岩石的裂縫之中。 Chamberlain說在懷俄明州境內可以找到像是這篇論文中研究的基性岩脈。此州境內有基性岩脈分布的地點包含了提頓山脈莫蘭山中的黑色岩脈、梅迪辛波峰東面的黑色水平帶狀岩石，以及懷俄明中部花崗岩山峰中縱橫交錯的岩脈。

Using labs at UW and UCLA, Chamberlain says his role in the project was to determine the magmatic ages of numerous mafic dikes through uranium-lead radiometric dating. He was one of four geochronology labs on the team and the only one based in the United States.

Chamberlain說他在這項研究計畫中的腳色是利用懷俄明州立大學和加州大學洛杉磯分校的實驗室，透過鈾鉛放射性定年法分析大量的基性岩脈以確認個別岩體的岩漿形成年代。他是這個團隊中四位地質定年學家中唯一在美國進行實驗的人員。

The linear dikes from these igneous events (large igneous provinces, or LIPs) are relatively narrow, roughly 100 meters or less, but can be 1,000 to 1,500 kilometers in length. They erupt in a radial pattern.

這些岩漿事件(大火成岩省(large igneous provinces, LIPs))形成的岩脈長度可以長達1000至1500公里，然而寬度相對而言並不寬，僅約100公尺甚至更窄。它們通常以輻射狀的模式噴發。

During later rifting, the continents broke into fragments, which later combined into subsequent new continents, such as our modern-day seven continents.

大陸在往後的張裂作用中會被撕成碎片，然而這些碎片之後又會再次組合成為新的大陸，好比說今日世上的七座大陸。

"There may have been four or five cycles of supercontinent formation," Chamberlain says.

「超大陸的形成循環可能已經發生了4或5次之有。」Chamberlain 說。

Each continental fragment preserves a dike swarm record, he explains. By comparing the temporal records called bar codes (since a plot of dike date vs. time looks like a bar code) of older fragments known as cratons (the cores of modern continents), Chamberlain says he was able to test whether the cratons were close enough to share LIP dike swarms. He adds the research team also can determine when the two cratons joined, as well as when they split apart.

他解釋大陸的每一塊碎片都保有自身的岩脈群記錄。藉著比對不同塊古老大陸的碎片，即穩定地塊(又稱克拉通(craton)，為現今大陸的核心)內這些稱作「條碼」的紀錄(這是因為岩脈年代對時間的作圖看起來就像條碼)，Chamberlain 說他可以驗證這些穩定地塊在當時是否相當靠近，而擁有相同的大火成岩省岩脈群。他補充說明研究團隊同樣可以依此來得知這兩座穩定地塊是何時相連，又是何時分開。

"In this new study, we believe that northern Laurentia (North America) and southern Siberia were joined for nearly 1.2 billion years from 1.9 billion years ago to 700 million years ago," he says. "Geologists are like detectives. It seems like we come to the crime scene after the fact and put together the pieces."

「在這項新研究中，我們認為勞倫大陸北部(北美)和西伯利亞大陸南部曾經相連長達將近12億年之久，約從19億年前至7億年前。」他說。「地質學家的工作就像是在案件發生後到達現場，將殘缺的證據拼湊出真相。從這點來看我們跟偵探可說是十分相似。」

This finding disproves previous constructions of Nuna-Columbia and Rodinia, and establishes new arrangements of the continental blocks within them, he says.

他說這項發現跟先前哥倫比亞大陸和羅迪尼亞大陸的重建結果相悖，而他們也將這兩塊大陸內部的陸塊以新的方式重新排列。

The project determined the ages of nearly 250 mafic dikes worldwide, a number Chamberlain says is large enough to build a database comparison between all of the older continental fragments from roughly 500 million years ago to 2,700 million years ago. The research group also worked on more recent LIPs -- about 400 million to 100 million years ago -- which have importance for oil and gas exploration, and hydrocarbon maturation models.

這項計畫定出了世界各地將近250條基性岩脈的年代。 Chamberlain說這麼龐大的數目足夠他們建立起一個資料庫，以比對所有較為古老，年代約從5000萬年前至2億7000萬年前的大陸地殼碎片。研究團隊也探討了年代更近，約從4000萬年前至1000萬年前的大火成岩省事件。這些事件對油氣探勘以及碳氫化合物熟成模型的研究上皆具有相當重要的意義。

A consortium of mining companies funded the research project for five years. Their reasoning: That the continental reconstructions for times when major, known metal deposits formed would be useful for prospecting new finds on the conjugate continents, Chamberlain says. These new deposits may be buried under hundreds of meters of younger rock. So, by establishing which continents were next to the known deposits when they formed, the hope is that additional minerals may be found in the future.

一個礦業財團資助這項計畫長達5年的時間，據Chamberlain說他們的理由為：「重建大型已知礦脈形成時的陸地樣貌，將有助於從過往結合在一起的其他陸地上探勘出新礦藏。」這些礦藏可能深埋於數百公尺厚的較年輕岩石之下，因此若能重建出在已知礦脈形成時與它毗鄰的陸地位置，那麼就有望在未來可以在此發現新礦藏。

"A lot of the major metal deposits in the earth formed in the early part of Earth's history," Chamberlain says.

「許多重要的金屬礦床都是在地球歷史相當早期形成的。」Chamberlain說。

引用自：University of Wyoming. "Links within two supercontinents." ScienceDaily. ScienceDaily, 12 April 2016. 

緩緩移動的斷層或許預示了地震即將到來

原文網址：www.sciencedaily.com/releases/2016/04/160405114218.htm

Slow fault movements may indicate impending earthquakes

緩緩移動的斷層或許預示了地震即將到來

Scientists from Nanyang Technological University (NTU Singapore) at its Earth Observatory of Singapore (EOS) have discovered a way to forecast earthquakes based on slow fault movements caused by moving sub layers of Earth.

南洋理工大學駐新加坡地球觀測站的科學家發現，藉由觀察地球內部地層錯動而引發的緩慢斷層活動，可以用來預告地震即將發生。

So far, scientists believe that larger earthquakes are unlikely to occur following tremors or earthquakes below a Richter scale of 2 that are caused by small vibrations or slow fault movements such as those observed in the area of Parkfield along the San Andreas Fault in California, USA.

目前為止，科學家依據觀測像美國加州聖安地列斯斷層上帕克菲爾德(Parkfield)地區的結果，認為在小型振動或斷層緩慢移動而引發了芮氏規模小於2的微震或地震之後，不可能會有大型地震接著發生。

However, the NTU team found that not only do these vibrations potentially point to an impending earthquake, they also discovered a discernible pattern to them.

然而，南洋理工大學不僅發現這種振動可能指出了地震即將到來，甚至還發現它們之間有可以依循的模式。

"This discovery defied our understanding of how faults accumulate and release stress over time. These vibration patterns are caused by alternating slow and fast ruptures occurring on the same patch of a fault," said Asst Prof Sylvain Barbot, from NTU's Asian School of the Environment and an earth scientist at EOS.

「這項發現挑戰了我們對於斷層隨著時間會如何累積與釋放應力的知識。在同一段斷層上因為破裂反覆地快慢交替發生，而造成了這種振動模式。」南洋理工大學亞洲環境學院的助理教授 Sylvain Barbot說，他也是新加坡地球觀測站的地球科學家。

"If only slow movements are detected, it does not mean that a large earthquake cannot happen there. On the contrary, the same area of the fault can rupture in a catastrophic earthquake," he warned.

「若在某個區段觀測到只有緩慢的運動發生，也不代表說這個區域之後就不會發生大地震。相反地，斷層上的同一區域有可能在將來破裂而發生毀滅性大地震。」他提出了這樣的警告。

The study, which has major significance on the prediction of earthquakes, was led by Asst Prof Barbot's PhD student, Miss Deepa Mele Veedu. It was published in Nature.

此篇對於地震預測有重大貢獻的研究刊登於《自然》期刊之上，主持人為 Barbot助理教授的博士生， Deepa Mele Veedu女士。

Seismic hazards in the Southeast Asia region will probably come from an impending large earthquake in the Mentawai seismic gap in Sumatra, Indonesia -- a current area of active monitoring and investigation.

東南亞地區的下一次地震災害可能會由印尼蘇門答臘明打威(Mentawai )地震空白帶(seismic gap)的大型地震造成。此地區現有大量的監測和調查活動進行中。

EOS scientists have earlier pointed out a large earthquake may occur any time in this area southwest of Padang -- the only place along a large fault where a big earthquake has not occurred in the past two centuries. The team's latest findings could potentially be applied in the seismic monitoring of the area to help better forecast large earthquakes in the region.

新加坡地球觀測站的科學家先前早已指出巴東(Padang )西南方隨時都可能發生大型地震。因為此地區是一條大型斷層帶上過去2個世紀以來唯一還未發生大地震的區域。此團隊最新的研究或許可以運用在巴東地區的地震監測上，而提高預測此地區地震的準確性。

EOS conducts fundamental research on earthquakes, volcanic eruptions, tsunamis and climate change in and around Southeast Asia, towards safer and more sustainable societies.

新加坡地球觀測站主要著重於東南亞及鄰近地區的地震、火山爆發、海嘯和氣候變遷的基礎研究。它們的宗旨是要創造更安全且更能永續發展的社會。

引用自：Nanyang Technological University. "Slow fault movements may indicate impending earthquakes." ScienceDaily. ScienceDaily, 5 April 2016. 

如何在大滅絕事件中存活下來？匆匆活著，早早死去

原文網址：www.sciencedaily.com/releases/2016/04/160405093103.htm

How to survive a mass extinction: Live fast, die young

如何在大滅絕事件中存活下來？匆匆活著，早早死去

Life history of ancient mammal relatives provides insight on survival tactics

古代哺乳類近親的生活史讓我們得以了解牠們的生存策略

Two hundred and fifty-two million years ago, a series of Siberian volcanoes erupted and sent the Earth into the greatest mass extinction of all time. As a result of this mass extinction, known as the Permo-Triassic Mass Extinction, billions of tons of carbon were propelled into the atmosphere, radically altering the Earth's climate. Yet, some animals thrived in the aftermath and scientists now know why.

2億5200萬年前，西伯利亞一連串的火山噴發事件引發了地球史上規模最劇的大滅絕事件。又稱作二疊紀-三疊紀滅絕事件(Permo-Triassic Mass Extinction)的那次大滅絕將數十億噸的碳噴發至大氣當中，因而劇烈改變了地球氣候。即使如此，仍有一些動物在這次浩劫過後倖存下來，而科學家現今知道牠們是如何辦到的。

In a new study published in Scientific Reports, a team of international paleontologists, including postdoctoral scholar Adam Huttenlocker of the Natural History Museum of Utah at the University of Utah, demonstrate that ancient mammal relatives known as therapsids were suited to the drastic climate change by having shorter life expectancies and would have had a better chance of success by breeding at younger ages than their predecessors.

在這篇發表於《科學報導》(Scientific Reports)期刊中的新研究，由國際古生物學家組成的團隊描述了一種哺乳類的古代表親，稱作「獸孔目」(therapsid)的動物藉由活得比預期壽命(life expectancy)要短來適應如此激烈的氣候變遷。跟牠們的祖先相比，牠們在較年輕時就開始繁殖後代來讓整體有較高的存活率。作者群之一包括了猶他州立大學猶他州立博物館的博士後研究學者 Adam Huttenlocker。

The research team studied growth patterns in therapsids from the South African Karoo Basin, a paleontologically significant area which preserves a wide range of fossils from the Permian to the Early Jurassic, or 300-180 million years ago.

研究團隊探討了來自南非卡魯盆地(Karoo Basin)的獸孔目化石的生長模式。這個盆地保存了年代為3億年至1億8000萬年前，也就是二疊紀至侏儸紀早期各式各樣的化石，因此在古生物學上具有重要地位。

By examining their bone microstructure before and after the extinction boundary, Huttenlocker and his colleagues were able to study how growth patterns in therapsids were affected by the extinction. By studying body size distributions in particularly abundant species from the Permian and Triassic, the team was able to interpret shifts in size class structure and in rates of survivorship.

Huttenlocker 和他的同僚藉由檢視大滅絕前後獸孔目化石骨骼中的微構造，來探討大滅絕如何影響牠們的生長模式。研究團隊研究了從二疊紀至三疊紀數量皆相當豐富的物種的個體體型分布情況，進而了解牠們體型分佈的結構和存活率如何變化，

In this study, special attention was paid to the genus Lystrosaurus because of its success in surviving the Permo-Triassic extinction; it dominated ecosystems across the globe for millions of years during the post-extinction recovery period, and makes up some 70-90% of the vertebrate fossils found in Early Triassic rocks in the Karoo.

此研究特別將注意力聚焦在水獸龍屬(Lystrosaurus)身上，這是因為牠們很成功地在二疊紀-三疊紀滅絕事件中倖存下來，並在大滅絕過後的回復期中統治了全球生態系數百萬年的時間。卡魯盆地早三疊統岩石裡的脊椎動物化石中，牠們就佔了總數的70至90%。

"Therapsid fossils like Lystrosaurus are important because they teach us about the resilience of our own extinct relatives in the face of extinction, and provide clues to which traits confered success on lineages during this tubulent time. Lystrosaurus was particularly prolific, making it possible to build a large dataset and to sacrifice some specimens for histology to study the growth patterns recorded in its bones," said Huttenlocker, one of the paper's authors.

「水獸龍之類的獸足類化石之所以如此重要，在於牠們告訴了我們在遭遇大滅絕事件時，我們這些已消失的近親有多麼頑強；還有在這段混亂不堪的時期，具有何種特徵的後裔子孫才能夠成功存活下來。水獸龍數目眾多的特性讓我們得以建立起內容豐富的資料庫，並且使我們可以犧牲某些樣品來進行組織學研究，以得到記錄在骨骼當中的生長模式。」作者之一 Huttenlocker說。

"Before the Permo-Triassic extinction, the famous therapsid Lystrosaurus had a life span of about 13 or 14 years based on the record of growth preserved in their bones," said Field Museum paleontologist Ken Angielczyk, another one of the paper's authors. "Yet, nearly all of the Lystrosaurus specimens we find from after the extinction are only 2¬-3 years old. This implies that they must have been breeding when they were still [relatively young] themselves."

「根據保存在骨骼當中的成長紀錄，這些著名的獸孔目水獸龍在二疊紀-三疊紀滅絕事件前的壽命大約為13至14歲。」此論文的另外一位作者，菲爾德自然史博物館的古生物學家 Ken Angielczyk說。「但是，在大滅絕之後我們發現的水獸龍樣品幾乎都僅僅只有2到3歲。這意味著牠們勢必在年幼時(相對於牠們自身所屬的物種)就已經繁衍了下一代。」

This adjustment in life history also meant a physical change for Lystrosaurus. Before the mass extinction, this creature would have been a couple meters long and weighed hundreds of pounds--about the size of a pygmy hippo. Post-extinction, its size dropped to that of a large dog, in large part due to its altered lifespan. Yet, these adaptations seemed to pay off for Lystrosaurus. Ecological simulations show that by breeding younger, Lystrosaurus could have increased its chance of survival by 40% in the unpredictable environments that existed in the aftermath of the extinction.

水獸龍在生命史長度上做出的調適意味著牠們的生理結構同時也產生了變化。在大滅絕之前，這些生物的身長大約有2公尺並且重達數百磅，跟侏儒河馬的體型相偌。但在大滅絕之後，牠們的體型迅速縮小成跟大型犬差不多大，這多半跟牠們的壽命改變有關。然而，對水獸龍而言這種適應似乎相當值得。生態模型顯示在大滅絕過後，水獸龍在這種變化莫測的環境下，可以藉由在年輕時就繁殖下一代，而提高40%的存活率。

This change in breeding behavior is not isolated to ancient animals either. In the past century, the Atlantic cod has undergone a similar effect due to human interference. Industrial fishing has removed most large individuals from the population, shifting the average size of cod significantly downward. Likewise, the remaining individuals are forced to breed as early in their lives as possible. Similar shifts have also been demonstrated in African monitor lizards exploited by humans.

這種繁殖策略的改變並不僅只局限於古代動物。在上個世紀，大西洋鱈也因為人類的干擾而經歷了這種變化。捕魚工業化幾乎撈除了族群中所有的大型個體，造成鱈魚的平均體型迅速縮小。同樣地，剩餘的個體被迫要盡量在還相當年輕時就繁殖後代。相同的變化也在被人類捕捉過後的非洲巨蜥身上描述到。

"Although it's hard to see the effects in our daily lives, there is substantial evidence that we are in the middle of a sixth mass extinction right now. It has been predicted that half of mammal species could become extinct by the end of the next century if present patterns continue; that's more than 1,000 times greater than previous estimates of natural extinctions, a trend not seen since the End-Permian or End-Cretaceous extinctions," said Huttenlocker.

「雖然在我們的日常生活中很難看到這類效應，但這的確是我們現在正處於第六次大滅絕的堅實證據。科學家預測若繼續維持現今的滅絕模式，在下個世紀末將會有一半的哺乳類動物就此消失。在這種模式下物種滅亡的速度是先前預估自然滅絕亡速率的1000倍以上，這是自二疊紀末或白堊紀末的大滅絕之後前所未見的。」 Huttenlocker說。

"With the world currently facing its sixth mass extinction, paleontological research helps us understand the world around us today," said Angielczyk. "By studying how animals like Lystrosaurus adapted in the face of disaster, we can better predict how looming environmental changes may affect modern species."

「在世界正經歷第六次大滅絕的此時，古生物研究可以讓我們更加了解周遭世界發生的一切。」 Angielczyk說。「藉著研究水獸龍這類的動物如何在面臨災禍時適應環境，我們可以更準確地預測悄然逼近的環境變遷會如何影響現存的生物。」

引用自：University of Utah. "How to survive a mass extinction: Live fast, die young: Life history of ancient mammal relatives provides insight on survival tactics." ScienceDaily. ScienceDaily, 5 April 2016.